Abstract 15751: The Epigenetic of Becoming a Cardiomyocyte: Elucidating the Link Between HDAC1 and Its Role In Regulating BMP2 Signaling During Cardiovascular Specific Differentiation of Embryonic and Induced Pluripotent Stem Cells
Cardiomyocytes derived from embryonic and induced pluripotent stem cells (ES/iPS) provide an excellent source for cell replacement therapies following myocardial ischemia. However, some of the obstacles in the realization of the full potential of iPS/ES cells arise from incomplete and poorly understood molecular mechanisms and epigenetic modifications that govern their cardiovascular specific differentiation. We identified Histone Deacetylase 1 (HDAC1) as a crucial regulator in early differentiation of mES and iPS cells. We propose a novel pathway in which HDAC1 regulates cardiovascular differentiation by regulating BMP2 signaling in differentiating pluripotent cells. Stable HDAC1 knock down mES and iPS clones were created using shRNA vectors. Differentiation through embryoid bodies (EB) was induced in wild type mES cells and iPS cells and in their HDAC1-null counterparts. The ability of these cells to differentiate into cardiovascular lineages was monitored. Compared to wild type cells, HDAC1-null EBs showed delayed and reduced spontaneous beating. Expression of cardiomyocyte markers as well as markers of other cardiovascular lineages was repressed in HDAC1 -null cells. EBs lacking HDAC1 differentiated slower and showed delayed suppression of pluripotency markers such as Oct4 Nanog and Sox2 and high Histone H3 acetylation levels at the regulatory regions of these genes even during differentiation. Lower methylation levels at the promoter regions of key mesodermal/cardiovascular master regulators indicated a cross talk between Histone acetylation and DNA methylation in these cells. However, supplementation with BMP2 during early differentiation recovered the ability in the HDAC1-null cells to differentiate into cardiovascular lineages. Taken together our data suggest an essential role for HDAC1 in early development and cardiovascular differentiation of pluripotent cells by repressing pluripotent genes and allowing for expression of early developmental genes such as SOX17 and BMP2. Further research in the molecular mechanisms involved in this process will greatly aid our understanding of the epigenetic circuitry of pluripotency and differentiation in pluripotent cells.
- © 2011 by American Heart Association, Inc.