title: Upregulation of HARP during in vitro myogenesis and rat soleus muscle regeneration.
abstract: Heparin affin regulatory peptide (HARP) is a heparin binding growth factor that belongs to a family of molecule whose biological function in myogenesis has been suspected without formal demonstration. In the present study, we investigated the expression and the distribution of HARP and its mRNA during soleus muscle regeneration using a crushed-induced regeneration model and also during differentiation of muscle satellite cells in primary cultures. We show that HARP mRNA and protein expression are increased during the regeneration process with a peak at day 5 after muscle crushing when new myotubes are formed. In situ hybridization and immunohistochemical studies showed that activated myoblasts expressed HARP at day two after crushing. Five days after muscle lesion, HARP is localised in newly formed myotubes as well as in prefused activated myoblasts. In regenerated myofibers, 15 days after crushing, expression of HARP was reduced. In vitro experiments using primary cultures of rat satellite cells indicated that HARP expression level increased during the differentiation process and peaked on fusion of myoblasts into myotubes. This is the first study demonstrating the presence of HARP in fusing myogenic cells suggests that this growth factor could play a function in myogenic differentiation.
authors.affiliation: Laboratoire de Recherche sur la Croissance Cellulaire, la Réparation et la Régénération Tissulaires FRE CNRS 2412, Université Paris Val de Marne, Avenue du Général de Gaulle, 94010 Créteil, France.
authors.forename: Danièle
authors.initials: D
authors.lastname: Caruelle
authors.forename: Zohra
authors.initials: Z
authors.lastname: Mazouzi
authors.forename: Irene
authors.initials: I
authors.lastname: Husmann
authors.forename: Jean
authors.initials: J
authors.lastname: Delbé
authors.forename: Arlette
authors.initials: A
authors.lastname: Duchesnay
authors.forename: Jean
authors.initials: J
authors.lastname: Gautron
authors.forename: Isabelle
authors.initials: I
authors.lastname: Martelly
authors.forename: José
authors.initials: J
authors.lastname: Courty
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D016207:Cytokines / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D066298:In Vitro Techniques; D024510:Muscle Development / Q000235:genetics / Q000502:physiology*; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000502:physiology; D032446:Myoblasts / Q000378:metabolism; D018008:Myogenin / Q000235:genetics / Q000502:physiology; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D012038:Regeneration / Q000502:physiology*; D032496:Satellite Cells, Skeletal Muscle / Q000737:chemistry; D013997:Time Factors; D015854:Up-Regulation / Q000502:physiology
chemical_list: D002352:Carrier Proteins; D016207:Cytokines; C503803:Myog protein, rat; D018008:Myogenin; D012333:RNA, Messenger; C066845:pleiotrophin