Loss of lamin A/C expression revealed by immuno-electron microscopy in dilated cardiomyopathy with atrioventricular block caused by LMNA gene defects

Laura Verga, Monica Concardi, Andrea Pilotto, Ornella Bellini, Michele Pasotti, Alessandra Repetto, Luigi Tavazzi, Eloisa Arbustini

Research output: Contribution to journalArticlepeer-review

Abstract

Mutations of the LMNA gene encoding the lamin A and C nuclear envelope proteins cause an autosomal dominant form of dilated cardiomyopathy (DCM) with atrioventricular block (AVB). The aim of this study was to investigate ultrastructural nuclear membrane changes by conventional electron microscopy and protein expression by immuno-electron microscopy in the heart of patients with DCM and AVB due to LMNA gene mutations. Four immunohistochemical techniques were used: pre-embedding and post-embedding in Epon-Araldite resin and London Resin White (LRW), with and without silver enhancement. Parallel light microscopy immunohistochemistry studies were performed. Conventional electron microscopy showed a loss of integrity of the myocyte nuclei with blebs of the nuclear membrane, herniations and delamination of the nuclear lamina and nuclear pore clustering. Post-embedding LRW was the most informative technique for morphology and immuno-labelling. Immuno-labelling was almost absent in the nuclear envelope of patients with LMNA gene mutations, but intensely present in controls. The loss of labelling selectively affected myocyte nuclei; the endothelial cell nuclei were immunostained in patients and controls. Light immunohistochemistry confirmed the results. These findings confirm the hypothesis that LMNA gene defects are associated with a loss of protein expression in the selective compartment of non-cycling myocyte nuclei.

Original languageEnglish
Pages (from-to)664-671
Number of pages8
JournalVirchows Archiv
Volume443
Issue number5
DOIs
Publication statusPublished - Nov 2003

Keywords

  • Atrioventricular block
  • Dilated cardiomyopathy
  • Immuno-electron microscopy
  • Lamin A/C

ASJC Scopus subject areas

  • Pathology and Forensic Medicine

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