Hori Shogo, Saitoh Osamu
Department of Animal Bio-Science, Faculty of Bio-Science, Nagahama Institute of Bio-Science and Technology, 1266 Tamura-cho, Nagahama-shi, Shiga, 526-0829, Japan.
Genome Editing Research Institute, Nagahama Institute of Bio-Science and Technology, 1266 Tamura-cho, Nagahama-shi, Shiga, 526-0829, Japan.
Biochem Biophys Res Commun. 2023 Mar 5;647:16-22. doi: 10.1016/j.bbrc.2023.01.060. Epub 2023 Jan 21.
In this study, we focused on TRPV1 of African lungfish, Protopterus annectens. During drought at high temperature, African lungfish can survive by undergoing into aestivation in mud cocoons. Therefore, lungfish is considered to have some specialized heat-sensor, TRPV1, for heat tolerance. Further, lungfish which shares similarities with fishes and amphibians, is one of important species for investigating the fish-tetrapod transition. Since fish TRPV1 and tetrapod TRPV1 have some differences, character of lungfish TRPV1 attracts attention. Here, we first cloned TRPV1 paralogue from lungfish, Protopterus annectens (lfTRPV1) and determined the chemical and thermal sensitivities of lfTRPV1 by two-electrode voltage clamp method using frog oocytes. We detected activation of lfTRPV1 by acid and 2-APB, but capsaicin-induced activation was not observed. The sensitivity to acid of lfTRPV1 was similar to that of rat TRPV1 (rTRPV1), but the 2-APB sensitivity of lfTRPV1 was relatively weaker than rTRPV1. Heat stimulation up to 44 °C did not activate lfTRPV1 and the heat-activation was not detected even on acid condition of pH6. This dramatically decreased heat-sensitivity of TRPV1 may contribute the heat tolerance of African lungfish. Moreover, this might be the property of ancient tetrapod-type TRPV1 gene.
在本研究中，我们聚焦于非洲肺鱼（Protopterus annectens）的瞬时受体电位香草酸亚型1（TRPV1）。在高温干旱期间，非洲肺鱼可以通过在泥茧中进入夏眠来存活。因此，肺鱼被认为具有某种特殊的热传感器TRPV1以实现耐热性。此外，肺鱼与鱼类和两栖动物有相似之处，是研究鱼类向四足动物过渡的重要物种之一。由于鱼类TRPV1和四足动物TRPV1存在一些差异，肺鱼TRPV1的特性备受关注。在此，我们首先从非洲肺鱼（Protopterus annectens）中克隆出TRPV1旁系同源物（lfTRPV1），并使用蛙卵母细胞通过双电极电压钳法测定了lfTRPV1的化学和热敏感性。我们检测到酸和2-氨基乙氧基二苯硼酸（2-APB）可激活lfTRPV1，但未观察到辣椒素诱导的激活。lfTRPV1对酸的敏感性与大鼠TRPV1（rTRPV1）相似，但lfTRPV1对2-APB的敏感性相对弱于rTRPV1。高达44°C的热刺激未激活lfTRPV1，即使在pH6的酸性条件下也未检测到热激活。TRPV1这种显著降低的热敏感性可能有助于非洲肺鱼的耐热性。此外，这可能是古老的四足动物型TRPV1基因的特性。
