Moesin is activated in cardiomyocytes in experimental autoimmune myocarditis and mediates cytoskeletal reorganization with protrusion formation

Am J Physiol Heart Circ Physiol. 2016 Aug 1;311(2):H476-86. doi: 10.1152/ajpheart.00180.2016. Epub 2016 Jun 24.

Abstract

Acute myocarditis is a self-limiting disease. Most patients with myocarditis recover without cardiac dysfunction in spite of limited capacity of myocardial regeneration. Therefore, to address intrinsic reparative machinery of inflamed hearts, we investigated the cellular dynamics of cardiomyocytes in response to inflammation using experimental autoimmune myocarditis (EAM) model. EAM was induced by immunization of BALB/c mice with α-myosin heavy chain peptides twice. The inflammatory reaction was evoked with myocardial damage with the peak at 3 wk after the first immunization (EAM3w). Morphological and functional restoration started from EAM3w, when active protrusion formation, a critical process of myocardial healing, was observed in cardiomyocytes. Shotgun proteomics revealed that cytoskeletal proteins were preferentially increased in cardiomyocytes at EAM3w, compared with preimmunized (EAM0w) hearts, and that moesin was the most remarkably upregulated among them. Immunoblot analyses demonstrated that the expression of both total and phosphorylated moesin was upregulated in isolated cardiomyocytes from EAM3w hearts. Immunofluorescence staining showed that moesin was localized at cardiomyocyte protrusions at EAM3w. Adenoviral vectors expressing wild-type, constitutively active and inactive form of moesin (wtMoesin, caMoesin, and iaMoesin, respectively) were transfected in neonatal rat cardiomyocytes. The overexpression of wtMoesin and caMoesin resulted in protrusion formation, while not iaMoesin. Finally, we found that cardiomyocyte protrusions were accompanied by cell-cell contact formation. The expression of moesin was upregulated in cardiomyocytes under inflammation, inducing protrusion formation in a phosphorylation-dependent fashion. Moesin signal could be a novel therapeutic target that stimulates myocardial repair by promoting contact formation of cardiomyocytes.

Keywords: cardiomyocyte; moesin; myocarditis; protrusion; shotgun proteomics.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Animals, Newborn
  • Autoimmune Diseases / chemically induced
  • Autoimmune Diseases / metabolism*
  • Cell Surface Extensions / genetics*
  • Cell Surface Extensions / pathology
  • Cell Survival
  • Cytoskeleton / metabolism*
  • Cytoskeleton / pathology
  • Disease Models, Animal
  • Echocardiography
  • Fluorescent Antibody Technique
  • Immunoblotting
  • Immunohistochemistry
  • Inflammation / metabolism*
  • Mice
  • Mice, Inbred BALB C
  • Microfilament Proteins / genetics
  • Microfilament Proteins / metabolism*
  • Myocarditis / chemically induced
  • Myocarditis / metabolism*
  • Myocytes, Cardiac / metabolism*
  • Myocytes, Cardiac / pathology
  • Myosin Heavy Chains / adverse effects
  • Peptides
  • Phosphoproteins / metabolism
  • Rats
  • Real-Time Polymerase Chain Reaction
  • Reverse Transcriptase Polymerase Chain Reaction

Substances

  • Microfilament Proteins
  • Peptides
  • Phosphoproteins
  • moesin
  • Myosin Heavy Chains