scholarly journals KLF3 Regulates Muscle-Specific Gene Expression and Synergizes with Serum Response Factor on KLF Binding Sites

2010 ◽  
Vol 30 (14) ◽  
pp. 3430-3443 ◽  
Author(s):  
Charis L. Himeda ◽  
Jeffrey A. Ranish ◽  
Richard C. M. Pearson ◽  
Merlin Crossley ◽  
Stephen D. Hauschka

ABSTRACT This study identifies KLF3 as a transcriptional regulator of muscle genes and reveals a novel synergistic interaction between KLF3 and serum response factor (SRF). Using quantitative proteomics, KLF3 was identified as one of several candidate factors that recognize the MPEX control element in the Muscle creatine kinase (MCK) promoter. Chromatin immunoprecipitation analysis indicated that KLF3 is enriched at many muscle gene promoters (MCK, Myosin heavy chain IIa, Six4, Calcium channel receptor α-1, and Skeletal α-actin), and two KLF3 isoforms are upregulated during muscle differentiation. KLF3 and SRF physically associate and synergize in transactivating the MCK promoter independently of SRF binding to CArG motifs. The zinc finger and repression domains of KLF3 plus the MADS box and transcription activation domain of SRF are implicated in this synergy. Our results provide the first evidence of a role for KLF3 in muscle gene regulation and reveal an alternate mechanism for transcriptional regulation by SRF via its recruitment to KLF binding sites. Since both factors are expressed in all muscle lineages, SRF may regulate many striated- and smooth-muscle genes that lack known SRF control elements, thus further expanding the breadth of the emerging CArGome.

2007 ◽  
Vol 85 (3-4) ◽  
pp. 349-359 ◽  
Author(s):  
Madhu Gupta ◽  
Vithida Sueblinvong ◽  
Mahesh P. Gupta

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.


2009 ◽  
Vol 284 (24) ◽  
pp. 16308-16316 ◽  
Author(s):  
Ju-Ryoung Kim ◽  
Hae Jin Kee ◽  
Ji-Young Kim ◽  
Hosouk Joung ◽  
Kwang-Il Nam ◽  
...  

Skeletal muscle differentiation is well regulated by a series of transcription factors. We reported previously that enhancer of polycomb1 (Epc1), a chromatin protein, can modulate skeletal muscle differentiation, although the mechanisms of this action have yet to be defined. Here we report that Epc1 recruits both serum response factor (SRF) and p300 to induce skeletal muscle differentiation. Epc1 interacted physically with SRF. Transfection of Epc1 to myoblast cells potentiated the SRF-induced expression of skeletal muscle-specific genes as well as multinucleation. Proximal CArG box in the skeletal α-actin promoter was responsible for the synergistic activation of the promoter-luciferase. Epc1 knockdown caused a decrease in the acetylation of histones associated with serum response element (SRE) of the skeletal α-actin promoter. The Epc1·SRF complex bound to the SRE, and the knockdown of Epc1 resulted in a decrease in SRF binding to the skeletal α-actin promoter. Epc1 recruited histone acetyltransferase activity, which was potentiated by cotransfection with p300 but abolished by si-p300. Epc1 directly bound to p300 in myoblast cells. Epc1+/− mice showed distortion of skeletal α-actin, and the isolated myoblasts from the mice had impaired muscle differentiation. These results suggest that Epc1 is required for skeletal muscle differentiation by recruiting both SRF and p300 to the SRE of muscle-specific gene promoters.


2000 ◽  
Vol 345 (3) ◽  
pp. 445-451 ◽  
Author(s):  
Paul R. KEMP ◽  
James C. METCALFE

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.


2006 ◽  
Vol 26 (17) ◽  
pp. 6664-6674 ◽  
Author(s):  
Claude Charvet ◽  
Christophe Houbron ◽  
Ara Parlakian ◽  
Julien Giordani ◽  
Charlotte Lahoute ◽  
...  

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.


2007 ◽  
Vol 17 (2) ◽  
pp. 136-144 ◽  
Author(s):  
S. J. Cooper ◽  
N. D. Trinklein ◽  
L. Nguyen ◽  
R. M. Myers

2000 ◽  
Vol 275 (39) ◽  
pp. 30387-30393 ◽  
Author(s):  
Blanca Camoretti-Mercado ◽  
Hong-W. Liu ◽  
Andrew J. Halayko ◽  
Sean M. Forsythe ◽  
John W. Kyle ◽  
...  

2010 ◽  
Vol 84 (9) ◽  
pp. 4481-4493 ◽  
Author(s):  
Patrizia Caposio ◽  
Anna Luganini ◽  
Matteo Bronzini ◽  
Santo Landolfo ◽  
Giorgio Gribaudo

ABSTRACT The major immediate-early promoter (MIEP) region of human cytomegalovirus (HCMV) plays a critical role in the regulation of lytic and latent infections by integrating multiple signals supplied by the infecting virus, the type and physiological state of the host cell, and its extracellular surroundings. The interaction of cellular transcription factors with their cognate binding sites, which are present at high densities within the enhancer upstream from the MIEP core promoter, regulate the rate of IE gene transcription and thus affect the outcome of HCMV infection. We have shown previously that the NF-κB binding sites within the MIEP enhancer and cellular NF-κB activity induced by HCMV infection are required for efficient MIEP activity and viral replication in quiescent cells (P. Caposio, A. Luganini, G. Hahn, S. Landolfo, and G. Gribaudo, Cell. Microbiol. 9:2040-2054, 2007). We now show that the inactivation of either the Elk-1 or serum response factor (SRF) binding site within the enhancer also reduces MIEP activation and viral replication of recombinant HCMV viruses in quiescent fibroblasts. In these cells, we show that the expression of either Elk-1 or SRF is required for optimal IE gene expression, and that the HCMV-stimulated activation of the MEK1/2-ERK1/2 signaling axis leads to Elk-1 transcriptional competency. Furthermore, the replication kinetics of recombinant viruses in which NF-κB, Elk-1, and SRF binding sites all are inactivated demonstrate that the higher levels of Elk-1 and SRF binding to MIEP in proliferating cells can compensate even for a lack of HCMV-induced NF-κB-mediated MIEP transactivation. These observations highlight the importance of the combination of different MIEP binding sites to optimize IE gene expression in cells in different physiological states.


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