Calcineurin B homologous protein 3 negatively regulates cardiomyocyte hypertrophy via inhibition of glycogen synthase kinase 3 phosphorylation

J Mol Cell Cardiol. 2015 Jul:84:133-42. doi: 10.1016/j.yjmcc.2015.04.018. Epub 2015 Apr 30.

Abstract

Cardiac hypertrophy is a leading cause of serious heart diseases. Although many signaling molecules are involved in hypertrophy, the functions of some proteins in this process are still unknown. Calcineurin B homologous protein 3 (CHP3)/tescalcin is an EF-hand Ca(2+)-binding protein that is abundantly expressed in the heart; however, the function of CHP3 is unclear. Here, we aimed to identify the cardiac functions of CHP3. CHP3 was expressed in hearts at a wide range of developmental stages and was specifically detected in neonatal rat ventricular myocytes (NRVMs) but not in cardiac fibroblasts in culture. Moreover, knockdown of CHP3 expression using adenoviral-based RNA interference in NRVMs resulted in enlargement of cardiomyocyte size, concomitant with increased expression of a pathological hypertrophy marker ANP. This same treatment elevated glycogen synthase kinase (GSK3α/β) phosphorylation, which is known to inhibit GSK3 function. In contrast, CHP3 overexpression blocked the insulin-induced phosphorylation of GSK3α/β without affecting the phosphorylation of Akt, which is an upstream kinase of GSK3α/β, in HEK293 cells, and it inhibited both IGF-1-induced phosphorylation of GSK3β and cardiomyocyte hypertrophy in NRVMs. Co-immunoprecipitation experiments revealed that GSK3β interacted with CHP3. However, a Ca(2+)-binding-defective mutation of CHP3 (CHP3-D123A) also interacted with GSK3β and had the same inhibitory effect on GSK3α/β phosphorylation, suggesting that the action of CHP3 was independent of Ca(2+). These findings suggest that CHP3 functions as a novel negative regulator of cardiomyocyte hypertrophy via inhibition of GSK3α/β phosphorylation and subsequent enzymatic activation of GSK3α/β.

Keywords: Calcineurin B homologous protein; Cardiac hypertrophy; Cardiomyocytes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Animals, Newborn
  • Binding Sites
  • Calcium / metabolism
  • Calcium-Binding Proteins / metabolism*
  • Gene Knockdown Techniques
  • Glycogen Synthase Kinase 3 / metabolism*
  • Glycogen Synthase Kinase 3 beta
  • HEK293 Cells
  • Humans
  • Hypertrophy
  • Immunoprecipitation
  • Insulin / pharmacology
  • Insulin-Like Growth Factor I / pharmacology
  • Mutant Proteins / metabolism
  • Myocardium / metabolism
  • Myocytes, Cardiac / drug effects
  • Myocytes, Cardiac / metabolism*
  • Myocytes, Cardiac / pathology*
  • Phosphorylation / drug effects
  • Proto-Oncogene Proteins c-akt / metabolism
  • Rats

Substances

  • Calcium-Binding Proteins
  • Insulin
  • Mutant Proteins
  • TESC protein, human
  • Tesc protein, rat
  • Insulin-Like Growth Factor I
  • GSK3B protein, human
  • Glycogen Synthase Kinase 3 beta
  • Gsk3b protein, rat
  • Proto-Oncogene Proteins c-akt
  • Glycogen Synthase Kinase 3
  • glycogen synthase kinase 3 alpha
  • Calcium