title: Differential assembly of cytoskeletal and sarcomeric actins in developing skeletal muscle cells in vitro.
abstract: Monoclonal antibodies (McAb) to actin were prepared to analyze the assembly of actin isoforms in developing muscle cells in vitro. One of the antibodies (SkA-06) was specific for alpha-sarcomeric actin isoforms in skeletal and cardiac muscles, while the others recognized cytoskeletal (beta, gamma) actin isoforms in smooth muscle and non-muscle tissues as well as the sarcomeric (alpha) actins. Using SkA-06 and a polyclonal antibody (PcAb) specific for cytoskeletal actins, the subcellular localization of the actin isoforms was examined by immunocytochemical methods. While in developing young myotubes, cytoskeletal and sarcomeric actins were co-localized in nascent myofibrils or stress-fiber-like structures, sarcomeric actins predominated in striated myofibrils in more developed myotubes. When FITC-labeled cytoskeletal and sarcomeric actins were introduced into young myotubes by a microinjection method, the latter became detectable in striated structures sooner than the former but they were finally incorporated into striated myofibrils. These results suggest that alpha-actin(s) as well as beta- and gamma-actins can be incorporated into myofibrils, but alpha-actin(s) is assembled preferentially into myofibrils in developing muscle cells.
authors.affiliation: Department of Biology, Faculty of Science, Chiba University, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Hayakawa
authors.forename: S
authors.initials: S
authors.lastname: Ono
authors.forename: R
authors.initials: R
authors.lastname: Nagaoka
authors.forename: O
authors.initials: O
authors.lastname: Saitoh
authors.forename: T
authors.initials: T
authors.lastname: Obinata
mesh_terms: D000199:Actins / Q000276:immunology / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal; D002478:Cells, Cultured; D002642:Chick Embryo; D003599:Cytoskeleton / Q000378:metabolism*; D019084:Fluorescent Antibody Technique, Indirect; D008969:Molecular Sequence Data; D024510:Muscle Development; D018482:Muscle, Skeletal / Q000166:cytology / Q000254:growth & development / Q000378:metabolism*; D012518:Sarcomeres / Q000378:metabolism*; D013347:Subcellular Fractions / Q000378:metabolism
chemical_list: D000199:Actins; D000911:Antibodies, Monoclonal