Park CS, Cha H, Kwon EJ, Jeong D, Hajjar RJ, Kranias EG, Cho C, Park WJ, Kim DH. AAV-mediated knock-down of HRC exacerbates transverse aorta constriction-induced heart failure.
PLoS One 2012;
7:e43282. [PMID:
22952658 PMCID:
PMC3429470 DOI:
10.1371/journal.pone.0043282]
[Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2012] [Accepted: 07/23/2012] [Indexed: 01/10/2023] Open
Abstract
Background
Histidine-rich calcium binding protein (HRC) is located in the lumen of sarcoplasmic reticulum (SR) that binds to both triadin (TRN) and SERCA affecting Ca2+ cycling in the SR. Chronic overexpression of HRC that may disrupt intracellular Ca2+ homeostasis is implicated in pathogenesis of cardiac hypertrophy. Ablation of HRC showed relatively normal phenotypes under basal condition, but exhibited a significantly increased susceptibility to isoproterenol-induced cardiac hypertrophy. In the present study, we characterized the functions of HRC related to Ca2+ cycling and pathogenesis of cardiac hypertrophy using the in vitro siRNA- and the in vivo adeno-associated virus (AAV)-mediated HRC knock-down (KD) systems, respectively.
Methodology/Principal Findings
AAV-mediated HRC-KD system was used with or without C57BL/6 mouse model of transverse aortic constriction-induced failing heart (TAC-FH) to examine whether HRC-KD could enhance cardiac function in failing heart (FH). Initially we expected that HRC-KD could elicit cardiac functional recovery in failing heart (FH), since predesigned siRNA-mediated HRC-KD enhanced Ca2+ cycling and increased activities of RyR2 and SERCA2 without change in SR Ca2+ load in neonatal rat ventricular cells (NRVCs) and HL-1 cells. However, AAV9-mediated HRC-KD in TAC-FH was associated with decreased fractional shortening and increased cardiac fibrosis compared with control. We found that phospho-RyR2, phospho-CaMKII, phospho-p38 MAPK, and phospho-PLB were significantly upregulated by HRC-KD in TAC-FH. A significantly increased level of cleaved caspase-3, a cardiac cell death marker was also found, consistent with the result of TUNEL assay.
Conclusions/Significance
Increased Ca2+ leak and cytosolic Ca2+ concentration due to a partial KD of HRC could enhance activity of CaMKII and phosphorylation of p38 MAPK, causing the mitochondrial death pathway observed in TAC-FH. Our results present evidence that down-regulation of HRC could deteriorate cardiac function in TAC-FH through perturbed SR-mediated Ca2+ cycling.
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