title: Insulin-like growth factor 1 regulation of proliferation and differentiation of Xenopus laevis myogenic cells in vitro.
abstract: To understand the mechanism of muscle remodeling during Xenopus laevis metamorphosis, we examined the in vitro effect of insulin-like growth factor 1 (IGF-1) on growth and differentiation of three different-fate myogenic cell populations: tadpole tail, tadpole dorsal, and young adult leg muscle. IGF-1 promoted growth and differentiation of both tail and leg myogenic cells only under conditions where these cells could proliferate. Inhibition of cell proliferation by DNA synthesis inhibitor cytosine arabinoside completely canceled the IGF-1's cell differentiation promotion, suggesting the possibility that IGF-1's differentiation-promotion effect is an indirect effect via IGF-1's cell proliferation promotion. IGF-1 promoted differentiation dose dependently with maximum effect at 100-500 ng/ml. RT-PCR analysis revealed the upregulation (11-fold) of ifg1 mRNA expression in developing limbs, suggesting that IGF-1 plays a role in promoting muscle differentiation during limb development. The combined effect of triiodo-L-thyronine (T3) and IGF-1 was also examined. In adult leg cells, IGF-1 promoted growth and differentiation irrespective of the presence of T3. In larval tail cells, cell count was 76% lower in the presence of T3, and IGF-1 did not promote proliferation and differentiation in T3-containing medium. In larval dorsal cells, cell count was also lower in the presence of T3, but IGF-1 enhanced proliferation and differentiation in T3-containing medium. This result is likely due to the presence among dorsal cells of both adult and larval types (1:1). Thus, IGF-1 affects only adult-type myogenic cells in the presence of T3and helps accelerate dorsal muscle remodeling during metamorphosis.
authors.affiliation: Biological Science and Biotechnology Course, Graduate School of Life and Environmental Science, Shimane University, 1060 Nishikawatsu, Matsue, Shimane, 690-0854, Japan.
authors.forename: Sairi
authors.initials: S
authors.lastname: Miyata
authors.affiliation: Biological Science and Biotechnology Course, Graduate School of Life and Environmental Science, Shimane University, 1060 Nishikawatsu, Matsue, Shimane, 690-0854, Japan.
authors.forename: Tomotaka
authors.initials: T
authors.lastname: Yada
authors.affiliation: Department of Biological Science, Faculty of Life and Environmental Science, Shimane University, Matsue, Japan.
authors.forename: Natsuko
authors.initials: N
authors.lastname: Ishikawa
authors.affiliation: Biological Science and Biotechnology Course, Graduate School of Life and Environmental Science, Shimane University, 1060 Nishikawatsu, Matsue, Shimane, 690-0854, Japan.
authors.forename: Kazi
authors.initials: K
authors.lastname: Taheruzzaman
authors.affiliation: Biological Science and Biotechnology Course, Graduate School of Life and Environmental Science, Shimane University, 1060 Nishikawatsu, Matsue, Shimane, 690-0854, Japan.
authors.forename: Ryohei
authors.initials: R
authors.lastname: Hara
authors.affiliation: Biological Science and Biotechnology Course, Graduate School of Life and Environmental Science, Shimane University, 1060 Nishikawatsu, Matsue, Shimane, 690-0854, Japan.|Department of Biological Science, Faculty of Life and Environmental Science, Shimane University, Matsue, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Matsuzaki
authors.affiliation: Biological Science and Biotechnology Course, Graduate School of Life and Environmental Science, Shimane University, 1060 Nishikawatsu, Matsue, Shimane, 690-0854, Japan. akio@life.shimane-u.ac.jp.|Department of Biological Science, Faculty of Life and Environmental Science, Shimane University, Matsue, Japan. akio@life.shimane-u.ac.jp.
authors.forename: Akio
authors.initials: A
authors.lastname: Nishikawa
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000235:genetics*; D049109:Cell Proliferation / Q000235:genetics; D005121:Extremities / Q000254:growth & development; D018507:Gene Expression Regulation, Developmental; D007334:Insulin-Like Growth Factor I / Q000096:biosynthesis* / Q000235:genetics; D007814:Larva / Q000235:genetics / Q000254:growth & development; D008675:Metamorphosis, Biological; D024510:Muscle Development / Q000235:genetics*; D018482:Muscle, Skeletal / Q000254:growth & development; D014284:Triiodothyronine / Q000235:genetics / Q000494:pharmacology; D014982:Xenopus laevis / Q000235:genetics* / Q000254:growth & development
chemical_list: D014284:Triiodothyronine; D007334:Insulin-Like Growth Factor I
keywords: Insulin-like growth factor 1; Metamorphosis; Myogenic cells; Thyroid hormone; Xenopus laevis