The Epigenetic Regulator HDAC1 Modulates Transcription of a Core Cardiogenic Program in Human Cardiac Mesenchymal Stromal Cells Through a p53-Dependent Mechanism

Abstract

Histone deacetylase (HDAC) regulation is an essential process in myogenic differentiation. Inhibitors targeting the activity of specific HDAC family members have been shown to enhance the cardiogenic differentiation capacity of discrete progenitor cell types; a key property of donor cell populations contributing to their afforded benefits in cardiac cell therapy applications. The influence of HDAC inhibition on cardiac-derived mesenchymal stromal cell (CMC) transdifferentiation or the role of specific HDAC family members in dictating cardiovascular cell lineage specification has not been investigated. In the current study, the consequences of HDAC inhibition on patient-derived CMC proliferation, cardiogenic program activation, and cardiovascular differentiation/cell lineage specification were investigated using pharmacologic and genetic targeting approaches. Here, CMCs exposed to the pan-HDAC inhibitor sodium butyrate (NaBu) exhibited induction of a cardiogenic transcriptional program and heightened expression of myocyte and endothelial lineage-specific markers when coaxed to differentiate in vitro. Further, shRNA knockdown screens revealed CMCs depleted of HDAC1 to promote the induction of a cardiogenic transcriptional program characterized by enhanced expression of cardiomyogenic- and vasculogenic-specific markers, a finding which depended upon and correlated with enhanced acetylation and stabilization of p53. Cardiogenic gene activation and elevated p53 expression levels observed in HDAC1-depleted CMCs were associated with improved aptitude to assume a cardiomyogenic/vasculogenic cell-like fate in vitro. These results suggest that HDAC1 depletion-induced p53 expression alters CMC cell fate decisions and identify HDAC1 as a potential exploitable target to facilitate CMC-mediated myocardial repair in ischemic cardiomyopathy.

Epigenetically modified cardiac mesenchymal stromal cells limit myocardial fibrosis and promote functional recovery in a model of chronic ischemic cardiomyopathy

“…Consistent with these reports, we previously identified HDAC1 as a novel regulator of CMC cardiovascular lineage specification [23]. We found that short-hairpin RNA interference (shRNAi)-targeted depletion of HDAC1 stimulated cardiogenic transcriptional program activation and cardiomyocyte-like differentiation in patient-derived CMCs in vitro [23]. Importantly, relative to naïve CMCs, HDAC1-depleted, cardiomyogenic lineage-committed CMCs exhibited distinct trophic factor secretion profiles and heightened in vitro paracrine signaling potency [22]—highlighting HDAC1 as a novel therapeutic target that may be exploited to augment CMC cardiac reparative capacity.…”

“…Further, all established CMC cell lines were validated via flow cytometry-based verification of the presence and absence of prototypical mesenchymal and hematopoietic cell lineage markers, respectively, as previous [23]. De-identified right atrial appendage specimens were collected via written consent agreement according to the approved protocol by the Institutional Review Board on human subject research (IRB number: 03.052J) at the University of Louisville.…”

“…Immunoblotting was performed according to previously described protocols [22, 23]. A detailed list of antibodies with corresponding dilutions is available in Supporting Information Table S1.…”

“…For this reason, various methodologies have been employed in effort to “forward reprogram” or stimulate mesenchymal progenitor cell cardiomyogenic lineage specification; this has been achieved using various experimental approaches, including recombinant protein overexpression as well as pharmacologic pre-treatment. The former includes ectopic expression of cardiogenic transcription factors (e.g., Gata4, Mef2c, and Tbx5) [12] and the latter, exposure to chromatin modifying agents, such as inhibitors of histone deacetylase (HDACi) [23, 43] or DNA methyltransferase (DNMTi) [17, 24, 27] enzymatic activity. Consistent with these reports, we previously identified HDAC1 as a novel regulator of CMC cardiovascular lineage specification [23].…”

“…The former includes ectopic expression of cardiogenic transcription factors (e.g., Gata4, Mef2c, and Tbx5) [12] and the latter, exposure to chromatin modifying agents, such as inhibitors of histone deacetylase (HDACi) [23, 43] or DNA methyltransferase (DNMTi) [17, 24, 27] enzymatic activity. Consistent with these reports, we previously identified HDAC1 as a novel regulator of CMC cardiovascular lineage specification [23]. We found that short-hairpin RNA interference (shRNAi)-targeted depletion of HDAC1 stimulated cardiogenic transcriptional program activation and cardiomyocyte-like differentiation in patient-derived CMCs in vitro [23].…”