title: Comparative expression of p2x receptors and ecto-nucleoside triphosphate diphosphohydrolase 3 in hypocretin and sensory neurons in zebrafish.
abstract: The hypocretin/orexin (HCRT/ORX) excitatory neuropeptides are expressed in a small population of lateral hypothalamic cells in mammals and fish. In humans, loss of these cells causes the sleep disorder narcolepsy. Identification of genes expressed in HCRT-producing cells may be revealing as to the regulation of sleep and the pathophysiology of narcolepsy. In this study, in situ hybridization analyses were performed to characterize the expression pattern of receptors and enzyme, which regulate ATP-mediated transmission in hypocretin cells of zebrafish larvae. The zebrafish cDNA encoding the ecto-nucleoside triphosphate diphosphohydrolase 3 (ENTPD3/NTPDase3) was isolated. This transcript was found to be expressed in zebrafish HCRT cells as previously reported in mammals. It was also expressed in the cranial nerves (gV, gVII, gIV and gX) and in primary sensory neurons (i.e., Rohon-Beard neurons) in the spinal cord. The expression of known zebrafish p2rx purinergic receptor family members was next studied and found to overlap with the entpd3 expression pattern. Specifically, p2rx2, p2rx3.1, p2rx3.2 and p2rx8 were expressed in the trigeminal ganglia and subsets of Rohon-Beard neurons. In contrast to mammals, p2rx2 was not expressed in HCRT cells; rather, p2rx8 was expressed with entpd3 in this hypothalamic region. The conservation of expression of these genes in HCRT cells and sensory neurons across vertebrates suggests an important role for ATP mediated transmission in the regulation of sleep and the processing of sensory inputs.
authors.affiliation: Department of Psychiatry and Behavioral Sciences, Stanford University, Palo Alto, CA 94305, USA.
authors.forename: Lior
authors.initials: L
authors.lastname: Appelbaum
authors.forename: Gemini
authors.initials: G
authors.lastname: Skariah
authors.forename: Philippe
authors.initials: P
authors.lastname: Mourrain
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Mignot
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D003391:Cranial Nerves / Q000166:cytology / Q000276:immunology / Q000502:physiology; D004625:Embryo, Nonmammalian / Q000502:physiology; D005260:Female; D018507:Gene Expression Regulation, Developmental; D007026:Hypothalamic Area, Lateral / Q000166:cytology / Q000196:embryology / Q000502:physiology*; D047908:Intracellular Signaling Peptides and Proteins / Q000502:physiology*; D008297:Male; D008969:Molecular Sequence Data; D009475:Neurons, Afferent / Q000502:physiology*; D009479:Neuropeptides / Q000502:physiology*; D000068797:Orexins; D011755:Pyrophosphatases / Q000235:genetics*; D018048:Receptors, Purinergic P2 / Q000235:genetics*; D013116:Spinal Cord / Q000166:cytology / Q000276:immunology / Q000502:physiology; D015027:Zebrafish
chemical_list: D047908:Intracellular Signaling Peptides and Proteins; D009479:Neuropeptides; D000068797:Orexins; D018048:Receptors, Purinergic P2; D000255:Adenosine Triphosphate; D011755:Pyrophosphatases; C439652:nucleoside-triphosphate diphosphohydrolase 3