Determinants of molecular specificity in phosphoinositide regulation
Determinants of molecular specificity in phosphoinositide regulation
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DOI：
10.1074/jbc.m801912200
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发表时间：
2008-09-19
影响因子：
4.8
通讯作者：
Gordon, Sharona E.
中科院分区：
文献类型：
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作者：
Klein, Rebecca M.;Ufret-Vincenty, Carmen A.;Gordon, Sharona E.
脂质曾经被认为只是维持细胞完整性的油性屏障，现在人们知道它在多种细胞过程中起着积极的作用。磷酸肌苷是特别感兴趣的，因为他们显著的能力影响许多信号通路。离子通道和转运体是磷酸肌苷信号传导的重要靶点，但具体的磷酸肌苷的识别一直难以捉摸。TRPV1就是一个很好的例子；虽然磷脂酰肌醇(4,5)-二磷酸（PI(4,5)P-2）可以有效调节其激活，但我们发现磷脂酰肌醇(4)-磷酸（PI(4)P）和磷脂酰肌醇(3,4,5)-三磷酸（PI(3,4,5)P-3）也可以。为了确定调节TRPV1的内源性磷酸肌肽的身份，我们将重组pleckstrin同源结构域应用于从内到外切除的斑块。虽然PI(4,5) p -2特异性pleckstrin同源结构域抑制TRPV1，但PI(3,4,5) p -3特异性pleckstrin同源结构域没有作用。同时共聚焦成像和表达雷帕霉素诱导的脂质磷酸酶的全细胞电生理记录也表明，PI(4,5)P-2的耗尽抑制辣椒素激活的TRPV1电流；磷酸酶产生的PI(4)P不足以支持TRPV1的功能。我们得出结论，PI(4,5)P-2是调节TRPV1通道的内源性磷酸肌肽，而不是其他磷酸肌肽或其他脂质。
Once thought of as simply an oily barrier that maintains cellular integrity, lipids are now known to play an active role in a large variety of cellular processes. Phosphoinositides are of particular interest because of their remarkable ability to affect many signaling pathways. Ion channels and transporters are an important target of phosphoinositide signaling, but identification of the specific phosphoinositides involved has proven elusive. TRPV1 is a good example; although phosphatidylinositol (4,5)-bisphosphate (PI(4,5)P-2) can potently regulate its activation, we show that phosphatidylinositol (4)-phosphate (PI(4)P) and phosphatidylinositol (3,4,5)-trisphosphate (PI(3,4,5)P-3) can as well. To determine the identity of the endogenous phosphoinositide regulating TRPV1, we applied recombinant pleckstrin homology domains to inside-out excised patches. Although a PI(4,5)P-2-specific pleckstrin homology domain inhibited TRPV1, a PI(3,4,5)P-3-specific pleckstrin homology domain had no effect. Simultaneous confocal imaging and electrophysiological recording of whole cells expressing a rapamycin-inducible lipid phosphatase also demonstrates that depletion of PI(4,5)P-2 inhibits capsaicin-activated TRPV1 current; the PI(4)P generated by the phosphatases was not sufficient to support TRPV1 function. We conclude that PI(4,5)P-2, and not other phosphoinositides or other lipids, is the endogenous phosphoinositide regulating TRPV1 channels.