Department of Biochemistry, Duke University Medical Center, Durham, United States.
Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, United States.
Elife. 2022 Jun 7;11:e78840. doi: 10.7554/eLife.78840.
TMEM16F, a Ca-activated phospholipid scramblase (CaPLSase), is critical for placental trophoblast syncytialization, HIV infection, and SARS-CoV2-mediated syncytialization, however, how TMEM16F is activated during cell fusion is unclear. Here, using trophoblasts as a model for cell fusion, we demonstrate that Ca influx through the Ca permeable transient receptor potential vanilloid channel TRPV4 is critical for TMEM16F activation and plays a role in subsequent human trophoblast fusion. GSK1016790A, a TRPV4 specific agonist, robustly activates TMEM16F in trophoblasts. We also show that TRPV4 and TMEM16F are functionally coupled within Ca microdomains in a human trophoblast cell line using patch-clamp electrophysiology. Pharmacological inhibition or gene silencing of TRPV4 hinders TMEM16F activation and subsequent trophoblast syncytialization. Our study uncovers the functional expression of TRPV4 and one of the physiological activation mechanisms of TMEM16F in human trophoblasts, thus providing us with novel strategies to regulate CaPLSase activity as a critical checkpoint of physiologically and disease-relevant cell fusion events.
TMEM16F 是一种钙激活的磷脂翻转酶（CaPLSase），对于胎盘滋养层细胞融合、HIV 感染和 SARS-CoV2 介导的融合至关重要，然而，TMEM16F 在细胞融合过程中是如何被激活的尚不清楚。在这里，我们使用滋养层细胞作为细胞融合的模型，证明通过钙通透性瞬时受体电位香草酸通道 TRPV4 的钙内流对于 TMEM16F 的激活至关重要，并在随后的人滋养层融合中发挥作用。TRPV4 的特异性激动剂 GSK1016790A 可在滋养层细胞中强烈激活 TMEM16F。我们还表明，在人滋养层细胞系中，使用膜片钳电生理学方法，TRPV4 和 TMEM16F 在 Ca 微域中具有功能偶联。TRPV4 的药理学抑制或基因沉默会阻碍 TMEM16F 的激活和随后的滋养层融合。我们的研究揭示了 TRPV4 在人滋养层细胞中的功能性表达和 TMEM16F 的一种生理激活机制，从而为我们提供了调节 CaPLSase 活性的新策略，作为生理和与疾病相关的细胞融合事件的关键检查点。
