Volen Center for Complex Systems, Department of Biology, Brandeis University, Waltham, MA 02454, USA.
Volen Center for Complex Systems, Department of Biology, Brandeis University, Waltham, MA 02454, USA; School of Neuroscience, Virginia Tech, Blacksburg, VA 24061, USA.
Neuron. 2019 Feb 20;101(4):738-747.e3. doi: 10.1016/j.neuron.2018.12.022. Epub 2019 Jan 14.
Thermosensation is critical for avoiding thermal extremes and regulating body temperature. While thermosensors activated by noxious temperatures respond to hot or cold, many innocuous thermosensors exhibit robust baseline activity and lack discrete temperature thresholds, suggesting they are not simply warm and cool detectors. Here, we investigate how the aristal Cold Cells encode innocuous temperatures in Drosophila. We find they are not cold sensors but cooling-activated and warming-inhibited phasic thermosensors that operate similarly at warm and cool temperatures; we propose renaming them "Cooling Cells." Unexpectedly, Cooling Cell thermosensing does not require the previously reported Brivido Transient Receptor Potential (TRP) channels. Instead, three Ionotropic Receptors (IRs), IR21a, IR25a, and IR93a, specify both the unique structure of Cooling Cell cilia endings and their thermosensitivity. Behaviorally, Cooling Cells promote both warm and cool avoidance. These findings reveal a morphogenetic role for IRs and demonstrate the central role of phasic thermosensing in innocuous thermosensation. VIDEO ABSTRACT.
热感觉对于避免极端温度和调节体温至关重要。虽然由有害温度激活的热感受器对热或冷有反应，但许多无害的热感受器表现出强大的基线活性，缺乏离散的温度阈值，这表明它们不仅仅是温暖和凉爽的探测器。在这里，我们研究了果蝇中的aristal Cold Cells 如何编码无害温度。我们发现它们不是冷感受器，而是冷却激活和加热抑制的相变式热感受器，在温暖和凉爽的温度下工作方式相似；我们建议将它们重新命名为“冷却细胞”。出乎意料的是，冷却细胞的热感觉不需要先前报道的 Brivido 瞬时受体电位 (TRP) 通道。相反，三个离子型受体 (IRs)，IR21a、IR25a 和 IR93a，分别指定了冷却细胞纤毛末端的独特结构及其热敏性。在行为上，冷却细胞促进了温暖和凉爽的回避。这些发现揭示了 IRs 的形态发生作用，并证明了相变式热感觉在无害热感觉中的核心作用。视频摘要。
