RESUMO
Presenilin is the enzymatic component of gamma-secretase, a multisubunit intramembrane protease that processes several transmembrane receptors, such as the amyloid precursor protein (APP). Mutations in human Presenilins lead to altered APP cleavage and early-onset Alzheimer's disease. Presenilins also play an essential role in Notch receptor cleavage and signaling. The Notch pathway is a highly conserved signaling pathway that functions during the development of multicellular organisms, including vertebrates, Drosophila, and C. elegans. Recent studies have shown that Notch signaling is sensitive to perturbations in subcellular trafficking, although the specific mechanisms are largely unknown. To identify genes that regulate Notch pathway function, we have performed two genetic screens in Drosophila for modifiers of Presenilin-dependent Notch phenotypes. We describe here the cloning and identification of 19 modifiers, including nicastrin and several genes with previously undescribed involvement in Notch biology. The predicted functions of these newly identified genes are consistent with extracellular matrix and vesicular trafficking mechanisms in Presenilin and Notch pathway regulation and suggest a novel role for gamma-tubulin in the pathway.
Assuntos
Proteínas de Drosophila/genética , Drosophila melanogaster/genética , Proteínas de Membrana/genética , Receptores Notch/genética , Alelos , Precursor de Proteína beta-Amiloide/genética , Animais , Cruzamentos Genéticos , Elementos Facilitadores Genéticos , Matriz Extracelular , Feminino , Masculino , Mutação , Presenilina-1 , Receptores Notch/metabolismo , Transdução de Sinais , Tubulina (Proteína)/metabolismoRESUMO
Mutations that inactivate the retinoblastoma (Rb) pathway are common in human tumors. Such mutations promote tumor growth by deregulating the G1 cell cycle checkpoint. However, uncontrolled cell cycle progression can also produce new liabilities for cell survival. To uncover such liabilities in Rb mutant cells, we performed a clonal screen in the Drosophila eye to identify second-site mutations that eliminate Rbf(-) cells, but allow Rbf(+) cells to survive. Here we report the identification of a mutation in a novel highly conserved peptidyl prolyl isomerase (PPIase) that selectively eliminates Rbf(-) cells from the Drosophila eye.
Assuntos
Drosophila melanogaster/embriologia , Olho/embriologia , Peptidilprolil Isomerase/genética , Proteína do Retinoblastoma/genética , Sequência de Aminoácidos , Animais , Drosophila melanogaster/enzimologia , Drosophila melanogaster/genética , Olho/enzimologia , Dados de Sequência Molecular , MutaçãoRESUMO
Achieving the potential of zebrafish models in biomedical research is contingent on the development of reverse-genetic resources. This review describes current technologies for genetic perturbations in zebrafish, including an ecdysone receptor-based system that permits conditional transgene expression. Such methodologies promise to enable new zebrafish models for interrogating human physiology and disease.
Assuntos
Regulação da Expressão Gênica/fisiologia , Engenharia Genética , Peixe-Zebra/genética , Peixe-Zebra/metabolismo , Animais , Proteínas de Peixe-Zebra/genética , Proteínas de Peixe-Zebra/metabolismoRESUMO
The zebrafish has emerged as a versatile model organism for biomedical research, yet its potential has been limited by a lack of conditional reverse-genetic tools. Here we report a chemically inducible gene expression technology that has orthogonality to vertebrate signaling processes, high induction levels, and rapid kinetics. Coupled with tissue-specific promoters, this system provides multidimensional control of gene expression and will enable new models of human disorders and diseases.