scholarly journals Expression and activity of serum response factor is required for expression of the muscle-determining factor MyoD in both dividing and differentiating mouse C2C12 myoblasts.

1996 ◽  
Vol 7 (5) ◽  
pp. 719-729 ◽  
Author(s):  
C Gauthier-Rouviere ◽  
M Vandromme ◽  
D Tuil ◽  
N Lautredou ◽  
M Morris ◽  
...  
Keyword(s):  
Serum Response Factor ◽  
Dominant Negative ◽  
C2c12 Cells ◽  
Dominant Negative Mutant ◽  
Response Factor ◽  
Serum Response ◽  
Determining Factor ◽  
Myod Expression ◽  
Expression And Activity

To understand the mechanism by which the serum response factor (SRF) is involved in the process of skeletal muscle differentiation, we have assessed the effect of inhibiting SRF activity or synthesis on the expression of the muscle-determining factor MyoD. Inhibition of SRF activity in mouse myogenic C2C12 cells through microinjection of either the SRE oligonucleotide (which acts by displacing SRF proteins from the endogenous SRE sequences), purified SRF-DB (a 30-kDa portion of SRF containing the DNA-binding domain of SRF, which acts as a dominant negative mutant in vivo), or purified anti-SRF antibodies rapidly prevents the expression of MyoD. Moreover, the rapid shutdown of MyoD expression after in vivo inhibition of SRF activity is observed not only in proliferating myoblasts but also in myoblasts cultured under differentiating conditions. Additionally, by using a cellular system expressing a glucocorticoid-inducible antisense-SRF (from aa 74 to 244) we have shown that blocking SRF expression by dexamethasone induction of antisense SRF results in the lack of MyoD expression as probed by both immunofluorescence and Northern blot analysis. Taken together these data demonstrate that SRF expression and activity are required for the expression of the muscle-determining factor MyoD.

scholarly journals Four isoforms of serum response factor that increase or inhibit smooth-muscle-specific promoter activity

2000 ◽  
Vol 345 (3) ◽  
pp. 445-451 ◽  
Author(s):  
Paul R. KEMP ◽  
James C. METCALFE
Keyword(s):  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Serum Response Factor ◽  
Muscle Cells ◽  
Dominant Negative ◽  
C2c12 Cells ◽  
Specific Gene ◽  
Response Factor ◽  
Transactivation Domain ◽  
Serum Response

Serum response factor (SRF) is a key transcriptional activator of the c-fos gene and of muscle-specific gene expression. We have identified four forms of the SRF coding sequence, SRF-L (the previously identified form), SRF-M, SRF-S and SRF-I, that are produced by alternative splicing. The new forms of SRF lack regions of the C-terminal transactivation domain by splicing out of exon 5 (SRF-M), exons 4 and 5 (SRF-S) and exons 3, 4 and 5 (SRF-I). SRF-M is expressed at similar levels to SRF-L in differentiated vascular smooth-muscle cells and skeletal-muscle cells, whereas SRF-L is the predominant form in many other tissues. SRF-S expression is restricted to vascular smooth muscle and SRF-I expression is restricted to the embryo. Transfection of SRF-L and SRF-M into C2C12 cells showed that both forms are transactivators of the promoter of the smooth-muscle-specific gene SM22α, whereas SRF-I acted as a dominant negative form of SRF.

scholarly journals Dominant Negative Murine Serum Response Factor: Alternative Splicing within the Activation Domain Inhibits Transactivation of Serum Response Factor Binding Targets

1999 ◽  
Vol 19 (7) ◽  
pp. 4582-4591 ◽  
Author(s):  
Narasimhaswamy S. Belaguli ◽  
Wei Zhou ◽  
Thuy-Hanh T. Trinh ◽  
Mark W. Majesky ◽  
Robert J. Schwartz
Keyword(s):  
Dna Binding ◽  
Serum Response Factor ◽  
Smooth Muscles ◽  
Dominant Negative ◽  
C2c12 Cells ◽  
Luciferase Reporter ◽  
Response Factor ◽  
Activation Domain ◽  
Alternatively Spliced ◽  
Serum Response

ABSTRACT Primary transcripts encoding the MADS box superfamily of proteins, such as MEF2 in animals and ZEMa in plants, are alternatively spliced, producing several isoformic species. We show here that murine serum response factor (SRF) primary RNA transcripts are alternatively spliced at the fifth exon, deleting approximately one-third of the C-terminal activation domain. Among the different muscle types examined, visceral smooth muscles have a very low ratio of SRFΔ5 to SRF. Increased levels of SRFΔ5 correlates well with reduced smooth muscle contractile gene activity within the elastic aortic arch, suggesting important biological roles for differential expression of SRFΔ5 variant relative to wild-type SRF. SRFΔ5 forms DNA binding-competent homodimers and heterodimers. SRFΔ5 acts as a naturally occurring dominant negative regulatory mutant that blocks SRF-dependent skeletal α-actin, cardiac α-actin, smooth α-actin, SM22α, and SRF promoter-luciferase reporter activities. Expression of SRFΔ5 interferes with differentiation of myogenic C2C12 cells and the appearance of skeletal α-actin and myogenin mRNAs. SRFΔ5 repressed the serum-induced activity of the c-fos serum response element. SRFΔ5 fused to the yeast Gal4 DNA binding domain displayed low transcriptional activity, which was complemented by overexpression of the coactivator ATF6. These results indicate that the absence of exon 5 might be bypassed through recruitment of transcription factors that interact with extra-exon 5 regions in the transcriptional activating domain. The novel alternatively spliced isoform of SRF, SRFΔ5, may play an important regulatory role in modulating SRF-dependent gene expression.

scholarly journals Myozap, a Novel Intercalated Disc Protein, Activates Serum Response Factor–Dependent Signaling and Is Required to Maintain Cardiac Function In Vivo

2010 ◽  
Vol 106 (5) ◽  
pp. 880-890 ◽  
Author(s):  
Thalia S. Seeger ◽  
Derk Frank ◽  
Claudia Rohr ◽  
Rainer Will ◽  
Steffen Just ◽  
...  
Keyword(s):  
Cardiac Function ◽  
Serum Response Factor ◽  
Response Factor ◽  
Intercalated Disc ◽  
Serum Response

Functional antagonism between YY1 and the serum response factor

1992 ◽  
Vol 12 (9) ◽  
pp. 4209-4214
Author(s):  
A Gualberto ◽  
D LePage ◽  
G Pons ◽  
S L Mader ◽  
K Park ◽  
...  
Keyword(s):  
Serum Response Factor ◽  
Regulatory Element ◽  
Target Sequence ◽  
Response Factor ◽  
Basal Expression ◽  
Actin Promoter ◽  
Alpha Actin ◽  
Serum Response

The rapid, transient induction of the c-fos proto-oncogene by serum growth factors is mediated by the serum response element (SRE). The SRE shares homology with the muscle regulatory element (MRE) of the skeletal alpha-actin promoter. It is not known how these elements respond to proliferative and cell-type-specific signals, but the response appears to involve the binding of the serum response factor (SRF) and other proteins. Here, we report that YY1, a multifunctional transcription factor, binds to SRE and MRE sequences in vitro. The methylation interference footprint of YY1 overlaps with that of the SRF, and YY1 competes with the SRF for binding to these DNA elements. Overexpression of YY1 repressed serum-inducible and basal expression from the c-fos promoter and repressed basal expression from the skeletal alpha-actin promoter. YY1 also repressed expression from the individual SRE and MRE sequences upstream from a TATA element. Unlike that of YY1, SRF overexpression alone did not influence the transcriptional activity of the target sequence, but SRF overexpression could reverse YY1-mediated trans repression. These data suggest that YY1 and the SRF have antagonistic functions in vivo.

Cardiomyopathy in transgenic mice with cardiac-specific overexpression of serum response factor

2001 ◽  
Vol 280 (4) ◽  
pp. H1782-H1792 ◽  
Author(s):  
Xiaomin Zhang ◽  
Gohar Azhar ◽  
Jianyuan Chai ◽  
Pamela Sheridan ◽  
Koichiro Nagano ◽  
...  
Keyword(s):  
Transgenic Mice ◽  
Cardiac Muscle ◽  
Serum Response Factor ◽  
Interstitial Fibrosis ◽  
Weight Ratio ◽  
Heart Weight ◽  
Cardiomyocyte Hypertrophy ◽  
Response Factor ◽  
Serum Response

Serum response factor (SRF), a member of the MCM1, agamous, deficiens, SRF (MADS) family of transcriptional activators, has been implicated in the transcriptional control of a number of cardiac muscle genes, including cardiac α-actin, skeletal α-actin, α-myosin heavy chain (α-MHC), and β-MHC. To better understand the in vivo role of SRF in regulating genes responsible for maintenance of cardiac function, we sought to test the hypothesis that increased cardiac-specific SRF expression might be associated with altered cardiac morphology and function. We generated transgenic mice with cardiac-specific overexpression of the human SRF gene. The transgenic mice developed cardiomyopathy and exhibited increased heart weight-to-body weight ratio, increased heart weight, and four-chamber dilation. Histological examination revealed cardiomyocyte hypertrophy, collagen deposition, and interstitial fibrosis. SRF overexpression altered the expression of SRF-regulated genes and resulted in cardiac muscle dysfunction. Our results demonstrate that sustained overexpression of SRF, in the absence of other stimuli, is sufficient to induce cardiac change and suggest that SRF is likely to be one of the downstream effectors of the signaling pathways involved in mediating cardiac hypertrophy.

scholarly journals Recruitment of the tinman homolog Nkx-2.5 by serum response factor activates cardiac alpha-actin gene transcription.

1996 ◽  
Vol 16 (11) ◽  
pp. 6372-6384 ◽  
Author(s):  
C Y Chen ◽  
R J Schwartz
Keyword(s):  
Dna Binding ◽  
Serum Response Factor ◽  
Binding Activity ◽  
Dominant Negative ◽  
Actin Gene ◽  
Response Factor ◽  
Dna Binding Activity ◽  
Actin Promoter ◽  
Alpha Actin ◽  
Serum Response

We recently showed that the cardiogenic homeodomain factor Nkx-2.5 served as a positive acting accessory factor for serum response factor (SRF) and that together they provided strong transcriptional activation of the cardiac alpha-actin promoter, depending upon intact serum response elements (SREs) (C. Y. Chen, J. Croissant, M. Majesky, S. Topouz, T. McQuinn, M. J. Frankovsky, and R. J. Schwartz, Dev. Genet. 19:119-130, 1996). As shown here, Nkx-2.5 and SRF collaborated to activate the endogenous murine cardiac alpha-actin gene in 10T1/2 fibroblasts by a mechanism in which SRF recruited Nkx-2.5 to the alpha-actin promoter. Activation of a truncated promoter consisting of the proximal alpha-actin SRE1 occurred even when Nkx-2.5 DNA-binding activity was blocked by a point mutation in the third helix of its homeodomain. Investigation of protein-protein interactions showed that Nkx-2.5 was bound to SRF in the absence of DNA in soluble protein complexes retrieved from cardiac myocyte nuclei but could also be detected in coassociated binding complexes on the proximal SRE1. Recruitment of Nkx-2.5 to an SRE depended upon SRF DNA-binding activity and was blocked by the dominant negative SRFpm1 mutant, which allowed for dimerization of SRF monomers but prevented DNA binding. Interactive regions shared by Nkx-2.5 and SRF were mapped to N-terminal/helix I and helix II/helix III regions of the Nkx-2.5 homeodomain and to the N-terminal extension of the MADS box. Our study suggests that physical association between Nkx-2.5 and SRF is one way that cardiac specified genes are activated in cardiac cell lineages.

scholarly journals Novel Transcription Coactivator Complex Containing Activating Signal Cointegrator 1

2002 ◽  
Vol 22 (14) ◽  
pp. 5203-5211 ◽  
Author(s):  
Dong-Ju Jung ◽  
Hee-Sook Sung ◽  
Young-Wha Goo ◽  
Hyun Mi Lee ◽  
Ok Ku Park ◽  
...  
Keyword(s):  
Nuclear Receptors ◽  
Serum Response Factor ◽  
Ectopic Expression ◽  
Nuclear Factor Κb ◽  
Dominant Negative ◽  
Mutant Form ◽  
Negative Effects ◽  
Direct Binding ◽  
Serum Response

ABSTRACT Human activating signal cointegrator 1 (hASC-1) was originally isolated as a transcriptional coactivator of nuclear receptors. Here we report that ASC-1 exists as a steady-state complex associated with three polypeptides, P200, P100, and P50, in HeLa nuclei; stimulates transactivation by serum response factor (SRF), activating protein 1 (AP-1), and nuclear factor κB (NF-κB) through direct binding to SRF, c-Jun, p50, and p65; and relieves the previously described transrepression between nuclear receptors and either AP-1 or NF-κB. Interestingly, ectopic expression of Caenorhabditis elegans ASC-1 (ceASC-1), an ASC-1 homologue that binds P200 and P100, like hASC-1, while weakly interacting only with p65, in HeLa cells appears to replace endogenous hASC-1 from the hASC-1 complex and exerts potent dominant-negative effects on AP-1, NF-κB, and SRF transactivation. In addition, neutralization of endogenous P50 by single-cell microinjection of a P50 antibody inhibits AP-1 transactivation; the inhibition is relieved by coexpression of wild-type P50, but not of P50ΔKH, a mutant form that does not interact with P200. Overall, these results suggest that the endogenous hASC-1 complex appears to play an essential role in AP-1, SRF, and NF-κB transactivation and to mediate the transrepression between nuclear receptors and either AP-1 or NF-κB in vivo.

scholarly journals Cardiac Tissue Enriched Factors Serum Response Factor and GATA-4 Are Mutual Coregulators

2000 ◽  
Vol 20 (20) ◽  
pp. 7550-7558 ◽  
Author(s):  
Narasimhaswamy S. Belaguli ◽  
Jorge L. Sepulveda ◽  
Vishal Nigam ◽  
Frédéric Charron ◽  
Mona Nemer ◽  
...  
Keyword(s):  
Zinc Finger ◽  
Cardiac Tissue ◽  
Serum Response Factor ◽  
Zinc Finger Protein ◽  
Response Factor ◽  
Mads Box ◽  
Cardiovascular Tissue ◽  
Serum Response

ABSTRACT 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.

scholarly journals Delayed liver regeneration in mice lacking liver serum response factor

2007 ◽  
Vol 292 (4) ◽  
pp. G996-G1001 ◽  
Author(s):  
M. Ujue Latasa ◽  
Dominique Couton ◽  
Claude Charvet ◽  
Aurélie Lafanechère ◽  
Jacques-Emmanuel Guidotti ◽  
...  
Keyword(s):  
Liver Regeneration ◽  
Partial Hepatectomy ◽  
Serum Response Factor ◽  
Early Response ◽  
Mutant Mice ◽  
Response Factor ◽  
Impaired Liver ◽  
Serum Response

Various immediate early genes (IEGs) upregulated during the early process of liver regeneration are transcriptional targets of the serum response factor (SRF). We show here that the expression of SRF is rapidly induced in rodent liver after partial hepatectomy. Because the inactivation of the SRF gene in mice is embryonic lethal, the in vivo role of SRF in liver regeneration after partial hepatectomy was analyzed in mutant mice conditionally deleted for SRF in the liver. We demonstrate that SRF is not an essential factor for liver ontogenesis. However, adult mutant mice show impaired liver regeneration after partial hepatectomy, associated with a blunted upregulation of various SRF target IEGs. In conclusion, our work suggests that SRF is an early response transcription factor that may contribute to the initial phases of liver regeneration through its activation of IEGs.

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