Cardiac fibroblast deletion of PTBP1 modulates the profibrotic response by alternative splicing.
Ontology highlight
ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE287133 | GEO | 2026/06/01
REPOSITORIES: GEO
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2024-07-31 | GSE239823 | GEO
Project description:RNA-binding proteins control gene expression in cardiac fibroblasts during TGFb-driven fibrotic responses, including the eukaryotic translation initiation factor 4G2 (eIF4G2), which was known to facilitate alternative mRNA translation during cellular stresses. However, the precise role of eIF4G2 in cardiac fibroblast activation in response to fibrotic stress remains unclear. In this study, we found increased eIF4G2 protein levels in the hearts of heart failure patients and myocardial infarcted mice, as well as in TGFb-treated immortalized human and primary mouse cardiac fibroblasts. Depletion of eIF4G2 led to predominant translational downregulation of genes that are enriched in focal adhesion and extracellular matrix pathways. eIF4G2 knockdown reduced the proliferation, migration, and collagen secretion of TGFb-treated cardiac fibroblasts. Mechanistically, we found that the translation of IGFBP7 mRNA relies on eIF4G2, which is crucial for ECM production in response to pro-fibrotic stimuli. The interaction between eIF4G2 and a DEAD box RNA helicase DDX24 can regulate IGFBP7 protein expression in cardiac fibroblasts. Together, these findings suggest that the TGFb-eIF4G2-IGFBP7 axis establishes a novel translational regulatory circuit that governs cardiac fibroblast activation. Furthermore, conditional knockout of Eif4g2 in POSTN-positive myofibroblasts reduced cardiac fibrosis in the myocardial infarction mouse model, thus improving cardiac function. Our study provides insights into the molecular mechanism of eIF4G2-mediated translational regulation of crucial physiological mRNAs during cardiac fibroblast activation.
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2016-04-06 | E-GEOD-77474 | biostudies-arrayexpress
Project description:Cardiac fibroblasts (CFs) are the primary cells tasked with extracellar matrix reorganization and significantly associated with heart failure (HF). Previous studies have shown that TEAD1 deficiency deteriorated heart development and homeostasis. However, the role of TEAD1 in fibroblasts during cardiac remodeling was still undiscovered. Our study demonstrated that TEAD1 was upregulated predominently in cardiac fibroblasts in mice 4 weeks after transverse aortic constriction (TAC) and Ang-II infusion. Echocardiographic and histological analyses demonstrated that CFs- and myofibroblasts-specific TEAD1 deficiency ameliorated TAC-induced cardiac remodeling and treatment with TEAD1 inhibitor, VT103, mimiced this phenotypic effect. Mechanistically, RNA-seq analysis , ChIP-Seq analysis identified TEAD1 promotes the fibroblast-to-myofibroblast transition through the Wnt signalling pathway. In conclusion, TEAD1 is an essential regulator of the pro-fibrotic CFs phenotype associated with pathological cardiac remodeling via the BRD4/Wnt4 signalling pathway.
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Project description:Dynamic fibroblast state transitions underlie the heart’s fibrotic response, raising the possibility that tactical control of these transitions could alter maladaptive fibrotic outcomes. Transcriptome maturation by Muscleblind-like 1 (MBNL1) has emerged as a driver of differentiated cell states. Indeed, MBNL1 expression is elevated in conjunction with profibrotic transcripts in lineage traced myofibroblasts and modeling this gain in function by fibroblast-specific overexpression of an MBNL1 transgene induced a myofibroblast transcriptional identity in healthy hearts and promoted maladaptive myocyte remodeling and scar maturation following injury. Both fibroblast-specific and myofibroblast-specific loss of MBNL1 limited scar production and maturation, which was ascribed to negligible myofibroblast activity. MBNL1 deletion drove expansion of all quiescent cardiac fibroblast states and promoted mesenchymal stem cell characteristics while forced MBNL1 expression restricted state diversity by transitioning most fibroblasts to the most mature myofibroblast identity. These data suggest MBNL1 is a post-transcriptional switch controlling quiescent to myofibroblast transitions during cardiac wound healing.
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Project description:Ribosomopathies constitute a range of disabling conditions associated with defective protein synthesis mainly affecting hematopoietic stem cells (HSCs) and erythroid development. Here we demonstrate that deletion of Polypyrimidine Tract Binding Protein 1 (PTBP1) in the hematopoietic compartment led to the development of a ribosomopathy-like condition. Specifically, loss of PTBP1 was associated with a decrease in HSC self-renewal, erythroid differentiation and protein synthesis. Consistent with its function as a splicing regulator, PTBP1 deficiency led to splicing defects in hundreds of genes and we demonstrate that the up-regulation of a specific isoform of CDC42 could partly mimic the protein synthesis defect associated with loss of PTBP1. Furthermore, PTBP1 deficiency was associated with a marked defect in ribosome biogenesis and a selective reduction in the translation of mRNAs encoding ribosomal proteins. Collectively, this work identifies PTBP1 as a key integrator of ribosomal functions and highlights the broad functional repertoire of RNA binding proteins.
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Project description:Cardiomyopathy is characterized by the deposition of extracellular matrix by activated resident cardiac fibroblasts, called myofibroblasts. A current lack of therapeutic approaches to blunt the development of pathological fibrosis and ventricle chamber stiffening that ultimately leads to heart failure necessitates the investigation of the mechanisms that underlie myofibroblast activation. We previously observed that increased degradation of p53 occurs during the cardiac fibroblast expansion phase that acutely follows pressure overload. We created tissue-specific mouse models to delete p53 in quiescent resident cardiac fibroblasts and in activated myofibroblasts, then evaluated consequences to cardiac physiology, cellular biology, and fibrotic remodeling. We then performed RNA sequencing to further elucidate the effects of p53 deletion in cardiac fibroblasts on gene expression at the single cell level. We confirmed these results with a series of in vitro experiments in primary mouse cardiac fibroblasts. Results - Here, we demonstrate that p53 knockout in resident cardiac fibroblasts significantly accelerates proliferation and temporarily insulates the heart from fibrotic remodeling and functional decline in response to pressure overload, but ultimately results in a more deleterious phenotype than in wildtype animals. Conversely, p53 knockout in activated myofibroblasts does not result in a delay in functional loss, and is uniformly deleterious to the heart. Single-cell RNA sequencing revealed that p53 knockout is associated with the development of constitutively mitotic fibroblasts, and increased recruitment of fibroblasts into a main activation trajectory that involves four states: quiescent, early transitional, late transitional, and fully activated. A quiescent, functionally specialized vascular support fibroblast population that is ubiquitous in the wildtype animal is additionally recruited into activation in the p53 knockout condition, resulting in the eventual extreme functional decline seen in these animals. In vitro experimentation using viral deletion of p53 supports these findings - quiescent fibroblasts lacking p53 are resistant to activation, but activated myofibroblasts lacking p53 do not reverse their activation. This was found to be due to parallel hyperactivation of Cdkn2a/Rb1-mediated G1 cell cycle arrest in the p53 knockout condition, which was supported by in vivo studies. Conclusions - These data establish p53 as a major regulator of the myofibroblast activation response to pressure overload. Moreover, the single-cell studies establish an activation trajectory for resident cardiac fibroblasts, and elucidate the fundamental importance of clinical intervention prior to irreversible myofibroblast activation seen in chronic stages of pressure overload.
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