title: Increased expression of neuregulin-1 in differentiating muscle satellite cells and in motoneurons during muscle regeneration.
abstract: Neuregulins belong to a family of multipotent growth-promoting proteins, and have been shown to have a crucial role in accumulating acetylcholine receptor at neuromuscular junctions. A functional role of neuregulins in muscle regeneration has not yet been identified. Using reverse transcription (RT)-PCR, Western blot and immunofluorescence analysis following bupivacaine injection into rat muscle, we investigated the expression pattern of neuregulin-1 (NRG-1) in normal and regenerating tibialis anterior (TA) muscle. In addition, we examined changes in NRG-1 expression in the spinal cord following muscle damage. Western blotting showed that muscle NRG-1 protein decreased soon after the damage, and increased gradually after the 4th day following the damage. The amount of NRG-1 mRNA in the muscle increased from the 2nd to 6th post-surgical day. The amount of NRG-1 protein, but not mRNA, increased gradually in the spinal cord after muscle damage. Immunofluorescence revealed NRG-1 protein in some quiescent satellite cells identified by c-Met. After 6 and 10 days, clear co-localization between NRG-1 and myogenin was noted in differentiating satellite cells. Thus, NRG-1 may play an important role in the differentiation of satellite cells in muscle regeneration, while increased NRG-1 expression in motoneurons may enhance the remodeling of partially damaged axons.
authors.affiliation: Department of Orthopedics, Kyoto Prefectural University of Medicine, 465 Kajii-cho, Kawaramachi-hirokoji, Kamigyo-ku, Kyoto, 602-8566, Japan.
authors.forename: Miyuki
authors.initials: M
authors.lastname: Hirata
authors.forename: Kunihiro
authors.initials: K
authors.lastname: Sakuma
authors.forename: Seiichiro
authors.initials: S
authors.lastname: Okajima
authors.forename: Hiroyoshi
authors.initials: H
authors.lastname: Fujiwara
authors.forename: Shuichiro
authors.initials: S
authors.lastname: Inashima
authors.forename: Masahiro
authors.initials: M
authors.lastname: Yasuhara
authors.forename: Toshikazu
authors.initials: T
authors.lastname: Kubo
mesh_terms: D000779:Anesthetics, Local / Q000494:pharmacology; D000818:Animals; D001973:Bromodeoxyuridine / Q000378:metabolism; D002038:Bungarotoxins / Q000378:metabolism; D002045:Bupivacaine / Q000494:pharmacology; D002454:Cell Differentiation / Q000187:drug effects; D016189:Dystrophin / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology*; D008297:Male; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D009046:Motor Neurons / Q000187:drug effects / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000187:drug effects / Q000503:physiopathology*; D009135:Muscular Diseases / Q000188:drug therapy / Q000473:pathology / Q000503:physiopathology; D018008:Myogenin / Q000378:metabolism; D020890:Neuregulin-1 / Q000235:genetics / Q000378:metabolism*; D019859:Proto-Oncogene Proteins c-met / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D012038:Regeneration / Q000502:physiology*; D032496:Satellite Cells, Skeletal Muscle / Q000187:drug effects / Q000378:metabolism*; D013997:Time Factors
chemical_list: D000779:Anesthetics, Local; D002038:Bungarotoxins; D016189:Dystrophin; C489787:MAP2 protein, rat; D008869:Microtubule-Associated Proteins; D018008:Myogenin; D020890:Neuregulin-1; D019859:Proto-Oncogene Proteins c-met; D001973:Bromodeoxyuridine; D002045:Bupivacaine