Sarcomeric lesions and remodeling proximal to intercalated disks in overload-induced cardiac hypertrophy

Exp Cell Res. 2016 Oct 15;348(1):95-105. doi: 10.1016/j.yexcr.2016.09.008. Epub 2016 Sep 14.

Abstract

Pressure overload induces cardiac remodeling involving both the contractile machinery and intercalated disks (IDs). Filamin C (FlnC) and Xin actin-binding repeat-containing proteins (XIRPs) are multi-adapters localizing in IDs of higher vertebrates. Knockout of the gene encoding Xin (Xirp1) in mice leads to a mild cardiac phenotype with ID mislocalization. In order to amplify this phenotype, we performed transverse aortic constriction (TAC) on control and Xirp1-deficient mice. TAC induced similar left ventricular hypertrophy in both genotypes, suggesting that the lack of Xin does not lead to higher susceptibility to cardiac overload. However, in both genotypes, FlnC appeared in "streaming" localizations across multiple sarcomeres proximal to the IDs, suggesting a remodeling response. Furthermore, FlnC-positive areas of remodeling, reminiscent of sarcomeric lesions previously described for skeletal muscles (but so far unreported in the heart), were also observed. These adaptations reflect a similarly strong effect of the pressure induced by TAC in both genotypes. However, 2 weeks post-operation TAC-treated knockout hearts had reduced levels of connexin43 and slightly increased incidents of ventricular tachycardia compared to their wild-type (WT) counterparts. Our findings highlight the FlnC-positive sarcomeric lesions and ID-proximal streaming as general remodeling responses in cardiac overload-induced hypertrophy.

Keywords: Connexin43; Cross-striated muscle cells; Filamin C; XIRP2; Xin actin-binding repeat-containing proteins; Xirp1.

MeSH terms

  • Animals
  • Aorta / pathology
  • Arrhythmias, Cardiac / complications
  • Arrhythmias, Cardiac / diagnostic imaging
  • Arrhythmias, Cardiac / pathology
  • Cardiomegaly / complications
  • Cardiomegaly / diagnostic imaging
  • Cardiomegaly / pathology*
  • Connexin 43 / metabolism
  • Constriction, Pathologic
  • DNA-Binding Proteins / deficiency
  • DNA-Binding Proteins / metabolism
  • Electrocardiography
  • Female
  • Filamins / metabolism
  • Hypertrophy, Left Ventricular / complications
  • Hypertrophy, Left Ventricular / diagnostic imaging
  • Hypertrophy, Left Ventricular / pathology
  • Mice
  • Myocardium / metabolism
  • Myocardium / pathology
  • Nuclear Proteins / deficiency
  • Nuclear Proteins / metabolism
  • Phenotype
  • Sarcomeres / pathology*
  • Tachycardia / complications
  • Tachycardia / diagnostic imaging
  • Tachycardia / pathology

Substances

  • Connexin 43
  • DNA-Binding Proteins
  • Filamins
  • Nuclear Proteins
  • Xin protein, mouse