RESUMO
Intrauterine infection with human cytomegalovirus (HCMV) is the leading viral cause of birth defects involving the central nervous system. Due to the highly species specific nature of the virus, its course of natural infection cannot be studied in animal models. Here we introduce a novel transgenic Drosophila model system for studying the effects of the major viral regulatory genes, the immediate-early genes, on normal embryonic development. We show that ectopic expression of the immediate-early genes in Drosophila led to increased embryonic lethality manifested in disintegration of the embryos. Further analysis suggested that immediate-early gene expression interfered with adherens junction maintenance, leading to the disruption of embryonic epithelial integrity. Owing to the evolutionary conservation of developmental mechanisms from invertebrates to mammals, we anticipate that the studies in Drosophila will be relevant also to humans and will ultimately provide a versatile system for studying different aspects of viral-host interactions.
Assuntos
Citomegalovirus/genética , Citomegalovirus/patogenicidade , Drosophila/embriologia , Drosophila/genética , Genes Precoces , Junções Aderentes/metabolismo , Junções Aderentes/ultraestrutura , Junções Aderentes/virologia , Animais , Animais Geneticamente Modificados , Proteínas do Domínio Armadillo/genética , Proteínas do Domínio Armadillo/metabolismo , Sequência de Bases , Infecções por Citomegalovirus/embriologia , Infecções por Citomegalovirus/genética , Primers do DNA/genética , DNA Viral/genética , Drosophila/metabolismo , Drosophila/virologia , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Feminino , Expressão Gênica , Interações Hospedeiro-Patógeno/genética , Humanos , Regiões Promotoras Genéticas , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismoRESUMO
The COP9 signalosome (CSN) is an essential eight-subunit repressor of light-regulated development in Arabidopsis. This complex has also been identified in animals, though its developmental role remains obscure. CSN subunits have been implicated in various cellular processes, suggesting a possible role for the CSN as an integrator of multiple signaling pathways. In order to elucidate the function of the CSN in animals, a Drosophila model system has previously been established. Gel-filtration analysis with antibodies against CSN subunits 4, 5 and 7 revealed that these proteins act as a complex in Drosophila that is similar in size to the plant and mammalian complexes. Null mutations in either one of two subunits, CSN4 or CSN5, are larval lethal. Successful embryogenesis appears to be a consequence of maternal contribution of the complex. Biochemical analysis indicates that the different subunits are found in both CSN-dependent and CSN-independent forms, and that these forms are differentially affected by the mutations. Phenotypic characterization of these two mutants indicates that they show both shared and unique phenotypes, which suggest specific roles for each subunit. Both mutants have defective oocyte and embryo patterning, and defects in response to DNA damage, while csn5 mutants develop melanotic tumors and csn4 mutants have phenotypes reminiscent of defects in ecdysone signaling.
