Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Yoshida-Honmachi, Sakyoku, Kyoto, Japan.
Graduate School of Biostudies, Kyoto University, Konoe-cho, Yoshida, Sakyoku, Kyoto, Japan.
Nat Commun. 2024 Aug 31;15(1):7566. doi: 10.1038/s41467-024-51939-w.
Cells establish the asymmetrical distribution of phospholipids and alter their distribution by phospholipid scrambling (PLS) to adapt to environmental changes. Here, we demonstrate that a protein complex, consisting of the ion channel Tmem63b and the thiamine transporter Slc19a2, induces PLS upon calcium (Ca) stimulation. Through revival screening using a CRISPR sgRNA library on high PLS cells, we identify Tmem63b as a PLS-inducing factor. Ca stimulation-mediated PLS is suppressed by deletion of Tmem63b, while human disease-related Tmem63b mutants induce constitutive PLS. To search for a molecular link between Ca stimulation and PLS, we perform revival screening on Tmem63b-overexpressing cells, and identify Slc19a2 and the Ca-activated K channel Kcnn4 as PLS-regulating factors. Deletion of either of these genes decreases PLS activity. Biochemical screening indicates that Tmem63b and Slc19a2 form a heterodimer. These results demonstrate that a Tmem63b/Slc19a2 heterodimer induces PLS upon Ca stimulation, along with Kcnn4 activation.
细胞通过磷脂翻转（PLS）来建立磷脂的不对称分布，并改变其分布，以适应环境变化。在这里，我们证明了一个由离子通道 Tmem63b 和硫胺素转运蛋白 Slc19a2 组成的蛋白质复合物，在钙离子（Ca）刺激下诱导 PLS。通过在高 PLS 细胞上使用 CRISPR sgRNA 文库进行复兴筛选，我们确定 Tmem63b 是一种 PLS 诱导因子。Ca 刺激介导的 PLS 被 Tmem63b 的缺失所抑制，而人类疾病相关的 Tmem63b 突变体则诱导组成性 PLS。为了寻找 Ca 刺激和 PLS 之间的分子联系，我们在 Tmem63b 过表达细胞上进行复兴筛选，鉴定出 Slc19a2 和 Ca 激活的钾通道 Kcnn4 是调节 PLS 的因子。这些基因的缺失都会降低 PLS 活性。生化筛选表明 Tmem63b 和 Slc19a2 形成异二聚体。这些结果表明，Tmem63b/Slc19a2 异二聚体在 Ca 刺激下与 Kcnn4 激活诱导 PLS。
