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Angiogenesis is well known to play a critical role in breast cancer. We previously reported that TNFAIP2 activates Rac1 to promote triple-negative breast cancer (TNBC) cell proliferation, migration, and chemoresistance. However, the potential contribution of TNFAIP2 to tumor angiogenesis remains unknown. In this study, we demonstrated that TNFAIP2 promotes TNBC angiogenesis by activating the Rac1-ERK-AP1-HIF1α signaling axis. Under hypoxia, TNFAIP2 activates Rac1 and ERK sequentially. Following that, ERK activates the AP-1 (c-Jun/Fra1) transcription factor. By employing chromatin immunoprecipitation and luciferase reporter assays, we showed that AP-1 directly interacts with the HIF1α gene promoter, thereby enhancing its transcription. The combined application of ERK inhibitors, U0126 or trametinib, with the VEGFR inhibitor Apatinib, additively suppresses angiogenesis and tumor growth of HCC1806 in nude mice. These findings provide new therapeutic strategies for TNBC., Competing Interests: Competing interests The authors declare no competing interests. Ethical approval Clinical samples were obtained from the Department of Pathology, Henan Provincial People’s Hospital, Zhengzhou University, Henan, China. This project has received medical ethics support (YS2021036). Animal experiments were approved by the animal ethics committee of Kunming Institute of Zoology, Chinese Academy of Sciences (IACUC-PA-2022-03-029)., (© 2024. The Author(s).)

Mammalian wounds leave visible scars, and there are no methods for complete regeneration. However, mouse fetuses regenerate their skin, including epidermal and dermal structures, up to embryonic day (E)13. This regeneration pattern requires the formation of actin cables in the wound margin epithelium; however, the molecular mechanisms are not fully understood. Rac1 alters actin in cells and is involved in the formation of filopodia. We investigated whether actin remodeling and skin regeneration patterns can be reproduced through the regulation of Rac1 signaling. Rac1 expression was downregulated in E13 wounds and upregulated after E15 when scars remained. NSC23766, a Rac1-specific inhibitor, altered actin dynamics at the cell margin from filopodia formation to cable formation and inhibited the migration of mouse epidermal keratinocyte, PAM212, by Rac1 signaling suppression. NSC23766 suppressed Rac1 activity and completely regenerated the fetal mouse wounds, even at E14, by changing actin dynamics. Knocked-out Rac1 transgenic mice experienced delayed epithelialization of wounds with suppressed epidermal migration in adults; however, in fetuses, complete wound regeneration via Rac1 signal suppression was observed. Therefore, Rac1 suppression in the wound epidermis can achieve regenerative wound healing in fetuses and may be a potential candidate for healing scars., (© 2024. The Author(s).)

Macrophages are essential immune cells for host defense against bacterial pathogens after radiation injury. However, the role of macrophage phagocytosis in infection following radiation injury remains poorly examined. Extracellular cold-inducible RNA-binding protein is a damage-associated molecular pattern that dysregulates host immune system responses such as phagocytosis. We hypothesized that radiation-induced extracellular cold-inducible RNA-binding protein release impairs macrophage phagocytosis of bacteria. Adult healthy mice were exposed to 6.5 Gy total body irradiation. Primary peritoneal macrophages isolated from adult healthy mice were exposed to 6.5 Gy radiation. Extracellular cold-inducible RNA-binding protein-neutralizing monoclonal antibody was added to the cell culture prior to irradiation. Bacterial phagocytosis by peritoneal macrophages was assessed using pHrodo Green-labeled Escherichia coli 7 d after irradiation ex vivo and in vitro. Bacterial phagocytosis was also assessed after treatment with recombinant murine cold-inducible RNA-binding protein. Rac1 and ARP2 protein expression in cell lysates and extracellular cold-inducible RNA-binding protein levels in the peritoneal lavage were assessed by western blotting. Bacterial phagocytosis by peritoneal macrophages was significantly decreased after irradiation compared with controls ex vivo and in vitro. Rac1 and ARP2 expression in the peritoneal macrophages were downregulated after total body irradiation. Total body irradiation significantly increased extracellular cold-inducible RNA-binding protein levels in the peritoneal cavity. Recombinant murine cold-inducible RNA-binding protein significantly decreased bacterial phagocytosis in a dose-dependent manner. Extracellular cold-inducible RNA-binding protein monoclonal antibody restored bacterial phagocytosis by peritoneal macrophages after irradiation. Ionizing radiation exposure impairs bacterial phagocytosis by macrophages after irradiation. Neutralization of extracellular cold-inducible RNA-binding protein restores the phagocytic ability of macrophages after irradiation. Our findings elucidate a novel mechanism of immune dysfunction and provide a potential new therapeutic approach for limiting infection after radiation injury., Competing Interests: Conflict of interest statement. None declared., (© The Author(s) 2024. Published by Oxford University Press on behalf of Society for Leukocyte Biology. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

MicroRNAs have been shown to play a critical role in lung inflammatory diseases. Here, we report that knocking out miR-144/451 in mice exacerbates lipopolysaccharide (LPS)-induced lung inflammation. The lung inflammation in mice was induced by intratracheal instillation of LPS. Loss-of-function experiments demonstrated that miR-144/451 gene knockout (KO) increased LPS-induced lung inflammation and oxidant stress compared with wild-type (WT) mice, as manifested by increased total bronchoalveolar lavage fluid cells and neutrophil counts, elevated TNF-α and IL-6 levels in bronchoalveolar lavage fluid, enhanced myeloperoxidase activity, and reduced catalase and glutathione peroxidase activity in lung tissues. We also found that LPS significantly decreased miR-451 expression in lung tissues and macrophages; while miR-451 overexpression in LPS-induced RAW264.7 cells remarkably reduced TNF-α and IL-6 levels as well as reactive oxygen species (ROS) production, suggesting a feedback loop might exist in inflammatory cells. Rac1 mRNA and protein levels were downregulated in miR-451-overexpressed RAW264.7 cells. Ex vivo stimulation experiments, performed using alveolar macrophages isolated from miR-144/451 KO mice, confirmed that Rac1 inhibitor alleviated levels of TNF-α and ROS in response to LPS stimulation compared with WT controls. Luciferase reporter assay demonstrated that STAT-3 is a direct target of miR-451. STAT-3 protein levels were elevated in miR-144/451 KO macrophages. LPS treatment also resulted in higher phosphorylation levels of STAT-3 in macrophages from KO mice than in WT cells. Our study identified miR-144/451 as an anti-inflammatory factor in LPS-induced lung inflammation that acts by downregulating Rac1 and STAT-3., (© 2024 Wiley Periodicals LLC.)

Harmine (HM), a β-carboline alkaloid extracted from plants, is a crucial component of traditional Chinese medicine (TCM) known for its diverse pharmacological activities. Thrombocytopenia, a common and challenging hematological disorder, often coexists with serious illnesses. Previous research has shown a correlation between HM and thrombocytopenia, but the mechanism needs further elucidation. The aim of this study was to clarify the mechanisms underlying the effects of HM on thrombocytopenia and to develop new therapeutic strategies. Flow cytometry, Giemsa staining, and Phalloidin staining were used to assess HM's impact on Meg-01 and HEL cell differentiation and maturation in vitro. A radiation-induced thrombocytopenic mouse model was employed to evaluate HM's effect on platelet production in vivo. Network pharmacology, molecular docking, and protein blotting were utilized to investigate HM's targets and mechanisms. The results demonstrated that HM dose-dependently promoted Meg-01 and HEL cell differentiation and maturation in vitro and restored platelet levels in irradiated mice in vivo. Subsequently, HM was found to be involved in the biological process of platelet production by upregulating the expressions of Rac1, Cdc42, JNK, and 5-HTR2A. Furthermore, the targeting of HM to 5-HTR2A and its correlation with downstream Rac1/Cdc42/JNK were also confirmed. In conclusion, HM regulates megakaryocyte differentiation and thrombopoiesis through the 5-HTR2A and Rac1/Cdc42/JNK pathways, providing a potential treatment strategy for thrombocytopenia., (© 2024 John Wiley & Sons Ltd.)

Ethnopharmacological Relevance: Anshen Dingzhi prescription (ADP), documented in "Yi Xue Xin Wu", is a famous prescription for treating panic-related mental disorders such as post-traumatic stress disorder (PTSD). However, the underlying mechanism remains unclear., Aim of the Study: This study aimed to investigate the mechanisms by which ADP intervened in PTSD-like behaviors., Methods: A mouse model of single prolonged stress (SPS) was established to evaluate the ameliorative effects and mechanisms of ADP on PTSD. Behavioral tests were used to assess PTSD-like behaviors in mice; transmission electron microscopy was used to observe changes in the ultrastructure of hippocampal synapses, and western blot, immunofluorescence, and ELISA were used to detect the expression of hippocampal deleted in colorectal cancer (DCC) and downstream Ras-related C3 botulinum toxin substrate 1 (Rac1) - P21-activated kinase 1 (PAK1) signal, as well as levels of synaptic proteins and inflammatory factors. Molecular docking technology simulated the binding of potential brain-penetrating components of ADP to DCC., Results: SPS induced PTSD-like behaviors in mice and increased expression of hippocampal netrin-1 (NT-1) and DCC on the 14th day post-modeling, with concurrent elevation in serum NT-1 levels. Simultaneously, SPS also decreased p-Rac1 level and increased p-PAK1 level, the down-stream molecules of DCC. Lentiviral overexpression of DCC induced or exacerbated PTSD-like behaviors in control and SPS mice, respectively, whereas neutralization antibody against NT-1 reduced DCC activation and ameliorated PTSD-like behaviors in SPS mice. Interestingly, downstream Rac1-PAK1 signal was altered according to DCC expression. Moreover, DCC overexpression down-regulated N-methyl-d-aspartate (NMDA) receptor 2A (GluN2A) and postsynaptic density 95 (PSD95), up-regulated NMDA receptor 2B (GluN2B) and increased neuroinflammatory responses. Administration of ADP (36.8 mg/kg) improved PTSD-like behaviors in the SPS mice, suppressed hippocampal DCC, and downstream Rac1-PAK1 signal, upregulated GluN2A and PSD95, downregulated GluN2B, and reduced levels of inflammatory factors NOD-like receptor protein 3 (NLRP3), nuclear factor kappa-B (NF-κB) and interleukin-6 (IL-6). Importantly, DCC overexpression could also reduce the ameliorative effect of ADP on PTSD. Additionally, DCC demonstrated a favorable molecular docking pattern with the potential brain-penetrating components of ADP, further suggesting DCC as a potential target of ADP., Conclusion: Our data indicate that DCC is a key target for the regulation of synaptic function and inflammatory response in the onset of PTSD, and ADP likely reduces DCC to prevent PTSD via modulating downstream Rac1-PAK1 pathway. This study provides a novel mechanism for the onset of PTSD and warrants the clinical application of ADP., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Cancer stem cells (CSCs) are a group of specially programmed tumor cells that possess the characteristics of perpetual cell renewal, increased invasiveness, and often, drug resistance. Hence, eliminating CSCs is a major challenge for cancer treatment. Understanding the cellular programs that maintain CSCs, and identifying the critical regulators for such programs, are major undertakings in both basic and translational cancer research. Recently, we have reported that RAB4A is a major regulator of epithelial-to-mesenchymal transition (EMT) and it does so mainly through regulating the activation of RAC1 GTPase. In the current study, we have delineated a new signaling circuitry through which RAB4A transmits its control of cancer stemness. Using in vitro and in vivo studies, we show that RAB4A, as the upstream regulator, relays signal stepwise to NUMB, NOTCH1, RAC1, and then SOX2 to control the self-renewal property of multiple cancer cells of diverse tissue origins. Knockdown of NUMB, or overexpression of NICD (the active fragment NOTCH1) or SOX2, rescued the in vitro sphere-forming and in vivo tumor-forming abilities that were lost upon RAB4A knockdown. Furthermore, we discovered that the chain of control is mostly through transcriptional regulation at every step of the pathway. The discovery of the novel signaling axis of RAB4A-NUMB-NOTCH-SOX2 opens the path for further expansion of the signaling chain and for the identification of new regulators and interacting proteins important for CSC functions, which can be explored to develop new and effective therapies., (© 2024. The Author(s).)

Colorectal cancer (CRC) is the third most commonly diagnosed type of cancer worldwide and is responsible for numerous deaths. 5-fluorouracil (5-FU) is an effective chemotherapy drug commonly used in the treatment of CRC, either as monotherapy or in combination with other drugs. However, half of CRC cases are resistant to 5-FU-based therapies. To contribute to the understanding of the mechanisms underlying CRC resistance or recurrence after 5-FU-based therapies, we performed a comprehensive study integrating in silico, in vitro, and in vivo approaches. We identified differentially expressed genes and enrichment of pathways associated with recurrence after 5-FU-based therapies. Using these bioinformatics data as a starting point, we selected a group of drugs that restored 5-FU sensitivity to 5-FU resistant cells. Interestingly, treatment with the novel Rac1 inhibitor, 1A-116, reversed morphological changes associated with 5-FU resistance.. Moreover, our in vivo studies have shown that 1A-116 affected tumor growth and the development of metastasis. All our data allowed us to postulate that targeting Rac1 represents a promising avenue for the development of new treatments for patients with CRC resistant to 5-FU-based therapies.

Osteoclasts are bone-resorbing multinucleated giant cells formed by the fusion of monocyte/macrophage lineages. Various small GTPases are involved in the multinucleation and differentiation of osteoclasts. However, the roles of small GTPases regulatory molecules in osteoclast differentiation remain unclear. In the present study, we examined the role of Dennd2c, a putative guanine nucleotide exchange factor for Rab GTPases, in osteoclast differentiation. Knockdown of Dennd2c promoted osteoclast differentiation, resorption, and expression of osteoclast markers. Morphologically, Dennd2c knockdown induced the formation of larger osteoclasts with several protrusions. In contrast, overexpression of Dennd2c inhibited the multinucleation and differentiation of osteoclasts, bone resorption, and the expression of osteoclast markers. Dennd2c -overexpressing macrophages exhibited spindle-shaped mononuclear cells and long thin protrusions. Treatment of Dennd2c -overexpressing cells with the Cdc42 inhibitor ML-141 or the Rac1 inhibitor 6-thio-GTP prevented protrusion formation. Moreover, treatment of Dennd2c -overexpressing cells with the actin polymerization inhibitor latrunculin B restored multinucleated and TRAP-positive osteoclast formation. These results indicate that Dennd2c negatively regulates osteoclast differentiation and multinucleation by modulating protrusion formation in macrophages.

Metastatic breast-cancer is one of the major causes of death, due to remaining dormant cancer cells for several years. Rac1 is upregulated with cancer and stay elevated throughout the metastatic pathway to regulate the formation of lamellipodia and filopodia. This work developed peptide FGDWS as novel inhibitor targeting Rac1-Tiam1 binding site by in-silico as it was found to be the strongest interacting peptide with Rac1 at the Tiam binding site. The binding and inhibition study of peptide with Rac1 was performed by Surface plasmon resonance and MTT assay, respectively. Cell-migration, apoptotic assay and western-blot in breast-cancer cells were performed with FGDWS and in combination with Doxorubicin (Dox). Tumor regression experiment was done with mice model. The strong binding of FGDWS with Rac1 and reduction of cell-viability were observed in breast-cancer cell-lines. The cell-migration was suppressed, and higher regression were obtained in synergy group. The apoptotic effect of FGDWS alone and with Dox were detected by annexin-V via activating caspase3/7. The tumor size was reduced by the treatment of FGDWS and more reduced in combinatorial effect. The combinatorial effect of FGDWS-Dox may enhance the treatment efficacy without side-effects., (© 2024. The Author(s).)

Alphavirus infection induces dramatic remodeling of host cellular membranes, producing filopodia-like and intercellular extensions. The formation of filopodia-like extensions has been primarily assigned to the replication protein nsP1, which binds and reshapes the host plasma membrane when expressed alone. While reported decades ago, the molecular mechanisms behind nsP1 membrane deformation remain unknown. Using mammalian epithelial cells and Chikungunya virus (CHIKV) as models, we characterized nsP1-induced membrane deformations as highly dynamic actin-rich lamellipodia and filopodia-like extensions. Through pharmacological inhibition and genetic invalidation, we identified the critical contribution of the Rac1 GTPase and its downstream effectors PAK1 and the actin nucleator Arp2 in nsP1-induced membrane deformation. An intact Rac1-PAK1-Arp2 signaling axis was also required for optimal CHIKV genome replication. Therefore, our results designate the Rac1-PAK1-Arp2 pathway as an essential signaling node for CHIKV infection and establish a parallel requirement for host factors involved in nsP1-induced plasma membrane reshaping and assembly of a functional replication complex.IMPORTANCEThe alphavirus nsP1 protein dramatically remodels host cellular membranes, resulting in the formation of filopodia-like extensions. Although described decades ago, the molecular mechanisms controlling these membrane deformations and their functional importance remain elusive. Our study provides mechanistic insight, uncovering the critical role of the Rac1 GTPase, along with its downstream effectors PAK1 and the actin nucleator Arp2, in the nsP1-associated phenotype. Furthermore, we demonstrate that the Rac1-PAK1-Arp2 pathway is essential for optimal CHIKV genome replication. Our findings establish a parallel in the cellular mechanisms governing nsP1-induced plasma membrane reshaping and the production of a functional replication complex in infected cells., Competing Interests: The authors declare no conflict of interest.

Contrast-induced acute kidney injury (CIAKI) is a common complication with limited treatments. Intermedin (IMD), a peptide belonging to the calcitonin gene-related peptide family, promotes vasodilation and endothelial stability, but its role in mitigating CIAKI remains unexplored. This study investigates the protective effects of IMD in CIAKI, focusing on its mechanisms, particularly the cAMP/Rac1 signaling pathway. Human umbilical vein endothelial cells (HUVECs) were treated with iohexol to simulate kidney injury in vitro. The protective effects of IMD were assessed using CCK8 assay, flow cytometry, ELISA, and Western blotting. A CIAKI rat model was utilized to evaluate renal peritubular capillary endothelial cell injury and renal function through histopathology, immunohistochemistry, immunofluorescence, Western blotting, and transmission electron microscopy. In vitro, IMD significantly enhanced HUVEC viability and mitigated iohexol-induced toxicity by preserving intercellular adhesion junctions and activating the cAMP/Rac1 pathway, with Rac1 inhibition attenuating these protective effects. In vivo, CIAKI caused severe damage to peritubular capillary endothelial cell junctions, impairing renal function. IMD treatment markedly improved renal function, an effect negated by Rac1 inhibition. IMD protects against renal injury in CIAKI by activating the cAMP/Rac1 pathway, preserving peritubular capillary endothelial integrity and alleviating acute renal injury from contrast media. These findings suggest that IMD has therapeutic potential in CIAKI and highlight the cAMP/Rac1 pathway as a promising target for preventing contrast-induced acute kidney injury in at-risk patients, ultimately improving clinical outcomes.

Phagocytosis of Mycobacterium tuberculosis ( Mtb ) followed by its integration into the matured lysosome is critical in the host defense against tuberculosis. How Mtb escapes this immune attack remains elusive. In this study, we unveiled a novel regulatory mechanism by which SIRT7 regulates cytoskeletal remodeling by modulating RAC1 activation. We discovered that SIRT7 expression was significantly reduced in CD14 + monocytes of TB patients. Mtb infection diminished SIRT7 expression by macrophages at both the mRNA and protein levels. SIRT7 deficiency impaired actin cytoskeleton-dependent macrophage phagocytosis, LC3II expression, and bactericidal activity. In a murine tuberculosis model, SIRT7 deficiency detrimentally impacted host resistance to Mtb , while Sirt7 overexpression significantly increased the host defense against Mtb , as determined by bacterial burden and inflammatory-histopathological damage in the lung. Mechanistically, we demonstrated that SIRT7 limits Mtb infection by directly interacting with and activating RAC1, through which cytoskeletal remodeling is modulated. Therefore, we concluded that SIRT7, in its role regulating cytoskeletal remodeling through RAC1, is critical for host responses during Mtb infection and proposes a potential target for tuberculosis treatment.IMPORTANCETuberculosis (TB), caused by Mycobacterium tuberculosis ( Mtb ), remains a significant global health issue. Critical to macrophages' defense against Mtb is phagocytosis, governed by the actin cytoskeleton. Previous research has revealed that Mtb manipulates and disrupts the host's actin network, though the specific mechanisms have been elusive. Our study identifies a pivotal role for SIRT7 in this context: Mtb infection leads to reduced SIRT7 expression, which, in turn, diminishes RAC1 activation and consequently impairs actin-dependent phagocytosis. The significance of our research is that SIRT7 directly engages with and activates Rac Family Small GTPase 1 (RAC1), thus promoting effective phagocytosis and the elimination of Mtb . This insight into the dynamic between host and pathogen in TB not only broadens our understanding but also opens new avenues for therapeutic development., Competing Interests: The authors declare no conflict of interest.

Background: Glioblastoma represents the most frequently diagnosed malignant neoplasm within the central nervous system. Human glioblastoma cells can be phenotypically reprogrammed into neuron-like cells through the forced expression of NEUROG2 and SOXC factors. NEUROG2 serves as a pioneer factor, establishing an initial framework for this transformation. However, the specific role of SOXC factors has not been fully elucidated., Methods: In this study, we used ChIP-seq to determine the potential target gene of NGN2. RNA-seq has been used to evaluate the transcriptional change during NGN2-SOX11-mediated neuron reprogramming. Immunofluorescence was used to determine the neuron reprogramming efficacy and cell proliferation ability. ChIP-qPCR, Co-IP, and Western Blot were performed to investigate the mechanism., Results: Our findings reveal that SOXC factors, in contrast to their previously identified function as transcriptional activators, act as transcriptional repressors. They achieve this by recruiting TRIM28 to suppress the expression of ECT2, a RhoGEF. This suppression results in the differential regulation of RhoA, RAC1, and CDC42 activities throughout the reprogramming process. We further establish that small molecules targeting RhoA and its effectors can substitute for SOXC factors in facilitating the neuronal reprogramming of glioblastoma cells., Conclusion: These results underscore the pivotal role of SOXC factors' transcriptional repression and illuminate one of their specific downstream targets., (© 2024 The Author(s). CNS Neuroscience & Therapeutics published by John Wiley & Sons Ltd.)

Kinases are known to have kinase activity independent functions. To gain further insights into potential kinase-independent functions of SLK/STK2, we have developed a kinase-dead allele, SLK K63R using in vivo CRISPR/Cas technology. Our studies show that blastocysts homozygote for SLK K63R do not develop into viable mice. However, heterozygotes are viable and fertile with no overt phenotypes. Analyses of mouse embryonic fibroblasts show that expression of SLK K63R results in a 50% decrease in kinase activity in heterozygotes. In contrast to previous studies, our data show that SLK does not form homodimers and that the kinase defective allele does not act in a dominant negative fashion. Expression of SLK K63R leads to altered Rac1 and RhoA activity, increased stress fiber formation and delayed focal adhesion turnover. Our data support a previously observed role for SLK in cell migration and suggest that at least 50% kinase activity is sufficient for embryonic development., Competing Interests: Declaration of competing interest None., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder distinguished by gradual depletion of motor neurons. RNA binding motif protein 5 (RBM5), an abundantly expressed RNA-binding protein, plays a critical role in the process of cellular death. However, little is known about the role of RBM5 in the pathogenesis of ALS. Here, we found that RBM5 was upregulated in ALS hSOD1 G93A -NSC34 cell models and hSOD1 G93A mice due to a reduction of miR-141-5p. The upregulation of RBM5 increased the apoptosis of motor neurons by inhibiting Rac1-mediated neuroprotection. In contrast, genetic knockdown of RBM5 rescued motor neurons from hSOD1 G93A -induced degeneration by activating Rac1 signaling. The neuroprotective effect of RBM5-knockdown was significantly inhibited by the Rac1 inhibitor, NSC23766. These findings suggest that RBM5 could potentially serve as a therapeutic target in ALS by activating the Rac1 signalling., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

The mammalian target of rapamycin (mTOR) pathway plays a key role in determining immune cells function through modulation of their metabolic status. By specific deletion of Rictor in CD11c+ myeloid cells (referred to here as CD11cRicΔ/Δ), we investigated the role of mTOR complex 2 (mTORC2) signaling in dendritic cells (DCs) function in mice. We showed that upon dextran sulfate sodium-induced colitis, the lack of mTORC2 signaling CD11c+ cells diminishes the colitis score and abrogates DC migration to the mesenteric lymph nodes, thereby diminishing the infiltration of T helper 17 cells in the lamina propria and subsequent inflammation. These findings corroborate with the abrogation of cytoskeleton organization and the decreased activation of Rac1 and Cdc42 GTPases observed in CD11c+-mTORC2-deficient cells. Meta-analysis on colonic samples from ulcerative colitis patients revealed increased gene expression of proinflammatory cytokines, which coincided with augmented expression of the mTOR pathway, a positive correlation between the DC marker ITGAX and interleukin-6, the expression of RICTOR, and CDC42. Together, this work proposes that targeting mTORC2 on DCs offers a key to hamper inflammatory responses, and this way, ameliorates the progression and severity of intestinal inflammatory diseases., Competing Interests: Conflict of interest statement. The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (© The Author(s) 2024. Published by Oxford University Press on behalf of Society for Leukocyte Biology. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

The WNT5B ligand regulates the non-canonical wingless-related integration site (WNT)-planar cell polarity (PCP) pathway. However, the detailed mechanism underlying the activity of WNT5B in the WNT-PCP pathway in non-small cell lung cancer (NSCLC) is unclear. In this study, we assessed the clinicopathological significance of WNT5B expression in NSCLC specimens. WNT5B-overexpression and -knockdown NSCLC cell lines were generated in vivo and in vitro, respectively. WNT5B overexpression in NSCLC specimens correlates with advanced tumor node metastasis (TNM) stage, lymph node metastasis, and poor prognosis in patients with NSCLC. Additionally, WNT5B promotes the malignant phenotype of NSCLC cells in vivo and in vitro. Interactions were identified among WNT5B, frizzled3 (FZD3), and disheveled3 (DVL3) in NSCLC cells, leading to the activation of WNT-PCP signaling. The FZD3 receptor initiates DVL3 recruitment to the membrane for phosphorylation in a WNT5B ligand-dependent manner and activates c-Jun N-terminal kinase (JNK) signaling via the small GTPase RAC1. Furthermore, the deletion of the DEP domain of DVL3 abrogated these effects. Overall, we demonstrated a novel signal transduction pathway in which WNT5B recruits DVL3 to the membrane via its DEP domain through interaction with FZD3 to promote RAC1-PCP-JNK signaling, providing a potential target for clinical intervention in NSCLC treatment., Competing Interests: Declaration of competing interest None., (Copyright © 2024. Published by Elsevier Inc.)

Piezo1 functions as a special transducer of mechanostress into electrochemical signals and is implicated in the pathogenesis of various diseases across different disciplines. However, whether Piezo1 contributes to the pathogenesis of lupus nephritis (LN) remains elusive. To study this, we applied an agonist and antagonist of Piezo1 to treat lupus-prone MRL/lpr mice. Additionally, a podocyte-specific Piezo1 knockout mouse model was also generated to substantiate the role of Piezo1 in podocyte injury induced by pristane, a murine model of LN. A marked upregulation of Piezo1 was found in podocytes in both human and murine LN. The Piezo1 antagonist, GsMTx4, significantly alleviated glomerulonephritis and tubulointerstitial damage, improved kidney function, decreased proteinuria, and mitigated podocyte foot process effacement in MRL/lpr mice. Moreover, podocyte-specific Piezo1 deletion showed protective effects on the progression of proteinuria and podocyte foot process effacement in the murine LN model. Mechanistically, Piezo1 expression was upregulated by inflammatory cytokines (IL-6, TNF-α and IFN-γ), soluble urokinase Plasminogen Activator Receptor and its own activation. Activation of Piezo1 elicited calcium influx, which subsequently enhanced Rac1 activity and increased active paxillin, thereby promoting cytoskeleton remodeling and decreasing podocyte motility. Thus, our work demonstrated that Piezo1 contributed to podocyte injury and proteinuria progression in LN. Hence, targeted therapy aimed at decreasing or inhibiting Piezo1 could represent a novel strategy to treat LN., (Copyright © 2024 International Society of Nephrology. Published by Elsevier Inc. All rights reserved.)

Purpose: Phosphatidylinositol-3,4,5-trisphosphate-dependent Rac exchange factor-1 (P-Rex1), as one of the members of Rac-GEFs, has been proven to play a critical role in cancer progression and metastasis. Nonetheless, its role in cardiac fibrosis remains elusive. In the present study, we aimed to investigate whether and how the P-Rex1 mediates AngII-induced cardiac fibrosis., Method: A cardiac fibrosis mouse model was established by chronic AngII perfusion. The heart structure, function, pathological changes of myocardial tissues, oxidative stress, and cardiac fibrotic protein expression were determined in an AngII induced mouse model. To provide a molecular mechanism for P-Rex1 involvement in cardiac fibrosis, a specific inhibitor or siRNA was used to block P-Rex1, and target the relationship between Rac1-GTPase and its downstream effector., Results: Blocking P-Rex1 showed down-regulation of its downstream effectors such as the profibrotic transcriptional regulator Paks, ERK1/2, and ROS generation. Intervention treatment with P-Rex1 inhibitor 1A-116 ameliorated AngII-induced abnormalities in heart structure and function. Moreover, pharmacological inhibition of the P-Rex1/Rac1 axis showed a protective effect in AngII-induced cardiac fibrosis through the down-regulation of collagen1, CTGF, and α-SMA expression., Conclusion: Our findings demonstrated for the first time that P-Rex1 was an essential signaling mediator in CFs activation and subsequent cardiac fibrosis, and 1A-116 could be a potential pharmacological development drug., (© 2023. The Author(s).)

Sarcopenia is characterized by accelerated muscle mass and function loss, which burdens and challenges public health worldwide. Several studies indicated that selenium deficiency is associated with sarcopenia; however, the specific mechanism remains unclear. Here, we demonstrated that selenoprotein W (SELENOW) containing selenium in the form of selenocysteine functioned in sarcopenia. SELENOW expression is up-regulated in dexamethasone (DEX)-induced muscle atrophy and age-related sarcopenia mouse models. Knockout (KO) of SELENOW profoundly aggravated the process of muscle mass loss in the two mouse models. Mechanistically, SELENOW KO suppressed the RAC1-mTOR cascade by the interaction between SELENOW and RAC1 and induced the imbalance of protein synthesis and degradation. Consistently, overexpression of SELENOW in vivo and in vitro alleviated the muscle and myotube atrophy induced by DEX. SELENOW played a role in age-related sarcopenia and regulated the genes associated with aging. Together, our study uncovered the function of SELENOW in age-related sarcopenia and provides promising evidence for the prevention and treatment of sarcopenia.

Patients who receive thoracic radiotherapy may suffer from radiation-induced lung injury, but the treatment options are limited as the underlying mechanisms are unclear. Using a mouse model of right thorax irradiation with fractionated doses of X-rays for three consecutive days (8 Gy/per day), this study found that the thoracic irradiation (Th-IR) induced tissue injury with aberrant infiltration of macrophages, and it significantly increased the secretion of TNF-α, IL-1β, IL-6, TGF-β1 and serum amyloid A (SAA) in mice. Interestingly, SAA could activate macrophages and then induce epithelial-mesenchymal transition (EMT) of lung epithelial cells and fibrosis progression in lung tissue. Mechanistically, SAA enhanced the transient binding of FPR2 to Rac1 protein and further activated NF-κB signaling pathway in macrophages. Inhibition of FPR2 significantly reduced pulmonary fibrosis induced by SAA administration in mice. In addition, cimetidine could reduce the level of SAA release after irradiation and attenuate the lung injury induced by SAA or Th-IR. In conclusion, our results demonstrated that SAA activated macrophages via FPR2/Rac1/NF-κB pathway and might contribute to the Th-IR induced lung injury, which may provide a new strategy to attenuate radiation-induced adverse effects during radiotherapy., Competing Interests: Competing Interests: The authors have declared that no competing interest exists., (© The author(s).)

Objective: To investigate the correlation between serum Rac1 enzyme (Rac1) level with asthma control, airway inflammatory response and lung function in asthmatic children., Methods: A retrospective analysis was performed on 79 children with asthma who were diagnosed and treated in our hospital from June 2020 to January 2023. According to the severity of the disease, the children were divided into mild group (25 cases), moderate group (30 cases) and severe group (24 cases). 36 healthy children who underwent physical examination at the same period in our hospital were selected as the control group. The state of an illness, control level, serum mRNA Rac1, inflammatory factors, and lung function of the children in two groups were compared between the control group and the observation group., Results: The Rac1 mRNA levels, forced vital capacity (FVC), forced expiratory volume in one second/FVC (FEV1/FVC), peak expiratory flow (PEF), and maximum mid-expiratory flow (MMEF) in the observation group were significantly lower than these in the control group (P < 0.05). The tumor necrosis factor-alpha (TNF-α), interleukin-5 (IL-5), IL-6, and IL-33 in the observation group were markedly higher than these in the control group (P < 0.05). As the state of an illness worsened, the Rac1 mRNA levels, FVC, FEV1/FVC, PEF, and MMEF gradually reduced (P < 0.05), while the levels of TNF-α, IL-5, IL-6, and IL-33 increased (P < 0.05). As the degree of disease control improved, the Rac1 mRNA levels, FVC, FEV1/FVC, PEF, and MMEF gradually elevated (P < 0.05), and the levels of TNF- α, IL-5, IL-6, and IL-33 showed the opposite trend (P < 0.05). Rac1 was negatively related to the levels of TNF-α, IL-5, IL-6 and IL-33 (P < 0.05), and positively to the levels of FVC, FEV1/FVC, PEF and MMEF (P < 0.001). Rac1 mRNA levels, FVC, FEV1/FVC, PEF and MMEF were protective factors, while TNF-α, IL-5, IL-6 and IL-33 were risk factors for the prognosis of children with asthma (P < 0.05)., Conclusion: Children with asthma have obviously lower serum Rac1 mRNA levels, higher inflammatory factor levels and lower lung function. Serum Rac1 mRNA level may be associated with better asthma control, lower airway inflammatory response, better lung function and lower disease severity. It has important reference value for the evaluation of the state of an illness, efficacy and prognosis of children with bronchial asthma., (© 2024. The Author(s).)

Background: Hepatocellular carcinoma (LIHC) has severe consequences due to late diagnosis and the lack of effective therapies. Currently, potential biomarkers for the diagnosis and prognosis of LIHC have not been systematically evaluated. Previous studies have reported that RAC1 is associated with the B cell receptor signaling pathway in various tumor microenvironments, but its relationship with LIHC remains unclear. We investigated the relationship between RAC1 and the prognosis and immune infiltration microenvironment of LIHC, exploring its potential as a prognostic biomarker for this type of cancer., Methods: In this study, we analyzed data from The Cancer Genome Atlas (TCGA) using the Wilcoxon signed-rank test and logistic regression to assess the association between RAC1 expression and clinical characteristics in LIHC patients. Additionally, Kaplan-Meier and Cox regression methods were employed to confirm the impact of RAC1 expression levels on overall survival. Immunohistochemistry was used to validate RAC1 protein expression in LIHC. We constructed RAC1 knockdown LIHC cells and studied the effects of RAC1 protein on cell proliferation and migration at both cellular and animal levels., Results: RAC1 expression levels were significantly elevated in LIHC tissues compared to normal tissues. High RAC1 expression was strongly associated with advanced pathological stages and was identified as an independent factor negatively affecting overall survival. At both cellular and animal levels, RAC1 knockdown significantly inhibited the proliferation and migration of LIHC cells. Furthermore, RAC1 expression was positively correlated with the infiltration of Th2 cells and macrophages in the tumor microenvironment, suggesting that RAC1 may contribute to the deterioration of the tumor immunosuppressive microenvironment and potentially lead to reduced patient survival., Conclusion: These findings indicate that RAC1 expression promotes LIHC proliferation and migration and influences the landscape of immune cell infiltration in the tumor microenvironment. Based on these results, RAC1 is proposed as a potential prognostic biomarker for LIHC, associated with both cancer progression and tumor immune cell infiltration., (© 2024. The Author(s).)

In developing brains, axons exhibit remarkable precision in selecting synaptic partners among many non-partner cells. Evolutionarily conserved teneurins are transmembrane proteins that instruct synaptic partner matching. However, how intracellular signaling pathways execute teneurins' functions is unclear. Here, we use in situ proximity labeling to obtain the intracellular interactome of a teneurin (Ten-m) in the Drosophila brain. Genetic interaction studies using quantitative partner matching assays in both olfactory receptor neurons (ORNs) and projection neurons (PNs) reveal a common pathway: Ten-m binds to and negatively regulates a RhoGAP, thus activating the Rac1 small GTPases to promote synaptic partner matching. Developmental analyses with single-axon resolution identify the cellular mechanism of synaptic partner matching: Ten-m signaling promotes local F-actin levels and stabilizes ORN axon branches that contact partner PN dendrites. Combining spatial proteomics and high-resolution phenotypic analyses, this study advanced our understanding of both cellular and molecular mechanisms of synaptic partner matching., Competing Interests: Declaration of interests L.L. is a member of the advisory board for Cell., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Activation of the maternal immune system leads to a downstream cascade of proinflammatory events that culminate in the activation of spontaneous uterine contractions, which is associated with preterm birth. Ras-related C3 botulinum toxin substrate 1 (Rac1) is a crucial protein related to cell contraction and inflammation. The main purpose of this study was to explore the role and function of Rac1's regulation of inflammation through in- vivo and in-vitro experiments. Rac1 inhibitor was used in animal model of preterm birth and cells isolated from the uterine tissues of pregnant mice on gestational day 16 were transfected with adenovirus to knockdown or overexpress Rac1 and treated with the Calcium-calmodulin-dependent protein kinase II (CaMKII) inhibitor KN93. The expression of Rac1, uterine contraction-associated proteins (CAPs) (COX-2 and Connexin43), and inflammatory cytokines, were assessed by Western blotting and RTPCR. LPS upregulated Rac1, COX-2 and Connexin43 expression in uterine smooth muscle cells (USMCs). The expression of inflammatory cytokines, COX-2, and Connexin43 was significantly decreased in shRac1-transfected cells compared with cells stimulated with LPS only. Rac1 overexpression led to an increase in the expression of inflammatory cytokines, COX-2, and Connexin43. Furthermore, after Rac1 overexpression, KN93 reduced the expression of uterine contraction-associated proteins and inflammatory cytokines. It is thought that the effect of Rac1 on inflammatory cytokine and contraction-associated protein expression in USMCs is mediated by CaMKII. Rac1 can modulate the expression of contraction-associated proteins and inflammatory cytokines through the CaMKII pathway. Rac1 could be an effective therapeutic target for improving the outcome of preterm birth., Competing Interests: Conflicts of Interest The authors declare that there are no conflicts of interest., (Copyright © 2024. Published by Elsevier B.V.)

Background: Aging is an independent risk factor for the development of cardiovascular, thrombotic, and other chronic diseases. However, mechanisms of platelet hyperactivation in aging remain poorly understood., Objectives: Here, we examine whether and how aging alters intracellular signaling in platelets to support platelet hyperactivity and thrombosis., Methods: Quantitative mass spectrometry with tandem mass tag labeling systematically measured protein phosphorylation in platelets from healthy aged (>65 years) and young human (<45 years) subjects. The role of platelet mechanistic target of rapamycin (mTOR) in aging-induced platelet hyperreactivity was assessed using pharmacologic mTOR inhibition and a platelet-specific mTOR-deficient mouse model (mTOR plt-/- )., Results: Quantitative phosphoproteomics uncovered differential site-specific protein phosphorylation within mTOR, Rho GTPase, and MAPK pathways in platelets from aged donors. Western blot confirmed constitutive activation of the mTOR pathway in platelets from both aged humans and mice, which was associated with increased aggregation compared with that in young controls. Inhibition of mTOR with either Torin 1 in aged humans or genetic deletion in aged mice reversed platelet hyperreactivity. In a collagen-epinephrine pulmonary thrombosis model, aged wild-type (mTOR plt+/+ ) mice succumbed significantly faster than young controls, while time to death of aged mTOR plt-/- mice was similar to that of young mTOR plt+/+ mice. Mechanistically, we noted increased Rac1 activation and levels of mitochondrial reactive oxygen species in resting platelets from aged mice, as well as increased p38 phosphorylation upstream of thromboxane generation following agonist stimulation., Conclusion: Aging-related changes in mTOR phosphorylation enhance Rac1 and p38 activation to enhance thromboxane generation, platelet hyperactivity, and thrombosis., Competing Interests: Declaration of competing interests The authors have no competing interests to disclose., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Background: Irisin, as a myokine, plays a protective role against cardiovascular disease, including myocardial infarction, atherosclerosis and hypertension. However, whether irisin attenuates salt-sensitive hypertension and the related underlying mechanisms is unknown., Methods: Male Dahl salt-resistant (DSR) and Dahl salt-sensitive (DSS) (12 weeks) rats were fed a high salt diet (8% NaCl) with or without irisin treatment by intraperitoneal injection for 8 weeks., Results: Compared with DSR rats, DSS rats showed higher systolic blood pressure (SBP), impaired natriuresis and diuresis and renal dysfunction. In addition, it was accompanied by downregulation of renal p-AMPKα and upregulation of renal RAC1 and nuclear mineralocorticoid receptor (MR). Irisin intervention could significantly up-regulated renal p-AMPKα level and down-regulated renal RAC1-MR signal, thereby improving renal sodium excretion and renal function, and ultimately reducing blood pressure in DSS rats. Ex vivo treatment with irisin reduced the expression of RAC1 and nuclear MR in primary renal distal convoluted tubule cells from DSS rats and the effects of irisin were abolished by cotreatment of compound C (AMPK inhibitor), indicating that the regulation of RAC1-MR signals by irisin depended on the activation of AMPK., Conclusions: Irisin administration lowered salt-sensitive hypertension through regulating RAC1-MR signaling via activation of AMPK, which may be a promising therapeutic approach for salt-sensitive hypertension.

Objectives: The small GTPase Rac1 (RAC1) has been linked to podocyte disorders and steroid-sensitive nephrotic syndrome (SSNS). The aim of this study was to explore and validate the potential causal association between circulating RAC1 and SSNS., Methods: The association between circulating RAC1 and SSNS at both gene expression and proteomic levels was investigated using Mendelian randomization analysis, and further validated by single-cell RNA-sequencing, proteomic analysis, and experimental studies. The genetic instruments comprised cis-expression quantitative trait loci (cis-eQTLs) associated with RAC1 gene expression and protein QTLs correlated with plasma RAC1 protein levels. Causal associations were estimated utilizing the inverse variance weighted and MR-PRESSO methods. Validation of RAC1 expression was conducted through single-cell RNA-sequencing of peripheral blood mononuclear cells from patients with SSNS and healthy controls. Proteomic analysis was performed among patients with minimal change nephrotic syndrome. Experimental validation was conducted using a puromycin aminonucleoside (PAN)-induced nephrosis model., Results: Increased expression of RAC1 was associated with a higher risk of SSNS (gene expression level: odds ratio [OR], 1.53; 95% confidence interval [CI], 1.02-2.28; protein level: OR, 1.82; 95% CI, 1.05-3.17). The results of MR-PRESSO were consistent (gene expression level: OR, 1.49; 95% CI, 1.17-1.92; protein level: OR, 1.81; 95% CI, 1.16-2.85). Single-cell RNA sequencing and proteomic analysis confirmed elevated RAC1 expression in patients with SSNS compared to healthy controls. Experimental data further supported increased RAC1 expression in PAN-induced nephropathy., Conclusions: Increased expression of RAC1 might be causally associated with SSNS, suggesting that targeting RAC1 might represent a potential therapeutic strategy for SSNS.

Background: WD repeat domain 12 (WDR12) plays a crucial role in the ribosome biogenesis pathway. However, its biological function in colorectal cancer (CRC) remains poorly understood. Therefore, this study aims to investigate the roles of WDR12 in the occurrence and progression of CRC, as well as its underlying mechanisms., Methods: The expression of WDR12 was assessed through The Cancer Genome Atlas (TCGA) and the Human Protein Atlas (HPA) database. Functional experiments including Celigo assay, MTT assay, and Caspase-3/7 assay were conducted to validate the role of WDR12 in the malignant progression of CRC. Additionally, mRNA chip-sequencing and ingenuity pathway analysis (IPA) were performed to identify the molecular mechanism., Results: WDR12 expression was significantly upregulated in CRC tissues compared to normal colorectal tissues. Knockdown of WDR12 reduced proliferation and promoted apoptosis of CRC cell lines in vitro and in vivo experiments. Furthermore, WDR12 expression had a significantly inverse association with diseases and functions, including cancer, cell cycle, DNA replication, recombination, cellular growth, proliferation and repair, as revealed by IPA analysis of mRNA chip-sequencing data. Moreover, the activation of cell cycle checkpoint kinases proteins in the cell cycle checkpoint control signaling pathway was enriched in the WDR12 knockdown CRC cell lines. Additionally, downregulation of rac family small GTPase 1 (RAC1) occurred upon WDR12 knockdown, thereby facilitating the proliferation and anti-apoptosis of CRC cells., Conclusion: Our study demonstrates that the WDR12/RAC1 axis promotes tumor progression in CRC. Therefore, WDR12 may serve as a novel oncogene and a potential target for individualized therapy in CRC. These findings provide an experimental foundation for the clinical development of drugs targeting the WDR12/RAC1 axis., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

The prognosis of HER2-positive breast cancer (BC) has improved with the development of anti-HER2 therapies; however, the problem remains that there are still cases where anti-HER2 therapies do not respond well. We found that the expression of SREBF2, a master transcriptional factor in the mevalonate pathway, was correlated with ERBB2 (HER2) expression and a poor prognosis in HER2-positive BC. The target gene expressions of SREBF2 were associated with higher expression of ERBB2 in HER2-positive BC cells. Statins, anti-hypercholesterolemia drugs that inhibit the mevalonate pathway, enhanced the efficacy of HER2-targeting agents with inducing apoptosis in a geranylgeranylation-dependent manner. Mechanistically, statins specifically inhibited membrane localization of Rac1, a target protein of geranylgeranylation, and suppressed the activation of HER2 downstreams AKT and ERK pathways. Consistently, retrospective analysis showed a longer recurrence-free survival in Rac1-high/HER2-positive BC patients treated with HER2-targeting agents with statins than without statins. Our findings thus suggest that Rac1 expression could be used as a biomarker to stratify HER2-positive BC patients that could benefit from dual blockade, i.e., targeting HER2 with inhibition of geranylgeranylation of Rac1 using statins, thereby opening avenues for precision medicine in a new subset of Rac1-high/HER2-positive BC., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Isao Yokota reports a relationship with KAKENHI that includes: funding grants. Isao Yokota reports a relationship with Japan Agency for Medical Research and Development (AMED) that includes: funding grants. Isao Yokota reports a relationship with Government of Japan Ministry of Health Labour and Welfare Policy Research Grants that includes: funding grants. Isao Yokota reports a relationship with Nihon Medi-Physics Co., Ltd. that includes: funding grants. Isao Yokota reports a relationship with Chugai Pharmaceutical Co., Ltd. that includes: speaking and lecture fees. Isao Yokota reports a relationship with AstraZeneca K.K. that includes: speaking and lecture fees. Isao Yokota reports a relationship with Pfizer K.K. that includes: speaking and lecture fees. Shogen Boku reports a relationship with Amgen Inc. that includes: funding grants. Shogen Boku reports a relationship with Ono Pharmaceutical Co., Ltd. that includes: funding grants. Shogen Boku reports a relationship with Taiho Pharmaceutical Co., Ltd. that includes: funding grants and speaking and lecture fees. Shogen Boku reports a relationship with AstraZeneca K.K. that includes: funding grants. Shogen Boku reports a relationship with Kyo-diagnostics Co., Ltd. that includes: funding grants. Shogen Boku reports a relationship with Nippon Kayaku Co., Ltd. that includes: speaking and lecture fees. Shogen Boku reports a relationship with MSD K.K. that includes: speaking and lecture fees. Shogen Boku reports a relationship with BMS K.K. that includes: speaking and lecture fees. Shogen Boku reports a relationship with Eisai Co., Ltd. that includes: speaking and lecture fees. Shogen Boku reports a relationship with Chugai Pharmaceutical Co., Ltd. that includes: speaking and lecture fees. Yasuto Naoi reports a relationship with Sysmex Corp that includes: speaking and lecture fees. Yasuto Naoi reports a relationship with Ono Pharmaceutical Co., Ltd. that includes: funding grants and speaking and lecture fees. Yasuto Naoi reports a relationship with Daiichi Sankyo Co., Ltd. that includes: funding grants and speaking and lecture fees. Yasuto Naoi reports a relationship with AstraZeneca K.K. that includes: funding grants and speaking and lecture fees. Yasuto Naoi reports a relationship with Pfizer K.K. that includes: speaking and lecture fees. Yasuto Naoi reports a relationship with Eli Lilly K.K. that includes: speaking and lecture fees. Yasuto Naoi reports a relationship with Chugai Pharmaceutical Co., Ltd. that includes: speaking and lecture fees. Yasuto Naoi has patent #Curebest™ 95GC Breast (JP.5725274.B2) licensed to Sysmex Corp. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Macrophage-to-osteoclast differentiation (osteoclastogenesis) plays an essential role in tumor osteolytic bone metastasis (BM), while its specific mechanisms remain largely uncertain in lung adenocarcinoma BM. In this study, we demonstrate that integrin-binding sialoprotein (IBSP), which is highly expressed in the cancer cells from bone metastatic and primary lesions of patients with lung adenocarcinoma, can facilitate BM and directly promote macrophage-to-osteoclast differentiation independent of RANKL/M-CSF. In vivo results further suggest that osteolytic BM in lung cancer specifically relies on IBSP-induced macrophage-to-osteoclast differentiation. Mechanistically, IBSP regulates the Rac family small GTPase 1 (Rac1)-NFAT signaling pathway and mediates the forward shift of macrophage-to-osteoclast differentiation, thereby leading to early osteolysis. Moreover, inhibition of Rac1 by EHT-1864 or azathioprine in mice models can remarkably alleviate IBSP-induced BM of lung cancer. Overall, our study suggests that tumor-secreted IBSP promotes BM by inducing macrophage-to-osteoclast differentiation, with potential as an early diagnostic maker for BM, and Rac1 can be the therapeutic target for IBSP-promoted BM in lung cancer., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Long-term synaptic plasticity is typically associated with morphological changes in synaptic connections. However, the molecular mechanisms coupling functional and structural aspects of synaptic plasticity are still poorly defined. The catalytic activity of type I phosphoinositide-3-kinase (PI3K) is required for specific forms of synaptic plasticity, such as NMDA receptor-dependent long-term potentiation (LTP) and mGluR-dependent long-term depression (LTD). On the other hand, PI3K signaling has been linked to neuronal growth and synapse formation. Consequently, PI3Ks are promising candidates to coordinate changes in synaptic strength with structural remodeling of synapses. To investigate this issue, we targeted individual regulatory subunits of type I PI3Ks in hippocampal neurons and employed a combination of electrophysiological, biochemical and imaging techniques to assess their role in synaptic plasticity. We found that a particular regulatory isoform, p85α, is selectively required for LTP. This specificity is based on its BH domain, which engages the small GTPases Rac1 and Cdc42, critical regulators of the actin cytoskeleton. Moreover, cofilin, a key regulator of actin dynamics that accumulates in dendritic spines after LTP induction, failed to do so in the absence of p85α or when its BH domain was overexpressed as a dominant negative construct. Finally, in agreement with this convergence on actin regulatory mechanisms, the presence of p85α in the PI3K complex determined the extent of actin polymerization in dendritic spines during LTP. Therefore, this study reveals a molecular mechanism linking structural and functional synaptic plasticity through the coordinate action of PI3K catalytic activity and a specific isoform of the regulatory subunits., (© 2024. The Author(s).)

Aberrant alternative splicing events play a critical role in cancer biology, contributing to tumor invasion, metastasis, epithelial-mesenchymal transition, and drug resistance. Recent studies have shown that alternative splicing is a key feature for transcriptomic variations in colorectal cancer, which ranks third among malignant tumors worldwide in both incidence and mortality. Long non-coding RNAs can modulate this process by acting as trans-regulatory agents, recruiting splicing factors, or driving them to specific targeted genes. LncH19 is a lncRNA dis-regulated in several tumor types and, in colorectal cancer, it plays a critical role in tumor onset, progression, and metastasis. In this paper, we found, that in colorectal cancer cells, the long non-coding RNA H19 can bind immature RNAs and splicing factors as hnRNPM and RBFOX2. Through bioinformatic analysis, we identified 57 transcripts associated with lncH19 and containing binding sites for both splicing factors, hnRNPM, and RBFOX2. Among these transcripts, we identified the mRNA of the GTPase-RAC1, whose alternatively spliced isoform, RAC1B, has been ascribed several roles in the malignant transformation. We confirmed, in vitro, the binding of the splicing factors to both the transcripts RAC1 and lncH19. Loss and gain of expression experiments in two colorectal cancer cell lines (SW620 and HCT116) demonstrated that lncH19 is required for RAC1B expression and, through RAC1B, it induces c-Myc and Cyclin-D increase. In vivo, investigation from biopsies of colorectal cancer patients showed higher levels of all the explored genes (lncH19, RAC1B, c-Myc and Cyclin-D) concerning the healthy counterpart, thus supporting our in vitro model. In addition, we identified a positive correlation between lncH19 and RAC1B in colorectal cancer patients. Finally, we demonstrated that lncH19, as a shuttle, drives the splicing factors RBFOX2 and hnRNPM to RAC1 allowing exon retention and RAC1B expression. The data shown in this paper represent the first evidence of a new mechanism of action by which lncH19 carries out its functions as an oncogene by prompting colorectal cancer through the modulation of alternative splicing., (© 2024. The Author(s).)

Ras-related C3 botulinum toxin substrate 1 (Rac1) has emerged as a key regulator in the treatment of cancer metastasis because of its involvement in the formation of cell plate pseudopods and effects on cell migration. In this study, we found that incarvine C, a natural product isolated from Incarvillea sinensis, and its seven analogues exhibited antitumour activity by inhibiting cell cytoskeleton formation, with moderate cytotoxicity. Accordingly, these compounds inhibited the cytoskeleton-mediated migration and invasion of MDA-MB-231 cells, with inhibition rates ranging from 37.30 % to 69.72 % and 51.27 % to 70.90 % in vitro, respectively. Moreover, they induced G 2 /M phase cell cycle arrest in MDA-MB-231 cells. A pull-down assay revealed that the interaction between Rac1 and its downstream effector protein PAK1 was inhibited by these compounds and that the compound Ano-6 exhibited substantial activity, with an inhibition rate of more than 90 %. Molecular docking showed that incarvine C and its analogues could bind to the nucleotide-binding pocket of Rac1, maintaining high levels of inactivated Rac1. As Ano-6 exhibited significant activity in vitro, its anti-cancer activity was tested in vivo. Four weeks of oral treatment with Ano-6 was well-tolerated in mice, and it induced a potential anti-tumour response in xenografts of MDA-MB-231 cells. Further studies demonstrated that Ano-6 was enriched in tumour tissues after 2 h of administration and induced an increase in the number of dead tumour cells. In summary, these findings not only reveal the mechanism of incarvine C but also provide a new molecular template for Rac1 inhibitors and identify a promising candidate for breast cancer treatment., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Periventricular nodular heterotopia (PNH), the most common brain malformation diagnosed in adulthood, is characterized by the presence of neuronal nodules along the ventricular walls. PNH is mainly associated with mutations in the FLNA gene - encoding an actin-binding protein - and patients often develop epilepsy. However, the molecular mechanisms underlying the neuronal failure still remain elusive. It has been hypothesized that dysfunctional cortical circuitry, rather than ectopic neurons, may explain the clinical manifestations. To address this issue, we depleted FLNA from cortical pyramidal neurons of a conditional Flna flox/flox mice by timed in utero electroporation of Cre recombinase. We found that FLNA regulates dendritogenesis and spinogenesis thus promoting an appropriate excitatory/inhibitory inputs balance. We demonstrated that FLNA modulates RAC1 and cofilin activity through its interaction with the Rho-GTPase Activating Protein 24 (ARHGAP24). Collectively, we disclose an uncharacterized role of FLNA and provide strong support for neural circuit dysfunction being a consequence of FLNA mutations., Competing Interests: Declaration of competing interest None., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

At least one-third of patients with epithelial ovarian cancer (OC) present ascites at diagnosis and almost all have ascites at recurrence especially because of the propensity of the OC cells to spread in the abdominal cavity leading to peritoneal metastasis. The influence of ascites on the development of pre-metastatic niches, and on the biological mechanisms leading to cancer cell colonization of the mesothelium, remains poorly understood. Here, we show that ascites weakens the mesothelium by affecting the morphology of mesothelial cells and by destabilizing their distribution in the cell cycle. Ascites also causes destabilization of the integrity of mesothelium by modifying the organization of cell junctions, but it does not affect the synthesis of N-cadherin and ZO-1 by mesothelial cells. Moreover, ascites induces disorganization of focal contacts and causes actin cytoskeletal reorganization potentially dependent on the activity of Rac1. Ascites allows the densification and reorganization of ECM proteins of the mesothelium, especially fibrinogen/fibrin, and indicates that it is a source of the fibrinogen and fibrin surrounding OC spheroids. The fibrin in ascites leads to the adhesion of OC spheroids to the mesothelium, and ascites promotes their disaggregation followed by the clearance of mesothelial cells. Both αV and α5β1 integrins are involved. In conclusion ascites and its fibrinogen/fibrin composition affects the integrity of the mesothelium and promotes the integrin-dependent implantation of OC spheroids in the mesothelium., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 CY Cergy Paris University. Published by Elsevier Inc. All rights reserved.)

Objective: The primary goal of this study was to investigate the expressions of TUFT1 (Tuftelin) and Rac1-GTP in the cancerous tissues of individuals with triple-negative breast cancer (TNBC). Additionally, we aimed to explore the correlation between TUFT1 and Rac1-GTP expressions and examine the associations of TUFT1 and Rac1-GTP expressions with the clinical and pathological indicators of the patients., Methods: Ninety-six patients diagnosed with TNBC, scheduled for surgery between May 2022 and November 2022, were enrolled in this study. Cancerous tissue specimens were collected from these patients, and immunohistochemistry was employed to evaluate the levels of TUFT1 and Rac1-GTP expressions in the cancerous tissues. Subsequent to data collection, a comprehensive analysis was conducted to examine the correlation between TUFT1 and Rac1-GTP expressions. Furthermore, we sought to assess the associations of TUFT1 and Rac1-GTP expressions with the clinical and pathological indicators of the patients., Results: The TUFT1 protein was expressed in both the membrane and cytoplasm of TNBC cancer cells, with notably higher expression observed in the cytoplasm. Rac1-GTP was primarily expressed in the cytoplasm. There was a positive correlation between the levels of TUFT1 and Rac1-GTP expressions (χ 2  = 9.816, P < 0.05). The levels of TUFT1 and Rac1-GTP protein expressions showed no correlation with patient age (χ 2  = 2.590, 2.565, P > 0.05); however, they demonstrated a positive correlation with tumor size (χ 2  = 5.592,5.118), histological grading (χ 2  = 6.730, 5.443), and lymph node metastasis (χ 2  = 8.221, 5.180) (all with a significance level of P < 0.05)., Conclusion: A significant correlation was identified between the levels of TUFT1 and Rac1-GTP expressions in the cancerous tissues of patients with TNBC, suggesting a close association with the progression of TNBC. The two molecules play significant roles in facilitating an early diagnosis and treatment of TNBC., (© 2024. The Author(s), under exclusive licence to Federación de Sociedades Españolas de Oncología (FESEO).)

Coordinated activation and inhibition of F-actin supports the movements of morphogenesis. Understanding the proteins that regulate F-actin is important, since these proteins are mis-regulated in diseases like cancer. Our studies of C. elegans embryonic epidermal morphogenesis identified the GTPase CED-10/Rac1 as an essential activator of F-actin. However, we need to identify the GEF, or Guanine-nucleotide Exchange Factor, that activates CED-10/Rac1 during embryonic cell migrations. The two-component GEF, CED-5/CED-12, is known to activate CED-10/Rac1 to promote cell movements that result in the engulfment of dying cells during embryogenesis, and a later cell migration of the larval Distal Tip Cell. It is believed that CED-5/CED-12 powers cellular movements of corpse engulfment and DTC migration by promoting F-actin formation. Therefore, we tested if CED-5/CED-12 was involved in embryonic migrations, and got a contradictory result. CED-5/CED-12 definitely support embryonic migrations, since their loss led to embryos that died due to failed epidermal cell migrations. However, CED-5/CED-12 inhibited F-actin in the migrating epidermis, the opposite of what was expected for a CED-10 GEF. To address how CED-12/CED-5 could have two opposing effects on F-actin, during corpse engulfment and cell migration, we investigated if CED-12 harbors GAP (GTPase Activating Protein) functions. A candidate GAP region in CED-12 faces away from the CED-5 GEF catalytic region. Mutating a candidate catalytic Arginine in the CED-12 GAP region (R537A) altered the epidermal cell migration function, and not the corpse engulfment function. We interfered with GEF function by interfering with CED-5's ability to bind Rac1/CED-10. Mutating Serine-Arginine in CED-5/DOCK predicted to bind and stabilize Rac1 for catalysis, resulted in loss of both ventral enclosure and corpse engulfment. Genetic and expression studies strongly support that the GAP function likely acts on different GTPases. Thus, we propose CED-5/CED-12 support the cycling of multiple GTPases, by using distinct domains, to both promote and inhibit F-actin nucleation., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Venkatachalam et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Thrombospondin-1 (TSP1) is a matricellular protein associated with the regulation of cell migration through direct binding interactions with integrin proteins and by associating with other receptors known to regulate integrin function, including CD47 and CD36. We previously demonstrated that deletion of an epithelial TSP1 receptor, CD47, attenuates epithelial wound repair following intestinal mucosal injury. However, the mechanisms by which TSP1 contributes to intestinal mucosal repair remain poorly understood. Our results show upregulated TSP1 expression in colonic mucosal wounds and impaired intestinal mucosal wound healing in vivo upon intestinal epithelium-specific loss of TSP1 (VillinCre/+ Thbs1fl/fl or Thbs1ΔIEC mice). We report that exposure to exogenous TSP1 enhanced migration of intestinal epithelial cells in a CD47- and TGF-β1-dependent manner and that deficiency of TSP1 in primary murine colonic epithelial cells resulted in impaired wound healing. Mechanistically, TSP1 modulated epithelial actin cytoskeletal dynamics through suppression of RhoA activity, activation of Rho family small GTPase (Rac1), and changes in filamentous-actin bundling. Overall, TSP1 was found to regulate intestinal mucosal wound healing via CD47 and TGF-β1, coordinate integrin-containing cell-matrix adhesion dynamics, and remodel the actin cytoskeleton in migrating epithelial cells to enhance cell motility and promote wound repair.

One of the most extensively studied members of the Ras superfamily of small GTPases, Rac1 is an intracellular signal transducer that remodels actin and phosphorylation signaling networks. Previous studies have shown that Rac1-mediated signaling is associated with hippocampal-dependent working memory and longer-term forms of learning and memory and that Rac1 can modulate forms of both pre- and postsynaptic plasticity. How these different cognitive functions and forms of plasticity mediated by Rac1 are linked, however, is unclear. Here, we show that spatial working memory in mice is selectively impaired following the expression of a genetically encoded Rac1 inhibitor at presynaptic terminals, while longer-term cognitive processes are affected by Rac1 inhibition at postsynaptic sites. To investigate the regulatory mechanisms of this presynaptic process, we leveraged new advances in mass spectrometry to identify the proteomic and post-translational landscape of presynaptic Rac1 signaling. We identified serine/threonine kinases and phosphorylated cytoskeletal signaling and synaptic vesicle proteins enriched with active Rac1. The phosphorylated sites in these proteins are at positions likely to have regulatory effects on synaptic vesicles. Consistent with this, we also report changes in the distribution and morphology of synaptic vesicles and in postsynaptic ultrastructure following presynaptic Rac1 inhibition. Overall, this study reveals a previously unrecognized presynaptic role of Rac1 signaling in cognitive processes and provides insights into its potential regulatory mechanisms., Competing Interests: JK, EB, PS, NM, PP, JK, WW, ES, BR, SS No competing interests declared, (© 2024, Kim et al.)

Rabies virus (RABV) is highly lethal and triggers severe neurological symptoms. The neuropathogenic mechanism remains poorly understood. Ras-related C3 botulinum toxin substrate 1 (Rac1) is a Rho-GTPase that is involved in actin remodeling and has been reported to be closely associated with neuronal dysfunction. In this study, by means of a combination of pharmacological inhibitors, small interfering RNA, and specific dominant-negatives, we characterize the crucial roles of dynamic actin and the regulatory function of Rac1 in RABV infection, dominantly in the viral entry phase. The data show that the RABV phosphoprotein interacts with Rac1. RABV phosphoprotein suppress Rac1 activity and impedes downstream Pak1-Limk1-Cofilin1 signaling, leading to the disruption of F-actin-based structure formation. In early viral infection, the EGFR-Rac1-signaling pathway undergoes a biphasic change, which is first upregulated and subsequently downregulated, corresponding to the RABV entry-induced remodeling pattern of F-actin. Taken together, our findings demonstrate for the first time the role played by the Rac1 signaling pathway in RABV infection and may provide a clue for an explanation for the etiology of rabies neurological pathogenesis.IMPORTANCEThough neuronal dysfunction is predominant in fatal rabies, the detailed mechanism by which rabies virus (RABV) infection causes neurological symptoms remains in question. The actin cytoskeleton is involved in numerous viruses infection and plays a crucial role in maintaining neurological function. The cytoskeletal disruption is closely associated with abnormal nervous symptoms and induces neurogenic diseases. In this study, we show that RABV infection led to the rearrangement of the cytoskeleton as well as the biphasic kinetics of the Rac1 signal transduction. These results help elucidate the mechanism that causes the aberrant neuronal processes by RABV infection and may shed light on therapeutic development aimed at ameliorating neurological disorders., Competing Interests: The authors declare no conflict of interest.

Dynamic changes in three-dimensional cell shape are important for tissue form and function. In the developing Drosophila eye, photoreceptor differentiation requires the progression across the tissue of an epithelial fold known as the morphogenetic furrow. Morphogenetic furrow progression involves apical cell constriction and movement of apical cell edges. Here, we show that cells progressing through the morphogenetic furrow move their basal edges in opposite direction to their apical edges, resulting in a cellular tilting movement. We further demonstrate that cells generate, at their basal side, oriented, force-generating protrusions. Knockdown of the protein kinase Src42A or photoactivation of a dominant-negative form of the small GTPase Rac1 reduces protrusion formation. Impaired protrusion formation stalls basal cell movement and slows down morphogenetic furrow progression and photoreceptor differentiation. This work identifies a cellular tilting mechanism important for the generation of dynamic tissue shape changes and cell differentiation., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

The small G-protein Ras-related C3 botulinum toxin substrate 1 (Rac1) promotes the formation of filamentous actin (F-actin). Actin is a major component of dendritic spines, and we previously found that alcohol alters actin composition and dendritic spine structure in the nucleus accumbens (NAc) and the dorsomedial striatum (DMS). To examine if Rac1 contributes to these alcohol-mediated adaptations, we measured the level of GTP-bound active Rac1 in the striatum of mice following 7 weeks of intermittent access to 20% alcohol. We found that chronic alcohol intake activates Rac1 in the DMS of male mice. In contrast, Rac1 is not activated by alcohol in the NAc and DLS of male mice or in the DMS of female mice. Similarly, closely related small G-proteins are not activated by alcohol in the DMS, and Rac1 activity is not increased in the DMS by moderate alcohol or natural reward. To determine the consequences of alcohol-dependent Rac1 activation in the DMS of male mice, we inhibited endogenous Rac1 by infecting the DMS of mice with an adeno-associated virus (AAV) expressing a dominant negative form of the small G-protein (Rac1-DN). We found that overexpression of AAV-Rac1-DN in the DMS inhibits alcohol-mediated Rac1 signaling and attenuates alcohol-mediated F-actin polymerization, which corresponded with a decrease in dendritic arborization and spine maturation. Finally, we provide evidence to suggest that Rac1 in the DMS plays a role in alcohol-associated goal-directed learning. Together, our data suggest that Rac1 in the DMS plays an important role in alcohol-dependent structural plasticity and aberrant learning., Competing Interests: The authors declare no competing financial interests., (Copyright © 2024 the authors.)

Hypoxia and low glucose abundance often occur simultaneously at sites of inflammation. In monocytes and macrophages, glucose-oxygen deprivation stimulates the assembly of the NLRP3 inflammasome to generate the proinflammatory cytokine IL-1β. We found that concomitant glucose deprivation and hypoxia activated the NLRP3 inflammasome by constraining the function of HMG-CoA reductase (HMGCR), the rate-limiting enzyme of the mevalonate kinase pathway. HMGCR is involved in the synthesis of geranylgeranyl pyrophosphate (GGPP), which is required for the prenylation and lipid membrane integration of proteins. Under glucose-oxygen deprivation, GGPP synthesis was decreased, leading to reduced prenylation of the small GTPase Rac1, increased binding of nonprenylated Rac1 to the scaffolding protein IQGAP1, and enhanced activation of the NLRP3 inflammasome. In response to restricted oxygen and glucose supply, patient monocytes with a compromised mevalonate pathway due to mevalonate kinase deficiency or Muckle-Wells syndrome released more IL-1β than did control monocytes. Thus, reduced GGPP synthesis due to inhibition of HMGCR under glucose-oxygen deprivation results in proinflammatory innate responses, which are normally kept in check by the prenylation of Rac1. We suggest that this mechanism is also active in inflammatory autoimmune conditions.

Wounds that occur in adults form scars due to fibrosis, whereas those in embryos regenerate. If wound healing in embryos is mimicked in adults, scarring can be reduced. We found that mouse fetuses could regenerate tissues up to embryonic day (E) 13, but visible scars remained thereafter. This regeneration pattern requires actin cable formation at the epithelial wound margin via activation of adenosine monophosphate (AMP)-activated protein kinase (AMPK). Here, we investigated whether the AMPK-activating effect of salicylate, an anti-inflammatory drug, promotes regenerative wound healing. Salicylate administration resulted in actin cable formation and complete wound regeneration in E14 fetuses, in which scarring should have normally occurred, and promoted contraction of the panniculus carnosus muscle, resulting in complete wound regeneration. In vitro, salicylate further induced actin remodeling in mouse epidermal keratinocytes in a manner dependent on cell and substrate target-specific AMPK activation and subsequent regulation of Rac1 signaling. Furthermore, salicylate promoted epithelialization, enhanced panniculus carnosus muscle contraction, and inhibited scar formation in adult mice. Administration of salicylates to wounds immediately after injury may be a novel method for preventing scarring by promoting a wound healing pattern similar to that of embryonic wounds., (© 2024. The Author(s).)

Dermatan sulfate (DS) is a glycosaminoglycan characterized by having a variable structure and wide distribution in animal tissues. We previously demonstrated that some structural variants of DS were able to rapidly induce moderate necroptosis in luminal breast cancer cells when used at a high concentration. We have now investigated the mechanisms underlying the DS-mediated activation of the necroptotic executor MLKL using immunofluorescence, Western blotting and pharmacological inhibition. The two main processes, by which DS influences the phosphorylation of MLKL, are the activation of NFκB, which demonstrates a suppressive impact, and the induction of oxidative stress, which has a stimulatory effect. Moreover, the triggering of the redox imbalance by DS occurs via the modulatory influence of this glycosaminoglycan on the rearrangement of the actin cytoskeleton, requiring alterations in the activity of small Rho GTP-ase Rac1. All of these processes that were elicited by DS in luminal breast cancer cells showed a dependence on the structure of this glycan and the type of cancer cells. Furthermore, our results suggest that a major mechanism that is involved in the stimulation of necroptosis in luminal breast cancer cells by high doses of DS is mediated via the effect of this glycan on the activity of adhesion molecules.

Failed skin wound healing, through delayed wound healing or wound dehiscence, is a global public health issue that imposes significant burdens on individuals and society. Although the application of growth factor is an effective method to improve the pace and quality of wound healing, the clinically approved factors are limited. Parathyroid hormone (PTH) demonstrates promising results in wound healing by promoting collagen deposition and cell migration, but its application is limited by potentially inhibitory effects when administered continuously and locally. Through partially replacing and repeating the amino acid domains of PTH(1-34), we previously designed a novel PTH analog, PTH(3-34)(29-34) or MY-1, and found that it avoided the inhibitory effects of PTH while retaining its positive functions. To evaluate its role in wound healing, MY-1 was encapsulated in liposomes and incorporated into the methacryloyl gelatin (GelMA) hydrogel, through which an injectable nanocomposite hydrogel (GelMA-MY@Lipo, or GML) was developed. In vitro studies revealed that the GML had similar properties in terms of the appearance, microstructure, functional groups, swelling, and degradation capacities as the GelMA hydrogel. In vitro drug release testing showed a relatively more sustainable release of MY-1, which was still detectable in vivo 9 days post-application. When the GML was topically applied to the wound areas of rat models, wound closure as well as tensile strength were improved. Further studies showed that the effects of GML on wound repair and tensile strength were closely related to the promotion of fibroblast migration to the wound area through the controlled release of MY-1. Mechanically, MY-1 enhanced fibroblast migration by activating PI3K/AKT signaling and its downstream molecule, Rac1, by which it increased fibroblast aggregation in the early stage and resulting in denser collagen deposition at a later time. Overall, these findings demonstrated that the nanocomposite hydrogel system promoted skin wound healing and increased tensile strength, thus offering new potential in the treatment of wound healing., (© 2024. The Author(s).)

Opioid pain medications, such as morphine, remain the mainstay for treating severe and chronic pain. Prolonged morphine use, however, triggers analgesic tolerance and hyperalgesia (OIH), which can last for a long period after morphine withdrawal. How morphine induces these detrimental side effects remains unclear. Here, we show that morphine tolerance and OIH are mediated by Tiam1-coordinated synaptic structural and functional plasticity in the spinal nociceptive network. Tiam1 is a Rac1 GTPase guanine nucleotide exchange factor that promotes excitatory synaptogenesis by modulating actin cytoskeletal dynamics. We found that prolonged morphine treatment activated Tiam1 in the spinal dorsal horn and Tiam1 ablation from spinal neurons eliminated morphine antinociceptive tolerance and OIH. At the same time, the pharmacological blockade of Tiam1-Rac1 signalling prevented the development and reserved the established tolerance and OIH. Prolonged morphine treatment increased dendritic spine density and synaptic NMDA receptor activity in spinal dorsal horn neurons, both of which required Tiam1. Furthermore, co-administration of the Tiam1 signalling inhibitor NSC23766 was sufficient to abrogate morphine tolerance in chronic pain management. These findings identify Tiam1-mediated maladaptive plasticity in the spinal nociceptive network as an underlying cause for the development and maintenance of morphine tolerance and OIH and provide a promising therapeutic target to reduce tolerance and prolong morphine use in chronic pain management., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

A ligature-induced periodontitis model was established in wild-type and CD146 CreERT2 ; Rosa tdTomato mice to explore the function of pericytes in alveolar bone formation. We found that during periodontitis progression and periodontal wound healing, CD146 + /NG2 + pericytes were enriched in the periodontal tissue areas, which could migrate to the alveolar bone surface and colocalize with ALP + /OCN + osteoblasts. Chemokine C-X-C motif receptor 4 (CXCR4) inhibition using AMD3100 blocked CD146-Cre + pericyte migration and osteogenesis, as well as further exacerbated periodontitis-associated bone loss. Next, primary pericytes were sorted out by magnetic-activated cell sorting and demonstrated that C-X-C motif chemokine ligand 12 (CXCL12) promotes pericyte migration and osteogenesis via CXCL12-CXCR4-Rac1 signaling. Finally, the local administration of an adeno-associated virus for Rac1 overexpression in NG2 + pericytes promotes osteoblast differentiation of pericytes and increases alveolar bone volume in periodontitis. Thus, our results provided the evidence that pericytes may migrate and osteogenesis via the CXCL12-CXCR4-Rac1 axis during the pathological process of periodontitis., Competing Interests: Declaration of Conflicting InterestsThe authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.