Human intestinal epithelial cell survival and anoikis -: Differentiation state-distinct regulation and roles of protein kinase B/Akt isoforms
Human intestinal epithelial cell survival and anoikis -: Differentiation state-distinct regulation and roles of protein kinase B/Akt isoforms
复制标题
DOI：
10.1074/jbc.m405323200
复制
发表时间：
2004-10-15
影响因子：
4.8
通讯作者：
Vachon, PH
中科院分区：
文献类型：
--
作者：
Dufour, G;Demers, MJ;Vachon, PH
我们以前已经表明，人类肠上皮细胞的生存和失巢凋亡是根据分化状态的独特调节。我们分析了蛋白激酶B/Akt亚型在这种分化状态差异中的作用。失巢凋亡在未分化和分化的肠上皮细胞中通过抑制粘着斑激酶（Fak;显性阴性突变体的药理学抑制或过表达）或β（1）整联蛋白（抗体阻断）或通过维持细胞悬浮来诱导。分析Akt同种型（Akt-1、Akt-2和Akt-3）和Fak的表达/活化参数。Akt亚型的活性也被阻断磷脂酰肌醇3-激酶的抑制或显性阴性突变体的过度表达。在这里，我们报告如下。1)Akt-1的表达/活化水平在肠细胞分化过程中总体增加，Akt-2的表达/活化水平降低，而Akt-3不表达。2)Akt-1激活依赖于β（1）整联蛋白/Fak信号传导，与分化状态无关。3)Akt-2活化仅在未分化细胞中依赖于β（1）整联蛋白/Fak信号传导。4)Akt-1的活化是磷脂酰肌醇3-激酶依赖性的，而Akt-2的活化不是。5)Akt-2不促进存活或凋亡/失巢凋亡。6)Akt-1对生存至关重要。7)Akt-2不能替代Akt-1抑制失巢凋亡。因此，Akt亚型的表达和调节显示出分化状态特异性的区别，最终反映了它们在人类肠上皮细胞存活的介导中的选择性含义。这些数据提供了新的见解同步调节细胞的生存/死亡，需要在动态更新过程中的组织，如肠上皮细胞。
We have shown previously that human intestinal epithelial cell survival and anoikis are distinctively regulated according to the state of differentiation. Here we analyzed the roles of protein kinase B/Akt isoforms in such differentiation state distinctions. Anoikis was induced in undifferentiated and differentiated enterocytes by inhibition of focal adhesion kinase (Fak; pharmacologic inhibition or overexpression of dominant-negative mutants) or beta(1) integrins (antibody blocking) or by maintaining cells in suspension. Expression/ activation parameters of Akt isoforms (Akt-1, Akt-2, and Akt-3) and Fak were analyzed. Activity of Akt isoforms was also blocked by inhibition of phosphatidylinositol 3-kinase or by overexpression of dominant-negative mutants. Here we report the following. 1) The expression/activation levels of Akt-1 increase overall during enterocytic differentiation, and those of Akt-2 decrease, whereas Akt-3 is not expressed. 2) Akt-1 activation is dependent on beta(1) integrins/Fak signaling, regardless of the differentiation state. 3) Akt-2 activation is dependent on beta(1) integrins/Fak signaling in undifferentiated cells only. 4) Activation of Akt-1 is phosphatidylinositol 3-kinase-dependent, whereas that of Akt-2 is not. 5) Akt-2 does not promote survival or apoptosis/anoikis. 6) Akt-1 is essential for survival. 7) Akt-2 cannot substitute for Akt-1 in the suppression of anoikis. Hence, the expression and regulation of Akt isoforms show differentiation state-specific distinctions that ultimately reflect upon their selective implication in the mediation of human intestinal epithelial cell survival. These data provide new insights into the synchronized regulation of cell survival/death that is required in the dynamic renewal process of tissues such as the intestinal epithelium.