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Disturbance in Z-disk mechanosensitive proteins induced by a persistent mutant myopalladin causes familial restrictive cardiomyopathy.

Abstract：

BACKGROUND:Familial restrictive cardiomyopathy (FRCM) has a poor prognosis due to diastolic dysfunction and restrictive physiology (RP). Myocardial stiffness, with or without fibrosis, underlie RP, but the mechanism(s) of restrictive remodeling is unclear. Myopalladin (MYPN) is a messenger molecule that links structural and gene regulatory molecules via translocation from the Z-disk and I-bands to the nucleus in cardiomyocytes. Expression of N-terminal MYPN peptide results in severe disruption of the sarcomere. OBJECTIVES:The aim was to study a nonsense MYPN-Q529X mutation previously identified in the FRCM family in an animal model to explore the molecular and pathogenic mechanisms of FRCM. METHODS:Functional (echocardiography, cardiac magnetic resonance [CMR] imaging, electrocardiography), morphohistological, gene expression, and molecular studies were performed in knock-in heterozygote (Mypn(WT/Q526X)) and homozygote mice harboring the human MYPN-Q529X mutation. RESULTS:Echocardiographic and CMR imaging signs of diastolic dysfunction with preserved systolic function were identified in 12-week-old Mypn(WT/Q526X) mice. Histology revealed interstitial and perivascular fibrosis without overt hypertrophic remodeling. Truncated Mypn(Q526X) protein was found to translocate to the nucleus. Levels of total and nuclear cardiac ankyrin repeat protein (Carp/Ankrd1) and phosphorylation of mitogen-activated protein kinase/extracellular signal-regulated kinase 1/2 (Erk1/2), Erk1/2, Smad2, and Akt were reduced. Up-regulation was evident for muscle LIM protein (Mlp), desmin, and heart failure (natriuretic peptide A [Nppa], Nppb, and myosin heavy chain 6) and fibrosis (transforming growth factor beta 1, alpha-smooth muscle actin, osteopontin, and periostin) markers. CONCLUSIONS:Heterozygote Mypn(WT/Q526X) knock-in mice develop RCM due to persistence of mutant Mypn(Q526X) protein in the nucleus. Down-regulation of Carp and up-regulation of Mlp and desmin appear to augment fibrotic restrictive remodeling, and reduced Erk1/2 levels blunt a hypertrophic response in Mypn(WT/Q526X) hearts.

journal_name

J Am Coll Cardiol

journal_title

Journal of the American College of Cardiology

authors

Huby AC,Mendsaikhan U,Takagi K,Martherus R,Wansapura J,Gong N,Osinska H,James JF,Kramer K,Saito K,Robbins J,Khuchua Z,Towbin JA,Purevjav E

doi

10.1016/j.jacc.2014.09.071

subject

Has Abstract

pub_date

2014-12-30 00:00:00

pages

2765-76

issue

eissn

0735-1097

issn

1558-3597

pii

S0735-1097(14)06749-7

journal_volume

pub_type

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Disturbance in Z-disk mechanosensitive proteins induced by a persistent mutant myopalladin causes familial restrictive cardiomyopathy.