title: Phosphorylation of connexin43 on S279/282 may contribute to laminopathy-associated conduction defects.
abstract: An understanding of the molecular mechanism behind the arrhythmic phenotype associated with laminopathies has yet to emerge. A-type lamins have been shown to interact and sequester activated phospho-ERK1/2(pERK1/2) at the nucleus. The gap junction protein connexin43 (Cx43) can be phosphorylated by pERK1/2 on S279/282 (pS279/282), inhibiting intercellular communication. We hypothesized that without A-type lamins, pS279/282 Cx43 will increase due to inappropriate phosphorylation by pERK1/2, resulting in decreased gap junction function. We observed a 1.6-fold increase in pS279/282 Cx43 levels in Lmna(-/-) mouse embryonic fibroblasts (MEFs) compared to Lmna(+/+), and 1.8-fold more pERK1/2 co-precipitated from Lmna(-/-) MEFs with Cx43 antibodies. We found a 3-fold increase in the fraction of non-nuclear pERK1/2 and a concomitant 2-fold increase in the fraction of pS279/282 Cx43 in Lmna(-/-) MEFs by immunofluorescence. In an assay of gap junctional function, Lmna(-/-) MEFs transferred dye to 60% fewer partners compared to Lmna(+/+) controls. These results are mirrored in 5-6 week-old Lmna(-/-) mice compared to their Lmna(+/+) littermates as we detect increased pS279/282 Cx43 in gap junctions by immunofluorescence and 1.7-fold increased levels by immunoblot. We conclude that increased pS279/282 Cx43 in the Lmna(-/-) background results in decreased cell communication and may contribute to the arrhythmic pathology in vivo.
authors.affiliation: Fred Hutchinson Cancer Research Center (FHCRC), Public Health Sciences Division, 1100 Fairview Ave. N., Seattle, WA 98109, USA.
authors.forename: Steven C
authors.initials: SC
authors.lastname: Chen
authors.forename: Brian K
authors.initials: BK
authors.lastname: Kennedy
authors.forename: Paul D
authors.initials: PD
authors.lastname: Lampe
mesh_terms: D000818:Animals; D001145:Arrhythmias, Cardiac / Q000378:metabolism / Q000473:pathology; D001692:Biological Transport; D002450:Cell Communication; D002467:Cell Nucleus / Q000378:metabolism; D018031:Connexin 43 / Q000235:genetics / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D017629:Gap Junctions / Q000235:genetics / Q000378:metabolism; D006329:Heart Conduction System / Q000378:metabolism / Q000473:pathology*; D034904:Lamin Type A / Q000235:genetics / Q000378:metabolism*; D020935:MAP Kinase Signaling System; D051379:Mice; D010766:Phosphorylation; D025941:Protein Interaction Mapping; D012694:Serine / Q000378:metabolism*; D014407:Tumor Cells, Cultured
chemical_list: D018031:Connexin 43; D034904:Lamin Type A; D012694:Serine