The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Joseph M Miano - One of the best experts on this subject based on the ideXlab platform.
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serum Response Factor is essential for maintenance of podocyte structure and function
Journal of The American Society of Nephrology, 2017Co-Authors: Orazio J Slivano, Eric M. Small, Ronald A Dirkx, Christine K Christie, Jan Czyzyk, Aram F Hezel, Ali G Gharavi, Joseph M MianoAbstract:Podocytes contain an intricate actin cytoskeleton that is essential for the specialized function of this cell type in renal filtration. Serum Response Factor (SRF) is a master transcription Factor for the actin cytoskeleton, but the in vivo expression and function of SRF in podocytes are unknown. We found that SRF protein colocalizes with podocyte markers in human and mouse kidneys. Compared with littermate controls, mice in which the Srf gene was conditionally inactivated with NPHS2 - Cre exhibited early postnatal proteinuria, hypoalbuminemia, and azotemia. Histologic changes in the mutant mice included glomerular capillary dilation and mild glomerulosclerosis, with reduced expression of multiple canonical podocyte markers. We also noted tubular dilation, cell proliferation, and protein casts as well as reactive changes in mesangial cells and interstitial inflammation. Ultrastructure analysis disclosed foot process effacement with loss of slit diaphragms. To ascertain the importance of SRF coFactors in podocyte function, we disabled the myocardin-related transcription Factor A and B genes. Although loss of either SRF coFactor alone had no observable effect in the kidney, deficiency of both recapitulated the Srf -null phenotype. These results establish a vital role for SRF and two SRF coFactors in the maintenance of podocyte structure and function.
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serum Response Factor regulates smooth muscle contractility via myotonic dystrophy protein kinases and l type calcium channels
PLOS ONE, 2017Co-Authors: Moon Young Lee, Orazio J Slivano, Chanjae Park, Robyn M Berent, Paul Park, Brian G Jorgensen, Robert D Corrigan, Nathan Grainger, Peter J Blair, Joseph M MianoAbstract:Serum Response Factor (SRF) transcriptionally regulates expression of contractile genes in smooth muscle cells (SMC). Lack or decrease of SRF is directly linked to a phenotypic change of SMC, leading to hypomotility of smooth muscle in the gastrointestinal (GI) tract. However, the molecular mechanism behind SRF-induced hypomotility in GI smooth muscle is largely unknown. We describe here how SRF plays a functional role in the regulation of the SMC contractility via myotonic dystrophy protein kinase (DMPK) and L-type calcium channel CACNA1C. GI SMC expressed Dmpk and Cacna1c genes into multiple alternative transcriptional isoforms. Deficiency of SRF in SMC of Srf knockout (KO) mice led to reduction of SRF-dependent DMPK, which down-regulated the expression of CACNA1C. Reduction of CACNA1C in KO SMC not only decreased intracellular Ca2+ spikes but also disrupted their coupling between cells resulting in decreased contractility. The role of SRF in the regulation of SMC phenotype and function provides new insight into how SMC lose their contractility leading to hypomotility in pathophysiological conditions within the GI tract.
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myoslid is a novel serum Response Factor dependent long noncoding rna that amplifies the vascular smooth muscle differentiation program
Arteriosclerosis Thrombosis and Vascular Biology, 2016Co-Authors: Jinjing Zhao, Pengtao Jiang, Angelene Richards, Harold A Singer, Deyou Zheng, David Jourdheuil, Arif Asif, Wen Wu, Wei Zhang, Joseph M MianoAbstract:Objective— Long noncoding RNAs (lncRNA) represent a growing class of noncoding genes with diverse cellular functions. We previously reported on SENCR , an lncRNA that seems to support the vascular smooth muscle cell (VSMC) contractile phenotype. However, information about the VSMC-specific lncRNAs regulated by myocardin (MYOCD)/serum Response Factor, the master switch for VSMC differentiation, is virtually unknown. Approach and Results— To define novel lncRNAs with functions related to VSMC differentiation, we performed RNA sequencing in human coronary artery SMCs that overexpress MYOCD. Several novel lncRNAs showed altered expression with MYOCD overexpression and one, named MYOcardin-induced smooth muscle lncRNA, inducer of differentiation ( MYOSLID ), was activated by MYOCD and selectively expressed in VSMCs. MYOSLID was a direct transcriptional target of both MYOCD/serum Response Factor and transforming growth Factor-β/SMAD pathways. Functional studies revealed that MYOSLID promotes VSMC differentiation and inhibits VSMC proliferation. MYOSLID showed reduced expression in failed human arteriovenous fistula samples compared with healthy veins. Although MYOSLID did not affect gene expression of transcription Factors, such as serum Response Factor and MYOCD, its depletion in VSMCs disrupted actin stress fiber formation and blocked nuclear translocation of MYOCD-related transcription Factor A (MKL1). Finally, loss of MYOSLID abrogated transforming growth Factor-β1–induced SMAD2 phosphorylation. Conclusions— We have demonstrated that MYOSLID , the first human VSMC-selective and serum Response Factor/CArG-dependent lncRNA, is a novel modulator in amplifying the VSMC differentiation program, likely through feed-forward actions of both MKL1 and transforming growth Factor-β/SMAD pathways.
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myoslid is a novel serum Response Factor dependent long noncoding rna that amplifies the vascular smooth muscle differentiation program
Arteriosclerosis Thrombosis and Vascular Biology, 2016Co-Authors: Jinjing Zhao, Pengtao Jiang, Angelene Richards, Harold A Singer, Deyou Zheng, David Jourdheuil, Arif Asif, Wen Wu, Wei Zhang, Joseph M MianoAbstract:Objective— Long noncoding RNAs (lncRNA) represent a growing class of noncoding genes with diverse cellular functions. We previously reported on SENCR , an lncRNA that seems to support the vascular smooth muscle cell (VSMC) contractile phenotype. However, information about the VSMC-specific lncRNAs regulated by myocardin (MYOCD)/serum Response Factor, the master switch for VSMC differentiation, is virtually unknown. Approach and Results— To define novel lncRNAs with functions related to VSMC differentiation, we performed RNA sequencing in human coronary artery SMCs that overexpress MYOCD. Several novel lncRNAs showed altered expression with MYOCD overexpression and one, named MYOcardin-induced smooth muscle lncRNA, inducer of differentiation ( MYOSLID ), was activated by MYOCD and selectively expressed in VSMCs. MYOSLID was a direct transcriptional target of both MYOCD/serum Response Factor and transforming growth Factor-β/SMAD pathways. Functional studies revealed that MYOSLID promotes VSMC differentiation and inhibits VSMC proliferation. MYOSLID showed reduced expression in failed human arteriovenous fistula samples compared with healthy veins. Although MYOSLID did not affect gene expression of transcription Factors, such as serum Response Factor and MYOCD, its depletion in VSMCs disrupted actin stress fiber formation and blocked nuclear translocation of MYOCD-related transcription Factor A (MKL1). Finally, loss of MYOSLID abrogated transforming growth Factor-β1–induced SMAD2 phosphorylation. Conclusions— We have demonstrated that MYOSLID , the first human VSMC-selective and serum Response Factor/CArG-dependent lncRNA, is a novel modulator in amplifying the VSMC differentiation program, likely through feed-forward actions of both MKL1 and transforming growth Factor-β/SMAD pathways.
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serum Response Factor utilizes distinct promoter and enhancer based mechanisms to regulate cytoskeletal gene expression in macrophages
Molecular and Cellular Biology, 2011Co-Authors: Amy L Sullivan, Joseph M Miano, Christopher Benner, Sven Heinz, Wendy Huang, Christopher K GlassAbstract:Cells of the monocyte/macrophage lineage play essential roles in tissue homeostasis and immune Responses, but mechanisms underlying the coordinated expression of cytoskeletal genes required for specialized functions of these cells, such as directed migration and phagocytosis, remain unknown. Here, using genetic and genomic approaches, we provide evidence that serum Response Factor (SRF) regulates both general and cell type-restricted components of the cytoskeletal gene expression program in macrophages. Genome-wide location analysis of SRF in macrophages demonstrates enrichment of SRF binding at ubiquitously expressed target gene promoters, as expected, but also reveals that the majority of SRF binding sites associated with cell type-restricted target genes are at distal inter- and intragenic locations. Most of these distal SRF binding sites are established by the prior binding of the macrophage- and the B cell-specific transcription Factor PU.1 and exhibit histone modifications characteristic of enhancers. Consistent with this, representative cytoskeletal target genes associated with these elements require both SRF and PU.1 for full expression. These findings suggest that SRF uses two distinct molecular strategies to regulate programs of cytoskeletal gene expression: a promoter-based strategy for ubiquitously expressed target genes and an enhancer-based strategy at target genes that exhibit cell type-restricted patterns of expression.
Richard Treisman - One of the best experts on this subject based on the ideXlab platform.
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actin together serum Response Factor its coFactors and the link to signal transduction
Trends in Cell Biology, 2006Co-Authors: Guido Posern, Richard TreismanAbstract:The vast diversity of cellular types and behaviours is mainly the result of combinatorial interactions between a limited number of transcription Factors and cellular signalling pathways whose activity is stringently controlled by developmental, cellular and extracellular cues. Studies of serum Response Factor (SRF) have provided a paradigm for such interactions for some years. Recent advances have shown that two families of SRF coFactors, the ternary complex Factors (TCFs) and the myocardin-related transcription Factors (MTRFs), are regulated by separate signalling pathways and thereby control SRF target genes differentially. The actin cytoskeleton is both an upstream regulator of MRTF activity, with monomeric actin directly acting as a signal transducer, and a downstream effector, because of the many cytoskeletal target genes. Here we discuss how the competition among coFactors might integrate these distinct signalling pathways into a specific transcriptional Response and biological function.
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mutant actins demonstrate a role for unpolymerized actin in control of transcription by serum Response Factor
Molecular Biology of the Cell, 2002Co-Authors: Guido Posern, Athanassia Sotiropoulos, Richard TreismanAbstract:Signal-induced activation of the transcription Factor serum Response Factor (SRF) requires alterations in actin dynamics. SRF activity can be inhibited by ectopic expression of β-actin, either because actin itself participates in SRF regulation or as a consequence of cytoskeletal perturbations. To distinguish between these possibilities, we studied actin mutants. Three mutant actins, G13R, R62D, and a C-terminal VP16 fusion protein, were shown not to polymerize in vivo, as judged by two-hybrid, immunofluorescence, and cell fractionation studies. These actins effectively inhibited SRF activation, as did wild-type actin, which increased the G-actin level without altering the F:G-actin ratio. Physical interaction between SRF and actin was not detectable by mammalian or yeast two-hybrid assays, suggesting that SRF regulation involves an unidentified coFactor. SRF activity was not blocked upon inhibition of CRM1-mediated nuclear export by leptomycin B. Two actin mutants were identified, V159N and S14C, whose expression favored F-actin formation and which strongly activated SRF in the absence of external signals. These mutants seemed unable to inhibit SRF activity, because their expression did not reduce the absolute level of G-actin as assessed by DNase I binding. Taken together, these results provide strong evidence that G-actin, or a subpopulation of it, plays a direct role in signal transduction to SRF.
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lim kinase and diaphanous cooperate to regulate serum Response Factor and actin dynamics
Journal of Cell Biology, 2002Co-Authors: O Geneste, John W Copeland, Richard TreismanAbstract:The small GTPase RhoA controls activity of serum Response Factor (SRF) by inducing changes in actin dynamics. We show that in PC12 cells, activation of SRF after serum stimulation is RhoA dependent, requiring both actin polymerization and the Rho kinase (ROCK)–LIM kinase (LIMK)–cofilin signaling pathway, previously shown to control F-actin turnover. Activation of SRF by overexpression of wild-type LIMK or ROCK-insensitive LIMK mutants also requires functional RhoA, indicating that a second RhoA-dependent signal is involved. This is provided by the RhoA effector mDia: dominant interfering mDia1 derivatives inhibit both serum- and LIMK-induced SRF activation and reduce the ability of LIMK to induce F-actin accumulation. These results demonstrate a role for LIMK in SRF activation, and functional cooperation between RhoA-controlled LIMK and mDia effector pathways.
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differential usage of signal transduction pathways defines two types of serum Response Factor target gene
Journal of Biological Chemistry, 2001Co-Authors: Dziugas Gineitis, Richard TreismanAbstract:Abstract Activation of the transcription Factor serum Response Factor (SRF) is dependent on Rho-controlled changes in actin dynamics. We used pathway-specific inhibitors to compare the roles of actin dynamics, extracellular signal-regulated kinase (ERK) signaling, and phosphatidylinositol 3-kinase in signaling either to SRF itself or to four cellular SRF target genes. Serum, lysophosphatidic acid, platelet-derived growth Factor, and phorbol 12-myristate 13-acetate (PMA) each activated transcription of a stably integrated SRF reporter gene dependent on functional RhoA GTPase. Inhibition of mitogen-activated protein kinase-ERK kinase (MEK) signalling reduced activation of the SRF reporter by all stimuli by about 50%, except for PMA, which was effectively blocked. Inhibition of phosphatidylinositol 3-kinase slightly reduced reporter activation by serum and lysophosphatidic acid but substantially inhibited activation by platelet-derived growth Factor and PMA. Reporter induction by all stimuli was absolutely dependent on actin dynamics. Regulation of the SRF (srf) and vinculin (vcl) genes was similar to that of the SRF reporter gene; activation by all stimuli was Rho-dependent and required actin dynamics but was largely independent of MEK activity. In contrast, activation of fos and egr1 occurred independently of RhoA and actin polymerization but was almost completely dependent on MEK activation. These results show that at least two classes of SRF target genes can be distinguished on the basis of their relative sensitivity to RhoA-actin and MEK-ERK signaling pathways.
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signal regulated activation of serum Response Factor is mediated by changes in actin dynamics
Cell, 1999Co-Authors: Athanassia Sotiropoulos, Dziugas Gineitis, John Copeland, Richard TreismanAbstract:Abstract Serum Response Factor (SRF) regulates transcription of many serum-inducible and muscle-specific genes. Using a functional screen, we identified LIM kinase-1 as a potent activator of SRF. We show that SRF activation by LIM kinase-1 is dependent on its ability to regulate actin treadmilling. LIM kinase activity is not essential for SRF activation by serum, but signals depend on alterations in actin dynamics. Studies with actin-binding drugs, the actin-specific C2 toxin, and actin overexpression demonstrate that G-actin level controls SRF. Regulation of actin dynamics is necessary for serum induction of a subset of SRF target genes, including vinculin, cytoskeletal actin, and srf itself, and also suffices for their activation. Actin treadmilling provides a convergence point for both serum- and LIM kinase-1-induced signaling to SRF.
Eric N Olson - One of the best experts on this subject based on the ideXlab platform.
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The serum Response Factor (SRF)/megakaryocytic acute leukemia (MAL) network participates in megakaryocyte development.
Leukemia, 2010Co-Authors: Christine Ragu, Siham Boukour, Gaelle Elain, Orianne Wagner-ballon, Hana Raslova, Dominique Daegelen, William Vainchenker, Najet Debili, Eric N Olson, Olivier BernardAbstract:The serum Response Factor (SRF)/megakaryocytic acute leukemia (MAL) network participates in megakaryocyte development
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serum Response Factor mads box serine 162 phosphorylation switches proliferation and myogenic gene programs
Proceedings of the National Academy of Sciences of the United States of America, 2006Co-Authors: Dinakar Iyer, Robert J Schwartz, Eric N Olson, Michael S Parmacek, David F Chang, Joe Marx, Ashok BalasubramanyamAbstract:Phosphorylation of a cluster of amino acids in the serum Response Factor (SRF) “MADS box” αI coil DNA binding domain regulated the transcription of genes associated with proliferation or terminal muscle differentiation. Mimicking phosphorylation of serine-162, a target of protein kinase C-α, with an aspartic acid substitution (SRF-S162D) completely inhibited SRF–DNA binding and blocked α-actin gene transcription even in the presence of potent myogenic coFactors, while preserving c-fos promoter activity because of stabilization of the ternary complex via Elk-1. Introduction of SRF-S162D into SRF null ES cells permitted transcription of the c-fos gene but was unable to rescue expression of myogenic contractile genes. Transition of proliferating C2C12 myoblasts to postfusion myocytes after serum withdrawal was associated with a progressive decline in SRF-S162 phosphorylation and an increase in α-actin gene expression. Hence, the phosphorylation status of serine-162 in the αI coil may constitute a novel switch that directs target gene expression into proliferation or differentiation programs.
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muscle specific signaling mechanism that links actin dynamics to serum Response Factor
Molecular and Cellular Biology, 2005Co-Authors: Koichiro Kuwahara, G Teg C Pipes, Tomasa Barrientos, Shijie Li, Eric N OlsonAbstract:Myocardin and the myocardin-related transcription Factors (MRTFs) MRTF-A and MRTF-B are coactivators for serum Response Factor (SRF), which regulates genes involved in cell proliferation, migration, cytoskeletal dynamics, and myogenesis. MRTF-A has been shown to translocate to the nucleus and activate SRF in Response to Rho signaling and actin polymerization. Previously, we described a muscle-specific actin-binding protein named striated muscle activator of Rho signaling (STARS) that also activates SRF through a Rho-dependent mechanism. Here we show that STARS activates SRF by inducing the nuclear translocation of MRTFs. The STARS-dependent nuclear import of MRTFs requires RhoA and actin polymerization, and the actin-binding domain of STARS is necessary and sufficient for this activity. A knockdown of endogenous STARS expression by using small interfering RNA significantly reduced SRF activity in differentiated C2C12 skeletal muscle cells and cardiac myocytes. The ability of STARS to promote the nuclear localization of MRTFs and SRF-mediated transcription provides a potential muscle-specific mechanism for linking changes in actin dynamics and sarcomere structure with striated muscle gene expression.
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requirement for serum Response Factor for skeletal muscle growth and maturation revealed by tissue specific gene deletion in mice
Proceedings of the National Academy of Sciences of the United States of America, 2005Co-Authors: Shijie Li, Franziska F Wiebel, Alfred Nordheim, James A Richardson, Michael P Czubryt, John Mcanally, Rhonda S Basselduby, Eric N OlsonAbstract:Serum Response Factor (SRF) controls the transcription of muscle genes by recruiting a variety of partner proteins, including members of the myocardin family of transcriptional coactivators. Mice lacking SRF fail to form mesoderm and die before gastrulation, precluding an analysis of the roles of SRF in muscle tissues. To investigate the functions of SRF in skeletal muscle development, we conditionally deleted the Srf gene in mice by skeletal muscle-specific expression of Cre recombinase. In mice lacking skeletal muscle SRF expression, muscle fibers formed, but failed to undergo hypertrophic growth after birth. Consequently, mutant mice died during the perinatal period from severe skeletal muscle hypoplasia. The myopathic phenotype of these mutant mice resembled that of mice expressing a dominant negative mutant of a myocardin family member in skeletal muscle. These findings reveal an essential role for the partnership of SRF and myocardin-related transcription Factors in the control of skeletal muscle growth and maturation in vivo.
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a myocardin related transcription Factor regulates activity of serum Response Factor in drosophila
Proceedings of the National Academy of Sciences of the United States of America, 2004Co-Authors: Xiumin Li, Jiang Wu, Eric N OlsonAbstract:Serum Response Factor (SRF) regulates genes involved in cell proliferation, migration, cytoskeletal organization, and myogenesis. Myocardin and myocardin-related transcription Factors (MRTFs) act as powerful transcriptional coactivators of SRF in mammalian cells. We describe an MRTF from Drosophila, called DMRTF, which shares high homology with the functional domains of mammalian myocardin and MRTFs. DMRTF forms a ternary complex with and stimulates the activity of Drosophila SRF, which has been implicated in branching of the tracheal (respiratory) system and formation of wing interveins. A loss-of-function mutation introduced into the DMRTF locus by homologous recombination results in abnormalities in tracheal branching similar to those in embryos lacking SRF. Misexpression in wing imaginal discs of a dominant negative DMRTF mutant also causes a diminution of wing interveins, whereas overexpression of DMRTF results in excess intervein tissue, abnormalities reminiscent of SRF loss- and gain-of-function phenotypes, respectively. Overexpression of these DMRTF mutants in mesoderm and in the tracheal system also perturbs mesoderm cell migration and tracheal branching, respectively. We conclude that the interaction of MRTFs with SRF represents an ancient protein partnership involved in cytoplasmic outgrowth and cell migration during development.
Robert J Schwartz - One of the best experts on this subject based on the ideXlab platform.
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serum Response Factor orchestrates nascent sarcomerogenesis and silences the biomineralization gene program in the heart
Proceedings of the National Academy of Sciences of the United States of America, 2008Co-Authors: Dinakar Iyer, Kathryn N Ivey, Simon J. Conway, Alfred Nordheim, James F Martin, Deepak Srivastava, Robert J SchwartzAbstract:Our conditional serum Response Factor (SRF) knockout, Srf Cko, in the heart-forming region blocked the appearance of rhythmic beating myocytes, one of the earliest cardiac defects caused by the ablation of a cardiac-enriched transcription Factor. The appearance of Hand1 and Smyd1, transcription and chromatin remodeling Factors; Acta1, Acta2, Myl3, and Myom1, myofibril proteins; and calcium-activated potassium-channel gene activity (KCNMB1), the channel protein, were powerfully attenuated in the SrfCKO mutant hearts. A requisite role for combinatorial coFactor interactions with SRF, as a major determinant for regulating the appearance of organized sarcomeres, was shown by viral rescue of SRF-null ES cells with SRF point mutants that block coFactor interactions. In the absence of SRF genes associated with biomineralization, GATA-6, bone morphogenetic protein 4 (BMP4), and periostin were strongly up-regulated, coinciding with the down regulation of many SRF dependent microRNA, including miR1, which exerted robust silencer activity over the induction of GATA-6 leading to the down regulation of BMP4 and periostin.
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serum Response Factor micromanaging cardiogenesis
Current Opinion in Cell Biology, 2007Co-Authors: Shuxing Zhang, Ankang Li, Robert J SchwartzAbstract:Serum Response Factor (SRF), a cardiac-enriched transcription Factor, is required for the appearance of beating sarcomeres in the heart. SRF may also direct the expression of microRNAs (miRs) that inhibit the expression of cardiac regulatory Factors. The recent knockout of miR-1-2, an SRF gene target, showed defective heart development, caused in part by the induction of GATA6, Irx4/5, and Hand2, that may alter cardiac morphogenesis, channel activity, and cell cycling. SRF and coFactors play an obligatory role in cardiogenesis, as major determinants of myocyte differentiation not only by regulating the biogenesis of muscle contractile proteins but also by driving the expression of silencer miRNA.
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serum Response Factor mads box serine 162 phosphorylation switches proliferation and myogenic gene programs
Proceedings of the National Academy of Sciences of the United States of America, 2006Co-Authors: Dinakar Iyer, Robert J Schwartz, Eric N Olson, Michael S Parmacek, David F Chang, Joe Marx, Ashok BalasubramanyamAbstract:Phosphorylation of a cluster of amino acids in the serum Response Factor (SRF) “MADS box” αI coil DNA binding domain regulated the transcription of genes associated with proliferation or terminal muscle differentiation. Mimicking phosphorylation of serine-162, a target of protein kinase C-α, with an aspartic acid substitution (SRF-S162D) completely inhibited SRF–DNA binding and blocked α-actin gene transcription even in the presence of potent myogenic coFactors, while preserving c-fos promoter activity because of stabilization of the ternary complex via Elk-1. Introduction of SRF-S162D into SRF null ES cells permitted transcription of the c-fos gene but was unable to rescue expression of myogenic contractile genes. Transition of proliferating C2C12 myoblasts to postfusion myocytes after serum withdrawal was associated with a progressive decline in SRF-S162 phosphorylation and an increase in α-actin gene expression. Hence, the phosphorylation status of serine-162 in the αI coil may constitute a novel switch that directs target gene expression into proliferation or differentiation programs.
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physical interaction between the mads box of serum Response Factor and the tea atts dna binding domain of transcription enhancer Factor 1
Journal of Biological Chemistry, 2001Co-Authors: Madhu Gupta, Narasimhaswamy S Belaguli, Robert J Schwartz, Paul Kogut, Francesca J Davis, Mahesh P GuptaAbstract:Abstract Serum Response Factor is a MADS box transcription Factor that binds to consensus sequences CC(A/T)6GG found in the promoter region of several serum-inducible and muscle-specific genes. In skeletal myocytes serum Response Factor (SRF) has been shown to heterodimerize with the myogenic basic helix-loop-helix family of Factors, related to MyoD, for control of muscle gene regulation. Here we report that SRF binds to another myogenic Factor, TEF-1, that has been implicated in the regulation of a variety of cardiac muscle genes. By using different biochemical assays such as affinity precipitation of protein, GST-pulldown assay, and coimmunoprecipitation of proteins, we show that SRF binds to TEF-1 both in in vitro and in vivoassay conditions. A strong interaction of SRF with TEF-1 was seen even when one protein was denatured and immobilized on nitrocellulose membrane, indicating a direct and stable interaction between SRF and TEF-1, which occurs without a coFactor. This interaction is mediated through the C-terminal subdomain of MADS box of SRF encompassing amino acids 204–244 and the putative 2nd and 3rd α-helix/β-sheet configuration of the TEA/ATTS DNA-binding domain of TEF-1. In the transient transfection assay, a positive cooperative effect of SRF and TEF-1 was observed when DNA-binding sites for both Factors, serum Response element and M-CAT respectively, were intact; mutation of either site abolished their synergistic effect. Similarly, an SRF mutant, SRFpm-1, defective in DNA binding failed to collaborate with TEF-1 for gene regulation, indicating that the synergistic trans-activation function of SRF and TEF-1 occurs via their binding to cognate DNA-binding sites. Our results demonstrate a novel association between SRF and TEF-1 for cardiac muscle gene regulation and disclose a general mechanism by which these two super families of Factors are likely to control diversified biological functions.
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cardiac tissue enriched Factors serum Response Factor and gata 4 are mutual coregulators
Molecular and Cellular Biology, 2000Co-Authors: Narasimhaswamy S Belaguli, Mona Nemer, Jorge L Sepulveda, Vishal Nigam, Frederic Charron, Robert J SchwartzAbstract:Combinatorial interaction among cardiac tissue-restricted enriched transcription Factors may facilitate the expression of cardiac tissue-restricted genes. Here we show that the MADS box Factor serum Response Factor (SRF) cooperates with the zinc finger protein GATA-4 to synergistically activate numerous myogenic and nonmyogenic serum Response element (SRE)-dependent promoters in CV1 fibroblasts. In the absence of GATA binding sites, synergistic activation depends on binding of SRF to the proximal CArG box sequence in the cardiac and skeletal α-actin promoter. GATA-4's C-terminal activation domain is obligatory for synergistic coactivation with SRF, and its N-terminal domain and first zinc finger are inhibitory. SRF and GATA-4 physically associate both in vivo and in vitro through their MADS box and the second zinc finger domains as determined by protein A pullout assays and by in vivo one-hybrid transfection assays using Gal4 fusion proteins. Other cardiovascular tissue-restricted GATA Factors, such as GATA-5 and GATA-6, were equivalent to GATA-4 in coactivating SRE-dependent targets. Thus, interaction between the MADS box and C4 zinc finger proteins, a novel regulatory paradigm, mediates activation of SRF-dependent gene expression.
Joanne S Richards - One of the best experts on this subject based on the ideXlab platform.
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egr 1 induction in rat granulosa cells by follicle stimulating hormone and luteinizing hormone combinatorial regulation by transcription Factors cyclic adenosine 3 5 monophosphate regulatory element binding protein serum Response Factor sp1 and early
Molecular Endocrinology, 2003Co-Authors: Darryl L Russell, Kari M H Doyle, Ignacio Gonzalesrobayna, Carlos Pipaon, Joanne S RichardsAbstract:Early growth Response Factor (Egr-1) is an inducible zinc finger transcription Factor that binds specific GC-rich enhancer elements and impacts female reproduction. These studies document for the first time that FSH rapidly induces Egr-1 expression in granulosa cells of small growing follicles. This Response is transient but is reinitiated in preovulatory follicles exposed to the LH analog, human chorionic gonadotropin. Immunohistochemical analysis also showed gonadotropin induced Egr-1 in theca cells. The Egr-1 gene regulatory region responsive to gonadotropin signaling was localized within −164 bp of the transcription initiation site. Binding of Sp1/Sp3 to a proximal GC-box at −64/−46 bp was enhanced by FSH in immature granulosa cells but reduced after human chorionic gonadotropin stimulation of preovulatory follicles despite constant protein expression. This dynamic regulation of Sp1 binding was dependent on gonadotropin-regulated mechanisms that modulate Sp1/3-DNA binding activity. Serum Response fact...
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egr 1 induction in rat granulosa cells by follicle stimulating hormone and luteinizing hormone combinatorial regulation by transcription Factors cyclic adenosine 3 5 monophosphate regulatory element binding protein serum Response Factor sp1 and early
Molecular Endocrinology, 2003Co-Authors: Darryl L Russell, Kari M H Doyle, Ignacio Gonzalesrobayna, Carlos Pipaon, Joanne S RichardsAbstract:Early growth Response Factor (Egr-1) is an inducible zinc finger transcription Factor that binds specific GC-rich enhancer elements and impacts female reproduction. These studies document for the first time that FSH rapidly induces Egr-1 expression in granulosa cells of small growing follicles. This Response is transient but is reinitiated in preovulatory follicles exposed to the LH analog, human chorionic gonadotropin. Immunohistochemical analysis also showed gonadotropin induced Egr-1 in theca cells. The Egr-1 gene regulatory region responsive to gonadotropin signaling was localized within −164 bp of the transcription initiation site. Binding of Sp1/Sp3 to a proximal GC-box at −64/−46 bp was enhanced by FSH in immature granulosa cells but reduced after human chorionic gonadotropin stimulation of preovulatory follicles despite constant protein expression. This dynamic regulation of Sp1 binding was dependent on gonadotropin-regulated mechanisms that modulate Sp1/3-DNA binding activity. Serum Response fact...
