RESUMEN
Sleep homeostasis is crucial for sleep regulation. The role of epigenetic regulation in sleep homeostasis is unestablished. Previous studies showed that octopamine is important for sleep homeostasis. However, the regulatory mechanism of octopamine reception in sleep is unknown. In this study, we identify an epigenetic regulatory cascade (Stuxnet-Polycomb-Octß2R) that modulates the octopamine receptor in Drosophila. We demonstrate that stuxnet positively regulates Octß2R through repression of Polycomb in the ellipsoid body of the adult fly brain and that Octß2R is one of the major receptors mediating octopamine function in sleep homeostasis. In response to octopamine, Octß2R transcription is inhibited as a result of stuxnet downregulation. This feedback through the Stuxnet-Polycomb-Octß2R cascade is crucial for sleep homeostasis regulation. This study demonstrates a Stuxnet-Polycomb-Octß2R-mediated epigenetic regulatory mechanism for octopamine reception, thus providing an example of epigenetic regulation of sleep homeostasis.
Asunto(s)
Proteínas de Drosophila , Drosophila melanogaster , Epigénesis Genética , Octopamina/farmacología , Sueño , Animales , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/genética , Drosophila melanogaster/metabolismo , Complejo Represivo Polycomb 1 , Receptores Acoplados a Proteínas G , Sueño/efectos de los fármacos , Sueño/genéticaRESUMEN
A search of the Drosophila genome for genes encoding components of the mitochondrial translocase of outer membrane (TOM) complex revealed duplication of genes encoding homologues of Tom20 and Tom40. Tom20 and Tom40 were represented by two differentially expressed homologues in the Drosophila genome. While dtom20 and dtom40 appeared to be expressed ubiquitously, the second variants, called tomboy20 and tomboy40, were expressed only in the male germ-line. Transcripts for tomboy20 and tomboy40 were detected in primary spermatocytes as well as post-meiotic stages. Transcription of tomboy20 and tomboy40 in spermatocytes was not dependent on the transcription factor Cannonball, which is responsible for controlling expression of gene products exclusively required for post-meiotic germ cell differentiation. Epitope-tagging and transient expression of dTom20 and Tomboy40 in mammalian cell culture showed proper targeting to mitochondria.
Asunto(s)
Proteínas de Drosophila/genética , Drosophila/genética , Variación Genética , Mutación de Línea Germinal/genética , Mitocondrias/genética , Secuencia de Aminoácidos , Animales , Secuencia Conservada , Proteínas de Drosophila/química , Genoma , Membranas Intracelulares , Proteínas de Transporte de Membrana/química , Proteínas de Transporte de Membrana/genética , Proteínas Mitocondriales/química , Proteínas Mitocondriales/genética , Datos de Secuencia Molecular , Receptores de Superficie Celular/química , Receptores de Superficie Celular/genética , Receptores Citoplasmáticos y Nucleares/química , Receptores Citoplasmáticos y Nucleares/genética , Alineación de Secuencia , Homología de Secuencia de AminoácidoRESUMEN
Niemann-Pick type C (NPC) disease is a fatal autosomal-recessive neurodegenerative disorder characterized by the inappropriate accumulation of unesterified cholesterol in aberrant organelles. The disease is due to mutations in either of two genes, NPC1, which encodes a transmembrane protein related to the Hedgehog receptor Patched, and NPC2, which encodes a secreted cholesterol-binding protein. Npc1 mutant mice can be partially rescued by treatment with specific steroids. We have created a Drosophila NPC model by mutating dnpc1a, one of two Drosophila genes related to mammalian NPC1. Cells throughout the bodies of dnpc1a mutants accumulated sterol in a punctate pattern, as in individuals with NPC1 mutations. The mutants developed only to the first larval stage and were unable to molt. Molting after the normal first instar period was restored to various degrees by feeding the mutants the steroid molting hormone 20-hydroxyecdysone, or the precursors of ecdysone biosynthesis, cholesterol and 7-dehydrocholesterol. dnpc1a is normally highly expressed in the ecdysone-producing ring gland. Ring gland-specific expression of dnpc1a in otherwise mutant flies allowed development to adulthood, suggesting that the lack of ecdysone in the mutants is the cause of death. We propose that dnpc1a mutants have sterols trapped in aberrant organelles, leading to a shortage of sterol in the endoplasmic reticulum and/or mitochondria of ring gland cells, and, consequently, inadequate ecdysone synthesis.