caa a22 4500 475744780 CHVBK 20180406123510.0 cr unu---uuuuu 170329e20000801xx s 000 0 eng 10.1023/A:1026561120566 doi (NATIONALLICENCE)springer-10.1023/A:1026561120566 Triad proteins and intracellular Ca2+ transients during development of human skeletal muscle cells in aneural and innervated cultures [Elektronische Daten] [Hiroaki Tanaka, Tokuro Furuya, Noriyoshi Kameda, Takayoshi Kobayashi, Hidehiro Mizusawa] Dihydropyridine receptors (DHPRs), ryanodine receptors (RyRs), and triadin are major components of triads of mature skeletal muscle and play crucial roles in Ca2+ release in excitation-contraction (E-C) coupling. We investigated the expression and localization of these proteins as well as intracellular Ca2+ transients during development of human muscle cells cultured aneurally and innervated with rat spinal cord. mRNAs encoding skeletal muscle isoforms of the DHPR α1 subunit (α1S-DHPR), the RyR, and triadin were scarce in myoblasts and increased remarkably after myotube formation. Immunocytochemically, α1S-DHPR was expressed after myoblast fusion and localized mainly within the cytoplasmic area of aneural myotubes whereas the cardiac isoform (α1C-DHPR) was abundant along the plasma membrane. RyRs and triadin were both detected after myotube formation and colocalized in the cytoplasm of aneural myotubes and innervated muscle fibers. Along the plasma membrane of aneural myotubes, colocalization of α1C-DHPR with the RyR was more frequently observed than that of α1S-DHPR. In innervated muscle fibers, α1S-DHPR and RyR were colocalized first along the plasma membrane and later in the cytoplasmic area and formed regular double rows of cross-striation. The α1C-DHPR diminished after innervation. In Ca2+ imaging, spontaneous irregular slow Ca2+ oscillations were observed in aneurally cultured myotubes whereas nerve-driven regular fast oscillations were observed in innervated muscle fibers. Both caffeine and depolarization induced Ca2+ transients in aneurally cultured myotubes and innervated muscle fibers. In aneurally cultured myotubes, depolarization-induced Ca2+ transients were highly dependent on extracellular Ca2+, suggesting immaturity of the Ca2+ release system. This dependence remarkably decreased after innervation. Our present results show that these proteins are expressed differently in aneurally cultured myotubes than in adult skeletal muscle, that Ca2+ release in aneurally cultured myotubes is different from in adult skeletal muscle, and that innervation induces formation of a mature skeletal muscle-like excitation-contraction coupling system in cultured human muscle cells. Kluwer Academic Publishers, 2000 Tanaka Hiroaki Department of Neurology, Tokyo Medical and Dental University School of Medicine, Yushima 1-5-45, Bunkyo-ku, 113-8519, Tokyo, Japan aut Furuya Tokuro Department of Neurology, Tokyo Medical and Dental University School of Medicine, Yushima 1-5-45, Bunkyo-ku, 113-8519, Tokyo, Japan aut Kameda Noriyoshi Department of Neurology, Tokyo Medical and Dental University School of Medicine, Yushima 1-5-45, Bunkyo-ku, 113-8519, Tokyo, Japan aut Kobayashi Takayoshi Department of Neurology, Tokyo Medical and Dental University School of Medicine, Yushima 1-5-45, Bunkyo-ku, 113-8519, Tokyo, Japan aut Mizusawa Hidehiro Department of Neurology, Tokyo Medical and Dental University School of Medicine, Yushima 1-5-45, Bunkyo-ku, 113-8519, Tokyo, Japan aut Journal of Muscle Research & Cell Motility Kluwer Academic Publishers 21/6(2000-08-01), 507-526 0142-4319 21:6<507 2000 21 10974 https://doi.org/10.1023/A:1026561120566 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1023/A:1026561120566 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Tanaka Hiroaki Department of Neurology, Tokyo Medical and Dental University School of Medicine, Yushima 1-5-45, Bunkyo-ku, 113-8519, Tokyo, Japan aut NATIONALLICENCE 700 1- Furuya Tokuro Department of Neurology, Tokyo Medical and Dental University School of Medicine, Yushima 1-5-45, Bunkyo-ku, 113-8519, Tokyo, Japan aut NATIONALLICENCE 700 1- Kameda Noriyoshi Department of Neurology, Tokyo Medical and Dental University School of Medicine, Yushima 1-5-45, Bunkyo-ku, 113-8519, Tokyo, Japan aut NATIONALLICENCE 700 1- Kobayashi Takayoshi Department of Neurology, Tokyo Medical and Dental University School of Medicine, Yushima 1-5-45, Bunkyo-ku, 113-8519, Tokyo, Japan aut NATIONALLICENCE 700 1- Mizusawa Hidehiro Department of Neurology, Tokyo Medical and Dental University School of Medicine, Yushima 1-5-45, Bunkyo-ku, 113-8519, Tokyo, Japan aut NATIONALLICENCE 773 0- Journal of Muscle Research & Cell Motility Kluwer Academic Publishers 21/6(2000-08-01), 507-526 0142-4319 21:6<507 2000 21 10974 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer