Abstract 946: Aberrant Activation of Nitric Oxide Synthase 1 in the Heart Accelerates Diastolic Dysfunction Though Protein S-nitrosylation

Abstract

Heart failure refers to an inappropriate blood supply to the periphery. Among subtype of heart failure, pathophysiology and effective therapeutic strategy of systolic heart failure is well established. However, molecular mechanism and specific regimens for diastolic heart failure (DHF) still remains unclear. Here we propose nitric oxide synthase (NOS) 1 mediated exacerbation of DHF and therapeutic potential for novel therapeutics. We screened alteration of posttranslational modifications in DHF which were induced either by SAUNA (SAlty drinking water/Unilateral Nephrectomy/Aldosterone) model or transverse aortic constriction (TAC) model and observed that protein S-nitrosylation was dramatically increased. Total RNA sequencing revealed that transcription amount of NOS1 was aberrantly increased in DHF, whereas NOS2 or NOS3 was not changed. Either non-selective NOS inhibitor or specific NOS1 inhibitor effectively blocked diastolic dysfunction. To elucidate the molecular target of S-nitrosylation, we performed biotin switch assay and requested protein sequencing which were newly appeared in the presence of GSNO. Among novel signal, we identified and confirmed that Histone deacetylase (HDAC) 2 was target molecule of NOS1. HDAC2 cysteine 262 and cysteine 274 were responsible residue of NOS1-mediated S-nitrosylation. We generated knock-in mice carrying S-nitrosylation defect HDAC2 mutant, HDAC2 C262A/C274A (2CA). HDAC2 2CA knock-in mice underwent SAUNA surgery or TAC and diastolic function of those mice was measured by early diastole (E) and mitral valve annulus movement (E’). When compared to wild type littermates, the diastolic function assessed by E/E’ ratio in HDAC2 2CA knock-in mice were relatively well conserved both in SAUNA- and TAC-induced DHF model. Survival rate after TAC operation was also dramatically ameliorated in HDAC2 2CA knock-in mice. Taken together, we proposed novel molecular axis, NOS1/S-NO HDAC2, accelerating diastolic dysfunction and which implicated notable molecular target for treatment of DHF patients.