The tyrosine phosphatase CD148 interacts with the p85 regulatory subunit of phosphoinositide 3-kinase
The tyrosine phosphatase CD148 interacts with the p85 regulatory subunit of phosphoinositide 3-kinase
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DOI：
10.1042/bj20071317
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发表时间：
2008-07-01
影响因子：
4.1
通讯作者：
Takahashi, Takamune
中科院分区：
文献类型：
--
作者：
Tsuboi, Nobuo;Utsunomiya, Tadahiko;Takahashi, Takamune
CD148 是一种跨膜酪氨酸磷酸酶，参与细胞生长和转化的调节。然而，CD148 的信号传导机制尚不完全清楚。为了鉴定参与 CD148 信号传导的特定细胞内分子，我们进行了改良的酵母双杂交筛选测定。使用 CD148 (CD148 D/A) 的底物捕获突变体形式作为诱饵，我们恢复了 PI3K（磷酸肌醇 3-激酶）的 p85 调节亚基。 CD148 D/A（但不是催化活性 CD148）在体外和完整细胞中以磷酸化依赖性方式与 p85 相互作用。生长因子受体和 PI3K 活性也通过来自过钒酸盐处理的细胞裂解物的 p85 被 CD149D/A 捕获。 CD148 在体外显着且特异性地使 p85 去磷酸化。 CD148 的共表达降低了活性 Src 诱导的 p85 磷酸化，并减弱了 PI3K 活性的增加，但 CD148 并未改变基础 PI3K 活性。最后，通过 siRNA（短干扰 RNA）敲低 CD148 增加了血清刺激后的 PI3K 活性。总而言之，这些结果表明，当 p85 磷酸化时，CD148 可能与 p85 相互作用并使 p85 去磷酸化，并调节 PI3K 活性的大小。
CD148 is a transmembrane tyrosine phosphatase that has been implicated in the regulation of cell growth and transformation. However, the signalling mechanisms of CD148 are incompletely understood. To identify the specific intracellular molecules involved in CD148 signalling, we carried out a modified yeast two-hybrid screening assay. Using the substrate-trapping mutant form of CD148 (CD148 D/A) as bait, we recovered the p85 regulatory subunit of PI3K (phosphoinositide 3-kinase). CD148 D/A, but not catalytically active CD148, interacted with p85 in a phosphorylation-dependent manner in vitro and in intact cells. Growth factor receptor and PI3K activity were also trapped by CD149D/A via p85 from pervanadate-treated cell lysates. CD148 prominently and specifically dephosphorylated p85 in vitro. Co-expression of CD148 reduced p85 phosphorylation induced by active Src, and attenuated the increases in PI3K activity, yet CD148 did not alter the basal PI3K activity. Finally, CD148 knock-down by siRNA (short interfering RNA) increased PI3K activity on serum stimulation. Taken together, these results demonstrate that CD148 may interact with and dephosphorylate p85 when it is phosphorylated and modulate the magnitude of PI3K activity.