The FASEB Journal最新文献

The transcriptional co-activator Yki, the central effector of the Hippo signaling pathway, plays essential roles in regulating tissue growth, regeneration, and tumorigenesis. Although upstream signaling mechanisms controlling Yki activity have been extensively characterized, the molecular mechanisms that govern Yki protein homeostasis remain incompletely understood. In this study, we identify TAR DNA-binding protein 43 (TDP-43) as a critical regulator of Yki proteostasis and demonstrate that stabilization of the autophagic receptor Ref(2)P is indispensable for TDP-43-mediated Yki turnover. Our findings reveal that TDP-43 elevates Ref(2)P levels through two distinct mechanisms. At the post-translational level in the cytoplasm, TDP-43 disrupts the interaction between Ref(2)P and the kinase Dco, thereby preventing phosphorylation-dependent proteasomal degradation of Ref(2)P. At the post-transcriptional level in the nucleus, TDP-43 promotes Ref(2)P mRNA stability by interacting with the nuclear m6A reader protein Ythdc1, which facilitates recognition of N6-methyladenosine (m6A)-modified Ref(2)P transcripts and protects them from decay. Together, these findings delineate a dual regulatory mechanism by which TDP-43 controls Ref(2)P abundance and Yki proteostasis, providing new insights into the fine-tuning of Hippo pathway activity.

Juvenile hormone (JH), one of the main hormones in insects, is primarily synthesized in the corpora allata (CA). Studies have suggested tissues outside CA synthesize JH locally. Herein, we provide evidence that the Drosophila fat body serves as a novel extra-CA source of JH. Fat body-specific knockdown of JH acid methyltransferase (Jhamt), the rate-limiting enzyme in JH biosynthesis, significantly reduced JH titers locally and induced severe structural and functional defects, phenocopying CA ablation. These developmental defects were effectively rescued by dietary supplementation with JH analog, confirming that these defects arose from JH deficiency. Moreover, this hormone imbalance triggered ecdysone signaling-mediated autophagy, which contributed to Jhamt knockdown-induced defects. Mechanistically, we found JNK acts as a key downstream effector of JH and ecdysone to evoke autophagy. Further analysis revealed that JNK is antagonistically regulated by JH and ecdysone signaling. Collectively, our findings demonstrate that the fat body synthesizes JH locally to antagonize ecdysone signaling, with JNK serving as a critical integration node, thereby elucidating a novel tissue-specific axis for the coordination of insect development and metabolism.

Bladder cancer (BLCA) remains a highly prevalent and aggressive malignancy of the urinary tract, characterized by frequent recurrence and metastasis. Mediator complex subunit 15 (MED15) functions as a key transcriptional coactivator bridging transcription factors and RNA polymerase II, yet its role in BLCA progression has not been elucidated. Here, we identify MED15 as markedly upregulated in BLCA tissues. Gene set enrichment analysis (GSEA) revealed that MED15 expression correlates with epithelial–mesenchymal transition (EMT)-related pathways. Functionally, loss- and gain-of-function assays demonstrated that MED15 promotes EMT and enhances cell migration in a YAP1-dependent manner. Mechanistically, MED15 interacts with YAP1 and stabilizes it by attenuating TRIM11-mediated ubiquitination. Furthermore, under sorbitol-induced stress conditions—mimicking selected features of the bladder urothelium—MED15 forms stress-inducible, protein condensates and exhibits increased colocalization with YAP1. Collectively, these findings uncover a previously unrecognized MED15-TRIM11-YAP1 regulatory axis and support a model in which stress-induced MED15 condensates are associated with YAP1 stabilization and pro-metastatic behavior in bladder cancer.

Among cerebrovascular malformations, brain arteriovenous malformation (bAVM) and cerebral cavernous malformation (CCM) primarily affect microvessels. Brain AVM originates from arterioles due to impaired expression of endothelial differentiation markers, whereas CCM arises due to aberrant sprouting angiogenesis. Recent advances in the field of lncRNAs have linked perturbations of the competitive endogenous RNA (ceRNA) lncRNA–miRNA–mRNA axis to the development of several pathological conditions. However, this mechanism remains poorly investigated in cerebrovascular phenotypes. Based on RNA-seq data and enrichment analysis, we identified lncRNA genes differentially expressed in endothelial cells (ECs) isolated from bAVM and CCM biopsies. We isolated RNA from both ECs and blood samples of larger patient cohorts. By quantitative real-time PCR, gene expression was compared between pathological ECs and human brain microvascular endothelial cells (HBMECs) and between blood samples of patients and healthy controls. We identified five lncRNA genes, MIR497HG, RMST, SNHG6, SOX2-OT, and ZSCAN16-AS1 overexpressed in both ECs and blood samples of bAVM patients. In CCM ECs, FGD5-AS1 and SNHG12 were upregulated and XIST, NORAD, SNHG29, and LINC0066 down-expressed. These lncRNAs act as molecular sponges for miRNAs targeting transcripts associated with the onset of the respective phenotypes. Specifically, arteriovenous differentiation and vascular smooth muscle cell function were the two most enriched pathways related to the bAVM phenotype. For the CCM condition, the most enriched pathways included Rho-GTPase, Delta-Notch, and VEGF signalling. These data suggest a novel investigation field to better elucidate the differences in the pathogenesis, differential diagnosis, and potential therapeutic strategies for bAVM and CCM phenotypes.

Store operated Ca²⁺ entry (SOCE) is altered in neonatal platelets with respect to adult platelets. Here, we aim to analyze the changes in STIMATE translation that leads to generating STIMATE-mustn1 and its possible involvement in SOCE in neonatal platelets. As a result, we have found different expression patterns of STIMATE, mustn1 and STIMATE-mustn1 in platelets isolated from mothers with respect to their newborns. Calcium (Ca²⁺) experiments using MEG-01 cells overexpressing STIMATE or the fused protein STIMATE-mustn1 reveal that mustn1 binding to STIMATE impairs its role in SOCE; meanwhile, overexpression of mustn1 alone does not alter SOCE. Confocal images of MEG-01 and HEK293 cells reveal that the alteration in the expression of STIMATE modifies the co-localization between Orai1 and STIM1. Furthermore, STIMATE or STIMATE-mustn1 overexpression exhibits different intracellular location patterns, which were also different when compared between MEG-01 and HEK293 cells. Finally, STIMATE overexpression arrests the cell cycle of MEG-01 cells in the G2 phase, which represents a key step during the maturation of MEG-01 cells, but STIMATE-mustn1 overexpression does not change the cell cycle of MEG-01. Summarizing, we propose that overexpression of STIMATE-mustn1 by neonatal platelets might be an attempt to limit the exacerbated activation of SOCE found in these platelets.