ATP signaling in the integrative neural center of Aplysia californica

János Györi,Daria Y Romanova,Leonid L Moroz,Andrea B Kohn

doi:10.1038/s41598-021-84981-5

Abstract

ATP and its ionotropic P2X receptors are components of the most ancient signaling system. However, little is known about the distribution and function of purinergic transmission in invertebrates. Here, we cloned, expressed, and pharmacologically characterized the P2X receptors in the sea slug Aplysia californica—a prominent neuroscience model. AcP2X receptors were successfully expressed in Xenopus oocytes and displayed activation by ATP with two-phased kinetics and Na+-dependence. Pharmacologically, they were different from other P2X receptors. The ATP analog, Bz-ATP, was a less effective agonist than ATP, and PPADS was a more potent inhibitor of the AcP2X receptors than the suramin. AcP2X were uniquely expressed within the cerebral F-cluster, the multifunctional integrative neurosecretory center. AcP2X receptors were also detected in the chemosensory structures and the early cleavage stages. Therefore, in molluscs, rapid ATP-dependent signaling can be implicated both in development and diverse homeostatic functions. Furthermore, this study illuminates novel cellular and systemic features of P2X-type ligand-gated ion channels for deciphering the evolution of neurotransmitters.

Highlights

ATP and its ionotropic P2X receptors are components of the most ancient signaling system
In 1983, rapid ATP-gated ion currents were discovered in neurons[9,10] and m uscles[11], and specific subtypes of the ligand-gated P2X receptors were identified in the 1990s12–15
We identified and cloned a single Aplysia P2X receptor with two splice forms (GenBank#: NP_001191558.1, NP_001191559.1), which shared 92% identity

Summary

Introduction

ATP and its ionotropic P2X receptors are components of the most ancient signaling system. AcP2X receptors were successfully expressed in Xenopus oocytes and displayed activation by ATP with two-phased kinetics and Na+-dependence. They were different from other P2X receptors. In molluscs, rapid ATP-dependent signaling can be implicated both in development and diverse homeostatic functions. In 1983, rapid ATP-gated ion currents were discovered in neurons[9,10] and m uscles[11], and specific subtypes of the ligand-gated P2X receptors were identified in the 1990s12–15. The 3D structure of P2X receptors was revealed in 2009–201216,17 These are distinctive trimeric ligand-gated channels showing a common architecture with acid-sensing ion channels but unrelated in their respective amino acid s equences[18]. P2X receptors were identified in this species with widespread expression across the C NS27 but unknown function(s)

Methods

Results

Conclusion