RESUMO
The survival motor neurons (smn) gene in mice is essential for embryonic viability. In humans, mutation of the telomeric copy of the SMN1 gene causes spinal muscular atrophy, an autosomal recessive disease. Here we report that the SMN protein interacts with the zinc-finger protein ZPR1 and that these proteins colocalize in small subnuclear structures, including gems and Cajal bodies. SMN and ZPR1 redistribute from the cytoplasm to the nucleus in response to serum. This process is disrupted in cells from patients with Werdnig-Hoffman syndrome (spinal muscular atrophy type I) that have SMN1 mutations. Similarly, decreased ZPR1 expression prevents SMN localization to nuclear bodies. Our data show that ZPR1 is required for the localization of SMN in nuclear bodies.
Assuntos
Proteínas de Transporte/metabolismo , Atrofia Muscular Espinal/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Dedos de Zinco , Processamento Alternativo , Animais , Células COS , Proteínas de Transporte/genética , Núcleo Celular/metabolismo , Chlorocebus aethiops , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico , Citoplasma/metabolismo , Células HeLa , Humanos , Proteínas de Membrana Transportadoras , Proteínas do Tecido Nervoso/genética , Precursores de RNA , Proteínas de Ligação a RNA , Proteínas do Complexo SMN , Proteína 1 de Sobrevivência do Neurônio MotorRESUMO
The zinc finger protein ZPR1 is present in the cytoplasm of quiescent mammalian cells and translocates to the nucleus upon treatment with mitogens, including epidermal growth factor (EGF). Homologues of ZPR1 were identified in yeast and mammals. These ZPR1 proteins bind to eukaryotic translation elongation factor-1alpha (eEF-1alpha). Studies of mammalian cells demonstrated that EGF treatment induces the interaction of ZPR1 with eEF-1alpha and the redistribution of both proteins to the nucleus. In the yeast Saccharomyces cerevisiae, genetic analysis demonstrated that ZPR1 is an essential gene. Deletion analysis demonstrated that the NH2-terminal region of ZPR1 is required for normal growth and that the COOH-terminal region was essential for viability in S. cerevisiae. The yeast ZPR1 protein redistributes from the cytoplasm to the nucleus in response to nutrient stimulation. Disruption of the binding of ZPR1 to eEF-1alpha by mutational analysis resulted in an accumulation of cells in the G2/M phase of cell cycle and defective growth. Reconstitution of the ZPR1 interaction with eEF-1alpha restored normal growth. We conclude that ZPR1 is essential for cell viability and that its interaction with eEF-1alpha contributes to normal cellular proliferation.
Assuntos
Proteínas de Transporte/genética , Proteínas de Transporte/metabolismo , Ciclo Celular/fisiologia , Fatores de Alongamento de Peptídeos/metabolismo , Proteínas de Saccharomyces cerevisiae , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/fisiologia , Sequência de Aminoácidos , Animais , Células COS , Proteínas de Transporte/química , Divisão Celular , Linhagem Celular , Sequência Consenso , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Fase G2 , Deleção de Genes , Genes Fúngicos , Genótipo , Humanos , Peptídeos e Proteínas de Sinalização Intracelular , Mamíferos , Proteínas de Membrana Transportadoras , Camundongos , Mitose , Dados de Sequência Molecular , Fator 1 de Elongação de Peptídeos , Fatores de Alongamento de Peptídeos/isolamento & purificação , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo , Mapeamento por Restrição , Saccharomyces cerevisiae/citologia , Schizosaccharomyces/genética , Alinhamento de Sequência , Homologia de Sequência de Aminoácidos , Dedos de ZincoRESUMO
The zinc finger protein ZPR1 translocates from the cytoplasm to the nucleus after treatment of cells with mitogens. The function of nuclear ZPR1 has not been defined. Here we demonstrate that ZPR1 accumulates in the nucleolus of proliferating cells. The role of ZPR1 was examined using a gene disruption strategy. Cells lacking ZPR1 are not viable. Biochemical analysis demonstrated that the loss of ZPR1 caused disruption of nucleolar function, including preribosomal RNA expression. These data establish ZPR1 as an essential protein that is required for normal nucleolar function in proliferating cells.