Swammerdam Institute for Life Sciences, Section of Molecular Cytology, van Leeuwenhoek Centre for Advanced Microscopy, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands.
Cell Signal. 2013 Jan;25(1):255-63. doi: 10.1016/j.cellsig.2012.09.022. Epub 2012 Sep 21.
Phospholipase C (PLC) β isoforms are implicated in various physiological processes and pathologies. However, mechanistic insight into the localization and activation of each of the isoforms is limited. Therefore, it is crucial to gain more in-depth knowledge as to the regulation of the different isoforms. Here we describe the subcellular location of full-length PLCβ isozymes and their C-terminal (CT) domains. Strikingly, we found isoforms PLCβ1 and PLCβ4 to be enriched at the plasma membrane, contrary to isoforms PLCβ2 and PLCβ3. We determined that the CT domain is an inhibitor of Gq-mediated increases in intracellular calcium, the potency of its effect being dependent upon the CT domain isoform used. Furthermore, ratiometric fluorescence resonance energy transfer (FRET) imaging was used to study the kinetics of the Gαq-CTβx interactions. By the use of recently developed tools, which enable the on-demand activation of Gαq, we could show that the interaction between constitutively active Gαq and PLCβ3 prolongs the residence time of PLCβ3 at the plasma membrane. These findings suggest that under physiological circumstances, PLCβ3 and Gαq interact in a kiss-and-run fashion, likely due to the GTPase-activating activity of PLCβ towards Gαq.
磷脂酶 C(PLC)β异构体参与各种生理过程和病理。然而,每种异构体的定位和激活的机制理解有限。因此,深入了解不同异构体的调节至关重要。在这里,我们描述了全长 PLCβ同工型及其 C 端(CT)结构域的亚细胞定位。引人注目的是,我们发现 PLCβ1 和 PLCβ4 同工型在质膜中富集,与 PLCβ2 和 PLCβ3 同工型相反。我们确定 CT 结构域是 Gq 介导的细胞内钙增加的抑制剂,其作用的效力取决于使用的 CT 结构域同工型。此外,比率荧光共振能量转移(FRET)成像用于研究 Gαq-CTβx 相互作用的动力学。通过使用最近开发的工具,这些工具能够按需激活 Gαq,我们可以表明,组成性激活的 Gαq 与 PLCβ3 之间的相互作用延长了 PLCβ3 在质膜上的停留时间。这些发现表明,在生理条件下,PLCβ3 和 Gαq 以亲吻和跑的方式相互作用,可能是由于 PLCβ 对 Gαq 的 GTPase 激活活性。