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Viola 2016 JACC: Basic to Translational Science

From Bioblast
Publications in the MiPMap
Viola HM, Johnstone VPA, Szappanos HC, Richman TR, Tsoutsman T, Filipovska A, Semsarian C, Seidman JG, Seidman CE, Hool LC (2016) The role of the L-type Ca2+ channel in altered metabolic activity in a murine model of hypertrophic cardiomyopathy. JACC: Basic to Translational Science 1: 61–72.

» PMID: 30167506 Open Access

Viola HM, Johnstone VPA, Szappanos HC, Richman TR, Tsoutsman T, Filipovska A, Semsarian C, Seidman JG, Seidman CE, Hool LC (2016) JACC Basic Transl Sci

Abstract: Highlights

Heterozygous mice (αMHC403/+) expressing the human hypertrophic cardiomyopathy (HCM) disease causing mutation Arg403Gln exhibit cardinal features of HCM. This study investigated the role of L-type Ca2+ channel (ICa-L) in regulating mitochondrial function in Arg403Gln (αMHC403/+) mice. Activation of ICa-L in αMHC403/+ mice caused a significantly greater increase in mitochondrial membrane potential and metabolic activity when compared to wild-type mice. Increases in mitochondrial membrane potential and metabolic activity were attenuated with ICa-L antagonists and when F-actin or β-tubulin were depolymerized. ICa-L antagonists may be effective in reducing the cardiomyopathy in HCM by altering metabolic activity.

Summary

Heterozygous mice (αMHC403/+) expressing the human disease-causing mutation Arg403Gln exhibit cardinal features of hypertrophic cardiomyopathy (HCM) including hypertrophy, myocyte disarray, and increased myocardial fibrosis. Treatment of αMHC403/+ mice with the L-type calcium channel (ICa-L) antagonist diltiazem has been shown to decrease left ventricular anterior wall thickness, cardiac myocyte hypertrophy, disarray, and fibrosis. However, the role of the ICa-L in the development of HCM is not known. In addition to maintaining cardiac excitation and contraction in myocytes, the ICa-L also regulates mitochondrial function through transmission of movement of ICa-L via cytoskeletal proteins to mitochondrial voltage-dependent anion channel. Here, the authors investigated the role of ICa-L in regulating mitochondrial function in αMHC403/+ mice. Whole-cell patch clamp studies showed that ICa-L current inactivation kinetics were significantly increased in αMHC403/+ cardiac myocytes, but that current density and channel expression were similar to wild-type cardiac myocytes. Activation of ICa-L caused a significantly greater increase in mitochondrial membrane potential and metabolic activity in αMHC403/+. These increases were attenuated with ICa-L antagonists and following F-actin or β-tubulin depolymerization. The authors observed increased levels of fibroblast growth factor-21 in αMHC403/+ mice, and altered mitochondrial DNA copy number consistent with altered mitochondrial activity and the development of cardiomyopathy. These studies suggest that the Arg403Gln mutation leads to altered functional communication between ICa-L and mitochondria that is associated with increased metabolic activity, which may contribute to the development of cardiomyopathy. ICa-L antagonists may be effective in reducing the cardiomyopathy in HCM by altering metabolic activity. Keywords: Calcium, Cardiomyopathy, L-type calcium channel, Mitochondria

O2k-Network Lab: AU Perth Filipovska A


Labels: MiParea: Respiration, Genetic knockout;overexpression  Pathology: Myopathy 

Organism: Mouse  Tissue;cell: Heart  Preparation: Isolated mitochondria 


Coupling state: OXPHOS  Pathway: N, S, CIV  HRR: Oxygraph-2k 

2016-05