Growth hormone binds to a single high affinity receptor site on mouse osteoblasts: modulation by retinoic acid and cell differentiation.
Growth hormone binds to a single high affinity receptor site on mouse osteoblasts: modulation by retinoic acid and cell differentiation.
复制标题
生长激素与小鼠成骨细胞上的单个高亲和力受体位点结合：通过视黄酸和细胞分化进行调节。
作者：
M. Slootweg;J. P. Salles;C. Ohlsson;C. de Vries;M. Engelbregt;J. Netelenbos
生长激素（GH）对成骨细胞具有直接的分化和增殖作用。我们研究了125 I标记的人（h）GH与来自胶原酶处理的18天胎鼠颅骨的原代小鼠成骨细胞的结合。Scatchard数据分析揭示了一类高亲和力GH受体（表观Ka = 5.74 × 10（9）M-1），每个细胞有2200个位点。亲和交联和SDS-PAGE电泳显示两条带，表观分子量为120和70 kDa。小鼠成骨细胞表达GH受体mRNA，基因转录物为4.2和1.2 kb，其水平约为小鼠肝脏的1/6和小鼠肌肉的1/3。两个群体的未分化和分化的成骨细胞，通过连续的胶原酶消化小鼠颅骨，用于研究成骨细胞表型和GH受体表达之间的关系。虽然未分化和分化细胞中受体的亲和力相同，但分化细胞中的能力显著更高（1.45 +/- 1.0% vs 2.39 +/-0.9%，P = 0.03）。这强调了成骨细胞作为GH靶细胞的特殊重要性。维生素A衍生物视黄酸的分化潜能随后被实验性地用于诱导细胞的分化。视黄酸增加125 I-hGH与前成骨细胞的结合（153%，P = 0.02）。总之，这些数据证明了小鼠成骨细胞中存在与分化相关的高亲和力GH受体。
Growth hormone (GH) exerts direct differentiative and proliferative effects on osteoblasts. We studied 125I-labeled human (h) GH binding to primary mouse osteoblasts derived from collagenase-treated 18-day fetal mouse calvaria. Scatchard analysis of the data revealed a single class of high affinity GH receptors (apparent Ka = 5.74 x 10(9) M-1) with 2200 sites per cell. Affinity crosslinking and SDS-PAGE electrophoresis showed two bands with apparent molecular masses of 120 and 70 kDa. Mouse osteoblasts express GH receptor mRNA with gene transcripts of 4.2 and 1.2 kb, at levels which reach approximately 1/6 of those in mouse liver and 1/3 of those in mouse muscle. Two populations of undifferentiated and diffentiated osteoblasts, obtained by sequential collagenase digestion of mouse calvaria, were used to study the relationship between osteoblastic phenotype and GH receptor expression. Although the affinity of the receptors in undifferentiated and differentiated cells was the same, the capacity was significantly higher (1.45 +/- 1.0% vs 2.39 +/- 0.9%, P = 0.03) in differentiated cells. This stresses the specific importance of the osteoblast as a target cell for GH. The differentiating potential of the vitamin A derivative retinoic acid was subsequently used experimentally to induce differentiation in the cells. Retinoic acid increased 125I-hGH binding to preosteoblasts (153%, P = 0.02). Together, these data demonstrate the presence of a high affinity GH receptor in mouse osteoblasts which is related to differentiation.