Ganglion-specific splicing of TRPV1 underlies infrared sensation in vampire bats

摘要

本期封面所示为一只正在飞的普通吸血蝙蝠rn([3esmodus rotundus)，是在墨西哥拍摄的。rn这些吸血蝙蝠形成了一种能够检测红外辐射、rn作为定位热血猎物身上热点位置的手段的本rn领。只有另外三类脊椎动物具有这种“第六rn感”，它们是三类有远亲关系的蛇一一蝮蛇rn(pit vipers)、蟒蛇(pythons)和王蛇(Ipeas)。rn对所有这些蛇来说，红外传感器都是一个被称rn为“颊窝器”的高度专门化的面部结构。在蛇rn类中， 个非热敏性的离子通道(脊椎动物的rnTRPA1)已成为 种红外探测器。正如本期rnNature上所报告的那样，吸血蝙蝠采用个稍rn有不同的分子机制，按照该机制，RNA剪接产rn生普遍存在的TRPV1热敏通道的一个变种，它rn能适应较低的温度。将这通道的基因序列与rn其他动物的对应序列所做的对比，为以下基于rn分子数据的假设提供了支持这些蝙蝠在演化rn上是与马、狗、母牛、鼹鼠和海豚(属于“劳rn亚兽总目”)属于类的，而不是像当初按照rn解剖标准所提出的那样与人类、猴子和啮齿类rn(属于“灵长总目”)属于一类。封面图片%Vampire bats (Desmodus rotundus) are obligate blood feeders that have evolved specialized systems to suit their sanguinary lifestyle~(1-3). Chief among such adaptations is the ability to detect infrared radiation as a means of locating hotspots on warm-blooded prey. Among vertebrates, only vampire bats, boas, pythons and pit vipers are capable of detecting infrared radiation~(1-4). In each case, infrared signals are detected by trigeminal nerve fibres that innervate specialized pit organs on the animal's face~(5-10). Thus, vampire bats and snakes have taken thermosensation to the extreme by developing specialized systems for detecting infrared radiation. As such, these creatures provide a window into the molecular and genetic mechanisms underlying evolutionary tuning of thermoreceptors in a species-specific or cell-type-specific manner. Previously, we have shown that snakes co-opt a non-heat-sensitive channel, vertebrate TRPA1 (transient receptor potential cation channel A1), to produce an infrared detector6. Here we show that vampire bats tune a channel that is already heat-sensitive, TRPV1, by lowering its thermal activation threshold to about 30 °C. This is achieved through alternative splicing of TRP VI transcripts to produce a channel with a truncated carboxy-terminal cytoplasmic domain. These splicing events occur exclusively in trigeminal ganglia, and not in dorsal root ganglia, thereby maintaining a role for TRPV1 as a detector of noxious heat in somatic afferents. This reflects a unique organization of the bat Trpvl gene that we show to be characteristic of Laurasiatheria mammals (cows, dogs and moles), supporting a close phylogenetic relationship with bats. These findings reveal a novel molecular mechanism for physiological tuning of thermosensory nerve fibres.