Myocardin Sumoylation Transactivates Cardiogenic Genes in Pluripotent 10T1/2 Fibroblasts

ABSTRACT Myocardin, a serum response factor (SRF)-dependent cofactor, is a potent activator of smooth muscle gene activity but a poor activator of cardiogenic genes in pluripotent 10T1/2 fibroblasts. Posttranslational modification of GATA4, another myocardin cofactor, by sumoylation strongly activated cardiogenic gene activity. Here, we found that myocardin's activity was strongly enhanced by SUMO-1 via modification of a lysine residue primarily located at position 445 and that the conversion of this residue to arginine (K445R) impaired myocardin transactivation. PIAS1 was involved in governing myocardin activity via its E3 ligase activity that stimulated myocardin sumoylation on an atypical sumoylation site(s) and by its physical association with myocardin. Myocardin initiated the expression of cardiac muscle-specified genes, such as those encoding cardiac α-actin and α-myosin heavy chain, in an SRF-dependent manner in 10T1/2 fibroblasts, but only in the presence of coexpressed SUMO-1/PIAS1. Thus, SUMO modification acted as a molecular switch to promote myocardin's role in cardiogenic gene expression.

Download Full-text

The single-strand DNA/RNA-binding protein, Purβ, regulates serum response factor (SRF)-mediated cardiac muscle gene expressionThis paper is one of a selection of papers published in this Special Issue, entitled The Cellular and Molecular Basis of Cardiovascular Dysfunction, Dhalla 70th Birthday Tribute.

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y07-009 ◽

2007 ◽

Vol 85 (3-4) ◽

pp. 349-359 ◽

Cited By ~ 7

Author(s):

Madhu Gupta ◽

Vithida Sueblinvong ◽

Mahesh P. Gupta

Keyword(s):

Gene Expression ◽

Cardiac Muscle ◽

Rna Binding ◽

Serum Response Factor ◽

Single Strand ◽

Specific Gene ◽

Response Factor ◽

Repressive Effect ◽

Muscle Gene ◽

Serum Response

Single-strand DNA-binding proteins, Purα and Purβ, play a role in cell growth and differentiation by modulating both transcriptional and translational controls of gene expression. We have previously characterized binding of Purα and Purβ proteins to a purine-rich negative regulatory (PNR) element of the rat cardiac α-myosin heavy chain (MHC) gene that controls cardiac muscle specificity. In this study we investigated the role of upstream sequences of the α-MHC promoter in Purβ-mediated gene repression. In the transient transfection analysis overexpression of Purβ revealed a negative regulatory effect on serum response factor (SRF)-dependent α-MHC and α-skeletal actin expression in muscle cell background. Contrary, in nonmuscle cells, Purβ showed no repressive effect. The results obtained from gel-shift assays demonstrated a sequence specific competitive binding of Purβ to the minus strand of the SRF-binding, CArG box sequences of different muscle genes, but not to the SRF-binding, SRE sequences of the c-fos gene. These element-specific associations of Purβ with muscle CArG boxes may, in part, explain why muscle gene expression is downregulated in disease states in which Purβ levels are elevated. This data also provide a mechanistic distinction between muscle CArG boxes and nonmuscle serum response element (SRE) sequences in terms of their affinity to bind to SRF and their ability to regulate cell-specific gene expression.

Download Full-text

New Role for Serum Response Factor in Postnatal Skeletal Muscle Growth and Regeneration via the Interleukin 4 and Insulin-Like Growth Factor 1 Pathways

Molecular and Cellular Biology ◽

10.1128/mcb.00138-06 ◽

2006 ◽

Vol 26 (17) ◽

pp. 6664-6674 ◽

Cited By ~ 53

Author(s):

Claude Charvet ◽

Christophe Houbron ◽

Ara Parlakian ◽

Julien Giordani ◽

Charlotte Lahoute ◽

...

Keyword(s):

Gene Expression ◽

Skeletal Muscle ◽

Growth Factor ◽

Serum Response Factor ◽

Muscle Growth ◽

Interleukin 4 ◽

Specific Gene ◽

Response Factor ◽

Insulin Like Growth Factor ◽

Serum Response

ABSTRACT Serum response factor (SRF) is a crucial transcriptional factor for muscle-specific gene expression. We investigated SRF function in adult skeletal muscles, using mice with a postmitotic myofiber-targeted disruption of the SRF gene. Mutant mice displayed severe skeletal muscle mass reductions due to a postnatal muscle growth defect resulting in highly hypotrophic adult myofibers. SRF-depleted myofibers also failed to regenerate following injury. Muscles lacking SRF had very low levels of muscle creatine kinase and skeletal alpha-actin (SKA) transcripts and displayed other alterations to the gene expression program, indicating an overall immaturity of mutant muscles. This loss of SKA expression, together with a decrease in beta-tropomyosin expression, contributed to myofiber growth defects, as suggested by the extensive sarcomere disorganization found in mutant muscles. However, we observed a downregulation of interleukin 4 (IL-4) and insulin-like growth factor 1 (IGF-1) expression in mutant myofibers which could also account for their defective growth and regeneration. Indeed, our demonstration of SRF binding to interleukin 4 and IGF-1 promoters in vivo suggests a new crucial role for SRF in pathways involved in muscle growth and regeneration.

Download Full-text

Alternative splicing and nonsense-mediated mRNA decay regulate gene expression of serum response factor

Gene ◽

10.1016/j.gene.2007.06.008 ◽

2007 ◽

Vol 400 (1-2) ◽

pp. 131-139 ◽

Cited By ~ 13

Author(s):

Xiaomin Zhang ◽

Gohar Azhar ◽

Chris Huang ◽

Cunqi Cui ◽

Ying Zhong ◽

...

Keyword(s):

Gene Expression ◽

Alternative Splicing ◽

Mrna Decay ◽

Serum Response Factor ◽

Response Factor ◽

Regulate Gene Expression ◽

Nonsense Mediated Mrna Decay ◽

Serum Response ◽

Regulate Gene

Download Full-text

Different regulatory sequences control creatine kinase-M gene expression in directly injected skeletal and cardiac muscle.

Molecular and Cellular Biology ◽

10.1128/mcb.13.2.1264 ◽

1993 ◽

Vol 13 (2) ◽

pp. 1264-1272 ◽

Cited By ~ 61

Author(s):

C K Vincent ◽

A Gualberto ◽

C V Patel ◽

K Walsh

Keyword(s):

Gene Expression ◽

Skeletal Muscle ◽

Creatine Kinase ◽

Cardiac Muscle ◽

Serum Response Factor ◽

Sequence Motif ◽

Regulatory Sequences ◽

Response Factor ◽

Specific Expression ◽

Serum Response

Regulatory sequences of the M isozyme of the creatine kinase (MCK) gene have been extensively mapped in skeletal muscle, but little is known about the sequences that control cardiac-specific expression. The promoter and enhancer sequences required for MCK gene expression were assayed by the direct injection of plasmid DNA constructs into adult rat cardiac and skeletal muscle. A 700-nucleotide fragment containing the enhancer and promoter of the rabbit MCK gene activated the expression of a downstream reporter gene in both muscle tissues. Deletion of the enhancer significantly decreased expression in skeletal muscle but had no detectable effect on expression in cardiac muscle. Further deletions revealed a CArG sequence motif at position -179 within the promoter that was essential for cardiac-specific expression. The CArG element of the MCK promoter bound to the recombinant serum response factor and YY1, transcription factors which control expression from structurally similar elements in the skeletal actin and c-fos promoters. MCK-CArG-binding activities that were similar or identical to serum response factor and YY1 were also detected in extracts from adult cardiac muscle. These data suggest that the MCK gene is controlled by different regulatory programs in adult cardiac and skeletal muscle.

Download Full-text

Serum Response Factor Regulates Immediate Early Host Gene Expression in Toxoplasma gondii-Infected Host Cells

PLoS ONE ◽

10.1371/journal.pone.0018335 ◽

2011 ◽

Vol 6 (3) ◽

pp. e18335 ◽

Cited By ~ 11

Author(s):

Mandi Wiley ◽

Crystal Teygong ◽

Eric Phelps ◽

Jay Radke ◽

Ira J. Blader

Keyword(s):

Gene Expression ◽

Toxoplasma Gondii ◽

Serum Response Factor ◽

Host Gene ◽

Host Cells ◽

Immediate Early ◽

Infected Host ◽

Response Factor ◽

Host Gene Expression ◽

Serum Response

Download Full-text

OTT-MAL Is a Deregulated Activator of Serum Response Factor-Dependent Gene Expression

Molecular and Cellular Biology ◽

10.1128/mcb.00303-08 ◽

2008 ◽

Vol 28 (20) ◽

pp. 6171-6181 ◽

Cited By ~ 25

Author(s):

Arnaud Descot ◽

Monika Rex-Haffner ◽

Geneviève Courtois ◽

Dominique Bluteau ◽

Antje Menssen ◽

...

Keyword(s):

Gene Expression ◽

Fusion Protein ◽

Serum Response Factor ◽

Mitogen Activated Protein Kinase ◽

Binding Motif ◽

Fusion Partner ◽

Response Factor ◽

Transactivation Domain ◽

Regulated Gene Expression ◽

Serum Response

ABSTRACT The OTT-MAL/RBM15-MKL1 fusion protein is the result of the recurrent translocation t(1;22) in acute megakaryocytic leukemia in infants. How it contributes to the malignancy is unknown. The 3′ fusion partner, MAL/MKL1/MRTF-A, is a transcriptional coactivator of serum response factor (SRF). MAL plays a key role in regulated gene expression depending on Rho family GTPases and G-actin. Here we demonstrate that OTT-MAL is a constitutive activator of SRF and target gene expression. This requires the SRF-binding motif and the MAL-derived transactivation domain. OTT-MAL localizes to the nucleus and is not regulated by upstream signaling. OTT-MAL deregulation reflects its independence from control by G-actin, which fails to interact with OTT-MAL in coimmunoprecipitation experiments. Regulation cannot be restored by reintroduction of the entire MAL N terminus into the fusion protein. OTT-MAL also caused a delayed induction of the MAL-independent, ternary complex factor-dependent target genes c-fos and egr-1 and the mitogen-activated protein kinase/Erk pathway. With testing in heterologous tissue culture systems, however, we observed considerable antiproliferative effects of OTT-MAL. Our data suggest that the deregulated activation of MAL-dependent and -independent promoters results in tissue-specific functions of OTT-MAL.

Download Full-text