Department of Physiology and Biophysics, University of Washington School of Medicine, Seattle, WA 98195-7290, USA.
J Cell Sci. 2022 Mar 1;135(5). doi: 10.1242/jcs.259145. Epub 2022 Feb 3.
Phosphatidylinositol(4,5)-bisphosphate (PtdInsP2) is an important modulator of many cellular processes, and its abundance in the plasma membrane is closely regulated. We examined the hypothesis that members of the Dishevelled scaffolding protein family can bind the lipid kinases phosphatidylinositol 4-kinase (PI4K) and phosphatidylinositol 4-phosphate 5-kinase (PIP5K), facilitating synthesis of PtdInsP2 directly from phosphatidylinositol. We used several assays for PtdInsP2 to examine the cooperative function of phosphoinositide kinases and the Dishevelled protein Dvl3 in the context of two receptor signaling cascades. Simultaneous overexpression of PI4KIIIα (also known as PI4KA) and PIP5KIγ (also known as PIP5K1C) had a synergistic effect on PtdInsP2 synthesis that was recapitulated by overexpression of Dvl3. Increasing the activity of Dvl3 by overexpression increased resting plasma membrane PtdInsP2. Knockdown of Dvl3 reduced resting plasma membrane PtdInsP2 and slowed PtdInsP2 resynthesis following receptor activation. We confirm that Dvl3 promotes coupling of PI4KIIIα and PIP5KIγ and show that this interaction is essential for efficient resynthesis of PtdInsP2 following receptor activation.
磷脂酰肌醇（4,5）-二磷酸（PtdInsP2）是许多细胞过程的重要调节剂，其在质膜中的丰度受到严格调控。我们检验了一个假说，即 Dishevelled 支架蛋白家族的成员可以与脂质激酶磷脂酰肌醇 4-激酶（PI4K）和磷脂酰肌醇 4-磷酸 5-激酶（PIP5K）结合，从而直接从磷脂酰肌醇合成 PtdInsP2。我们使用几种 PtdInsP2 测定法，在两种受体信号转导途径的背景下，研究了磷酸肌醇激酶和 Dishevelled 蛋白 Dvl3 的协同功能。PI4KIIIα（也称为 PI4KA）和 PIP5KIγ（也称为 PIP5K1C）的同时过表达对 PtdInsP2 合成具有协同作用，这可以通过 Dvl3 的过表达来重现。通过过表达增加 Dvl3 的活性会增加静止状态的质膜 PtdInsP2。Dvl3 的敲低会降低静止状态的质膜 PtdInsP2，并减缓受体激活后 PtdInsP2 的重新合成。我们证实 Dvl3 促进了 PI4KIIIα 和 PIP5KIγ 的偶联，并表明这种相互作用对于受体激活后 PtdInsP2 的有效重新合成是必不可少的。
