Project description:Mechanical cues influence the shape, growth, and function of tissues and organs and are necessary for the development of engineered tissues. Yet, how cells sense mechanical cues and transduce them into changes in gene expression is not well understood. It is known that mechanical forces transmitted to the nucleus induce chromatin remodeling, promote DNA repair, contribute to the motion of intranuclear organelles and cause direct dissociation of protein complexes inside nuclei. Yet, the extent to which such signals impact gene expression is not understood. Because mechanical forces from the cytoskeleton to the nucleus interior are transmitted by the LINC (linker of nucleoskeleton-to-cytoskeleton) complex, we disrupted the LINC complex and performed genome wide expression studies using RNA sequencing. LINC disruption altered the expression of hundreds of genes at a genome-wide scale. We asked how LINC disruption affected the mechanosensitivity of individual genes by quantifying fold changes in gene expression on soft and stiff substrates. Remarkably, LINC disruption tended to preserve gene mechanosensitivity, but to reverse its direction. LINC disruption did not cause changes in nuclear shape, nor eliminated nuclear shape sensitivity to substrate rigidity. Our results show for the first time that the LINC complex regulates mechano-sensing at a genome-wide level, and argue for a distinct mechanism that does not require changes in nuclear morphology.
Project description:Mechanical cues influence the shape, growth, and function of tissues and organs and are necessary for the development of engineered tissues. Yet, how cells sense mechanical cues and transduce them into changes in gene expression is not well understood. It is known that mechanical forces transmitted to the nucleus induce chromatin remodeling, promote DNA repair, contribute to the motion of intranuclear organelles and cause direct dissociation of protein complexes inside nuclei. Yet, the extent to which such signals impact gene expression is not understood. Because mechanical forces from the cytoskeleton to the nucleus interior are transmitted by the LINC (linker of nucleoskeleton-to-cytoskeleton) complex, we disrupted the LINC complex and performed genome wide expression studies using RNA sequencing. LINC disruption altered the expression of hundreds of genes at a genome-wide scale. We asked how LINC disruption affected the mechanosensitivity of individual genes by quantifying fold changes in gene expression on soft and stiff substrates. Remarkably, LINC disruption tended to preserve gene mechanosensitivity, but to reverse its direction. LINC disruption did not cause changes in nuclear shape, nor eliminated nuclear shape sensitivity to substrate rigidity. Our results show for the first time that the LINC complex regulates mechano-sensing at a genome-wide level, and argue for a distinct mechanism that does not require changes in nuclear morphology.
Project description:Microgravity is known to affect the organization of the cytoskeleton, cell and nuclear morphology and to elicit differential expression of genes associated with the cytoskeleton, focal adhesions and the extracellular matrix. Although the nucleus is mechanically connected to the cytoskeleton through the LInker of Nucleoskeleton and Cytoskeleton (LINC) complex, the role of this group of proteins in these responses to microgravity has yet to be defined. Therefore, we used simulated microgravity achieved by growing cells on a 3d clinostat to investigate whether the LINC complex acts to mediate responses to the microgravity environment. We show that nuclear shape and differential gene expression are both responsive to simulated microgravity in a LINC-dependent manner and that this response changes with the duration of exposure to simulated microgravity. These LINC-dependent genes likely represent elements normally regulated by the mechanical forces imposed by gravity on Earth.
Project description:To test the hypothesis that circRNAs might encode functional peptides in mammalian cells, we studied the long intergenic non-protein coding RNA, p53 induced transcript (LINC-PINT), which was previously reported as a tumor suppressor and connected p53 activation with polycomb repressive complex 2 (PRC2). We selected this long noncoding RNA (lncRNA) for further analysis because LINC-PINT has a long exon 2 which in accordance with the bioinformatical analyzed circular RNA standard.The following immunoblotting showed 87aa peptide level also decreased, indicating that this peptide is encoded by circPINTexon2. We name this circRNA encoded peptide PINT87aa. To investigate the possible regulatory role of PINT87aa, we did the expression micro array in PINT87aa stably transfect U251 or U87 glioblastoma cells and their control cells. The array analysis reveals that PINT87aa may involve in the cell cycle regulation, anti-apoptosis effects and multiple oncogenic signaling pathway activation.
Project description:To test the hypothesis that circRNAs might encode functional peptides in mammalian cells, we studied the long intergenic non-protein coding RNA, p53 induced transcript (LINC-PINT), which was previously reported as a tumor suppressor and connected p53 activation with polycomb repressive complex 2 (PRC2). We selected this long noncoding RNA (lncRNA) for further analysis because LINC-PINT has a long exon 2 which in accordance with the bioinformatical analyzed circular RNA standard.The following immunoblotting showed 87aa peptide level also decreased, indicating that this peptide is encoded by circPINTexon2. We name this circRNA encoded peptide PINT87aa.
Project description:Long noncoding RNAs (lncRNAs) are involved in the regulation of skeletal muscle development. In the present study, differentially expressed lncRNAs were identified from RNA-seq data derived from myoblasts and myotubes. We conducted studies to elucidate the function and molecular mechanism of action of Linc-smad7 during skeletal muscle development. Our findings show that Linc-smad7 is upregulated during the early phase of myoblasts differentiation. In in vitro studies, we showed that overexpression of Linc-smad7 promoted the arrest of myoblasts in G1 phase, inhibited DNA replication, and induced myoblast differentiation. Our in vivo studies suggest that Linc-smad7 stimulates skeletal muscle regeneration in cardiotoxin-induced muscle injury. Mechanistically, Linc-smad7 overexpression increased smad7 and IGF2 protein levels. On the contrary, overexpression of miR-125b reduced smad7 and IGF2 protein levels. Results of RNA immunoprecipitation analysis and biotin-labeled miR-125b capture suggest that Linc-smad7 could act as a competing endogenous RNA (ceRNA) for miRNA-125b. Taken together, our findings suggest that the novel noncoding regulator Linc-smad7 regulates skeletal muscle development.