Inhibition of Histone Deacetylase 6 activity provides protection against atherogenesis: A role of HDAC6 NEDDylation

Histone Deacetylase 6 (HDAC6) has been recently shown to play critical role in endothelial function through the regulation of H 2 S producing enzyme‐Cystathionine Gamma Lyase (CSEg). However, whether HDAC6 play any role in atherogenesis in unclear. Further mechanism(s) regulating HDAC6 activity in endothelial cell leading to atherosclerosis is still unknown. We aim to evaluate whether pharmacological inhibition of HDAC6 by small molecule inhibitor‐ tubacin can attenuate atherogenesis and determine the specific molecular mechanism(s) that regulates HDAC6 activity. We have previously shown that HDAC6 can regulate CSEg expression and our preliminary unpublished data suggest that overexpression of HDAC6 dramatically reduce endothelial nitric oxide synthase expression. Given eNOS and CSE are the two of the most critical gene responsible for governing endothelial function, these data sheds light on the importance of HDAC6 in endothelial dysfunction. To test this, we adopt a novel strategy to induce atherosclerosis in mice which involved single i.p injection of PCSK9 AAV followed by high fat diet (HFD) for 12 weeks and evaluated whether administration of tubacin can reverse this phenomenon. Indeed, tubacin significantly blunted the enhanced pulse wave velocity (index of vascular stiffness and overall vascular health) (PCSK9+HFD: 4.4±0.11 vs. PCSK9+HFD+tubacin: 4.0±0.08 vs. control: 3.7±0.10, P<0.001) caused in atherogenic mice. Further, tubacin significantly protected endothelial function evaluated by acetycholine mediated relaxation using wire myograph ‐ (PCSK9+HFD: Log EC 50 −7.19±0.11, 95%CI −7.40 to −6.97 vs. PCSK9+HFD+tubacin: Log EC 50 −7.35±0.06, 95%CI −7.47 to −7.22 vs. control: Log EC 50 −7.58±0.04, 95%CI −7.67 to −7.50, P<0.001). Plaque burden determined by Oil Red O staining was also found to be significantly less in tubacin injected mice. Further, inhibition of Nedd8 activating enzyme 1 (NAE1) by MLN4924 significantly increased HDAC6 activity in Human Aortic Endothelial Cells (HAEC). Interestingly, the levels of HDAC6 remain unchanged which is consistent with the post‐translational modification. Indeed, non‐biased proteomics study by another group has identified HDAC6 as the potential substrate for NEDD8. Human aortic endothelial cells exposed to atherogenic stimuli OxLDL exhibited enhanced HDAC6 activity which was attenuated by the pre‐treatment with MLN4924 in a dose response manner. Taken together, HDAC6 Neddylation provides a novel molecular pathway that could regulate critical gene important for endothelial function. Hence, tubacin represents a novel pharmacological intervention for atherogenesis. Support or Funding Information American Heart Association Scientific Development Grant to DPJohns Hopkins University Department of Cardiology “ Magic that Matters” Grant to DPJohns Hopkins University Department of Anesthesiology and Critical Care Medicine “ StAAR Award” to DP This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .