RESUMO
The pigment-dispersing factor (PDF) is a neuropeptide controlling circadian behavioral rhythms in Drosophila, but its receptor is not yet known. From a large-scale temperature preference behavior screen in Drosophila, we isolated a P insertion mutant that preferred different temperatures during the day and night. This mutation, which we named han, reduced the transcript level of CG13758. We found that Han was expressed specifically in 13 pairs of circadian clock neurons in the adult brain. han null flies showed arrhythmic circadian behavior in constant darkness. The behavioral characteristics of han null mutants were similar to those of pdf null mutants. We also found that PDF binds specifically to S2 cells expressing Han, which results in the elevation of cAMP synthesis. Therefore, we herein propose that Han is a PDF receptor regulating circadian behavioral rhythm through coordination of activities of clock neurons.
Assuntos
Ritmo Circadiano/fisiologia , Proteínas de Drosophila/metabolismo , Regulação da Expressão Gênica/fisiologia , Neuropeptídeos/metabolismo , Receptores Acoplados a Proteínas G/metabolismo , Sequência de Aminoácidos , Animais , Anticorpos/metabolismo , Comportamento Animal , Ligação Competitiva , Northern Blotting/métodos , Encéfalo/citologia , Linhagem Celular , AMP Cíclico/metabolismo , Relação Dose-Resposta a Droga , Drosophila , Proteínas de Drosophila/genética , Proteínas de Drosophila/imunologia , Proteínas de Drosophila/fisiologia , Regulação da Expressão Gênica/efeitos dos fármacos , Imuno-Histoquímica/métodos , Atividade Motora/fisiologia , Mutação , Neurônios/metabolismo , Periodicidade , Ligação Proteica/fisiologia , RNA Mensageiro/biossíntese , Receptores Acoplados a Proteínas G/genética , Receptores Acoplados a Proteínas G/imunologia , Receptores Acoplados a Proteínas G/fisiologia , Reação em Cadeia da Polimerase Via Transcriptase Reversa/métodos , Alinhamento de Sequência , Sensação Térmica/genética , Sensação Térmica/fisiologiaRESUMO
Temperature profoundly influences various life phenomena, and most animals have developed mechanisms to respond properly to environmental temperature fluctuations. To identify genes involved in sensing ambient temperature and in responding to its change, >27,000 independent P-element insertion mutants of Drosophila were screened. As a result, we found that defects in the genes encoding for proteins involved in histamine signaling [histidine decarboxylase (hdc), histamine-gated chloride channel subunit 1 (hisCl1), ora transientless (ort)] cause abnormal temperature preferences. The abnormal preferences shown in these mutants were restored by genetic and pharmacological rescue and could be reproduced in wild type using the histamine receptor inhibitors cimetidine and hydroxyzine. Spatial expression of these genes was observed in various brain regions including pars intercerebralis, fan-shaped body, and circadian clock neurons but not in dTRPA1-expressing neurons, an essential element for thermotaxis. We also found that the histaminergic mutants showed reduced tolerance for high temperature and enhanced tolerance for cold temperature. Together, these results suggest that histamine signaling may have important roles in modulating temperature preference and in controlling tolerance of low and high temperature.