title: Myosin VI in skeletal muscle: its localization in the sarcoplasmic reticulum, neuromuscular junction and muscle nuclei.
abstract: Myosin VI (MVI) is a unique unconventional motor moving backwards on actin filaments. In non-muscle cells, it is involved in cell migration, endocytosis and intracellular trafficking, actin cytoskeleton dynamics, and possibly in gene transcription. An important role for MVI in striated muscle functioning was suggested in a report showing that a point mutation (H236R) within the MVI gene was associated with cardiomyopathy (Mohiddin et al., J Med Genet 41:309-314, 2004). Here, we have addressed MVI function in striated muscle by examining its expression and distribution in rat hindlimb skeletal muscle. We found that MVI was present predominantly at the muscle fiber periphery, and it was also localized within muscle nuclei. Analysis of both the hindlimb and cardiac muscle longitudinal sections revealed ~3 μm striation pattern, corresponding to the sarcoplasmic reticulum. Moreover, MVI was detected in the sarcoplasmic reticulum fractions isolated from skeletal and cardiac muscle. The protein also localized to the postsynaptic region of the neuromuscular junction. In denervated muscle, the defined MVI distribution pattern was abolished and accompanied by significant increase in its amount in the muscle fibers. In addition, we have identified several novel potential MVI-binding partners, which seem to aid our observations that in striated muscle MVI could be involved in postsynaptic trafficking as well as in maintenance of and/or transport within the sarcoplasmic reticulum and non-sarcomeric cytoskeleton.
authors.affiliation: Department of Biochemistry, Nencki Institute of Experimental Biology, 3 Pasteur St. 02-093, Warsaw, Poland.
authors.forename: Justyna
authors.initials: J
authors.lastname: Karolczak
authors.forename: Magdalena
authors.initials: M
authors.lastname: Sobczak
authors.forename: Lukasz
authors.initials: L
authors.lastname: Majewski
authors.forename: Marine
authors.initials: M
authors.lastname: Yeghiazaryan
authors.forename: Anna
authors.initials: A
authors.lastname: Jakubiec-Puka
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Ehler
authors.forename: Urszula
authors.initials: U
authors.lastname: Sławińska
authors.forename: Grzegorz M
authors.initials: GM
authors.lastname: Wilczyński
authors.forename: Maria Jolanta
authors.initials: MJ
authors.lastname: Rędowicz
mesh_terms: D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism*; D003714:Denervation; D005260:Female; D006614:Hindlimb; D051379:Mice; D008810:Mice, Inbred C57BL; D018485:Muscle Fibers, Skeletal / Q000737:chemistry / Q000378:metabolism*; D032383:Myocytes, Cardiac / Q000737:chemistry / Q000378:metabolism; D018995:Myosin Heavy Chains / Q000032:analysis / Q000378:metabolism*; D009469:Neuromuscular Junction / Q000378:metabolism*; D011485:Protein Binding; D051381:Rats; D017208:Rats, Wistar; D012519:Sarcoplasmic Reticulum / Q000378:metabolism*; D013570:Synaptic Membranes / Q000378:metabolism
chemical_list: C089785:myosin VI; D018995:Myosin Heavy Chains