HuR stabilizes HTT mRNA via interacting with its exon 11 in a mutant HTT-dependent manner.
Ontology highlight
ABSTRACT:
SUBMITTER: Zhao Q
PROVIDER: S-EPMC7237150 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:A high expression level of the beta-actin protein is required for important biological mechanisms, such as maintaining cell shape, growth, and motility. Although the elevated cellular level of the beta-actin protein is directly linked to the long half-life of its mRNA, the molecular mechanisms responsible for this effect are unknown. Here we show that the RNA-binding protein HuR stabilizes the beta-actin mRNA by associating with a uridine-rich element within its 3' untranslated region. Using RNA interference to knock down the expression of HuR in HeLa cells, we demonstrate that HuR plays an important role in the stabilization but not in the nuclear/cytoplasmic distribution of the beta-actin mRNA. HuR depletion in HeLa cells alters key beta-actin-based cytoskeleton functions, such as cell adhesion, migration, and invasion, and these defects correlate with a loss of the actin stress fiber network. Together our data establish that the posttranscriptional event involving HuR-mediated beta-actin mRNA stabilization could be a part of the regulatory mechanisms responsible for maintaining cell integrity, which is a prerequisite for avoiding transformation and tumor formation.
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Project description:Occludin is a transmembrane tight junction (TJ) protein that plays an important role in TJ assembly and regulation of the epithelial barrier function, but the mechanisms underlying its post-transcriptional regulation are unknown. The RNA-binding protein HuR modulates the stability and translation of many target mRNAs. Here, we investigated the role of HuR in the regulation of occludin expression and therefore in the intestinal epithelial barrier function. HuR bound the 3'-untranslated region of the occludin mRNA and enhanced occludin translation. HuR association with the occludin mRNA depended on Chk2-dependent HuR phosphorylation. Reduced HuR phosphorylation by Chk2 silencing or by reduction of Chk2 through polyamine depletion decreased HuR-binding to the occludin mRNA and repressed occludin translation, whereas Chk2 overexpression enhanced (HuR/occludin mRNA) association and stimulated occludin expression. In mice exposed to septic stress induced by cecal ligation and puncture, Chk2 levels in the intestinal mucosa decreased, associated with an inhibition of occludin expression and gut barrier dysfunction. These results indicate that HuR regulates occludin mRNA translation through Chk2-dependent HuR phosphorylation and that this influence is crucial for maintenance of the epithelial barrier integrity in the intestinal tract.
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Project description:N6-methyladenosine (m6A) is the most abundant and reversible modification on messenger RNAs. The differential m6A profiles in different cell types are installed by writers (such as METTL3) and removed by erasers (such as FTO). The m6A-modified RNAs are recognized by readers to trigger downstream regulation of RNA metabolism, eventually contributing to the regulation of cell fates. Primordial germ cells (PGCs) are specified early during embryogenesis and establish the germ cell lineage for transmitting genetic and epigenetic information from parents to offspring. Defects in the establishment of germline may lead to infertility, germ cell tumors, and birth defects. Despite extensive research, the m6A-mediated epigenetic regulation of the specification of PGCs remains elusive. In this study, we discovered that knock-out of m6A writer or over-expression of erasers leads to increased percentage of human PGC-like cells (hPGCLCs) induced from embryonic stem cells. We identified the m6A reader IGF2BP1 as the key factor for restricting hPGCLC fate induction by stabilizing OTX2 mRNAs in an m6A-dependent manner. Moreover, we discovered that OTX2 suppresses TFAP2C during germ cell lineage specification. In summary, we characterized the m6A-IGF2BP1-OTX2-TFAP2C axis in restricting the specification of human germ cell fate.
2024-04-30 | PXD051996 |
Project description:Syndapin 1 FBAR, a member of the Bin-amphiphysin-Rvs (BAR) domain protein family, is known to induce membrane curvature and is an essential component in biological processes like endocytosis and formation and growth of neurites. We quantify the curvature sensing of FBAR on reconstituted porcine brain lipid vesicles and show that it senses membrane curvature at low density whereas it induces and reinforces tube stiffness at higher density. FBAR strongly up-concentrates on the high curvature tubes pulled out of Giant Unilamellar lipid Vesicles (GUVs), this sorting behavior is strongly amplified at low protein densities. Interestingly, FBAR from syndapin 1 has a large affinity for tubular membranes with curvatures larger than its own intrinsic concave curvature. Finally, we studied the effect of FBAR on membrane relaxation kinetics with high temporal resolution and found that the protein increases relaxation time of the tube holding force in a density-dependent fashion.
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Project description:The p53 pathway is a highly complex signaling network including several key regulators. HAUSP is a critical component of the p53 pathway acting as a deubiquitinase for both p53 and its key repressor Mdm2. Here, we identified a novel HAUSP-interacting protein, HLA-B-associated transcript 3 (Bat3) and found it to be capable of inducing p53 stabilization and activation via a HAUSP-dependent mechanism, resulting in cell growth inhibition. Surprisingly, the deubiquitylating enzymatic activity of HAUSP was not required for this phenomenon. Co-immunoprecipitation showed that p53 coexisted in a complex with Bat3 and HAUSP in vivo, and HAUSP may serve as a binding mediator to enhance the interaction between p53 and Bat3. Further studies revealed that formation of this three-protein complex interfered with the binding of p53 to its proteasome receptor S5a and promoted the accumulation of p53 in nucleus. Notably, Mdm2 protein abundance is also regulated by Bat3 in the presence of HAUSP. Overexpression of Bat3 and HAUSP increases Mdm2 protein levels without influencing the p53-Mdm2 interaction and Mdm2-mediated p53 ubiquitination, indicating that Bat3-HAUSP-mediated protein stabilization is not specific to p53 and different mechanisms may be involved in Bat3-mediated regulation of p53-Mdm2 pathway. Together, our study unravels a novel mechanism by which p53 is stabilized and activated by HAUSP-mediated interaction with Bat3 and implies that Bat3 might function as a tumor suppressor through the stabilization of p53.
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Project description:The activation of cytosolic phospholipase A(2)? (cPLA(2)?) plays an important role in initiating the inflammatory response. The regulation of cPLA(2)? mRNA turnover has been proposed to control cPLA(2)? gene expression under cytokine and growth factor stimulation. However, the detailed mechanism is still unknown. In this report, we have demonstrated that the cPLA(2)? mRNA stability was increased under IL-1? treatment in A549 cells. By using EMSAs, HuR was identified as binding with the cPLA(2)? mRNA 3'-UTR, and the binding region was located at nucleotides 2716-2807, a fragment containing AUUUA flanked by U-rich sequences. IL-1? treatment enhanced the association of cPLA(2)? mRNA with cytosolic HuR. The reduction of HuR expression by RNA interference technology inhibited IL-1?-induced cPLA(2)? mRNA and protein expression. Furthermore, blocking the p38 MAPK signaling pathway with SB203580 abolished the effect of IL-1?-induced cPLA(2)? gene expression. Phosphorylation at residue Thr-118 of HuR is crucial in regulating the interaction between HuR and its target mRNAs. Mutation of HuR Thr-118 reduced the association between HuR and cPLA(2)? mRNA under IL-1? treatment. This inhibitory effect was also observed in binding with COX-2 mRNA. This result indicated that p38 MAPK-mediated Thr-118 phosphorylation may play a key role in regulating the interaction of HuR with its target mRNAs in inflammation.
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Project description:BRCA1 exon 11 is one of the biggest human exons, spanning 3426 bases. This gene is potentially involved in DNA repair as well as cell growth and cell cycle control. Exon 11 is regulated at the splicing level producing three main different combinations of BRCA1 mature transcripts; one including the whole of exon 11 (full isoform), one skipping the entire exon (D11 isoform), and one including only 117 base pairs of exon 11 (D11q isoform). Using minigene and deletion analyses, we have previously described important splicing regulatory sequences located at the beginning of this exon (5' end). We have now found additional important sequences located at its 3' end. In particular, we describe the presence of a strong splicing enhancer adjacent to the downstream 5' splice site, which minimizes competition from an upstream 5' splice site and so ensures long exon inclusion. Analyses of the proteins binding these RNA sequences have revealed that Tra2beta and hnRNP L are involved in the regulation of BRCA1 exon 11 by influencing the recognition of donor sites. Interestingly, BRCA1 exon 11 carrying deletion of the regulatory sequences bound by these factors also showed unexpected responses to up- or downregulation of these regulatory proteins, suggesting that they can also bind elsewhere in this large exon and elicit different effects on its recognition. The identification of sequences and proteins relevant for the regulation of BRCA1 exon 11 now provides better knowledge on how this exon is recognized and may represent an important step toward understanding how large exons are regulated.
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Project description:A hallmark of acute respiratory distress syndrome (ARDS) is accumulation of protein-rich edema in the distal airspaces and its removal is critical for patient survival. Previous studies have shown a detrimental role of Glycogen Synthase Kinase (GSK) 3β during ARDS via inhibition of alveolar epithelial protein transport. We hypothesized that post-transcriptional regulation of GSK3β could play a functional role in ARDS resolution. To address this hypothesis, we performed an in silico analysis to identify regulatory genes whose expression correlation to GSK3β messenger RNA utilizing two lung cancer cell line array datasets. Among potential regulatory partners of GSK3β, these studies identified the RNA-binding protein ELAVL-1/HuR (Embryonic Lethal, Abnormal Vision, Drosophila-Like) as a central component in a likely GSK3β signaling network. ELAVL-1/HuR is a RNA-binding protein that selectively binds to AU-rich elements of mRNA and enhances its stability thereby increasing target gene expression. Subsequent studies with siRNA suppression of ELAVL-1/HuR demonstrated deceased GSK3β mRNA and protein expression and improved clearance of FITC-albumin in A549 cells. Conversely, stabilization of ELAVL-1/HuR with the proteasome inhibitor MG-132 resulted in induction of GSK3β at mRNA and protein level and attenuated FITC-albumin clearance. Utilizing ventilator-induced lung injury or intra-tracheal installation of hydrochloric acid to induce ARDS in mice, we observed increased mRNA and protein expression of ELAVL-1/HuR and GSK3β. Together, our findings indicate a previously unknown interaction between GSK3β and ELAV-1 during ARDS, and suggest the inhibition of the ELAV-1- GSK3β pathways as a novel ARDS treatment approach.
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