N-cadherin/catenin-based costameres in cultured chicken cardiomyocytes.
N-cadherin is a member of the Ca(2+)-dependent cell adhesion molecules and plays an important role in the assembly of the adherens junction in chicken cardiomyocytes. In addition to being present at the cell-cell junction, N-cadherin is associated with costameres in extrajunctional regions. The significance of the N-cadherin-associated costameres and whether catenins are components of costameres in chicken cardiomyocytes are not known. In this study, double-labeling immunofluorescence microscopy was used to determine the extrajunctional distribution of both N-cadherin and its cytoplasmic associated proteins, alpha- and beta-catenins, and their relationship to myofibrillar Z-disc alpha-actinin. N-cadherin, alpha-, and beta-catenins were all found to be present at the extrajunctional region and, in some cases, were codistributed with myofibrillar alpha-actinin exhibiting a periodic staining pattern. Confocal microscopy confirmed that both N-cadherin and beta-catenin colocalized with peripheral myofibrillar alpha-actinin on the dorsal surface of cardiomyocytes as components of the costameres. Intracellular application of antibodies specific for the cytoplasmic portions of N-cadherin, alpha-, and beta-catenin, either by electroporation or microinjection, resulted in myofibril disorganization and disassembly. These results suggest the existence of N-cadherin/catenin-based costameres in the dorsal surface of cultured chicken cardiomyocytes in addition to the integrin/vinculin-based costameres found in the ventral surface and indicate that the former set of costameres is essential for cardiac myofibrillogenesis.
Wu
J C
JC
Department of Anatomy, College of Medicine, National Taiwan University, Taipei 10018, Taiwan. jcwu@ha.mc.ntu.tw
Chung
T H
TH
Tseng
Y Z
YZ
Wang
S M
SM
D000185:Actinin / Q000378:metabolism; D000818:Animals; D015820:Cadherins / Q000378:metabolism*; D002478:Cells, Cultured; D002645:Chickens; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D018274:Electroporation; D005455:Fluorescent Antibody Technique; D008845:Microinjections; D018613:Microscopy, Confocal; D009206:Myocardium / Q000166:cytology / Q000378:metabolism*; D009210:Myofibrils / Q000378:metabolism; D015534:Trans-Activators; D051178:alpha Catenin; D051176:beta Catenin
D015820:Cadherins; D003598:Cytoskeletal Proteins; D015534:Trans-Activators; D051178:alpha Catenin; D051176:beta Catenin; D000185:Actinin