Activation of Rac1 by phosphatidylinositol 3-kinase in vivo:: role in activation of mitogen-activated protein kinase (MAPK) pathways and retinoic acid-induced neuronal differentiation of SH-SY5Y cells
Activation of Rac1 by phosphatidylinositol 3-kinase in vivo:: role in activation of mitogen-activated protein kinase (MAPK) pathways and retinoic acid-induced neuronal differentiation of SH-SY5Y cells
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DOI：
10.1111/j.1471-4159.2005.03106.x
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发表时间：
2005-05-01
影响因子：
4.7
通讯作者：
Singh, US
中科院分区：
文献类型：
--
作者：
Pan, J;Kao, YL;Singh, US
Rho GTP酶如RhoA、Rac 1和Cdc 42是调节神经元分化所需的信号转导途径的关键参与者。使用神经母细胞瘤SH-SY 5 Y细胞的体外细胞培养模型，我们先前证明了RhoA是组织转氨酶（TGase）的体内底物，并且视黄酸（RA）通过转酰胺促进RhoA的活化。虽然RhoA的激活促进SH-SY 5 Y细胞骨架重排，但它不参与诱导神经突生长。在这里，我们证明，RA促进激活的Rac 1在SH-SY 5 Y细胞中的一个transamidation独立的方式。RA诱导的Rac 1活化是由磷脂酰肌醇3-激酶（PI 3 K）介导的，可能是因为Src激酶磷酸化p85调节亚基。组成型活性PI 3 K或Rac 1-V12的过表达诱导神经突生长、促分裂原活化蛋白激酶（MAPK）的活化和神经元标记物的表达。PI 3 K抑制剂LY 294002或显性负Rac 1-N17的过表达阻断RA诱导的神经突生长、MAPK活化和神经元标记物的表达，表明PI 3 K/Rac 1信号传导的活化代表了SH-SY 5 Y细胞中调节神经元分化的潜在机制。
Rho GTPases such as RhoA, Rac1 and Cdc42 are crucial players in the regulation of signal transduction pathways required for neuronal differentiation. Using an in vitro cell culture model of neuroblastoma SH-SY5Y cells, we demonstrated previously that RhoA is an in vivo substrate of tissue transglutaminase (TGase) and retinoic acid (RA) promoted activation of RhoA by transamidation. Although activation of RhoA promoted cytoskeletal rearrangement in SH-SY5Y cells, it was not involved in induction of neurite outgrowth. Here, we demonstrate that RA promotes activation of Rac1 in SH-SY5Y cells in a transamidation-independent manner. RA-induced activation of Rac1 is mediated by phosphatidylinositol 3-kinase (PI3K), probably because of phosphorylation of the p85 regulatory subunit by Src kinases. Over-expression of constitutively active PI3K or Rac1-V12 induces neurite outgrowth, activation of mitogen activated protein kinases (MAPKs), and expression of neuronal markers. The PI3K inhibitor LY294002, or over-expression of dominant negative Rac1-N17, blocks RA-induced neurite outgrowth, activation of MAPKs, and expression of neuronal markers, suggesting that activation of PI3K/Rac1 signaling represents a potential mechanism for regulation of neuronal differentiation in SH-SY5Y cells.