DNA methylation of a GC repressor element in the smooth muscle myosin heavy chain promoter facilitates binding of the Notch-associated transcription factor, RBPJ/CSL1.
نویسندگان
چکیده
OBJECTIVE The goal of the present study was to identify novel mechanisms that regulate smooth muscle cell (SMC) differentiation marker gene expression. APPROACH AND RESULTS We demonstrate that the CArG-containing regions of many SMC-specific promoters are imbedded within CpG islands. A previously identified GC repressor element in the SM myosin heavy chain (MHC) promoter was highly methylated in cultured aortic SMC but not in the aorta, and this difference was inversely correlated with SM MHC expression. Using an affinity chromatography/mass spectroscopy-based approach, we identified the multifunctional Notch transcription factor, recombination signal binding protein for immunoglobulin κ J region (RBPJ), as a methylated GC repressor-binding protein. RBPJ protein levels and binding to the endogenous SM MHC GC repressor were enhanced by platelet-derived growth factor-BB treatment. A methylation mimetic mutation to the GC repressor that facilitated RBPJ binding inhibited SM MHC promoter activity as did overexpression of RBPJ. Consistent with this, knockdown of RBPJ in phenotypically modulated human aortic SMC enhanced endogenous SMC marker gene expression, an effect likely mediated by increased recruitment of serum response factor and Pol II to the SMC-specific promoters. In contrast, the depletion of RBPJ in differentiated transforming growth factor-β-treated SMC inhibited SMC-specific gene activation, supporting the idea that the effects of RBPJ/Notch signaling are context dependent. CONCLUSIONS Our results indicate that methylation-dependent binding of RBPJ to a GC repressor element can negatively regulate SM MHC promoter activity and that RBPJ can inhibit SMC marker gene expression in phenotypically modulated SMC. These results will have important implications on the regulation of SMC phenotype and on Notch-dependent transcription.
منابع مشابه
Evolutionarily conserved promoter region containing CArG*-like elements is crucial for smooth muscle myosin heavy chain gene expression.
In recent years, significant progress has been made toward understanding skeletal muscle development. However, the mechanisms that regulate smooth muscle development and differentiation are presently unknown. To better understand smooth muscle-specific gene expression, we have focused our studies on the smooth muscle myosin heavy chain (SMHC) gene, a highly specific marker of differentiated smo...
متن کاملA G/C element mediates repression of the SM22alpha promoter within phenotypically modulated smooth muscle cells in experimental atherosclerosis.
A hallmark of smooth muscle cell (SMC) phenotypic switching in atherosclerotic lesions is suppression of SMC differentiation marker gene expression. Yet little is known regarding the molecular mechanisms that control this process. Here we show that transcription of the SMC differentiation marker gene SM22alpha is reduced in atherosclerotic lesions and identify a cis regulatory element in the SM...
متن کاملSelective modulation of the SM22alpha promoter by the binding of BTEB3 (basal transcription element-binding protein 3) to TGGG repeats.
We have previously identified a C2H2 zinc-finger transcription factor [BTEB3 (basal transcription element-binding protein 3)/KLF13 (Krüppel-like factor 13)] that activates the minimal promoter for the smooth muscle-specific SM22alpha gene in other types of cell. We show that recombinant BTEB3 binds to three TGGG motifs in the minimal SM22alpha promoter. By mutation analysis, only one of these b...
متن کاملA Transforming Growth Factor b (TGFb) Control Element Drives TGFb-induced Stimulation of Smooth Muscle a-Actin Gene Expression in Concert with Two CArG Elements*
The goal of the present study was to determine the molecular mechanism whereby transforming growth factor b (TGFb) increases smooth muscle (SM) a-actin expression. Confluent, growth-arrested rat aortic smooth muscle cells (SMC) were transiently transfected with various SM a-actin promoter/chloramphenicol acetyltransferase deletion mutants and stimulated with TGFb (2.5 ng/ml). Results demonstrat...
متن کاملGATA-6 is involved in PPARgamma-mediated activation of differentiated phenotype in human vascular smooth muscle cells.
OBJECTIVE Peroxisome proliferator-activated receptor-gamma (PPARgamma) is a member of the nuclear receptor superfamily involved in the growth and differentiation of many cell types. Although the activation of PPARgamma in human vascular smooth muscle cells (VSMCs) inhibits the growth of these cells, the precise mechanism of this effect is unknown. PPARgamma-mediated growth inhibition of VSMCs i...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
- Arteriosclerosis, thrombosis, and vascular biology
دوره 34 12 شماره
صفحات -
تاریخ انتشار 2014