title: Growth factor regulation of neural chemorepellent Sema3A expression in satellite cell cultures.
abstract: Successful regeneration and remodeling of the intramuscular motoneuron network and neuromuscular connections are critical for restoring skeletal muscle function and physiological properties. The regulatory signals of such coordination remain unclear, although axon-guidance molecules may be involved. Recently, satellite cells, resident myogenic stem cells positioned beneath the basal lamina and at high density at the myoneural junction regions of mature fibers, were shown to upregulate a secreted neural chemorepellent semaphorin 3A (Sema3A) in response to in vivo muscle-crush injury. The initial report on that expression centered on the observation that hepatocyte growth factor (HGF), an essential cue in muscle fiber growth and regeneration, remarkably upregulates Sema3A expression in early differentiated satellite cells in vitro [Tatsumi et al., Am J Physiol Cell Physiol 297: C238-C252, 2009]. Here, we address regulatory effects of basic fibroblast growth factor (FGF2) and transforming growth factor (TGF)-βs on Sema3A expression in satellite cell cultures. When treated with FGF2, Sema3A message and protein were upregulated as revealed by reverse transcription-polymerase chain reaction and immunochemical studies. Sema3A upregulation by FGF2 was dose dependent with a maximum (8- to 1-fold relative to the control) at 2.5 ng/ml (150 pM) and occurred exclusively at the early differentiation stage. The response was highly comparable in dose response and timing to effects of HGF treatment, without any additive or synergistic effect from treatment with a combination of both potent upregulators. In contrast, TGF-β2 and -β3 potently decreased basal Sema3A expression; the maximum effect was at very low concentrations (40 and 8 pM, respectively) and completely cancelled the activities of FGF2 and HGF to upregulate Sema3A. These results therefore encourage the prospect that a time-coordinated increase in HGF, FGF2, and TGF-β ligands and their receptors promotes a programmed strategy for Sema3A expression that guarantees successful intramuscular motor reinnervation by delaying sprouting and reattachment of motoneuron terminals onto damaged muscle fibers early in regeneration pending restoration of muscle fiber contractile integrity.
authors.affiliation: Department of Animal and Marine Bioresource Sciences, Graduate School of Agriculture, Kyushu University, Fukuoka, Japan.
authors.forename: Mai-Khoi Q
authors.initials: MK
authors.lastname: Do
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Sato
authors.forename: Naomi
authors.initials: N
authors.lastname: Shimizu
authors.forename: Takahiro
authors.initials: T
authors.lastname: Suzuki
authors.forename: Jun-ichi
authors.initials: J
authors.lastname: Shono
authors.forename: Wataru
authors.initials: W
authors.lastname: Mizunoya
authors.forename: Mako
authors.initials: M
authors.lastname: Nakamura
authors.forename: Yoshihide
authors.initials: Y
authors.lastname: Ikeuchi
authors.forename: Judy E
authors.initials: JE
authors.lastname: Anderson
authors.forename: Ryuichi
authors.initials: R
authors.lastname: Tatsumi
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D016222:Fibroblast Growth Factor 2 / Q000378:metabolism*; D017228:Hepatocyte Growth Factor / Q000378:metabolism; D008297:Male; D024510:Muscle Development; D018482:Muscle, Skeletal / Q000293:injuries / Q000294:innervation / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D032496:Satellite Cells, Skeletal Muscle / Q000378:metabolism*; D040121:Semaphorin-3A / Q000378:metabolism*; D053781:Transforming Growth Factor beta2 / Q000378:metabolism*; D053782:Transforming Growth Factor beta3 / Q000378:metabolism*; D015854:Up-Regulation; D014945:Wound Healing
chemical_list: C488218:Sema3a protein, rat; D040121:Semaphorin-3A; D053781:Transforming Growth Factor beta2; D053782:Transforming Growth Factor beta3; D016222:Fibroblast Growth Factor 2; D017228:Hepatocyte Growth Factor