Search

Abstract Although messenger RNA translation is tightly regulated to preserve protein synthesis and cellular homeostasis, chronic exposure to interferon‐γ (IFN‐γ) in several cancers can lead to tryptophan (Trp) shortage via the indoleamine‐2,3‐dioxygenase (IDO)‐ kynurenine pathway and therefore promotes the production of aberrant peptides by ribosomal frameshifting and tryptophan‐to‐phenylalanine (W>F) codon reassignment events (substitutants) specifically at Trp codons. However, the effect of Trp depletion on the generation of aberrant peptides by ribosomal mistranslation in gastric cancer (GC) is still obscure. Here, it is shows that the abundant infiltrating lymphocytes in EBV‐positive GC continuously secreted IFN‐γ, upregulated IDO1 expression, leading to Trp shortage and the induction of W>F substitutants. Intriguingly, the production of W>F substitutants in EBV‐positive GC is linked to antigen presentation and the activation of the mTOR/eIF4E signaling pathway. Inhibiting either the mTOR/eIF4E pathway or EIF4E expression counteracted the production and antigen presentation of W>F substitutants. Thus, the mTOR/eIF4E pathway exposed the vulnerability of gastric cancer by accelerating the production of aberrant peptides and boosting immune activation through W>F substitutant events. This work proposes that EBV‐positive GC patients with mTOR/eIF4E hyperactivation may benefit from anti‐tumor immunotherapy.

Abstract The progression of spermatogenesis along specific developmental trajectories depends on the coordinated regulation of pre‐mRNA alternative splicing (AS) at the post‐transcriptional level. However, the fundamental mechanism of AS in spermatogenesis remains to be investigated. Here, it is demonstrated that CWF19L2 plays a pivotal role in spermatogenesis and male fertility. In germline conditional Cwf19l2 knockout mice exhibiting male sterility, impaired spermatogenesis characterized by increased apoptosis and decreased differentiated spermatogonia and spermatocytes is observed. That CWF19L2 interacted with several spliceosome proteins to participate in the proper assembly and stability of the spliceosome is discovered. By integrating RNA‐seq and LACE‐seq data, it is further confirmed CWF19L2 directly bound and regulated the splicing of genes related to spermatogenesis (Znhit1, Btrc, and Fbxw7) and RNA splicing (Rbfox1, Celf1, and Rbm10). Additionally, CWF19L2 can indirectly amplify its effect on splicing regulation through modulating RBFOX1. Collectively, this research establishes that CWF19L2 orchestrates a splicing factor network to ensure accurate pre‐mRNA splicing during the early steps of spermatogenesis.

Abstract Tumor‐initiating cells (TICs) resilience and an immunosuppressive microenvironment are aggressive oncogenic phenotypes that contribute to unsatisfactory long‐term outcomes in lung adenocarcinoma (LUAD) patients. The molecular mechanisms mediating the interaction between TICs and immune tolerance have not been elucidated. The role of Galectin‐9 in oncogenesis and immunosuppressive microenvironment is still unknown. This study explored the potential role of galectin‐9 in TIC regulation and immune modulation in LUAD. The results show that galectin‐9 supports TIC properties in LUAD. Co‐culture of patient‐derived organoids and matched peripheral blood mononuclear cells showed that tumor‐secreted galectin‐9 suppressed T cell cytotoxicity and induced regulatory T cells (Tregs). Clinically, galectin‐9 is upregulated in human LUAD. High expression of galectin‐9 predicted poor recurrence‐free survival and correlated with high levels of Treg infiltration. LGALS9, the gene encoding galectin‐9, is found to be transcriptionally regulated by the nuclear factor of activated T cells 2 (NFATc2), a previously reported TIC regulator, via in silico prediction and luciferase reporter assays. Overall, the results suggest that the NFATc2/galectin‐9 axis plays a dual role in TIC regulation and immune suppression.

Abstract The uterine epithelium undergoes a dramatic spatiotemporal transformation to enter a receptive state, involving a complex interaction between ovarian hormones and signals from stromal and epithelial cells. Redox homeostasis is critical for cellular physiological steady state; emerging evidence reveals that excessive lipid peroxides derail redox homeostasis, causing various diseases. However, the role of redox homeostasis in early pregnancy remains largely unknown. It is found that uterine deletion of Glutathione peroxidase 4 (GPX4), a key factor in repairing oxidative damage to lipids, confers defective implantation, leading to infertility. To further pinpoint Gpx4’s role in different cell types, uterine epithelial‐specific Gpx4 is deleted by a lactotransferrin (Ltf)‐Cre driver; the resultant females are infertile, suggesting increased lipid peroxidation levels in uterine epithelium compromises receptivity and implantation. Lipid peroxidation inhibitor administration failed to rescue implantation due to carbonylation of major receptive‐related proteins underlying high lipid reactive oxygen species. Intriguingly, superimposition of Acyl‐CoA synthetase long‐chain family member 4 (ACSL4), an enzyme that promotes biosynthesis of phospholipid hydroperoxides, along with uterine epithelial GPX4 deletion, preserves reproductive capacity. This study reveals the pernicious impact of unbalanced redox signaling on embryo implantation and suggests the obliteration of lipid peroxides as a possible therapeutic approach to prevent implantation defects.

Abstract Glutathione S‐transferase pi (GSTP1), a phase II detoxification enzyme, is known to be overexpressed and mediates chemotherapeutic resistance in lung cancer. However, whether GSTP1 supports cancer stem cells (CSCs) and the underlying mechanisms in lung adenocarcinoma (LUAD) remain largely unknown. This study unveiled that GSTP1 is upregulated in lung CSCs and supports tumor self‐renewal, metastasis, and resistance to targeted tyrosine kinase inhibitors of LUAD both in vitro and in vivo. Mechanistically, CaMK2A (calcium/calmodulin‐dependent protein kinase 2 isoform A)/NRF2 (nuclear factor erythroid 2‐related factor 2)/GSTP1 is uncovered as a regulatory axis under hypoxia. CaMK2A increased GSTP1 expression through phosphorylating the Sersine558 residue of NRF2 and promoting its nuclear translocation, a novel mechanism for NRF2 activation apart from conventional oxidization‐dependent activation. Upregulation of GSTP1 in turn suppressed reactive oxygen species levels and supported CSC phenotypes. Clinically, GSTP1 analyzed by immunohistochemistry is upregulated in a proportion of LUAD and serves as a prognostic marker for survival. Using patient‐derived organoids from an ALK‐translocated LUAD, the therapeutic potential of a specific GSTP1 inhibitor ezatiostat in combination treatment with the ALK inhibitor crizotinib is demonstrated. This study demonstrates GSTP1 to be a promising therapeutic target for long‐term control of LUAD through targeting CSCs.

Abstract Optogenetics has become a widely used technique in neuroscience research, capable of controlling neuronal activity with high spatiotemporal precision and cell‐type specificity. Expressing exogenous opsins in the selected cells can induce neuronal activation upon light irradiation, and the activation depends on the power of incident light. However, high optical power can also lead to off‐target neuronal activation or even cell damage. Limiting the incident power, but enhancing power distribution to the targeted neurons, can improve optogenetic efficiency and reduce off‐target effects. Here, the use of optical lenses made of polystyrene microspheres is demonstrated to achieve effective focusing of the incident light of relatively low power to neighboring neurons via photonic jets. The presence of microspheres significantly localizes and enhances the power density to the target neurons both in vitro and ex vivo, resulting in increased inward current and evoked action potentials. In vivo results show optogenetic stimulation with microspheres that can evoke significantly more motor behavior and neuronal activation at lowered power density. In all, a proof‐of‐concept of a strategy is demonstrated to increase the efficacy of optogenetic neuromodulation using pulses of reduced optical power.

Abstract Gallbladder cancer (GBC) is a rare but the most malignant type of biliary tract tumor. It is usually diagnosed at an advanced stage and conventional treatments are unsatisfactory. As a proteasome inhibitor, bortezomib (BTZ) exhibits excellent antitumor ability in GBC. However, the long‐term treatment efficacy is limited by its resistance, poor stability, and high toxicity. Herein, BTZ‐encapsulated pH‐responsive copolymeric nanoparticles with estrone (ES‐NP(BTZ; Ce6)) for GBC‐specific targeted therapy is reported. Due to the high estrogen receptor expression in GBC, ES‐NP(BTZ; Ce6) can rapidly enter the cells and accumulate near the nucleus via ES‐mediated endocytosis. Under acidic tumor microenvironment (TME) and 808 nm laser irradiation, BTZ is released and ROS is generated by Ce6 to destroy the “bounce‐back” response pathway proteins, such as DDI2 and p97, which can effectively inhibit proteasomes and increase apoptosis. Compared to the traditional treatment using BTZ monotherapy, ES‐NP(BTZ; Ce6) can significantly impede disease progression at lower BTZ concentrations and improve its resistance. Moreover, ES‐NP(BTZ; Ce6) demonstrates similar antitumor abilities in patient‐derived xenograft animal models and five other types of solid tumor cells, revealing its potential as a broad‐spectrum antitumor formulation.

Abstract The regulation of cardiomyocyte differentiation is a fundamental aspect of cardiac development and regenerative medicine. PTEN plays important roles during embryonic development. However, its role in cardiomyocyte differentiation remains unknown. In this study, a low‐cost protocol for cardiomyocyte differentiation from mouse embryonic stem cells (ESCs) is presented and it is shown that Pten deletion potently suppresses cardiomyocyte differentiation. Transcriptome analysis shows that the expression of a series of cardiomyocyte marker genes is downregulated in Pten−/− cardiomyocytes. Pten ablation induces Dnmt3b expression via the AKT/FoxO3a pathway and regulates the expression of a series of imprinted genes, including Igf2. Double knockout of Dnmt3l and Dnmt3b rescues the deficiency of cardiomyocyte differentiation of Pten−/− ESCs. The DNA methylomes from wild‐type and Pten−/− embryoid bodies and cardiomyocytes are analyzed by whole‐genome bisulfite sequencing. Pten deletion significantly promotes the non‐CG (CHG and CHH) methylation levels of genomic DNA during cardiomyocyte differentiation, and the non‐CG methylation levels of cardiomyocyte genes and Igf2 are increased in Pten−/− cardiomyocytes. Igf2 or Igf1r deletion also suppresses cardiomyocyte differentiation through the MAPK/ERK signaling pathway, and IGF2 supplementation partially rescues the cardiomyocyte differentiation. Finally, Pten conditional knockout mice are generated and the role of PTEN in cardiomyocyte differentiation is verified in vivo.

Abstract A number of genes involved in zygotic genome activation (ZGA) have been identified, but the RNA‐binding maternal factors that are directly related to ZGA in mice remain unclear. The present study shows that maternal deletion of Igf 2bp2 (also commonly known as Imp2) in mouse embryos causes early embryonic developmental arrest in vitro at the 2‐cell‐stage. Transcriptomics and proteomics analyses of 2‐cell‐stage embryos in mice reveal that deletion of IMP2 downregulates the expression of Ccar1 and Rps14, both of which are required for early embryonic developmental competence. IGF2, a target of IMP2, when added in culture media, increases the proportion of wild‐type embryos that develop successfully to the blastocyst stage: from 29% in untreated controls to 65% (50 × 10−9 m IGF2). Furthermore, in an experiment related to embryo transfer, foster mothers receiving IGF2‐treated embryos deliver more pups per female than females who receive untreated control embryos. In clinically derived human oocytes, the addition of IGF2 to the culture media significantly enhances the proportion of embryos that develop successfully. Collectively, the findings demonstrate that IMP2 is essential for the regulation and activation of genes known to be involved in ZGA and reveal the potential embryonic development‐related utility of IGF2 for animal biotechnology and for assisted reproduction in humans.