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Ovarian serous carcinoma is a gynecological malignancy associated with a high mortality rate, which is commonly diagnosed in the first instance at a late stage and has a propensity to develop resistance to platinum-based chemotherapy. Identifying reliable biomarkers for platinum sensitivity is critical for improving patient outcomes. The present retrospective study included 64 patients with high-grade serous ovarian carcinoma (Federation of Gynecology and Obstetrics stages III or IV). Patients were classified as platinum-sensitive (no relapse within 6 months of the last platinum administration) or platinum-resistant (relapse within 6 months). Immunohistochemical analysis was performed to evaluate Fyn expression in tumor tissues, and Fyn knockdown experiments were performed using the OVSAHO ovarian cancer cell line to assess carboplatin sensitivity. Fyn expression was significantly higher in platinum-resistant patients compared with in platinum-sensitive patients (P<0.01). A weighted Fyn expression score was developed and a cutoff score of 6 was determined to predict platinum sensitivity with a specificity of 65.5% and a sensitivity of 62.9%. Patients with low Fyn expression (score ≤6) exhibited higher platinum sensitivity and longer overall survival (P<0.05). Multivariate analysis identified Fyn expression and postoperative residual tumor size as independent predictors of platinum sensitivity (P=0.033 and P=0.023, respectively). In vitro, Fyn knockdown significantly increased carboplatin sensitivity in ovarian cancer cells (P<0.05). Fyn, a member of the Src family of kinases, serves a crucial role in various cellular functions and has been implicated in chemotherapy resistance. The results demonstrated a notable association between Fyn expression and platinum sensitivity in ovarian serous carcinoma. The findings suggested that Fyn may serve as a predictive biomarker for response to platinum-based chemotherapy, offering the potential for more personalized treatment strategies. To the best of our knowledge, the present study is the first to establish an association between Fyn expression and platinum sensitivity in advanced ovarian serous carcinoma. Prospective studies with larger, multi-center cohorts and comprehensive biomarker analyses are recommended to validate and extend these results, ultimately improving therapeutic strategies and patient prognosis. [ABSTRACT FROM AUTHOR]

Sepsis, characterized by a widespread and dysregulated immune response to infection leading to organ dysfunction, presents significant challenges in diagnosis and treatment. In this study, we investigated 203 coagulation-related genes in sepsis patients to explore their roles in the disease. Through differential gene expression analysis, we identified 20 genes with altered expression patterns. Subsequent correlation analysis, visualized through circos plots and heatmaps, revealed significant relationships among these genes. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses indicated that these genes are involved in immune response activation, coagulation, and immune receptor activity. Disease Ontology (DO) enrichment analysis further linked these genes to autoimmune hemolytic anemia and tumor-related signaling pathways. Additionally, the CIBERSORT analysis highlighted differences in immune cell composition in sepsis patients, revealing an increase in neutrophils and monocytes and a decrease in inactive NK cells, CD8 T cells, and B cells. We employed machine learning techniques, including random forest and SVM, to construct a diagnostic model, identifying FCER1G and FYN as key biomarkers. These biomarkers were validated through their expression levels and ROC curve analysis in an independent validation cohort, demonstrating strong diagnostic potential. Single-cell analysis from the GSE167363 dataset further confirmed the distinct expression profiles of these genes across various cell types, with FCER1G predominantly expressed in monocytes, NK cells, and platelets, and FYN in CD4+ T cells and NK cells. Enrichment analysis via GSEA and ssGSEA revealed that these genes are involved in critical pathways, including intestinal immune networks, fatty acid synthesis, and antigen processing. In conclusion, our comprehensive analysis identifies FCER1G and FYN as promising biomarkers for sepsis, providing valuable insights into the molecular mechanisms of this complex condition. These findings offer new avenues for the development of targeted diagnostic and therapeutic strategies in sepsis management. [ABSTRACT FROM AUTHOR]

Objectives: This study aimed to explore the expression, clinical significance, and functional mechanism of FYN in lower-grade gliomas (LGG). Methods: The mRNA and protein expression of FYN in LGG tissues were detected using databases including OncoLnc, GEPIA, and Human protein atlas (HPA). The UCSC Xena browser, TIMER, STRING and Metascape databases were used to investigate Kaplan–Meier survival curves, correlations between FYN expression and various types of immune cell infiltration, protein interaction network and possible functional mechanism. Results: FYN expression in LGG, IDH mutation or 1p19q co-deletion subgroup was significantly higher than in corresponding control groups (p < 0.05). Patients with higher FYN expression had longer overall survival (p < 0.05). Male or no 1p19q co-deletion groups with higher FYN expression also had longer overall survival (p < 0.05). FYN expression had close correlation with infiltrating levels of cell purity, CD4+T cells, macrophages, and CD8+T cells (p < 0.05). Protein interaction network result showed correlation among FYN, SH2D1A, LCK, CAV1, SRC, CBL and PTK2. Functional enrichment analysis revealed that FYN and its related genes mainly participated in bacterial invasion of epithelial cells and natural killer cell mediated cytotoxicity. Peptidyl-tyrosine phosphorylation, negative regulation of anoikis, immune effector process, transmembrane receptor protein tyrosine kinase signaling pathway, epidermal growth factor receptor signaling pathway, and negative regulation of protein modification process may be the critical biological process. Conclusions: FYN is up-expressed in LGG and related to its good prognosis. It participated in tumor pathophysiological processes and may be a therapeutic target for LGG. [ABSTRACT FROM AUTHOR]

The SS18-SSX fusion protein is an oncogenic driver in synovial sarcoma. At the molecular level, SS18-SSX functions as both an activator and a repressor to coordinate transcription of different genes responsible for tumorigenesis. Here, we identify the proto-oncogene FYN as a new SS18-SSX target gene and examine its relation to synovial sarcoma therapy. FYN is a tyrosine kinase that promotes cancer growth, metastasis and therapeutic resistance, but SS18-SSX appears to negatively regulate FYN expression in synovial sarcoma cells. Using both genetic and histone deacetylase inhibitor (HDACi)-based pharmacologic approaches, we show that suppression of SS18-SSX leads to FYN reactivation. In support of this notion, we find that blockade of FYN activity synergistically enhances HDACi action to reduce synovial sarcoma cell proliferation and migration. Our results support a role for FYN in attenuation of anti-cancer activity upon inhibition of SS18-SSX function and demonstrate the feasibility of targeting FYN to improve the effectiveness of HDACi treatment against synovial sarcoma. [ABSTRACT FROM AUTHOR]

Abstract Glioma, particularly glioblastomas (GBM), is incurable brain tumor. The most targeted receptor tyrosine kinase (RTKs) drugs did not bring benefit to GBM patients. The mechanism of glioma growth continues to be explored to find more effective treatment. Here, we reported that Ser/Thr protein kinase YANK2 (yet another kinase 2) is upregulated in glioma tissues and promotes the growth and proliferation of glioma in vitro and in vivo. Further, we confirmed that oncogene Fyn directly activated YANK2 through phosphorylation its Y110, and Fyn-mediated YANK2 phosphorylation at Y110 site promotes glioma growth by increasing its stability. Finally, YANK2 was proved to be a novel upstream kinase of p70S6K and promotes glioma growth by directly phosphorylating p70S6K at T389. Taken together, we found a new mTOR-independent p70S6K activation pathway, Fyn-YANK2-p70S6K, which promotes glioma growth, and YANK2 is a potential oncogene and serves as a novel therapeutic target for glioma.

Abstract Background Circular RNAs (circRNAs) play critical roles in the tumorigenesis and radiosensitivity of multiple cancers. Nevertheless, the biological functions of circRNA periostin (circ‐POSTN) in esophageal cancer (EC) progression and radiosensitivity have not been well elucidated. Methods The expression of circ‐POSTN, microRNA‐876‐5p (miR‐876‐5p), and proto‐oncogene tyrosine‐protein kinase (FYN) was analyzed by quantitative reverse transcription PCR (RT‐qPCR). Cell proliferation was assessed by MTT, colony formation, and 5‐ethynyl‐2′‐deoxyuridine (EDU) assays. All protein levels were detected by western blot assay. Cell apoptosis and invasion were assessed by flow cytometry analysis and transwell assay, respectively. Dual‐luciferase reporter and RNA immunoprecipitation (RIP) assays were used to validate the interaction between miR‐876‐5p and circ‐POSTN or FYN. The role of circ‐POSTN in vivo was explored by establishing mice xenograft model. Results Circ‐POSTN was overexpressed in EC tissues and cells. Knockdown of circ‐POSTN inhibited cell proliferation and invasion and elevated apoptosis and radiosensitivity in EC cells. MiR‐876‐5p was a direct target of circ‐POSTN, and its knockdown reversed the role of sh‐circ‐POSTN in EC cells. FYN was a direct target of miR‐876‐5p, and FYN elevation weakened the effects of miR‐876‐5p overexpression on the progression and radiosensitivity of EC cells. Moreover, circ‐POSTN acted as a miR‐876‐5p sponge to regulate FYN expression. Circ‐POSTN interference also suppressed tumor growth and enhanced radiosensitivity in vivo. Conclusion Circ‐POSTN knockdown inhibited proliferation and invasion, but increased apoptosis and enhanced radiosensitivity in EC cells via modulating miR‐876‐5p/FYN axis, which might be a potential diagnostic and therapeutic target for EC.

Background: Circular RNAs (circRNAs) play critical roles in the tumorigenesis and radiosensitivity of multiple cancers. Nevertheless, the biological functions of circRNA periostin (circ‐POSTN) in esophageal cancer (EC) progression and radiosensitivity have not been well elucidated. Methods: The expression of circ‐POSTN, microRNA‐876‐5p (miR‐876‐5p), and proto‐oncogene tyrosine‐protein kinase (FYN) was analyzed by quantitative reverse transcription PCR (RT‐qPCR). Cell proliferation was assessed by MTT, colony formation, and 5‐ethynyl‐2′‐deoxyuridine (EDU) assays. All protein levels were detected by western blot assay. Cell apoptosis and invasion were assessed by flow cytometry analysis and transwell assay, respectively. Dual‐luciferase reporter and RNA immunoprecipitation (RIP) assays were used to validate the interaction between miR‐876‐5p and circ‐POSTN or FYN. The role of circ‐POSTN in vivo was explored by establishing mice xenograft model. Results: Circ‐POSTN was overexpressed in EC tissues and cells. Knockdown of circ‐POSTN inhibited cell proliferation and invasion and elevated apoptosis and radiosensitivity in EC cells. MiR‐876‐5p was a direct target of circ‐POSTN, and its knockdown reversed the role of sh‐circ‐POSTN in EC cells. FYN was a direct target of miR‐876‐5p, and FYN elevation weakened the effects of miR‐876‐5p overexpression on the progression and radiosensitivity of EC cells. Moreover, circ‐POSTN acted as a miR‐876‐5p sponge to regulate FYN expression. Circ‐POSTN interference also suppressed tumor growth and enhanced radiosensitivity in vivo. Conclusion: Circ‐POSTN knockdown inhibited proliferation and invasion, but increased apoptosis and enhanced radiosensitivity in EC cells via modulating miR‐876‐5p/FYN axis, which might be a potential diagnostic and therapeutic target for EC. [ABSTRACT FROM AUTHOR]

Objective Hypoxic–ischemic brain injury in infants often leads to hemiplegic motor dysfunction. The mechanism of their motor dysfunction has been attributed to deficiencies of the transcription factor sex-determining region (SRY) box 2 (Sox2) or the non–receptor-type tyrosine kinase Fyn (involved in neuronal signal transduction), which causes a defect in myelin formation. Constraint-induced movement therapy (CIMT) following cerebral hypoxia–ischemia may stimulate myelin growth by regulating Sox2/Fyn, Ras homolog protein family A (RhoA), and rho-associated kinase 2 (ROCK2) expression levels. This study investigated how Sox2/Fyn regulates myelin remodeling following CIMT to improve motor function in rats with hemiplegic cerebral palsy (HCP). Methods To investigate the mechanism of Sox2 involvement in myelin growth and neural function in rats with HCP, Lentivirus (Lenti)-Sox2 adeno-associated virus and negative control–Lenti-Sox2 (LS) adeno-associated virus were injected into the lateral ventricle. The rats were divided into a control group and an HCP group with different interventions (CIMT, LS, or negative control–LS [NS] treatment), yielding the HCP, HCP plus CIMT (HCP + CIMT), HCP + LS, HCP + LS + CIMT, HCP + NS, and HCP + NS + CIMT groups. Front-limb suspension and RotaRod tests, Golgi-Cox staining, transmission electron microscopy, immunofluorescence staining, western blotting, and quantitative polymerase chain reaction experiments were used to analyze the motor function, dendrite/axon area, myelin ultrastructure, and levels of expression of oligodendrocytes and Sox2/Fyn/RhoA/ROCK2 in the motor cortex. Results The rats in the HCP + LS + CIMT group had better values for motor function, dendrite/axon area, myelin ultrastructure, oligodendrocytes, and Sox2/Fyn/RhoA/ROCK2 expression in the motor cortex than rats in the HCP and HCP + NS groups. The improvement of motor function and myelin remodeling, the expression of oligodendrocytes, and the expression of Sox2/Fyn/RhoA/ROCK2 in the HCP + LS group were similar to those in the HCP + CIMT group. Conclusion CIMT might overcome RhoA/ROCK2 signaling by upregulating the transcription of Sox2 to Fyn in the brain to induce the maturation and differentiation of oligodendrocytes, thereby promoting myelin remodeling and improving motor function in rats with HCP. Impact The pathway mediated by Sox2/Fyn could be a promising therapeutic target for HCP. [ABSTRACT FROM AUTHOR]

Protein zero related (PZR) serves as a substrate and anchor protein for SHP-2, the product of the proto-oncogene PTPN11 that is frequently mutated in cancers. The expression level of PZR is elevated in various cancers, which is correlated with an unfavorable prognosis. The role of PZR in lung cancer is not fully studied. To investigate how PZR affects signaling pathways involved in LUAD development, we utilized the CRISPR technology to knock out PZR expression in SPC-A1 lung adenocarcinoma cells and then conducted RNA sequencing to profile the transcriptome. Our results showed that 226 genes exhibited differential expressions in PZR-knockout SPC-A1 cells vs wild-type cells. Many of the genes encode proteins involved in cell adhesion, migration, actin cytoskeleton organization, and regulation of cell shape. Furthermore, our experimental data showed that PZR-knockout SPC-A1 cells displayed faster attachment to tissue culture dishes and slower detachment from the dishes upon EDTA treatment. The data suggest an important role of PZR in cell–matrix interaction and may provide new insights into the signaling events that regulate cancer development. [ABSTRACT FROM AUTHOR]

Objectives: FTO is known to be involved in cerebral ischemia/reperfusion (I/R) injury. However, its related specific mechanisms during this condition warrant further investigations. This study aimed at exploring the impacts of FTO and the FYN/DRP1 axis on mitochondrial fission, oxidative stress (OS), and ferroptosis in cerebral I/R injury and the underlying mechanisms. Methods: The cerebral I/R models were established in mice via the temporary middle cerebral artery occlusion/reperfusion (tMCAO/R) and hypoxia/reoxygenation models were induced in mouse hippocampal neurons via oxygen–glucose deprivation/reoxygenation (OGD/R). After the gain‐ and loss‐of‐function assays, related gene expression was detected, along with the examination of mitochondrial fission, OS‐ and ferroptosis‐related marker levels, neuronal degeneration and cerebral infarction, and cell viability and apoptosis. The binding of FTO to FYN, m6A modification levels of FYN, and the interaction between FYN and Drp1 were evaluated. Results: FTO was downregulated and FYN was upregulated in tMCAO/R mouse models and OGD/R cell models. FTO overexpression inhibited mitochondrial fission, OS, and ferroptosis to suppress cerebral I/R injury in mice, which was reversed by further overexpressing FYN. FTO overexpression also suppressed mitochondrial fission and ferroptosis to increase cell survival and inhibit cell apoptosis in OGD/R cell models, which was aggravated by additionally inhibiting DRP1. FTO overexpression inhibited FYN expression via the m6A modification to inactive Drp1 signaling, thus reducing mitochondrial fission and ferroptosis and enhancing cell viability in cells. Conclusions: FTO overexpression suppressed FYN expression through m6A modification, thereby subduing Drp1 activity and relieving cerebral I/R injury. [ABSTRACT FROM AUTHOR]

Branched chain α-keto acid dehydrogenase kinase (BCKDK) is a key enzyme involved in the metabolism of branched-chain amino acids (BCAAs). Its potential as a therapeutic target and prognostic factor for a variety of cancers has been widely reported. In this study, we investigated the expression of BCKDK in clinical glioma samples and found that BCKDK was significantly overexpressed in glioblastoma (GBM) and was associated with its poor prognosis. We further found that BCKDK is phosphorylated by tyrosine protein kinase Fyn at Y151, which increases its catalytic activity and stability, and demonstrate through in vivo and in vitro experiments that BCKDK phosphorylation promotes GBM cell proliferation. In addition, we found that the levels of the metabolite N-acetyl-L-alanine (NAAL) in GBM cells with high BCKDK were higher than those in the silencing group, and silencing or inhibition of BCKDK promotes the expression of ACY1, an enzyme that catalyzes the hydrolysis of NAAL into acetic acid and alanine. Exogenous addition of NAAL can activate the ERK signaling pathway and promote the proliferation of GBM cells. Taken together, we identified a novel mechanism of BCKDK activation and found NAAL is a novel oncogenic metabolite. Our study confirms the importance of the Fyn-BCKDK-ACY1-NAAL signalling axis in the development of GBM and suggests that p-BCKDK (Y151) and NAAL can serve as potential predictors of GBM progression and prognosis.

The SS18-SSX fusion protein is an oncogenic driver in synovial sarcoma. At the molecular level, SS18-SSX functions as both an activator and a repressor to coordinate transcription of different genes responsible for tumorigenesis. Here, we identify the proto-oncogene FYN as a new SS18-SSX target gene and examine its relation to synovial sarcoma therapy. FYN is a tyrosine kinase that promotes cancer growth, metastasis and therapeutic resistance, but SS18-SSX appears to negatively regulate FYN expression in synovial sarcoma cells. Using both genetic and histone deacetylase inhibitor (HDACi)-based pharmacologic approaches, we show that suppression of SS18-SSX leads to FYN reactivation. In support of this notion, we find that blockade of FYN activity synergistically enhances HDACi action to reduce synovial sarcoma cell proliferation and migration. Our results support a role for FYN in attenuation of anti-cancer activity upon inhibition of SS18-SSX function and demonstrate the feasibility of targeting FYN to improve the effectiveness of HDACi treatment against synovial sarcoma.

Diabetic nephropathy (DN) is a significant complication of diabetes and the leading cause of end-stage renal disease. Hyperglycemia-induced dysfunction of the glomerular podocytes is a major contributor to the deterioration of renal function in DN. Previously, we demonstrated that podocyte-specific disruption of the Src homology phosphatase 2 (Shp2) ameliorated lipopolysaccharide-induced renal injury. This study aims to evaluate the contribution of Shp2 to podocyte function under hyperglycemia and explore the molecular underpinnings. We report elevated Shp2 in the E11 podocyte cell line under high glucose and the kidney under streptozotocin- and high-fat diet-induced hyperglycemia. Consistently, Shp2 disruption in podocytes was associated with partial renoprotective effects under hyperglycemia, as evidenced by the preserved renal function. At the molecular level, Shp2 deficiency was associated with altered renal insulin signaling and diminished hyperglycemia-induced renal endoplasmic reticulum stress, inflammation, and fibrosis. Additionally, Shp2 knockdown in E11 podocytes mimicked the in vivo deficiency of this phosphatase and ameliorated the deleterious impact of high glucose, whereas Shp2 reconstitution reversed these effects. Moreover, Shp2 deficiency attenuated high glucose-induced E11 podocyte migration. Further, we identified the protein tyrosine kinase FYN as a putative mediator of Shp2 signaling in podocytes under high glucose. Collectively, these findings suggest that Shp2 inactivation may afford protection to podocytes under hyperglycemia and highlight this phosphatase as a potential target to ameliorate glomerular dysfunction in DN.

Abstract Background The Ca2+-independent contraction of vascular smooth muscle is a leading cause of cardiovascular and cerebrovascular spasms. In the previous study, we demonstrated the involvement of Src family protein tyrosine kinase Fyn and Rho-kinase in the sphingosylphosphorylcholine (SPC)-induced abnormal and Ca2+-independent contraction of vascular smooth muscle, but the specific mechanism has not been completely clarified. Methods Paxillin knockdown human coronary artery smooth muscle cells (CASMCs) and smooth muscle-specific paxillin knockout mice were generated by using paxillin shRNA and the tamoxifen-inducible Cre-LoxP system, respectively. CASMCs contraction was observed by time-lapse recording. The vessel contractility was measured by using a myography assay. Fyn, Rho-kinase, and myosin light chain activation were assessed by immunoprecipitation and western blotting. The paxillin expression and actin stress fibers were visualized by histological analysis and immunofluorescent staining. Results The SPC-induced abnormal contraction was inhibited in paxillin knockdown CASMCs and arteries of paxillin knockout mice, indicating that paxillin is involved in this abnormal contraction. Further study showed that paxillin knockdown inhibited the SPC-induced Rho-kinase activation without affecting Fyn activation. In addition, paxillin knockdown significantly inhibited the SPC-induced actin stress fiber formation and myosin light chain phosphorylation. These results suggest that paxillin, as an upstream molecule of Rho-kinase, is involved in the SPC-induced abnormal contraction of vascular smooth muscle. Conclusions The present study demonstrated that paxillin participates in the SPC-induced abnormal vascular smooth muscle contraction by regulating Rho-kinase activation. Video Abstract

The role of tumor necrosis factor-α (TNF-α) in Alzheimer's disease (AD) has recently become a topic of debate. TNF-α levels increase in the blood of patients with AD, and amyloid beta (Aβ) plaques contain TNF-α deposits. The therapeutic efficacy of blocking TNF-α in patients with AD remains controversial as it is mostly based on preclinical studies. Thus, whether and how TNF-α contributes to amyloidogenic processes in AD is still an open question to be addressed. We analyzed plasma TNF-α and Aβ42 levels in patients with subjective cognitive impairment (SCI), mild cognitive impairment (MCI), and AD, and in healthy volunteers (HLT). In addition, we performed correlation analysis to evaluate whether changes in plasma TNF-α levels correlate with cognitive decline, Aβ42 levels, age, and BMI, which are all factors considered to contribute to or predispose individuals to AD. We found that TNF-α and Aβ42 plasma levels were higher in patients with AD than in HLT individuals. High TNF-α levels were also observed in patients with SCI, in whom TNF-α and Aβ42 levels were negatively correlated. Notably, TNF-α did not affect the amyloidogenic pathway in human microglial cultures exposed to 48 h of incubation, although it did trigger neuroinflammatory processes. These results imply that high TNF-α levels are more likely to be a clinical condition linked to AD than are direct contributors. Nonetheless, elevated levels of TNF-α in early-stage patients, like those with SCI and MCI, may provide a distinguishing feature for identifying clinical profiles that are at risk of having a poorer outcome in AD and could benefit from tailored therapies. [ABSTRACT FROM AUTHOR]

Five muscarinic acetylcholine (mACh) receptor subtypes are divided into two classes: the M1 class (M1, M3, and M5) and the M2 class (M2 and M4). The former is coupled to Gq proteins, while the latter is coupled to Gi/o proteins. Accumulating evidence indicates that mACh receptors play a significant role in the regulation of the Src family kinase (SFK), a subfamily of non-receptor tyrosine kinases. mACh receptors exert their roles in a subtype-dependent fashion and preferentially target Src and Fyn, two members of SFKs that are expressed in the brain and enriched at synaptic sites. While the M1 receptor positively modulates SFK activity, the M4 receptor inhibits it. By modulating SFKs, mACh receptors are actively involved in the regulation of expression and function of a variety of receptors, structural proteins, and signaling molecules. In particular, the M4 receptor and the dopamine D1 receptor are coexpressed in striatonigral projection neurons of the striatum. Gi/o-coupled M4 and Gq-coupled D1 receptors antagonistically regulate SFK activity, thereby forming a dynamic balance controlling glutamate receptor activity, excitability of neurons, and synaptic plasticity. In summary, mACh receptors play a crucial role in regulating SFK activity in heterologous cells and neurons. [ABSTRACT FROM AUTHOR]

Background: The Ca2+-independent contraction of vascular smooth muscle is a leading cause of cardiovascular and cerebrovascular spasms. In the previous study, we demonstrated the involvement of Src family protein tyrosine kinase Fyn and Rho-kinase in the sphingosylphosphorylcholine (SPC)-induced abnormal and Ca2+-independent contraction of vascular smooth muscle, but the specific mechanism has not been completely clarified. Methods: Paxillin knockdown human coronary artery smooth muscle cells (CASMCs) and smooth muscle-specific paxillin knockout mice were generated by using paxillin shRNA and the tamoxifen-inducible Cre-LoxP system, respectively. CASMCs contraction was observed by time-lapse recording. The vessel contractility was measured by using a myography assay. Fyn, Rho-kinase, and myosin light chain activation were assessed by immunoprecipitation and western blotting. The paxillin expression and actin stress fibers were visualized by histological analysis and immunofluorescent staining. Results: The SPC-induced abnormal contraction was inhibited in paxillin knockdown CASMCs and arteries of paxillin knockout mice, indicating that paxillin is involved in this abnormal contraction. Further study showed that paxillin knockdown inhibited the SPC-induced Rho-kinase activation without affecting Fyn activation. In addition, paxillin knockdown significantly inhibited the SPC-induced actin stress fiber formation and myosin light chain phosphorylation. These results suggest that paxillin, as an upstream molecule of Rho-kinase, is involved in the SPC-induced abnormal contraction of vascular smooth muscle. Conclusions: The present study demonstrated that paxillin participates in the SPC-induced abnormal vascular smooth muscle contraction by regulating Rho-kinase activation. Ak4aWCsjd4r4atTQ7PUYn2 Video Abstract [ABSTRACT FROM AUTHOR]

Micro/nano topological modification is critical for improving the in vivo behaviors of bone implants, regulating multiple cellular functions. Titania (TiO2) nanotubes show the capacity of promoting osteoblast-related cell differentiation and induce effective osseointegration, serving as a model material for studying the effects of micro/nano-topological modifications on cells. However, the intracellular signaling pathways by which TiO2 nanotubes regulate the osteogenic differentiation of stem cells are not fully defined. Thy-1 (CD90), a cell surface glycoprotein anchored by glycosylphosphatidylinositol, has been considered a key molecule in osteoblast differentiation in recent years. Nevertheless, whether the micro/nano topology of the implant surface leads to changes in Thy-1 is unknown, as well as whether these changes promote osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs). Here, TiO2 nanotubes of various diameters were prepared by adjusting the anodizing voltage. qPCR and immunoblot were carried out to assess the mechanism by which TiO2 nanotubes regulate Thy-1. The results revealed Ti plates harboring TiO2 nanotubes ∼100-nm diameter (TNT-100) markedly upregulated Thy-1. Subsequently, upregulated Thy-1 promoted the activation of Fyn/RhoA/MLC Ⅱ/F-actin axis, which enhanced the nuclear translocation of YAP. After Thy-1 knockdown by siRNA, the Fyn/RhoA/MLC Ⅱ/F-actin axis was significantly inhibited and TiO2 nanotubes showed decreased effects on osteogenic differentiation. Therefore, Thy-1 upregulation might be a major mechanism by which micro/nano-topological modification of TiO2 nanotubes promotes osteogenic differentiation in BMSCs. This study provides novel insights into the molecular mechanism of TiO2 nanotubes, which may help design improved bone implants for clinical application.

Our previous studies demonstrated that traumatic brain injury (TBI) and ventricular administration of thrombin caused hippocampal neuron loss and cognitive dysfunction via activation of Src family kinases (SFKs). Based on SFK localization in brain, we hypothesized SFK subtypes Fyn and c-Src, as well as SFK downstream molecule Rho-associated protein kinase (ROCK), contribute to cell death and cognitive dysfunction after TBI. We administered nanoparticle wrapped small interfering RNA (siRNA)-Fyn and siRNA-c-Src, or ROCK inhibitor Y-27632 to adult rats subjected to moderate lateral fluid percussion (LFP)-induced TBI. Spatial memory function was assessed from 12 to 16 days, and NeuN stained hippocampal neurons were assessed 16 days after TBI. The combination of siRNA-Fyn and siRNA-c-Src, but neither alone, prevented hippocampal neuron loss and spatial memory deficits after TBI. The ROCK inhibitor Y-27632 also prevented hippocampal neuronal loss and spatial memory deficits after TBI. The data suggest that the combined actions of three kinases (Fyn, c-Src, ROCK) mediate hippocampal neuronal cell death and spatial memory deficits produced by LFP-TBI, and that inhibiting this pathway prevents the TBI-induced cell death and memory deficits.

Thyroid hormones (THs) are essential in neuronal and glial cell development and differentiation, synaptogenesis, and myelin sheath formation. In addition to nuclear receptors, TH acts through αvβ3-integrin on the plasma membrane, influencing transcriptional regulation of signaling proteins that, in turn, affect adhesion and survival of nerve cells in various neurologic disorders. TH exhibits protective properties during brain hypoxia; however, precise intracellular mechanisms responsible for the preventive effects of TH remain unclear. In this study, we investigated the impact of TH on integrin αvβ3-dependent downstream systems in normoxic and hypoxic conditions of pheochromocytoma PC12 cells. Our findings reveal that triiodothyronine (T3), acting through αvβ3-integrin, induces activation of the JAK2/STAT5 pathway and suppression of the SHP2 in hypoxic PC12 cells. This activation correlates with the downregulation of the expression palmitoyltransferase-ZDHHC2 and ZDHHC9 genes, leading to a subsequent decrease in palmitoylation and phosphorylation of Fyn tyrosine kinase. We propose that these changes may occur due to STAT5-dependent epigenetic silencing of the palmitoyltransferase gene, which in turn reduces palmitoylation/phosphorylation of Fyn with a subsequent increase in the survival of cells. In summary, our study provides the first evidence demonstrating the involvement of integrin-dependent JAK/STAT pathway, SHP2 suppression, and altered post-translational modification of Fyn in protective effects of T3 during hypoxia.

Abstract Background The identification of pathogenic mutations in Alzheimer’s disease (AD) causal genes led to a better understanding of the pathobiology of AD. Familial Alzheimer’s disease (FAD) is known to be associated with mutations in the APP, PSEN1, and PSEN2 genes involved in Aβ production; however, these genetic defects occur in only about 10–20% of FAD cases, and more genes and new mechanism causing FAD remain largely obscure. Methods We performed exome sequencing on family members with a FAD pedigree and identified gene variant ZDHHC21 p.T209S. A ZDHHC21T209S/T209S knock-in mouse model was then generated using CRISPR/Cas9. The Morris water navigation task was then used to examine spatial learning and memory. The involvement of aberrant palmitoylation of FYN tyrosine kinase and APP in AD pathology was evaluated using biochemical methods and immunostaining. Aβ and tau pathophysiology was evaluated using ELISA, biochemical methods, and immunostaining. Field recordings of synaptic long-term potentiation were obtained to examine synaptic plasticity. The density of synapses and dendritic branches was quantified using electron microscopy and Golgi staining. Results We identified a variant (c.999A > T, p.T209S) of ZDHHC21 gene in a Han Chinese family. The proband presented marked cognitive impairment at 55 years of age (Mini-Mental State Examination score = 5, Clinical Dementia Rating = 3). Considerable Aβ retention was observed in the bilateral frontal, parietal, and lateral temporal cortices. The novel heterozygous missense mutation (p.T209S) was detected in all family members with AD and was not present in those unaffected, indicating cosegregation. ZDHHC21T209S/T209S mice exhibited cognitive impairment and synaptic dysfunction, suggesting the strong pathogenicity of the mutation. The ZDHHC21 p.T209S mutation significantly enhanced FYN palmitoylation, causing overactivation of NMDAR2B, inducing increased neuronal sensitivity to excitotoxicity leading to further synaptic dysfunction and neuronal loss. The palmitoylation of APP was also increased in ZDHHC21T209S/T209S mice, possibly contributing to Aβ production. Palmitoyltransferase inhibitors reversed synaptic function impairment. Conclusions ZDHHC21 p.T209S is a novel, candidate causal gene mutation in a Chinese FAD pedigree. Our discoveries strongly suggest that aberrant protein palmitoylation mediated by ZDHHC21 mutations is a new pathogenic mechanism of AD, warranting further investigations for the development of therapeutic interventions.

Metastasis is the leading cause of death in breast cancer patients due to the lack of effective therapies. Elevated levels of paxillin expression have been observed in various cancer types, with tyrosine phosphorylation shown to play a critical role in driving cancer cell migration. However, the specific impact of the distinct tyrosine phosphorylation events of paxillin in the progression of breast cancer remains to be fully elucidated. Here, we found that paxillin overexpression in breast cancer tissue is associated with a patient's poor prognosis. Paxillin knockdown inhibited the migration and invasion of breast cancer cells. Furthermore, the phosphorylation of paxillin tyrosine residue 31 (Tyr31) was significantly increased upon the TGF-β1-induced migration and invasion of breast cancer cells. Inhibiting Fyn activity or silencing Fyn decreases paxillin Tyr31 phosphorylation. The wild-type and constitutively active Fyn directly phosphorylate paxillin Tyr31 in an in vitro system, indicating that Fyn directly phosphorylates paxillin Tyr31. Additionally, the non-phosphorylatable mutant of paxillin at Tyr31 reduces actin stress fiber formation, migration, and invasion of breast cancer cells. Taken together, our results provide direct evidence that Fyn-mediated paxillin Tyr31 phosphorylation is required for breast cancer migration and invasion, suggesting that targeting paxillin Tyr31 phosphorylation could be a potential therapeutic strategy for mitigating breast cancer metastasis. [ABSTRACT FROM AUTHOR]

The tyrosine kinase Fyn is a member of the SRC family of kinases, and its sustained activation is closely linked to tumor cell migration, proliferation, and cell metabolism. Recently, Fyn has been found to be expressed in various tumor tissues, and the expression and function of Fyn vary between tumors, with Fyn acting as an oncogene to promote proliferation and metastasis in some tumors. This article summarizes the recent studies on the role of Fyn in different human tumors, focusing on the role of Fyn in melanoma, breast cancer, glioma, lung cancer, and peripheral T-cell lymphoma in order to provide a basis for future research and targeted therapy in different human tumors. [ABSTRACT FROM AUTHOR]

In the developing and adult CNS, new oligodendrocytes (OLs) are generated from a population of cells known as oligodendrocyte precursor cells (OPCs). As they begin to differentiate, OPCs undergo a series of highly regulated changes to morphology, gene expression, and membrane organization. This stage represents a critical bottleneck in oligodendrogliogenesis, and the regulatory program that guides it is still not fully understood. Here, we show that in vivo toxin-mediated cleavage of the vesicle associated SNARE proteins VAMP2/3 in the OL lineage of both male and female mice impairs the ability of early OLs to mature into functional, myelinating OLs. In the developing mouse spinal cord, many VAMP2/3-cleaved OLs appeared to stall in the premyelinating, early OL stage, resulting in an overall loss of both myelin density and OL number. The Src kinase Fyn, a key regulator of oligodendrogliogenesis and myelination, is highly expressed among premyelinating OLs, but its expression decreases as OLs mature. We found that OLs with cleaved VAMP2/3 in the spinal cord white matter showed significantly higher expression of Fyn compared with neighboring control cells, potentially because of an extended premyelinating stage. Overall, our results show that functional VAMP2/3 in OL lineage cells is essential for proper myelin formation and plays a major role in controlling the maturation and terminal differentiation of premyelinating OLs. [ABSTRACT FROM AUTHOR]

Abstract Background FYN is a nonreceptor tyrosine kinase that regulates diverse pathological processes. The pro-cancer role of FYN in multiple malignancies has been elucidated. However, the mechanisms that FYN promotes gastric cancer (GC) progression remain largely unknown. Methods In vitro and in vivo assays were used to investigate the function of FYN. FYN, TOPK, p-TOPK expression in GC specimens were detected by immunohistochemistry. Phosphoproteomics assays identify TOPK downstream substrate molecules. The molecular mechanism was determined using COIP assays, pull-down assays, immunofluorescence co-localization assays, western blotting, 32p-labeled isotope radioautography assays, vitro kinase assays, and TOPK knockout mice. Results FYN was found to be significantly upregulated in GC tissues as well as in GC cells. Knockdown of FYN expression markedly attenuated the malignant phenotype of GC cells in vitro and in vivo. Mechanistically, we identified TOPK/PBK as a novel downstream substrate of FYN, FYN directly phosphorylates TOPK at Y272. One phosphospecific antibodies against Y272 was developed to validate the phosphorylation of TOPK by FYN. Moreover, the TOPK-272F mutation impaired the interaction between TOPK and FYN, leading to disappeared TOPK phosphorylation. Consistently, human GC tissues displayed increased p-TOPK(Y272), which correlated with poor survival. Phosphoproteomics results showed a significant downregulation of both HSPB1 and p-HSPB1(ser15) in TOPK-knockdown cells, which was confirmed by TOPK-konckout mice. Conclusions FYN directly binds to TOPK in GC cells and phosphorylates TOPK at the Y272, which leads to proliferation and metastasis of GC. FYN-TOPK axis facilitates GC progression by phosphorylating HSPB1. Collectively, our study elucidates the pivotal role of the FYN-TOPK-HSPB1 cascade in GC.

Background: Tyrosine kinase Fyn is a member of the Src family of kinases. In addition to the wild type, three mRNA splice isoforms of Fyn have been identified; Fyn-B, Fyn-T, and Fyn-C. Fyn-T is highly expressed in T lymphocytes, and its expression level is significantly higher in mature T cells than in immature T cells. The abnormal expression of Fyn is closely related to the metabolism, proliferation, and migration of tumor cells. Recent studies have shown that Fyn is expressed in a variety of tumor tissues, and its expression and function vary among different tumors. In some tumors, Fyn acts as a pro-oncogene to promote tumor proliferation and metastasis. Moreover, Fyn mutations have been detected in many hematological tumors in recent years, suggesting a critical regulatory role of Fyn in the development of malignancies. Methods: This review analyzed the relevant literature in PubMed and other databases. Purpose: The aim of this study was to systemically review recent research findings on various aspects of Fyn in the pathogenesis and treatment of different types of hematological malignancies and suggests possible future research directions for targeted tumor therapy. Conclusion: Fyn could be a novel prognostic marker and therapeutic target. Treatment option targeting Fyn might be beneficial for future studies. [ABSTRACT FROM AUTHOR]

Background: Reduced folate status and elevated levels of circulating homocysteine are modifiable risk factors for cognitive decline and dementia. Disturbances in one‐carbon metabolism are associated with the pathological accumulation of phosphorylated tau, a hallmark feature of prevalent dementia, including Alzheimer's disease and subgroups of frontotemporal dementia. Methods: Here, using transgenic TAU58/2 mouse models of human tauopathy, we tested whether dietary supplementation with L‐methylfolate (the active folate form), choline and betaine can reduce tau phosphorylation and associated behavioural phenotypes. Results: TAU58/2 mice fed with the methyl donor‐enriched diet showed reduced phosphorylation of tau at the pathological S202 (CP13) and S396/S404 (PHF‐1) epitopes and alleviation of associated motor and learning deficits. Compared with mice on the control diet, the decrease in cortical phosphorylated tau levels in mice fed with the methyl donor‐enriched diet was associated with enhanced methylation of protein phosphatase 2A, the major brain tau Ser/Thr phosphatase. It also correlated with a reduction in protein levels of Fyn, a tau tyrosine kinase that plays a central role in mediating pathological tau‐induced neurodegeneration. Conversely, Fyn expression levels were increased in mice with deficiencies in folate metabolism. Conclusions: Our findings provide the first experimental evidence that boosting one‐carbon metabolism with L‐methylfolate, choline and betaine can mitigate key pathological, learning and motor deficits in a tauopathy mouse model. They give support to using a combination of methyl donors as a preventive or disease‐modifying strategy for tauopathies. [ABSTRACT FROM AUTHOR]

Background: The identification of pathogenic mutations in Alzheimer's disease (AD) causal genes led to a better understanding of the pathobiology of AD. Familial Alzheimer's disease (FAD) is known to be associated with mutations in the APP, PSEN1, and PSEN2 genes involved in Aβ production; however, these genetic defects occur in only about 10–20% of FAD cases, and more genes and new mechanism causing FAD remain largely obscure. Methods: We performed exome sequencing on family members with a FAD pedigree and identified gene variant ZDHHC21 p.T209S. A ZDHHC21T209S/T209S knock-in mouse model was then generated using CRISPR/Cas9. The Morris water navigation task was then used to examine spatial learning and memory. The involvement of aberrant palmitoylation of FYN tyrosine kinase and APP in AD pathology was evaluated using biochemical methods and immunostaining. Aβ and tau pathophysiology was evaluated using ELISA, biochemical methods, and immunostaining. Field recordings of synaptic long-term potentiation were obtained to examine synaptic plasticity. The density of synapses and dendritic branches was quantified using electron microscopy and Golgi staining. Results: We identified a variant (c.999A > T, p.T209S) of ZDHHC21 gene in a Han Chinese family. The proband presented marked cognitive impairment at 55 years of age (Mini-Mental State Examination score = 5, Clinical Dementia Rating = 3). Considerable Aβ retention was observed in the bilateral frontal, parietal, and lateral temporal cortices. The novel heterozygous missense mutation (p.T209S) was detected in all family members with AD and was not present in those unaffected, indicating cosegregation. ZDHHC21T209S/T209S mice exhibited cognitive impairment and synaptic dysfunction, suggesting the strong pathogenicity of the mutation. The ZDHHC21 p.T209S mutation significantly enhanced FYN palmitoylation, causing overactivation of NMDAR2B, inducing increased neuronal sensitivity to excitotoxicity leading to further synaptic dysfunction and neuronal loss. The palmitoylation of APP was also increased in ZDHHC21T209S/T209S mice, possibly contributing to Aβ production. Palmitoyltransferase inhibitors reversed synaptic function impairment. Conclusions: ZDHHC21 p.T209S is a novel, candidate causal gene mutation in a Chinese FAD pedigree. Our discoveries strongly suggest that aberrant protein palmitoylation mediated by ZDHHC21 mutations is a new pathogenic mechanism of AD, warranting further investigations for the development of therapeutic interventions. [ABSTRACT FROM AUTHOR]

Tubulointerstitial fibrosis is a common pathological change in end-stage renal disease. However, limited treatment methods are developed, and unexplained potential mechanisms of renal diseases are urgent problems to be solved. In the present research, we first elucidated the role of podocarpusflavone (POD), a biflavone compound, in unilateral ureteral obstruction (UUO) in rodent model which is characterized by inflammation and fibrosis. The changes in histology and immunohistochemistry were observed that POD exerted renoprotective effects by retarding the infiltration of macrophage and aberrant deposition of ɑ-SMA, Col1a1, and fibronectin. Consistent with in vivo assay, POD treatment also ameliorated the process of fibrosis in TGF-β1-stimulated renal tubular epithelial cells and inflammation in LPS-induced RAW264.7 cells in vitro. In terms of mechanism, our results showed that treatment with POD inhibited the aggravated activation of Fyn in the UUO group, and weakened the level of phosphorylation of Stat3 which indicated that POD may alleviate the process of fibrosis by the Fyn/Stat3 signaling pathway. Furthermore, the gain of function assay by lentivirus-mediated exogenous forced expression of Fyn abrogated the therapeutic effect of the POD on renal fibrosis and inflammation. Collectively, it can be concluded that POD exerted a protective effect on renal fibrosis by mediating Fyn/Stat3 signaling pathway. [ABSTRACT FROM AUTHOR]

Abstract Background Oligodendrocytes have robust regenerative ability and are key players in remyelination during physiological and pathophysiological states. However, the mechanisms of brain microenvironmental cue in regulation of the differentiation of oligodendrocytes still needs to be further investigated. Results We demonstrated that myelin-associated glycoprotein (MAG) was a novel receptor for angiopoietin-like protein 2 (ANGPTL2). The binding of ANGPTL2 to MAG efficiently promoted the differentiation of oligodendrocytes in vitro, as evaluated in an HCN cell line. Angptl2-null mice had a markedly impaired myelination capacity in the early stage of oligodendrocyte development. These mice had notably decreased remyelination capacities and enhanced motor disability in a cuprizone-induced demyelinating mouse model, which was similar to the Mag-null mice. The loss of remyelination ability in Angptl2-null/Mag-null mice was similar to the Angptl2-WT/Mag-null mice, which indicated that the ANGPTL2-mediated oligodendrocyte differentiation effect depended on the MAG receptor. ANGPTL2 bound MAG to enhance its phosphorylation level and recruit Fyn kinase, which increased Fyn phosphorylation levels, followed by the transactivation of myelin regulatory factor (MYRF). Conclusion Our study demonstrated an unexpected cross-talk between the environmental protein (ANGPTL2) and its surface receptor (MAG) in the regulation of oligodendrocyte differentiation, which may benefit the treatment of many demyelination disorders, including multiple sclerosis.

Abstract Src family protein kinases (SFKs) play a key role in cell adhesion, invasion, proliferation, survival, apoptosis, and angiogenesis during tumor development. In humans, SFKs consists of eight family members with similar structure and function. There is a high level of overexpression or hyperactivity of SFKs in tumor, and they play an important role in multiple signaling pathways involved in tumorigenesis. FYN is a member of the SFKs that regulate normal cellular processes. Additionally, FYN is highly expressed in many cancers and promotes cancer growth and metastasis through diverse biological functions such as cell growth, apoptosis, and motility migration, as well as the development of drug resistance in many tumors. Moreover, FYN is involved in the regulation of multiple cancer-related signaling pathways, including interactions with ERK, COX-2, STAT5, MET and AKT. FYN is therefore an attractive therapeutic target for various tumor types, and suppressing FYN can improve the prognosis and prolong the life of patients. The purpose of this review is to provide an overview of FYN’s structure, expression, upstream regulators, downstream substrate molecules, and biological functions in tumors.

Thirteen benzylethoxyaryl ureas have been synthesized and biologically evaluated as multitarget inhibitors of VEGFR-2 and PD-L1 proteins to overcome resistance phenomena offered by cancer. The antiproliferative activity of these molecules on several tumor cell lines (HT-29 and A549), on the endothelial cell line HMEC-1, on immune cells (Jurkat T) and on the non-tumor cell line HEK-293 has been determined. Selective indexes (SI) have been also determined and compounds bearing p-substituted phenyl urea unit together with a diaryl carbamate exhibited high SI values. Further studies on these selected compounds to determine their potential as small molecule immune potentiators (SMIPs) and as antitumor agents have been performed. From these studies, we have concluded that the designed ureas have good tumor antiangiogenic properties, exhibit good inhibition of CD11b expression, and regulate pathways involved in CD8 T-cell activity. These properties suggest that these compounds could be potentially useful in the development of new cancer immune treatments. [ABSTRACT FROM AUTHOR]

Background: FYN is a nonreceptor tyrosine kinase that regulates diverse pathological processes. The pro-cancer role of FYN in multiple malignancies has been elucidated. However, the mechanisms that FYN promotes gastric cancer (GC) progression remain largely unknown. Methods: In vitro and in vivo assays were used to investigate the function of FYN. FYN, TOPK, p-TOPK expression in GC specimens were detected by immunohistochemistry. Phosphoproteomics assays identify TOPK downstream substrate molecules. The molecular mechanism was determined using COIP assays, pull-down assays, immunofluorescence co-localization assays, western blotting, 32p-labeled isotope radioautography assays, vitro kinase assays, and TOPK knockout mice. Results: FYN was found to be significantly upregulated in GC tissues as well as in GC cells. Knockdown of FYN expression markedly attenuated the malignant phenotype of GC cells in vitro and in vivo. Mechanistically, we identified TOPK/PBK as a novel downstream substrate of FYN, FYN directly phosphorylates TOPK at Y272. One phosphospecific antibodies against Y272 was developed to validate the phosphorylation of TOPK by FYN. Moreover, the TOPK-272F mutation impaired the interaction between TOPK and FYN, leading to disappeared TOPK phosphorylation. Consistently, human GC tissues displayed increased p-TOPK(Y272), which correlated with poor survival. Phosphoproteomics results showed a significant downregulation of both HSPB1 and p-HSPB1(ser15) in TOPK-knockdown cells, which was confirmed by TOPK-konckout mice. Conclusions: FYN directly binds to TOPK in GC cells and phosphorylates TOPK at the Y272, which leads to proliferation and metastasis of GC. FYN-TOPK axis facilitates GC progression by phosphorylating HSPB1. Collectively, our study elucidates the pivotal role of the FYN-TOPK-HSPB1 cascade in GC. [ABSTRACT FROM AUTHOR]

Adipogenesis is a finely controlled process and its dysfunction may contribute to metabolic disorders such as obesity. Metastasis suppressor 1 (MTSS1) is a player in tumorigenesis and metastasis of various types of cancers. To date, it is not known whether and how MTSS1 plays a role in adipocyte differentiation. In the current study, we found that MTSS1 was upregulated during adipogenic differentiation of established mesenchymal cell lines and primary cultured bone marrow stromal cells. Gain‐of‐function and loss‐of‐function experiments uncovered that MTSS1 facilitated adipocyte differentiation from mesenchymal progenitor cells. Mechanistic explorations revealed that MTSS1 bound and interacted with FYN, a member of Src family of tyrosine kinases (SFKs), and protein tyrosine phosphatase receptor‐δ (PTPRD). We demonstrated that PTPRD was capable of inducing the differentiation of adipocytes. Overexpression of PTPRD attenuated the impaired adipogenesis induced by the siRNA targeting MTSS1. Both MTSS1 and PTPRD activated SFKs by suppressing the phosphorylation of SFKs at Tyr530 and inducing the phosphorylation of FYN at Tyr419. Further investigation showed that MTSS1 and PTPRD were able to activate FYN. Collectively, our study has for the first time unraveled that MTSS1 plays a role in adipocyte differentiation in vitro through interacting with PTPRD and thereby activating SFKs such as FYN tyrosine kinase. [ABSTRACT FROM AUTHOR]

Neuroinflammation is the common pathological feature of neuropsychiatric diseases. Chrysin, a kind of natural flavonoid compound, was reported to exert antidepressant effects, however the direct targets of chrysin remain unclear. Currently studies showed chrysin alleviated CUMS-induced depressive-like behaviors in mice. We found chrysin inhibited CUMS-induced microglia activation in mice. We further found that chrysin inhibited the activation of Fyn and NF-κB pathway, and decreased the expression of iNOS, COX2 and NLRP3. Furthermore, our data showed that chrysin can bind to Fyn using pull-down assay. Transfection siRNA-Fyn abolished the inhibitory effect of chrysin on activation of NF-κB pathway. This study revealed that targeting inhibition of Fyn by chrysin to alleviate CUMS-induced neuroinflammation and depressive-like behaviors via inhibiting the expression of iNOS, COX2 and NLRP3 mediated by inhibition of NF-κB pathway. Thus, this study has revealed, for the first time, Fyn was the direct target of chrysin against neuroinflammation and neuroinflammation-related depression.

Fyn is a member of the Src family of protein tyrosine kinases (PTKs) that plays an important role not only in normal synaptic functions but also in brain pathologies including alcohol use disorder. We previously reported that repeated cycles of binge drinking and withdrawal activate Fyn in the dorsomedial striatum (DMS) of rodents, and that Fyn signaling in the DMS contributes to rat alcohol intake and relapse. Here, we used AZD0530, a CNS penetrable inhibitor of Src PTKs developed for the treatment of Alzheimer disease and cancer and tested its efficacy to suppress alcohol-dependent molecular and behavioral effects. We show that systemic administration of AZD0530 prevents alcohol-induced Fyn activation and GluN2B phosphorylation in the DMS of mice. We further report that a single dose of AZD0530 reduces alcohol operant self-administration and promotes extinction of alcohol self-administration without altering basal and dopamine D1 receptor-dependent locomotion. Together, our findings suggest that AZD0530, through its inhibitory actions on Fyn kinase, dampens alcohol seeking and drinking.

We previously discovered that the SPC/Fyn/Rho-kinase (ROK) pathway mediates the Ca2+-sensitization of coronary arterial smooth muscle (CASM) contraction leading to vasospasm, a major cause of sudden death. Lately, we have been trying to find and develop more natural edible compounds which can treat and/or prevent the SPC-induced abnormal CASM contraction, and finally the first to discover that tangeretin (5,6,7,8,4′-pentamethoxyflavone), a natural compound extracted from citrus plants, can inhibit the SPC-induced CASM contraction both in the pretreatment and posttreatment. In porcine CASM tissues, tangeretin showed remarkable inhibitory effects on the SPC-induced contraction with modest inhibitory effects on the high K+-depolarization-induced Ca2+-dependent contraction, both in pretreatment and posttreatment at the optimal concentrations; Regarding the mechanisms, tangeretin markedly abolished the SPC-induced cell contraction through inhibiting the SPC-induced activation and translocation of Fyn and ROK from the cytoplasm to the cell membrane in cultured CASM cells, resulting in the reduction of phosphorylation of myosin light chain. Taken together, these findings indicate that tangeretin, upon pre- or post-treatment, inhibits the SPC-induced CASM contraction through suppressing the Fyn/ROK signaling pathway, thereby suggesting that tangeretin can be a potential candidate for the treatment and/or prevention of vasospasm.

Src family protein kinases (SFKs) play a key role in cell adhesion, invasion, proliferation, survival, apoptosis, and angiogenesis during tumor development. In humans, SFKs consists of eight family members with similar structure and function. There is a high level of overexpression or hyperactivity of SFKs in tumor, and they play an important role in multiple signaling pathways involved in tumorigenesis. FYN is a member of the SFKs that regulate normal cellular processes. Additionally, FYN is highly expressed in many cancers and promotes cancer growth and metastasis through diverse biological functions such as cell growth, apoptosis, and motility migration, as well as the development of drug resistance in many tumors. Moreover, FYN is involved in the regulation of multiple cancer-related signaling pathways, including interactions with ERK, COX-2, STAT5, MET and AKT. FYN is therefore an attractive therapeutic target for various tumor types, and suppressing FYN can improve the prognosis and prolong the life of patients. The purpose of this review is to provide an overview of FYN's structure, expression, upstream regulators, downstream substrate molecules, and biological functions in tumors. [ABSTRACT FROM AUTHOR]

Abstract Background Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide with high mortality. Advanced stage upon diagnosis and cancer metastasis are the main reasons for the dismal prognosis of HCC in large part. The role of proliferation associated protein 2G4 (PA2G4) in tumorigenesis and cancer progression has been widely investigated in various cancers. However, whether and how PA2G4 participates in HCC metastasis is still underexplored. Results We found that the mRNA and protein levels of PA2G4 were higher in HCC samples than in normal liver tissues, and high expression of PA2G4 in HCC was correlated with a poor prognosis, by an integrative analysis of immunohistochemistry (IHC), western blot and bioinformatic approach. Moreover, the expression of PA2G4 was elevated in HCC patients with metastases than those metastasis-free. Cell migration, invasion, phalloidin staining and western blot analyses demonstrated that PA2G4 promoted epithelial to mesenchymal transition (EMT) of HCC cells in vitro. And a lung metastasis animal model exhibited that PA2G4 enhanced metastatic ability of HCC cells in vivo. RNA-sequencing combined with dual luciferase reporter assay and evaluation of mRNA half-time indicated that PA2G4 increased FYN expression by stabilizing its mRNA transcript. Recovering the impaired FYN level induced by PA2G4 knockdown rescued the impeded cell mobilities. Furthermore, endogenous immunoprecipitation (IP) and in-situ immunofluorescence (IF) showed that YTH N6-methyladenosine RNA binding protein 2 (YTHDF2) was the endogenous binding patterner of PA2G4. In addition, RNA binding protein immunoprecipitation (RIP) and anti- N6-methyladenosine immunoprecipitation (MeRIP) assays demonstrated that FYN mRNA was N6-methyladenosine (m6A) modified and bound with PA2G4, as well as YTHDF2. Moreover, the m6A catalytic ability of YTHDF2 was found indispensable for the regulation of FYN by PA2G4. At last, the correlation of expression levels between PA2G4 and FYN in HCC tissues was verified by IHC and western blot analysis. Conclusions These results indicate that PA2G4 plays a pro-metastatic role by increasing FYN expression through binding with YTHDF2 in HCC. PA2G4 may become a reliable prognostic marker or therapeutic target for HCC patients.

Abstract Background Hepatocellular carcinoma (HCC) is the third-most deadly cancer worldwide. More breakthroughs are needed in the clinical practice for liver cancer are needed, and new treatment strategies are required. This study aims to determine the significant differences in genes associated with LIHC and further analyze its prognostic value further. Methods Here, we used the TCGA-LIHC database and the profiles of GSE25097 from GEO to explore the differentially co-expressed genes in HCC tissues compared with paratumor (or healthy) tissues. Then, we utilized WGCNA to screen differentially co-expressed genes. Finally, we explored the function of FYN in HCC cells and xenograft tumor models. Results We identified ten hub genes in the protein–protein interaction (PPI) network, but only three (COLEC10, TGFBR3, and FYN) appeared closely related to the prognosis. The expression of FYN was positively correlated with the prognosis of HCC patients. The xenograft model showed that overexpression of FYN could significantly inhibit malignant tumor behaviors and promote tumor cell apoptosis. Conclusion Thus, FYN may be central to the development of LIHC and maybe a novel biomarker for clinical diagnosis and treatment.

Metastasis is the leading cause of death in breast cancer patients due to the lack of effective therapies. Elevated levels of paxillin expression have been observed in various cancer types, with tyrosine phosphorylation shown to play a critical role in driving cancer cell migration. However, the specific impact of the distinct tyrosine phosphorylation events of paxillin in the progression of breast cancer remains to be fully elucidated. Here, we found that paxillin overexpression in breast cancer tissue is associated with a patient’s poor prognosis. Paxillin knockdown inhibited the migration and invasion of breast cancer cells. Furthermore, the phosphorylation of paxillin tyrosine residue 31 (Tyr31) was significantly increased upon the TGF-β1-induced migration and invasion of breast cancer cells. Inhibiting Fyn activity or silencing Fyn decreases paxillin Tyr31 phosphorylation. The wild-type and constitutively active Fyn directly phosphorylate paxillin Tyr31 in an in vitro system, indicating that Fyn directly phosphorylates paxillin Tyr31. Additionally, the non-phosphorylatable mutant of paxillin at Tyr31 reduces actin stress fiber formation, migration, and invasion of breast cancer cells. Taken together, our results provide direct evidence that Fyn-mediated paxillin Tyr31 phosphorylation is required for breast cancer migration and invasion, suggesting that targeting paxillin Tyr31 phosphorylation could be a potential therapeutic strategy for mitigating breast cancer metastasis.

In recent years, research has identified the molecular and neural substrates underlying the transition of moderate "social" consumption of alcohol to the characteristic alcohol use disorder (AUD) phenotypes including excessive and compulsive alcohol use which we define in the review as the GO signaling pathways. In addition, growing evidence points to the existence of molecular mechanisms that keep alcohol consumption in check and that confer resilience for the development of AUD which we define herein as the STOP signaling pathways. In this review, we focus on examples of the GO and the STOP intracellular signaling pathways and discuss our current knowledge of how manipulations of these pathways may be used for the treatment of AUD.

Abstract Background High glucose (HG) is linked to dopaminergic neuron loss and related Parkinson’s disease (PD), but the mechanism is unclear. Results Rats and differentiated SH-SY5Y cells were used to investigate the effect of HG on dopaminergic neuronal apoptotic death. We found that a 40-day HG diet elevated cleaved caspase 3 levels and activated Fyn and mTOR/S6K signaling in the substantia nigra of rats. In vitro, 6 days of HG treatment activated Fyn, enhanced binding between Fyn and mTOR, activated mTOR/S6K signaling, and induced neuronal apoptotic death. The proapoptotic effect of HG was rescued by either the Fyn inhibitor PP1 or the mTOR inhibitor rapamycin. PP1 inhibited mTOR/S6K signaling, but rapamycin was unable to modulate Fyn activation. Conclusions HG induces dopaminergic neuronal apoptotic death via the Fyn/mTOR/S6K pathway.

Major surgery induces systemic inflammation leading to pro-inflammatory activation of endothelial cells. Endothelial inflammation is one of the drivers of postoperative organ damage, including acute kidney injury Tumour Necrosis Factor alpha (TNF-α) is an important component of surgery-induced pro-inflammatory activation of endothelial cells. Kinases, the backbone of signalling cascades, can be targeted by pharmacological inhibition. This is a promising treatment option to interfere with excessive endothelial inflammation. In this study, we identified activated kinases as potential therapeutic targets. These targets were pharmacologically inhibited to reduce TNF-α-induced pro-inflammatory signalling in endothelial cells. Kinome profiling using PamChip arrays identified 64 protein tyrosine kinases and 88 serine-threonine kinases, the activity of which was determined at various timepoints (5–240 min) following stimulation with 10 ng/ml TNF-α in Human umbilical vein endothelial cells in vitro. The PTKs Axl and Fyn were selected based on high kinase activity profiles. Co-localisation experiments with the endothelial-specific protein CD31 showed Axl expression in endothelial cells of glomeruli and Fyn in arterioles and glomeruli of both control and TNF-α-exposed mice. Pharmacological inhibition with Axl inhibitor BMS-777607 and Fyn inhibitor PP2 significantly reduced TNF-α-induced pro-inflammatory activation of E-selectin, VCAM-1, ICAM-1, IL-6 and IL-8 at mRNA and VCAM-1, ICAM-1, and IL-6 at protein level in HUVEC in vitro. Upon pharmacological inhibition with each inhibitor, leukocyte adhesion to HUVEC was also significantly reduced, however to a minor extent. In conclusion, pre-treatment of endothelial cells with kinase inhibitors BMS-777607 and PP2 reduces TNF-α-induced endothelial inflammation in vitro.

Myelination is critical for fast saltatory conduction of action potentials. Recent studies have revealed that myelin is not a static structure as previously considered but continues to be made and remodeled throughout adulthood in tune with the network requirement. Synthesis of new myelin requires turning on the switch in oligodendrocytes (OL) to initiate the myelination program that includes synthesis and transport of macromolecules needed for myelin production as well as the metabolic and other cellular functions needed to support this process. A significant amount of information is available regarding the individual intrinsic and extrinsic signals that promote OL commitment, expansion, terminal differentiation, and myelination. However, it is less clear how these signals are made available to OL lineage cells when needed, and how multiple signals are integrated to generate the correct amount of myelin that is needed in a given neural network state. Here we review the pleiotropic effects of some of the extracellular signals that affect myelination and discuss the cellular processes used by the source cells that contribute to the variation in the temporal and spatial availability of the signals, and how the recipient OL lineage cells might integrate the multiple signals presented to them in a manner dialed to the strength of the input. [ABSTRACT FROM AUTHOR]

BackgroundHyperexcitability of neuronal networks can lead to excessive release of the excitatory neurotransmitter glutamate, which in turn can cause neuronal damage by overactivating NMDA-type glutamate receptors and related signaling pathways. This process (excitotoxicity) has been implicated in the pathogenesis of many neurological conditions, ranging from childhood epilepsies to stroke and neurodegenerative disorders such as Alzheimer's disease (AD). Reducing neuronal levels of the microtubule-associated protein tau counteracts network hyperexcitability of diverse causes, but whether this strategy can also diminish downstream excitotoxicity is less clear.MethodsWe established a cell-based assay to quantify excitotoxicity in primary cultures of mouse hippocampal neurons and investigated the role of tau in exicitotoxicity by modulating neuronal tau expression through genetic ablation or transduction with lentiviral vectors expressing anti-tau shRNA or constructs encoding wildtype versus mutant mouse tau.ResultsWe demonstrate that shRNA-mediated knockdown of tau reduces glutamate-induced, NMDA receptor-dependent Ca2+ influx and neurotoxicity in neurons from wildtype mice. Conversely, expression of wildtype mouse tau enhances Ca2+ influx and excitotoxicity in tau-deficient (Mapt -/-) neurons. Reconstituting tau expression in Mapt -/- neurons with mutant forms of tau reveals that the tau-related enhancement of Ca2+ influx and excitotoxicity depend on the phosphorylation of tau at tyrosine 18 (pY18), which is mediated by the tyrosine kinase Fyn. These effects are most evident at pathologically elevated concentrations of glutamate, do not involve GluN2B-containing NMDA receptors, and do not require binding of Fyn to tau's major interacting PxxP motif or of tau to microtubules.ConclusionsAlthough tau has been implicated in diverse neurological diseases, its most pathogenic forms remain to be defined. Our study suggests that reducing the formation or level of pY18-tau can counteract excitotoxicity by diminishing NMDA receptor-dependent Ca2+ influx.

Neoadjuvant chemotherapy (NAC) followed by surgery is the current standard of treatment for locally advanced uterine cervical cancer; however, its value and outcomes remain contested. Identifying biomarkers that allow for the prediction of the effect of NAC efficacy before initiation of treatment is essential, in order to assist in choosing the optimum therapeutic regimen to maximize the beneficial outcomes of treatment. In the present retrospective study, 44 patients with locally advanced uterine cervical squamous cell carcinoma who underwent NAC were divided into two groups: A NAC successful group and a NAC failure group, depending on the efficacy of NAC. Subsequently, the association between Fyn expression, a non-receptor tyrosine kinase that is a member of the Src family kinases, and NAC efficacy was determined; Fyn expression was detected by immunohistochemistry and assessed using a weighted scoring method. Additionally, the effect of Fyn knockdown on the sensitivity of a uterine cervical cancer cell line to cisplatin was determined. Notably, there were no significant differences between the two groups of patients regarding their characteristics. Regarding overall survival, the NAC successful group had a significantly longer survival time than the NAC failure group (P=0.01). Furthermore, the expression levels of Fyn in tumor tissues were significantly lower in the NAC successful group compared with those in the NAC failure group (P=0.003). The patients were subsequently divided into two groups (high expression group and low expression group) according to a cutoff value of 3, which was determined by producing a receiver operating characteristic curve from the weighted scores. The low expression group was significantly more sensitive to NAC than the high expression group (P<0.001). In vitro experiments revealed that Fyn knockdown significantly enhanced the sensitivity of uterine cancer cells to cisplatin (P<0.05). In conclusion, Fyn expression may be a potentially useful biomarker for predicting the response to NAC in patients with locally advanced uterine cervical squamous cell carcinoma, and may also be a promising molecular target for the management of uterine cancer. [ABSTRACT FROM AUTHOR]

Sepsis, characterized by a widespread and dysregulated immune response to infection leading to organ dysfunction, presents significant challenges in diagnosis and treatment. In this study, we investigated 203 coagulation-related genes in sepsis patients to explore their roles in the disease. Through differential gene expression analysis, we identified 20 genes with altered expression patterns. Subsequent correlation analysis, visualized through circos plots and heatmaps, revealed significant relationships among these genes. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses indicated that these genes are involved in immune response activation, coagulation, and immune receptor activity. Disease Ontology (DO) enrichment analysis further linked these genes to autoimmune hemolytic anemia and tumor-related signaling pathways. Additionally, the CIBERSORT analysis highlighted differences in immune cell composition in sepsis patients, revealing an increase in neutrophils and monocytes and a decrease in inactive NK cells, CD8 T cells, and B cells. We employed machine learning techniques, including random forest and SVM, to construct a diagnostic model, identifying FCER1G and FYN as key biomarkers. These biomarkers were validated through their expression levels and ROC curve analysis in an independent validation cohort, demonstrating strong diagnostic potential. Single-cell analysis from the GSE167363 dataset further confirmed the distinct expression profiles of these genes across various cell types, with FCER1G predominantly expressed in monocytes, NK cells, and platelets, and FYN in CD4+ T cells and NK cells. Enrichment analysis via GSEA and ssGSEA revealed that these genes are involved in critical pathways, including intestinal immune networks, fatty acid synthesis, and antigen processing. In conclusion, our comprehensive analysis identifies FCER1G and FYN as promising biomarkers for sepsis, providing valuable insights into the molecular mechanisms of this complex condition. These findings offer new avenues for the development of targeted diagnostic and therapeutic strategies in sepsis management., Competing Interests: 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., (Copyright © 2024 Ge, Deng, Zhou, Hu, Zhang and Zheng.)

Epilepsy and Alzheimer's disease share some common pathologies such as neurodegeneration, seizures and impaired cognition. However, the molecular mechanisms of these changes are still largely unknown. Fyn, a Src-family non-receptor tyrosine kinase (SFK), and its interaction with tau in mediating brain pathology in epilepsy and Alzheimer's disease can be a potential therapeutic target for disease modification. Although Fyn and tau pathology occurs in both Alzheimer's disease and epilepsy, the dynamics of Fyn-tau and PSD95-NR2B interactions affected by seizures and their impact on brain pathology in epilepsy have not been investigated. In this study, we demonstrate a significant increase of Fyn-tau interactions following seizure induction by kainate in both acute and chronic rodent models and in human epilepsy. In the early phase of epileptogenesis, we show increased Fyn/tau/NR2B/PSD95/neuronal nitric oxide synthase complexes after status epilepticus and a postsynaptic increase of phosphorylated tau (pY18 and AT8), Fyn (pSFK-Y416), NMDAR (pNR2B-Y1472) and neuronal nitric oxide synthase. Hippocampal proximity ligation assay and co-immunoprecipitation revealed a sustained increase of Fyn-tau and NR2B-PSD95 complexes/binding in rat chronic epilepsy at 3 months post-status epilepticus. Enhanced Fyn-tau complexes strongly correlated with the frequency of spontaneously recurring convulsive seizures and epileptiform spikes in the chronic epilepsy model. In human epileptic brains, we also identified increased Fyn-tau and NR2B-PSD95 complexes, tau phosphorylation (pY18 and AT8) and Fyn activation (pSFK-Y416), implying the translational and therapeutic potential of these molecular interactions. In tau knockout mice and in rats treated with a Fyn/SFK inhibitor saracatinib, we found a significant reduction of phosphorylated Fyn, tau (AT8 in saracatinib-treated), NR2B and neuronal nitric oxide synthase and their interactions (Fyn-tau and NR2B-PSD95 in saracatinib-treated group; NR2B-PSD95 in tau knockout group). The reduction of Fyn-tau and NR2B-PSD95 interactions in the saracatinib-treated group, in contrast to the vehicle-treated group, correlated with the modification in seizure progression in the rat chronic epilepsy model. These findings from animal models and human epilepsy provide evidence for the role of Fyn-tau and NR2B-PSD95 interactions in seizure-induced brain pathology and suggest that blocking such interactions could modify the progression of epilepsy., Competing Interests: The authors report no competing interests., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Guarantors of Brain.)