Habib T, Hejna J A, Moses R E, Decker S J
Department of Cell Biology, Parke-Davis Pharmaceutical Research Division, Ann Arbor, Michigan 48105, USA.
J Biol Chem. 1998 Jul 17;273(29):18605-9. doi: 10.1074/jbc.273.29.18605.
Antibodies raised against the 51C/SHIP2 inositol polyphosphate 5'-phosphatase were used to examine the effects of growth factors and insulin on the metabolism of this protein. Immunoblot analysis revealed that the 51C/SHIP2 protein was widely expressed in fibroblast and nonhematopoietic tumor cell lines, unlike the SHIP protein, which was found only in cell lines of hematopoietic origin. The 51C/SHIP2 antiserum precipitated a protein of approximately 145 kDa along with an activity which hydrolyzed phosphatidylinositol 3,4, 5-trisphosphate to phosphatidylinositol 3,4-bisphosphate. Tyrosine phosphorylation of the 51C/SHIP2 protein occurred in response to treatment of cells with epidermal growth (EGF), platelet-derived growth factor (PDGF), nerve growth factor (NGF), insulin-like growth factor-1 (IGF-1), or insulin. EGF and PDGF induced transient tyrosine phosphorylation of 51C/SHIP2, with maximal tyrosine phosphorylation occurring at 5-10 min following treatment and returning to near basal levels within 20 min. In contrast, treatment of cells with NGF, IGF-1, or insulin resulted in prolonged tyrosine phosphorylation of 51C/SHIP2 protein, with 40-80% maximal phosphorylation sustained for up to 2 h following agonist treatment. The kinetics of activation of the Akt/PKB protein kinase by the various factors correlated well with the kinetics of tyrosine phosphorylation of 51C/SHIP2. EGF, NGF, and PDGF stimulated the association of 51C/SHIP2 protein with the Shc adapter protein; however, no Shc could be detected in 51C/SHIP2-immune precipitates from cells treated with IGF-1 or insulin. The data suggest that 51C/SHIP2 may play a significant role in regulation of phosphatidylinositol 3'-kinase signaling by growth factors and insulin.
用针对51C/SHIP2肌醇多磷酸5'-磷酸酶产生的抗体来检测生长因子和胰岛素对该蛋白代谢的影响。免疫印迹分析显示，51C/SHIP2蛋白在成纤维细胞和非造血肿瘤细胞系中广泛表达，这与SHIP蛋白不同，SHIP蛋白仅在造血起源的细胞系中发现。51C/SHIP2抗血清沉淀出一种约145 kDa的蛋白以及一种将磷脂酰肌醇3,4,5-三磷酸水解为磷脂酰肌醇3,4-二磷酸的活性。51C/SHIP2蛋白的酪氨酸磷酸化发生在用表皮生长因子（EGF）、血小板衍生生长因子（PDGF）、神经生长因子（NGF）、胰岛素样生长因子-1（IGF-1）或胰岛素处理细胞后。EGF和PDGF诱导51C/SHIP2的瞬时酪氨酸磷酸化，在处理后5 - 10分钟出现最大酪氨酸磷酸化，并在20分钟内恢复到接近基础水平。相比之下，用NGF、IGF-1或胰岛素处理细胞导致51C/SHIP2蛋白的酪氨酸磷酸化延长，激动剂处理后40 - 80%的最大磷酸化可持续长达2小时。各种因子激活Akt/PKB蛋白激酶的动力学与51C/SHIP2酪氨酸磷酸化的动力学密切相关。EGF、NGF和PDGF刺激51C/SHIP2蛋白与Shc衔接蛋白的结合；然而，在用IGF-1或胰岛素处理的细胞的51C/SHIP2免疫沉淀物中未检测到Shc。数据表明，51C/SHIP2可能在生长因子和胰岛素对磷脂酰肌醇3'-激酶信号传导的调节中起重要作用。
