Institut für Allgemeine Pharmakologie und Toxikologie, Universitätsklinikum, Goethe-Universität, Theodor-Stern-Kai 7, 60590 Frankfurt am Main, Germany.
Dipartimento di Scienze Biomediche, Sperimentali e Cliniche, Università degli Studi di Firenze, Viale Morgagni 50, 50134 Firenze, Italy.
Biochim Biophys Acta Mol Cell Biol Lipids. 2020 Jul;1865(7):158704. doi: 10.1016/j.bbalip.2020.158704. Epub 2020 Mar 31.
Sphingosine kinases (SphK) catalyse the formation of sphingosine-1-phosphate (S1P) and play important roles in the cardiovascular, nervous and immune systems. We have shown before that G-coupled receptors induce a rapid and long-lasting translocation of SphK1 to the plasma membrane and cross-activation of S1P receptors. Here, we further addressed G regulation of SphK1 by analysing the influence of the WD40 repeat protein, WDR36. WDR36 has been described as a scaffold tethering Gα to phospholipase C (PLC)-β and the thromboxane A receptor-β (TPβ receptor). Overexpression of WDR36 in HEK-293 cells enhanced TPβ receptor-induced inositol phosphate production, as reported (Cartier et al. 2011), but significantly attenuated inositol phosphate production induced by muscarinic M and bradykinin B receptors. In agreement with its effect on PLCβ, WDR36 augmented TPβ receptor-induced [Ca] increases. Surprisingly, WDR36 also augmented M receptor-induced [Ca] increases, which was due to increased Ca mobilization while the Ca content of thapsigargin-sensitive stores remained unaltered. Interestingly, overexpression of WDR36 significantly delayed SphK1 translocation by G-coupled M, B and H receptors in HEK-293 cells, while TPβ receptor-induced SphK1 translocation was generally slow and not altered by WDR36 in these cells. Finally, in C2C12 myoblasts, overexpression of WDR36 delayed SphK1 translocation induced by B receptors. It is concluded that WDR36 reduces signalling of G-coupled receptors other than TPβ towards PLC and SphK1, most likely by scavenging Gα and PLCβ. Our results support a role of WDR36 in orchestration of G signalling complexes, and might help to functionally unravel its genetic association with asthma and allergy.
鞘氨醇激酶(SphK)催化鞘氨醇-1-磷酸(S1P)的形成,在心血管、神经和免疫系统中发挥重要作用。我们之前已经表明,G 蛋白偶联受体诱导 SphK1 快速且持久地向质膜易位,并交叉激活 S1P 受体。在这里,我们通过分析 WD40 重复蛋白 WDR36 对 SphK1 的 G 调节作用,进一步研究了 G 的调节作用。WDR36 已被描述为一种支架,将 Gα 与磷脂酶 C(PLC)-β 和血栓素 A 受体-β(TPβ 受体)连接起来。在 HEK-293 细胞中过表达 WDR36 增强了 TPβ 受体诱导的肌醇磷酸产生,正如报道的那样(Cartier 等人,2011 年),但显著减弱了由毒蕈碱 M 和缓激肽 B 受体诱导的肌醇磷酸产生。与它对 PLCβ 的作用一致,WDR36 增强了 TPβ 受体诱导的[Ca]增加。令人惊讶的是,WDR36 还增强了 M 受体诱导的[Ca]增加,这是由于钙动员增加,而 thapsigargin 敏感储存库的钙含量保持不变。有趣的是,在 HEK-293 细胞中,WDR36 显著延迟了 G 偶联 M、B 和 H 受体诱导的 SphK1 易位,而在这些细胞中,TPβ 受体诱导的 SphK1 易位通常较慢,不受 WDR36 影响。最后,在 C2C12 成肌细胞中,WDR36 延迟了 B 受体诱导的 SphK1 易位。结论是,WDR36 减少了除 TPβ 以外的 G 偶联受体向 PLC 和 SphK1 的信号转导,很可能是通过清除 Gα 和 PLCβ。我们的结果支持 WDR36 在协调 G 信号复合物中的作用,并可能有助于从功能上解开其与哮喘和过敏的遗传关联。
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