Regulation of desmin expression in adult-type myogenesis and muscle maturation during Xenopus laevis metamorphosis.
Isoforms of myosin heavy chain and tropomyosin convert during metamorphosis of Xenopus laevis with larval-to-adult remodeling of dorsal muscle (Nishikawa and Hayashi, 1994 , Dev. Biol. 165: 86-94). In the present study, other markers for muscle remodeling during metamorphosis were determined by SDS-PAGE analysis. The amounts of twelve muscle proteins changed remarkably during metamorphosis. Among these, a 54-kDa molecule was found to be desmin, and the relative content/total proteins decreased dramatically through metamorphosis. In hindlimb muscle, desmin content increased fourfold during prometamorphosis, when myoblast proliferation and fusion occurred. With further myotube maturation, this content decreased by 1/2 while that of muscle actin continued to increase. Thus, desmin up- and down-regulation in hindlimbs mark early and late phases of myogenesis, respectively. In tall muscle, the desmin content decreased continuously to (1/8) before and during metamorphosis, due to tall muscle growth and maturation. In dorsal muscle, three desmin changes occurred: a pre-metamorphic decrease, a transient increase at prometamorphosis, and a rapid decrease at the climax stage. Immunohistochemical analysis showed desmin+ cells to be present between young (adult-type) myotubes and replicating (PCNA+) cells in dorsal muscles, correlating the transient desmin upregulation in dorsal muscle with the initiation of adult-type myogenesis. After the upregulation, dorsal muscle desmin decreased to (1/8). This rapid down-regulation was replicated by administration of triiodothyronine (T3) to tadpoles, suggesting a significant role for T3 in dorsal muscle remodeling during metamorphosis. Collectively, these results show that analysis of desmin expression and PCNA-immunohistochemistry are good tools for determining the sites and timing of larval-to-adult muscle remodeling during Xenopus laevis metamorphosis.
Kawakami
Kiyoshi
K
Department of Biological Science, Faculty of Life and Environmental Science, Shimane University, Matsue, Shimane 690-8504, Japan.
Kuroda
Masaaki
M
Nishikawa
Akio
A
D000818:Animals; D000906:Antibodies; D003893:Desmin / Q000235:genetics / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects / Q000502:physiology; D007814:Larva / Q000254:growth & development / Q000378:metabolism; D008675:Metamorphosis, Biological / Q000502:physiology*; D024510:Muscle Development / Q000502:physiology*; D018482:Muscle, Skeletal / Q000254:growth & development*; D013974:Thyroxine / Q000494:pharmacology; D014982:Xenopus laevis / Q000254:growth & development*
D000906:Antibodies; D003893:Desmin; D013974:Thyroxine