Project description:Myogenesis is a highly orchestrated process whereby muscle precursor cells, myoblasts, develop into muscle fibers to form skeletal muscle during embryogenesis and regenerate adult muscle. Here, we studied the RNA-binding protein FUS (fused in sarcoma), which has been implicated in muscular and neuromuscular pathologies but is poorly characterized in myogenesis. Given that FUS levels declined in human and mouse models of skeletal myogenesis, and that silencing FUS enhanced myogenesis, we hypothesized that FUS might be a repressor of myogenic differentiation. Interestingly, overexpression of FUS delayed myogenesis, accompanied by slower production of muscle differentiation markers. To identify the mechanisms through which FUS inhibits myogenesis, we uncovered RNA targets of FUS by ribonucleoprotein immunoprecipitation (RIP) followed by RNA-sequencing (RNA-seq) analysis. Stringent selection of the bound transcripts uncovered Tnnt1 mRNA, encoding troponin T (TNNT1), as a major effector of FUS influence on myogenesis. We found that in myoblasts, FUS sequestered Tnnt1 mRNA in the nucleus, preventing TNNT1 expression; however, reduction of FUS during myogenesis or by silencing FUS released Tnnt1 mRNA for export to the cytoplasm, where it accumulated and was translated into TNNT1, promoting myogenesis. We propose that FUS inhibits myogenesis by suppressing TNNT1 expression through a mechanism of nuclear mRNA retention.
Project description:Myogenesis is a highly orchestrated process whereby muscle precursor cells, myoblasts, develop into muscle fibers to form skeletal muscle during embryogenesis and regenerate adult muscle. Here, we studied the RNA-binding protein FUS (fused in sarcoma), which has been implicated in muscular and neuromuscular pathologies but is poorly characterized in myogenesis. Given that FUS levels declined in human and mouse models of skeletal myogenesis, and that silencing FUS enhanced myogenesis, we hypothesized that FUS might be a repressor of myogenic differentiation. Interestingly, overexpression of FUS delayed myogenesis, accompanied by slower production of muscle differentiation markers. To identify the mechanisms through which FUS inhibits myogenesis, we uncovered RNA targets of FUS by ribonucleoprotein immunoprecipitation (RIP) followed by RNA-sequencing (RNA-seq) analysis. Stringent selection of the bound transcripts uncovered Tnnt1 mRNA, encoding troponin T (TNNT1), as a major effector of FUS influence on myogenesis. We found that in myoblasts, FUS sequestered Tnnt1 mRNA in the nucleus, preventing TNNT1 expression; however, reduction of FUS during myogenesis or by silencing FUS released Tnnt1 mRNA for export to the cytoplasm, where it accumulated and was translated into TNNT1, promoting myogenesis. We propose that FUS inhibits myogenesis by suppressing TNNT1 expression through a mechanism of nuclear mRNA retention.
Project description:The aim of our study is to identify the role of FUS in shaping the transcriptome. RNA-seq of two FUS KO clones was performed and compared to wt; for each, four replicates were sequenced. RNA molecules associated with the FUS protein were determined by means of a RNA immuno-precipitation, followed by high-throughput sequencing. Total RNA was used as a control. SH-SY5Y cells were used for both experiments. RNA-seq: 4 wt samples, 4 A4 KO samples, 4 A5 KO samples. RIP-seq: 1 input control sample, 3 anti-FUS IP replicates.
Project description:Complex organisms are able to generate differential gene expression through the same set of DNA sequences in distinct cells. The communication between chromatin and RNA regulates how cells behave in tissues. However, little is known about how chromatin, especially the histone modifications, regulates RNA polyadenylation. Here, we find that FUS is recruited to chromatin by H3K36me3 at gene bodies. Once H3K36me3 is abolished, FUS is dissociated from chromatin to increase the binding with RNA, resulting in increased distal polyadenylation selections that are far from the stop codon. The H3K36me3 recognition of FUS is mediated by the proline residues in ZNF domain, mutations of which lead to reduced chromatin association of FUS, increased RNA binding of FUS, and distal polyadenylation selections. Proline mutation, which corresponds to the mutation in amyotrophic lateral sclerosis, contributes to the hyperactivation of mitochondria and hyperdifferentiation in mouse embryonic stem cells. These findings reveal FUS as an H3K36me3 reader protein that links chromatin-mediated alternative polyadenylation to human disease.
Project description:We performed RNA immunoprecipitation (IP) and microarray (RIP-chip) analyses to identify and compare the biological mRNA targets of two RNA-binding protein (RBP), TDP-43 and FUS, associated to cytoplasmic ribonucleoprotein (RNP) complexes of motoneuronal NSC34 cells with the final aim to unravel their role in mRNA transport, stability, and translation in neuronal cells. To identify the transcripts contained and bound in the isolated RNP complexes, a chip analysis was performed using the recovered mRNAs from triplicate experimantal RIP samples (TDP-43-IP samples, the FUS-IP samples and the control IgG-IP sample).
Project description:The RNA binding protein FUS exerts its function in several RNA biosynthetic processes; moreover, mutations leading to changes in its expression levels or alterations in cellular compartmentalization have been linked to the pathogenesis of Amyotrophic Lateral Sclerosis. Here, we describe an additional novel function of FUS, that is the control of back-splicing reactions which lead to circular RNA (circRNA) production. We identified circRNAs expressed in murine ES-derived motoneurons and then compared their levels in control versus FUS-/- cells. We discovered that a considerable number of circRNAs is affected by FUS levels.