Nishiyama Kazuhiro, Nishimura Akiyuki, Shimoda Kakeru, Tanaka Tomohiro, Kato Yuri, Shibata Takahiro, Tanaka Hiroshi, Kurose Hitoshi, Azuma Yasu-Taka, Ihara Hideshi, Kumagai Yoshito, Akaike Takaaki, Eaton Philip, Uchida Koji, Nishida Motohiro
Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka 812-8582, Japan.
National Institute for Physiological Sciences (NIPS), National Institutes of Natural Sciences (NINS), Okazaki 444-8787, Japan.
Sci Signal. 2022 Jan 11;15(716):eabj0644. doi: 10.1126/scisignal.abj0644.
After ligand stimulation, many G protein–coupled receptors (GPCRs) undergo β-arrestin–dependent desensitization, during which they are internalized and either degraded or recycled to the plasma membrane. Some GPCRs are not subject to this type of desensitization because they lack the residues required to interact with β-arrestins. We identified a mechanism of redox-dependent alternative internalization (REDAI) that promotes the internalization and degradation of the purinergic P2Y receptor (P2YR). Synthetic and natural compounds containing electrophilic isothiocyanate groups covalently modified P2YR at Cys, which promoted the ubiquitylation of Lys and receptor internalization and degradation in various mouse and human cultured cell lines. Endogenous electrophiles also promoted ligand-dependent P2YR internalization and degradation. P2YR is highly abundant in inflammatory cells and promotes the pathogenesis of colitis. Deficiency in P2YR protected mice against experimentally induced colitis, and mice expressing a form of P2YR in which Cys was mutated to nonmodifiable serine were more sensitive to the induction of colitis. Several other GPCRs, including AAR, contain cysteine and lysine residues at the appropriate positions to mediate REDAI, and isothiocyanate stimulated the internalization of AAR and of a form of P2YR with insertions of the appropriate residues. Thus, endogenous and exogenous electrophiles may limit colitis progression through cysteine modification of P2YR and may also mediate internalization of other GPCRs.
配体刺激后，许多G蛋白偶联受体（GPCR）会经历β-抑制蛋白依赖性脱敏，在此过程中它们会被内化，然后降解或再循环至质膜。一些GPCR不会发生这种类型的脱敏，因为它们缺乏与β-抑制蛋白相互作用所需的残基。我们发现了一种氧化还原依赖性替代内化（REDAI）机制，该机制促进嘌呤能P2Y受体（P2YR）的内化和降解。含有亲电异硫氰酸酯基团的合成和天然化合物在半胱氨酸处共价修饰P2YR，这促进了赖氨酸的泛素化以及受体在各种小鼠和人类培养细胞系中的内化和降解。内源性亲电试剂也促进了配体依赖性P2YR的内化和降解。P2YR在炎症细胞中高度丰富，并促进结肠炎的发病机制。P2YR缺陷可保护小鼠免受实验性诱导的结肠炎影响，而表达半胱氨酸突变为不可修饰丝氨酸形式的P2YR的小鼠对结肠炎的诱导更敏感。其他几种GPCR，包括AAR，在适当位置含有半胱氨酸和赖氨酸残基以介导REDAI，异硫氰酸酯刺激了AAR和具有适当残基插入的P2YR形式的内化。因此，内源性和外源性亲电试剂可能通过对P2YR的半胱氨酸修饰来限制结肠炎的进展，并且还可能介导其他GPCR的内化。
