GATA4‐controlled HDAC1/HDAC2‐regulated Cardiogenesis of Mesenchymal Stem Cells

Abstract

Histone modifications correlate with gene expression and contribute to cell fate commitment. We have reported that inhibition of histone deacetylase1 (HDAC1) or HDAC2 enhanced histone acetylation at cardiac gene loci and promoted cardiogenesis of mesenchymal stem cells (MSC). MSC infected with cardiac transcription factor GATA4 gene have demonstrated increased myocardial differentiation, indicating the transcription machinery in guidance of cardiac cell fate. However it is unclear whether functions of transcription factors and histone modifications are interdependent in control of cardiac cell fate. We hypothesize that HDAC1/HDAC2 and GATA4 competitively bind to cardiac‐specific gene promoters, thereby governing cardiac gene expression.MethodsMSC were isolated from bone marrow of C57BL mice based on our published methods. MSC were transfected with siRNA of scramble, HDAC1 or HDAC2, or infected with retrovirus vectors (GATA4 RV/Control ‐ EGFP only; GATA4 RV ‐ EGFP+GATA4). Cardiac gene expression, histone acetylation and DNA‐binding levels of GATA4 or HDAC1/HDAC2 were analyzed at cardiac specific gene promoters by Chromatin Immunoprecipitation–qPCR and RT‐qPCR.ResultsKnock‐down of HDAC1 or HDAC2 enhanced GATA4 occupancy at promoters of cardiac α‐MHC (Myh6) and troponin T (cTnT) in MSCimagewith increased gene expression and local levels of acH3/acH4. GATA4 overexpression [figure2A] did not change nuclear protein levels of HDAC1 and HDAC2 in MSC, but limited HDAC1/HDAC2 recruitment and decreased their bindings to Myh6 and cTnT promoters [figure2B]. Notably, this decreased occupancy of HDAC1 and HDAC2 was associated with upregulated gene expression and enhanced acH3/acH4 enrichment at the tested gene loci. Our results represent initial evidence that the interplay between GATA4 and HDAC1/HDAC2 controls promoter accessibility of cardiac genes, thus directing MSC cardiac commitment.