ATP and its ionotropic P2X receptors are components of one of the most ancient signaling systems. However, little is known about the distribution and function of purinergic transmission in invertebrates. Here, we cloned, expressed, and pharmacologically characterized P2X receptors in the sea slug Aplysia californica, a prominent model in cellular and system neuroscience. We showed that ATP and P2X receptors are essential signaling components within the unique bioenergetic center located in the CNS of Aplysia, also known as the cerebral F-cluster of insulin-containing neurons. Functional P2X receptors were successfully expressed in Xenopus oocytes to characterize their ATP-dependence (EC50 = 306uM), two-phased kinetics, ion selectivity (Na+-dependence), sensitivity to the ATP analog Bz-ATP (~20% compare to ATP) and antagonists (with PPADS as a more potent inhibitor compared to suramin). Next, using RNA-seq, we characterized the expression of P2X receptors across more than a dozen Aplysia peripheral tissues and developmental stages. We showed that P2X receptors are predominantly expressed in chemosensory structures and during early cleavage stages. The localization and pharmacology of P2X receptors in Aplysia highlight the evolutionary conservation of bioenergetic sensors and chemosensory purinergic transmission across animals. This study also provides a foundation to decipher homeostatic mechanisms in development and neuroendocrine systems.

中文翻译：

---

加州海螺中的P2X受体：化学传感系统，生物能和发育

ATP及其离子性P2X受体是最古老的信号系统之一的组成部分。然而，关于无脊椎动物的嘌呤能传递的分布和功能了解甚少。在这里，我们在海Aplysia californica（细胞和系统神经科学中的杰出模型）中克隆，表达和药理学表征了P2X受体。我们表明，ATP和P2X受体是位于Aplysia中枢神经系统（也称为含胰岛素的神经元的大脑F簇）中独特的生物能中心内必不可少的信号传导成分。功能性P2X受体已在非洲爪蟾卵母细胞中成功表达，以表征其ATP依赖性（EC50 = 306uM），两阶段动力学，离子选择性（Na +依赖性），对ATP类似物Bz-ATP（约比ATP约20％）和拮抗剂（与苏拉明相比，PPADS作为更有效的抑制剂）具有敏感性。接下来，我们使用RNA-seq来表征P2X受体在十几个海葵外围组织和发育阶段中的表达。我们表明，P2X受体主要在化学感觉结构和早期卵裂阶段表达。P2X受体在海兔中的定位和药理作用突出了生物能传感器的进化保守性以及跨动物的化学感觉性嘌呤能传递。这项研究还为破译发育和神经内分泌系统中的稳态机制提供了基础。我们特征化了P2X受体在十几个Aplysia周围组织和发育阶段中的表达。我们表明，P2X受体主要在化学感觉结构和早期卵裂阶段表达。P2X受体在海兔中的定位和药理作用突出了生物能传感器的进化保守性以及跨动物的化学感觉性嘌呤能传递。这项研究也为破译发育和神经内分泌系统中的稳态机制提供了基础。我们特征化了P2X受体在十几个Aplysia周围组织和发育阶段中的表达。我们表明，P2X受体主要在化学感觉结构和早期卵裂阶段表达。P2X受体在海兔中的定位和药理作用突出了生物能传感器的进化保守性以及跨动物的化学感觉性嘌呤能传递。这项研究也为破译发育和神经内分泌系统中的稳态机制提供了基础。P2X受体在海兔中的定位和药理作用突出了生物能传感器的进化保守性以及跨动物的化学感觉性嘌呤能传递。这项研究也为破译发育和神经内分泌系统中的稳态机制提供了基础。P2X受体在海兔中的定位和药理作用突出了生物能传感器的进化保守性以及跨动物的化学感觉性嘌呤能传递。这项研究也为破译发育和神经内分泌系统中的稳态机制提供了基础。