Bellows C G, Jia D, Jia Y, Hassanloo A, Heersche J N M
Faculty of Dentistry, University of Toronto, 124 Edward Street, Toronto, Ontario M5G 1G6, Canada.
Calcif Tissue Int. 2006 Jul;79(1):57-65. doi: 10.1007/s00223-005-0234-1. Epub 2006 Jul 31.
We investigated the effects of insulin (1-1,000 nM), insulin-like growth factor (IGF)-I, and IGF-II (3-100 nM each) alone or together with 10 nM dexamethasone (DEX) or 10 nM 1,25-dihydroxyvitamin D(3) (1,25OHD(3)) on proliferation and differentiation of adipocyte and osteoblast progenitors in bone cell populations derived from fetal rat calvaria. The effects on differentiation were evaluated by counting the number of bone or osteoid nodules and adipocyte colonies and the effects on proliferation, by measuring their size by image analysis. The types of cells studied were 1,25(OH)(2)D(3)- and DEX-responsive adipocyte progenitors and DEX-dependent and independent osteoprogenitors. Both IGF-I and IGF-II stimulated osteoprogenitor differentiation both alone and in the presence of DEX, while insulin stimulated osteoprogenitor differentiation only in the absence of DEX. Neither IGF-I/-II nor insulin affected proliferation of osteoprogenitors. Insulin had little effect on adipocyte differentiation by itself but strongly stimulated differentiation in the presence of either 1,25(OH)(2)D(3) or DEX, while IGF-II stimulated adipocyte differentiation in both the absence and presence of 1,25(OH)(2)D(3) or DEX. IGF-I by itself or in the presence of DEX strongly stimulated adipocyte cell differentiation but had little effect in the presence of 1,25(OH)(2)D(3). Our results demonstrate that insulin, IGF-II, and IGF-I have specific and different effects on the differentiation and proliferation of different groups of progenitor cells.
我们研究了胰岛素（1 - 1000 nM）、胰岛素样生长因子（IGF）-I和IGF-II（各3 - 100 nM）单独作用，或与10 nM地塞米松（DEX）或10 nM 1,25 - 二羟基维生素D(3)（1,25OHD(3)）共同作用，对源自胎鼠颅骨的骨细胞群体中脂肪细胞和成骨细胞祖细胞增殖与分化的影响。通过计数骨或类骨质结节以及脂肪细胞集落的数量来评估对分化的影响，通过图像分析测量其大小来评估对增殖的影响。所研究的细胞类型为对1,25(OH)(2)D(3)和DEX有反应的脂肪细胞祖细胞以及依赖和不依赖DEX的骨祖细胞。IGF-I和IGF-II单独作用以及在DEX存在时均刺激骨祖细胞分化，而胰岛素仅在无DEX时刺激骨祖细胞分化。IGF-I/-II和胰岛素均不影响骨祖细胞的增殖。胰岛素自身对脂肪细胞分化影响不大，但在1,25(OH)(2)D(3)或DEX存在时强烈刺激分化，而IGF-II在1,25(OH)(2)D(3)或DEX存在与不存在时均刺激脂肪细胞分化。IGF-I单独作用或在DEX存在时强烈刺激脂肪细胞分化，但在1,25(OH)(2)D(3)存在时影响不大。我们的结果表明，胰岛素、IGF-II和IGF-I对不同组祖细胞的分化和增殖具有特定且不同的影响。
