Investigation on Molecular Link Between the Phosphatidylinositol 3-Kinase Signaling Pathway and the Cell Cycle Machinery

磷脂酰肌醇 3-激酶信号通路与细胞周期机制之间的分子联系研究

• 批准号: 11670035
• 负责人: TAKUWA Noriko
• 金额: $ 2.5万
• 依托单位: Kanazawa University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1999
• 资助国家: 日本
• 起止时间: 1999 至 2000
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11670035/
• 关键词: Phosphtidylinositol 3-kinase; cyclin D; cell cycle; p70^<s6k>; mTOR; NIH3T3 fibroblasts; 優性不活型変異体; 構成活性型変異体; NIH3T3細胞

Phosphatidylinositol (PI) 3-kinase is required for G1 to S phase cell cycle progression stimulated by a variety of growth factors, and is implicated as a regulator for activation of several downstream targets, including p70^<S6K>. However, molecular mechanisms by which PI 3-kinase is engaged in the activation of the cell cycle machinery is not fully understood. Here we report that a transient expression of wild type p110α catalytic subunit of PI 3-kinase was capable of inducing cyclin D1 protein in quiescent NIH3T3 (M17) fibroblasts. This effect of p110 was strongly attenuated by either the PI 3-kinase inhibitor LY294002 or rapamycin, but not by an induced expression of a dominant negative (DN-) Ras, Ras(Asn17). The expression of wild type p110 also greatly potentiated epidermal growth factor (EGF)-stimulated cyclin D1 protein expression. Conversely, the expression of a DN-form of either p110 or p85 regulatory subunit of PI 3-kinase strongly inhibited EGF-induced up-regulation of cyclin D1 protein. LY294002 and another PI 3-kinase inhibitor wortmannin completely abrogated EGF-stimulated increases in both mRNA and protein levels of cyclin D1, pRb phosphorylation and S phase entry. However, rapamycin had little inhibitory effect, if any, on either of these events despite potent p70^<S6K> inhibition throughout the G1 phase. These results indicate that PI 3-kinase is both necessary and sufficient for up-regulation of cyclin D1, with the downstream mTOR -p70^<S6K> signaling pathway differentially required depending on cellular conditions.

磷脂酰肌醇（PI）3-激酶是由多种生长因子刺激的G1至S期细胞周期进程所必需的，并且涉及作为激活若干下游靶点（包括p70 β）的调节剂<S6K>。然而，PI 3-激酶参与细胞周期机制激活的分子机制尚未完全了解。在这里，我们报告了PI 3-激酶野生型p110α催化亚基的瞬时表达能够诱导静止期NIH 3 T3（M17）成纤维细胞中的细胞周期蛋白D1蛋白。PI 3-激酶抑制剂LY 294002或雷帕霉素强烈减弱了p110的这种作用，但不诱导显性阴性（DN-）Ras，Ras（Asn 17）的表达。野生型p110的表达也大大增强了表皮生长因子（EGF）刺激的细胞周期蛋白D1蛋白的表达。相反，PI 3-激酶的p110或p85调节亚基的DN形式的表达强烈抑制EGF诱导的细胞周期蛋白D1蛋白的上调。LY 294002和另一种PI 3激酶抑制剂wortmannin完全消除EGF刺激的细胞周期蛋白D1的mRNA和蛋白水平的增加，pRb磷酸化和S期进入。然而，雷帕霉素对这些事件中的任何一个都几乎没有抑制作用（如果有的话），尽管在整个G1期都有有效的p70 β<S6K>抑制。这些结果表明，PI 3-激酶对于细胞周期蛋白D1的上调是必要的和足够的，下游mTOR-p70-<S6K>β信号传导途径取决于细胞条件而不同地需要。

项目成果

Noriko TAKUWA et al.: "Cyclin D1 expression mediated by phosphatidylinositol 3-kinase through mTOR-p70 sik-independent signaling in growth factor-stimulated NIH3T3 fibroblasts"Molecular and Cellular Biology. Vol.19,No.2. 1346-1358 (1999)

Noriko TAKUWA 等人：“在生长因子刺激的 NIH3T3 成纤维细胞中，磷脂酰肌醇 3 激酶通过 mTOR-p70 sik 独立信号传导介导细胞周期蛋白 D1 表达”分子和细胞生物学。

H.Mitsui, et al.: "The MEKI-ERK-MAP Kinase pathway and the PI 3-kinase-Akt pathway independently mediate anti-apoptotic Signals in HepG2 Qiver cancer cells."Int.J.Cancer. (in press). (2001)

H.Mitsui 等人：“MEKI-ERK-MAP 激酶途径和 PI 3-激酶-Akt 途径独立介导 HepG2 Qiver 癌细胞中的抗凋亡信号。”Int.J.Cancer。

Y.Takuwa, H.Okamoto, N.Takuwa, K.Gonda, N.Sugimoto and S.Sakurada.: "Subtype-Specific, Differential Activities of the EDG Family Receptors for Sphingosine-1-Phosphate, a Novel Lysophospholipid Mediateor."Mol.Cell.Endocrinol.. (in press). (2001)

Y.Takuwa、H.Okamoto、N.Takuwa、K.Gonda、N.Sugimoto 和 S.Sakurada.：“EDG 家族受体对 1-磷酸鞘氨醇（一种新型溶血磷脂介质）的亚型特异性、差异活性。”