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Heart-specific deletion of CnB1 reveals multiple mechanisms whereby calcineurin regulates cardiac growth and function.

ABSTRACT: Calcineurin is a protein phosphatase that is uniquely regulated by sustained increases in intracellular Ca(2+) following signal transduction events. Calcineurin controls cellular proliferation, differentiation, apoptosis, and inducible gene expression following stress and neuroendocrine stimulation. In the adult heart, calcineurin regulates hypertrophic growth of cardiomyocytes in response to pathologic insults that are associated with altered Ca(2+) handling. Here we determined that calcineurin signaling is directly linked to the proper control of cardiac contractility, rhythm, and the expression of Ca(2+)-handling genes in the heart. Our approach involved a cardiomyocyte-specific deletion using a CnB1-LoxP-targeted allele in mice and three different cardiac-expressing Cre alleles/transgenes. Deletion of calcineurin with the Nkx2.5-Cre knock-in allele resulted in lethality at 1 day after birth due to altered right ventricular morphogenesis, reduced ventricular trabeculation, septal defects, and valvular overgrowth. Slightly later deletion of calcineurin with the alpha-myosin heavy chain Cre transgene resulted in lethality in early mid adulthood that was characterized by substantial reductions in cardiac contractility, severe arrhythmia, and reduced myocyte content in the heart. Young calcineurin heart-deleted mice died suddenly after pressure overload stimulation or neuroendocrine agonist infusion, and telemetric monitoring of older mice showed arrhythmia leading to sudden death. Mechanistically, loss of calcineurin reduced expression of key Ca(2+)-handling genes that likely lead to arrhythmia and reduced contractility. Loss of calcineurin also directly impacted cellular proliferation in the postnatal developing heart. These results reveal multiple mechanisms whereby calcineurin regulates cardiac development and myocyte contractility.

SUBMITTER: Maillet M

PROVIDER: S-EPMC2825466 | biostudies-literature | 2010 Feb

REPOSITORIES: biostudies-literature

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Heart-specific deletion of CnB1 reveals multiple mechanisms whereby calcineurin regulates cardiac growth and function.

Maillet Marjorie M Davis Jennifer J Auger-Messier Mannix M York Allen A Osinska Hanna H Piquereau Jérôme J Lorenz John N JN Robbins Jeffrey J Ventura-Clapier Renée R Molkentin Jeffery D JD

The Journal of biological chemistry 20091227 9

Calcineurin is a protein phosphatase that is uniquely regulated by sustained increases in intracellular Ca(2+) following signal transduction events. Calcineurin controls cellular proliferation, differentiation, apoptosis, and inducible gene expression following stress and neuroendocrine stimulation. In the adult heart, calcineurin regulates hypertrophic growth of cardiomyocytes in response to pathologic insults that are associated with altered Ca(2+) handling. Here we determined that calcineurin ...[more]

PMID: 20037164

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Heart-specific deletion of CnB1 reveals multiple mechanisms whereby calcineurin regulates cardiac growth and function.

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Heart-specific deletion of CnB1 reveals multiple mechanisms whereby calcineurin regulates cardiac growth and function.

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