Differential regulation of gene expression by two isoforms of the human transcriptional coactivator MKL1
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ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE47209 | GEO | 2015/05/14
SECONDARY ACCESSION(S): PRJNA205115
REPOSITORIES: GEO
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Project description:We identified two isoforms of human MKL1 that differ in their N-terminal domains. Since MKL1 is a transcriptional coactivator of SRF and regulates many SRF target genes, we wanted to analyze if transcription is differentially regulated by the two isoforms upon stimulation of the Rho-actin-MKL1-SRF pathway. Activity of the Rho-actin-MKL1 pathway was induced in EcR293 cell lines stably over-expressing the empty vector control, a 5’UTR-full length MKL1_S construct, or a 5’UTR-full length MKL1_L construct by LPA treatment.
2015-05-14 | E-GEOD-47209 | biostudies-arrayexpress
Project description:Actins and regulators of actin dynamics generate contractile forces providing major mechanical and structural support for the cell. Whether and how they actively participate in cell fate control is not clear. Here, we report the actin responsive transcription factor complex MKL1/SRF, the major transcriptional regulator of large numbers of actin cytoskeletal genes, as an important regulator of genomic accessibility and cell fate outcome. Somatic cells with weaker MKL1/SRF activity progress toward pluripotency efficiently while sustained MKL1/SRF activity at a level seen in typical fibroblasts is sufficient to stall cells on their trajectory toward pluripotency. This altered cell fate outcome is associated with an overactive actin cytoskeleton, which connects to chromatin via the LINC complex, preventing its conversion into a relaxed, open conformation that allows sufficient accessibility to pluripotency-inducing transcription factors. Interfering with actin polymerization at appropriate times promotes pluripotency induction. Thus, we reveal a previously unappreciated aspect of cell fate control exerted by the actin based cytoskeletal system.
2019-03-01 | GSE120399 | GEO
Project description:Megakaryoblastic Leukemia 1 (MKL1) was identified as part of the t(1;22) translocation specific to acute megakaryoblastic leukemia, but nothing is known regarding its role in hematopoiesis. Here we show that overexpression of MKL1 enhances megakaryocytic differentiation of the Human Erythroleukemia cell line (HEL). Microarray analysis reveals that MKL1 promotes expression of megakaryocyte-specific genes such as glycoprotein V (GP5), as well as cytoskeletal and adhesion molecule genes relevant to megakaryocyte differentiation and proplatelet formation. MKL1 is a transcriptional coactivator of Serum Response Factor. In this study, MKL1 also upregulates known SRF targets. Results provide insight into the role of MKL1 in megakaryocytopoiesis.
2008-12-10 | GSE13710 | GEO
Project description:Cellular differentiation is regulated through activation and repression of defined transcription factors. A hallmark of differentiation is a pronounced change in cell shape, which is determined by dynamics of the actin cytoskeleton. In de-differentiated fat (DFAT) cells and 3T3-L1 cells, we showed that treatment with the ROCK inhibitor Y-27632, by inducing remodeling of the actin cytoskelton, causes adipocyte differentiation. In addition, we found that depletion of MKL1, an actin binding transcriptional coactivator, elicits adipogenesis. To investigate whether regulation of MKL1 by actin cytoskeleton dynamics drives adipocyte differentiation, we compared the gene expression changes resulting from DFAT cells after treatment with Y-27632 and transfection of Mkl1 siRNA. Using Affymetrix mouse genome array, we compared global gene expression profiles in DFAT cells after treatment with Y-27632 and transfection with Mkl1 siRNA to search for particular biological functions in genes of which expression intensities were increased and decreased.
2014-03-28 | E-GEOD-52334 | biostudies-arrayexpress
Project description:Insulin resistance in skeletal muscle is a key phenotype associated with type 2 diabetes (T2D) and is even present in offspring of diabetic parents. However, molecular mediators of insulin resistance remain unclear. We find that the top-ranking gene set in expression analysis of muscle from humans with T2D and normoglycemic insulin resistant subjects with parental family history (FH+) of T2D is increased expression of actin cytoskeleton genes regulated by serum response factor (SRF) and its coactivator MKL1. Furthermore, the SRF activator STARS is upregulated in FH+ and T2D and inversely correlated with insulin sensitivity. These patterns are recapitulated in insulin resistant mice, and linked to alterations in two other regulators of this pathway: reduced G-actin and increased nuclear localization of MKL1. Both genetic and pharmacologic manipulation of STARS/MKL1/SRF pathway significantly alter insulin action: 1) Overexpression of MKL1 or reduction in G-actin decreased insulin-stimulated Akt phosphorylation; 2) reduced STARS expression increased insulin signalling and glucose uptake, and 3) SRF inhibition by CCG-1423 reduced nuclear MKL1, improved glucose uptake, and improved glucose tolerance in insulin resistant mice in vivo. Thus, SRF pathway alterations are a signature of insulin resistance which may also contribute to T2D pathogenesis and be a novel therapeutic target. Skeletal muscle samples were obtained from 10 subjects with type 2 diabetes, 25 subjects with a family history of type 2 diabetes (one or both parents), and 15 subjects with no family history of type 2 diabetes. In this analysis RNA was isolated for cRNA preparation and hybridized to Affymetrix Human Genome U133 Plus 2.0 microarrays.
2011-03-01 | E-GEOD-25462 | biostudies-arrayexpress
Project description:Characterize the genes regulated by MKL1/SRF complex in human megakaryocytes (MKs) derived from cord blood or cytapheresis : Using a knock down approach by small interference of MKL1 in MK progenitors, we observed a decrease in the percentage of cells with actin polymerization after adhesion on various substrates, an increase of mean ploidy level and apoptosis. Furthermore, MKL1 inhibition induced a major defect in pro-platelet formation and MKs migration. These results clearly demonstrate that MKL1 is involved in the cytoskeleton organization and maturation of MKs as well as in platelet formation. The goal of gene profiling was to identify new potential MKL1/SRF targets the expression level of which was down regulated after MKL1 inhibition: Human CD34+ cells isolated from cord blood or cytapheresis were transduced by a control lentivirus (designed as SCR; scramble) or by the lentivirus encoding for shRNA of MKL1 (designed as shMKL1) both containing a GFP expressed under the control of PGK promoter. The cells were than grown in serum free medium supplemented by thrombopoietin leading to a generation of megakaryocytes. At day 9 of culture (80% of MKs), the GFP positive cells were sorted, RNAs were extracted and submitted to hybridization as described in annex protocols. Two lists of genes (one for cord blood samples and one for cytapheresis samples) deregulated after the repression of MKL1 were done comparing the intensity of hybridization between SCR and shMKL1 samples. The common list of genes deregulated in MKs from cord blood and cytapheresis after the repression of MKL1 was than generated.
2009-09-14 | E-TABM-640 | biostudies-arrayexpress
Project description:Cellular differentiation is regulated through activation and repression of defined transcription factors. A hallmark of differentiation is a pronounced change in cell shape, which is determined by dynamics of the actin cytoskeleton. In de-differentiated fat (DFAT) cells and 3T3-L1 cells, we showed that treatment with the ROCK inhibitor Y-27632, by inducing remodeling of the actin cytoskelton, causes adipocyte differentiation. In addition, we found that depletion of MKL1, an actin binding transcriptional coactivator, elicits adipogenesis. To investigate whether regulation of MKL1 by actin cytoskeleton dynamics drives adipocyte differentiation, we compared the gene expression changes resulting from DFAT cells after treatment with Y-27632 and transfection of Mkl1 siRNA.
2014-03-28 | GSE52334 | GEO
Project description:Insulin resistance in skeletal muscle is a key phenotype associated with type 2 diabetes (T2D) and is even present in offspring of diabetic parents. However, molecular mediators of insulin resistance remain unclear. We find that the top-ranking gene set in expression analysis of muscle from humans with T2D and normoglycemic insulin resistant subjects with parental family history (FH+) of T2D is increased expression of actin cytoskeleton genes regulated by serum response factor (SRF) and its coactivator MKL1. Furthermore, the SRF activator STARS is upregulated in FH+ and T2D and inversely correlated with insulin sensitivity. These patterns are recapitulated in insulin resistant mice, and linked to alterations in two other regulators of this pathway: reduced G-actin and increased nuclear localization of MKL1. Both genetic and pharmacologic manipulation of STARS/MKL1/SRF pathway significantly alter insulin action: 1) Overexpression of MKL1 or reduction in G-actin decreased insulin-stimulated Akt phosphorylation; 2) reduced STARS expression increased insulin signalling and glucose uptake, and 3) SRF inhibition by CCG-1423 reduced nuclear MKL1, improved glucose uptake, and improved glucose tolerance in insulin resistant mice in vivo. Thus, SRF pathway alterations are a signature of insulin resistance which may also contribute to T2D pathogenesis and be a novel therapeutic target.
2011-03-01 | GSE25462 | GEO
Project description:SRF is a ubiquitous transcription factor that binds DNA in association with myocardin-family proteins (e.g. MKL1), or the ternary complex factor (TCF) family of ETS proteins. In primary hematopoietic cells, knockout of either SRF or MKL1 decreases megakaryocyte maturation caused thrombocytopenia, and MKL1 over-expression (MKL1OE) in the Human Erythroleukemia (HEL) cell line enhances megakaryopoiesis, but the mechanisms underlying these effects are unknown. To elucidate the role of SRF and MKL1 in megakaryopoiesis, integrated analysis was performed of anti-SRF ChIP-seq and RNA-seq data in undifferentiated and differentiated HEL cells, both with and without induction of MKL1OE. MKL1OE enhances TPA-induced megakaryopoiesis with 25% of genes upregulated, as opposed to 11% with TPA alone. MKL1OE increases SRF binding to genomic sites, and enhances expression of specific target cytoskeletal genes in response to TPA. Genes upregulated in response to TPA are predicted to be regulated by SRF and ETS factors, whereas those upregulated in TPA plus MKL1OE lack ETS binding motifs. Using ChIP-PCR, we validated that both SRF and MKL1 have increased binding at target upregulated genes, e.g. CORO1A, with MKL1OE. We show for the first time that MKL1 increases both the genomic association and activity of SRF, and upregulates genes that enhance megakaryopoiesis.
2018-10-29 | GSE112277 | GEO
Project description:SRF is a ubiquitous transcription factor that binds DNA in association with myocardin-family proteins (e.g. MKL1), or the ternary complex factor (TCF) family of ETS proteins. In primary hematopoietic cells, knockout of either SRF or MKL1 decreases megakaryocyte maturation caused thrombocytopenia, and MKL1 over-expression (MKL1OE) in the Human Erythroleukemia (HEL) cell line enhances megakaryopoiesis, but the mechanisms underlying these effects are unknown. To elucidate the role of SRF and MKL1 in megakaryopoiesis, integrated analysis was performed of anti-SRF ChIP-seq and RNA-seq data in undifferentiated and differentiated HEL cells, both with and without induction of MKL1OE. MKL1OE enhances TPA-induced megakaryopoiesis with 25% of genes upregulated, as opposed to 11% with TPA alone. MKL1OE increases SRF binding to genomic sites, and enhances expression of specific target cytoskeletal genes in response to TPA. Genes upregulated in response to TPA are predicted to be regulated by SRF and ETS factors, whereas those upregulated in TPA plus MKL1OE lack ETS binding motifs. Using ChIP-PCR, we validated that both SRF and MKL1 have increased binding at target upregulated genes, e.g. CORO1A, with MKL1OE. We show for the first time that MKL1 increases both the genomic association and activity of SRF, and upregulates genes that enhance megakaryopoiesis.
2018-10-29 | GSE112265 | GEO