Myofibrillogenesis and formation of cell contacts mediate the localization of N-RAP in cultured chick cardiomyocytes.
The expression of N-RAP was investigated in immuofluorescently stained embryonic chick cardiomyocyte cultures. After 1 day in culture, the cardiomyocytes were spherical and N-RAP, titin, alpha-actinin, and vinculin were all diffusely distributed. As the cardiomyocytes spread and formed myofibrils and cell contacts, N-RAP became localized to distinct areas in the cells. During myofibrillogenesis, N-RAP was found concentrated in premyofibrils. As the premyofibrils transformed into bundles of mature myofibrils, N-RAP became concentrated at the longitundal ends of the cells, and was not found in the mature sarcomeres. At sites of cell-cell contacts, N-RAP was localized to the cell junction even in cells without any significant myofibril formation. As the cell-cell contacts became more extensive and formed structures resembling the intercalated disks found in hearts, N-RAP became even more specifically concentrated at these junctions. The results show that myofibrillogenesis and cell contact formation can each independently target N-RAP to the longitudinal ends of cardiomyocytes.
Carroll
S L
SL
Laboratory of Physical Biology, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, Maryland 20892-2755, USA.
Horowits
R
R
D000185:Actinin / Q000032:analysis; D000818:Animals; D002448:Cell Adhesion; D002454:Cell Differentiation; D002478:Cells, Cultured; D002642:Chick Embryo; D064211:Connectin; D005455:Fluorescent Antibody Technique; D008954:Models, Biological; D009124:Muscle Proteins / Q000032:analysis / Q000378:metabolism*; D009206:Myocardium / Q000378:metabolism* / Q000648:ultrastructure; D009210:Myofibrils / Q000378:metabolism* / Q000648:ultrastructure; D011494:Protein Kinases / Q000032:analysis; D016596:Vinculin / Q000032:analysis
D064211:Connectin; D009124:Muscle Proteins; D000185:Actinin; D016596:Vinculin; D011494:Protein Kinases