Department of Anesthesiology and Intensive Care Medicine, Hannover Medical School, 30625 Hannover, Germany.
Department of Anesthesiology and Intensive Care Medicine, Hannover Medical School, 30625 Hannover, Germany.
Cell Calcium. 2021 Jun;96:102391. doi: 10.1016/j.ceca.2021.102391. Epub 2021 Mar 17.
Redox-sensitivity is a common property of several transient receptor potential (TRP) ion channels. Oxidants and UVA-light activate TRPV2 by oxidizing methionine pore residues which are conserved in the capsaicin-receptor TRPV1. However, the redox-sensitivity of TRPV1 is regarded to depend on intracellular cysteine residues. In this study we examined if TRPV1 is gated by UVA-light, and if the conserved methionine residues are relevant for redox-sensitivity of TRPV1. Patch clamp recordings were performed to explore wildtype (WT) and mutants of human TRPV1 (hTRPV1). UVA-light induced hTRPV1-mediated membrane currents and potentiated both proton- and heat-evoked currents. The reducing agent dithiothreitol (DTT) prevented and partially reversed UVA-light induced sensitization of hTRPV1. UVA-light induced sensitization was reduced in the mutant hTRPV1-C158A/C387S/C767S (hTRPV1-3C). The remaining sensitivity to UVA-light of hTRRPV1-3C was not further reduced upon exchange of the methionine residues M568 and M645. While UVA-induced sensitization was reduced in the protein kinase C-insensitive mutant hTRPV1-S502A/S801A, the PKC-inhibitors chelerythrine chloride, staurosporine and Gö6976 did not reduce UVA-induced effects on hTRPV1-WT. While hTRPV1-3C was insensitive to the cysteine-selective oxidant diamide, it displayed a residual sensitivity to HO and chloramine-T. However, the exchange of M568 and M645 in hTRPV1-3C did not further reduce these effects. Our data demonstrate that oxidants and UVA-light gate hTRPV1 by cysteine-dependent as well as cysteine-independent mechanisms. In contrast to TRPV2, the methionine residues 568 and 645 seem to be of limited relevance for redox-sensitivity of hTRPV1. Finally, UVA-light induced gating of hTRPV1 does not seem to require activation of protein kinase C.
氧化还原敏感性是几种瞬时受体电位 (TRP) 离子通道的共同特性。氧化剂和 UVA 光通过氧化半胱氨酸残基来激活 TRPV2，这些半胱氨酸残基在辣椒素受体 TRPV1 中保守。然而，TRPV1 的氧化还原敏感性被认为取决于细胞内的半胱氨酸残基。在这项研究中，我们检查了 TRPV1 是否被 UVA 光门控，以及保守的蛋氨酸残基是否与 TRPV1 的氧化还原敏感性有关。通过膜片钳记录来研究野生型 (WT) 和人 TRPV1 (hTRPV1) 突变体。UVA 光诱导 hTRPV1 介导的膜电流，并增强质子和热诱发的电流。还原剂二硫苏糖醇 (DTT) 可预防和部分逆转 UVA 光诱导的 hTRPV1 敏化。在突变体 hTRPV1-C158A/C387S/C767S (hTRPV1-3C) 中，UVA 光诱导的敏化作用降低。交换蛋氨酸残基 M568 和 M645 后，hTRPV1-3C 对 UVA 光的剩余敏感性没有进一步降低。虽然 UVA 诱导的敏化作用在蛋白激酶 C 不敏感的突变体 hTRPV1-S502A/S801A 中降低，但蛋白激酶 C 抑制剂 Chelerythrine Chloride、Staurosporine 和 Gö6976 并不能降低 UVA 对 hTRPV1-WT 的作用。虽然 hTRPV1-3C 对半胱氨酸选择性氧化剂二酰胺不敏感，但它对 HO 和氯胺-T 仍有残留敏感性。然而，在 hTRPV1-3C 中交换 M568 和 M645 并没有进一步降低这些作用。我们的数据表明，氧化剂和 UVA 光通过半胱氨酸依赖和非半胱氨酸依赖的机制门控 hTRPV1。与 TRPV2 不同，蛋氨酸残基 568 和 645 似乎对 hTRPV1 的氧化还原敏感性的相关性有限。最后，UVA 光诱导的 hTRPV1 门控似乎不需要蛋白激酶 C 的激活。
