Abstract 1944: HDAC3 Is Critical in Endothelial Survival and Atherosclerosis Development in Response to Disturbed Flow
Background - Histone deacetylase 3 (HDAC3) is known to play a crucial role in differentiation of endothelial progenitors. The role of HDAC3 in mature endothelial cells (EC) however, is not well understood.
Methods and Results - Here, we investigated the function of HDAC3 in preserving the endothelial integrity in areas of disturbed blood flow, i.e. bifurcation areas prone to atherosclerosis development. En face staining of aortas from ApoE−/− mice revealed increased expression of HDAC3, specifically in these branching areas in vivo, while rapid upregulation of HDAC3 protein was observed in EC exposed to disturbed flow in vitro. Interestingly, phosphorylation of HDAC3 at Ser/Thr was observed in these cells, suggesting that disturbed flow leads to posttranscriptional modification and stabilization of the HDAC3 protein. Co-immunoprecipitation experiments showed that HDAC3 and Akt form a complex. Using a series of constructs harbouring deletions, residues 136–206 of HDAC3 were found to be crucial in this interaction. Enforced expression of HDAC3 resulted in increased phosphorylation of Akt and upregulation of its kinase activity, while higher viability was also observed when EC were treated with H2O2, indicating that elevation of HDAC3 expression acts as a prosurvival signal in conditions of oxidative stress. Blocking deacetylase activity with trichostatin A did not affect these responses, suggesting a novel function of HDAC3 that is independent of its deacetylase activity. In line with these findings knockdown of HDAC3 using lentiviral vectors (Lenti-shHDAC3) led to a dramatic decrease in cell survival accompanied by apoptosis in EC. In aortic isografts of ApoE−/− mice treated with Lenti-shHDAC3, a robust atherosclerotic lesion was formed. Surprisingly, 3 out of the 8 mice that received a Lenti-shHDAC3 infected grafts died within 2 days postoperationally. Miller staining of the isografts revealed a disruption of the basement membrane and rupture of the vessel.
Conclusions - Our findings demonstrated that HDAC3 serves as an essential prosurvival signal with a critical role in maintaining the endothelial integrity via Akt activation, and that severe atherosclerosis and vessel rupture in isografted vessels of ApoE−/− mice occur when HDAC3 is knockdown.