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1.
Mol Biol Cell ; 12(8): 2422-32, 2001 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-11514626

RESUMEN

We have identified the yeast gene STM1 in an overexpression screen for new proteasomal substrates. Stm1 is unstable in wild-type cells and stabilized in cells with defective proteasomal activity and thus a bona fide substrate of the proteasome. It is localized in the perinuclear region and is required for growth in the presence of mutagens. Overexpression in cells with impaired proteasomal degradation leads to cell death accompanied with cytological markers of apoptosis: loss of plasma membrane asymmetry, chromatin condensation, and DNA cleavage. Cells lacking Stm1 display deficiency in the apoptosis-like cell death process induced by treatment with low concentrations of H(2)O(2). We suggest that Stm1 is involved in the control of the apoptosis-like cell death in yeast. Survival is increased when Stm1 is completely missing from the cells or when inhibition of Stm1 synthesis permits proteasomal degradation to decrease its amount in the cell. Conversely, Stm1 accumulation induces cell death. In addition we identified five other genes whose overexpression in proteasomal mutants caused similar apoptotic phenotypes.


Asunto(s)
Cisteína Endopeptidasas/genética , Proteínas Fúngicas/metabolismo , Complejos Multienzimáticos/genética , Factores de Iniciación de Péptidos , ARN Nucleotidiltransferasas/metabolismo , Saccharomyces cerevisiae/fisiología , Animales , Antibióticos Antineoplásicos/farmacología , Bleomicina/farmacología , Cafeína/farmacología , Muerte Celular , Cromatina/metabolismo , Cisteína Endopeptidasas/metabolismo , Factores Eucarióticos de Iniciación , Proteínas Fúngicas/genética , Biblioteca de Genes , Peróxido de Hidrógeno/farmacología , Etiquetado Corte-Fin in Situ , Microscopía Fluorescente , Complejos Multienzimáticos/metabolismo , Oxidantes/farmacología , Inhibidores de Fosfodiesterasa/farmacología , Complejo de la Endopetidasa Proteasomal , Proteínas Recombinantes de Fusión/metabolismo , Saccharomyces cerevisiae/efectos de los fármacos , Saccharomyces cerevisiae/ultraestructura , Proteínas de Saccharomyces cerevisiae/metabolismo , Rayos Ultravioleta
2.
J Cell Biol ; 145(4): 757-67, 1999 May 17.
Artículo en Inglés | MEDLINE | ID: mdl-10330404

RESUMEN

Oxygen radicals are important components of metazoan apoptosis. We have found that apoptosis can be induced in the yeast Saccharomyces cerevisiae by depletion of glutathione or by low external doses of H2O2. Cycloheximide prevents apoptotic death revealing active participation of the cell. Yeast can also be triggered into apoptosis by a mutation in CDC48 or by expression of mammalian bax. In both cases, we show oxygen radicals to accumulate in the cell, whereas radical depletion or hypoxia prevents apoptosis. These results suggest that the generation of oxygen radicals is a key event in the ancestral apoptotic pathway and offer an explanation for the mechanism of bax-induced apoptosis in the absence of any established apoptotic gene in yeast.


Asunto(s)
Apoptosis , Estrés Oxidativo , Saccharomyces cerevisiae/metabolismo , Adenosina Trifosfatasas , Biomarcadores , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Cicloheximida/farmacología , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Glutatión/metabolismo , Peróxido de Hidrógeno/farmacología , Mutagénesis , Oxígeno , Fenotipo , Inhibidores de la Síntesis de la Proteína/farmacología , Proteínas Proto-Oncogénicas/biosíntesis , Proteínas Proto-Oncogénicas/genética , Proteínas Proto-Oncogénicas c-bcl-2/biosíntesis , Proteínas Proto-Oncogénicas c-bcl-2/genética , Especies Reactivas de Oxígeno/metabolismo , Saccharomyces cerevisiae/citología , Saccharomyces cerevisiae/efectos de los fármacos , Proteínas de Saccharomyces cerevisiae , Proteína que Contiene Valosina , Proteína X Asociada a bcl-2
3.
FEBS Lett ; 438(1-2): 61-5, 1998 Oct 30.
Artículo en Inglés | MEDLINE | ID: mdl-9821959

RESUMEN

Apoptosis is co-regulated by the conserved family of Bcl-2-related proteins, which includes both its agonists (Bax) and antagonists (Bcl-X(L)). A mutant strain of the yeast Saccharomyces cerevisiae has been shown to express all morphological signs of apoptosis. Overexpression of Bax is lethal in S. cerevisiae, whereas simultaneous overexpression of Bcl-X(L) rescues the cells. We report that overexpression of mammalian Bax in a S. cerevisiae wild type strain triggers morphological changes similar to those of apoptotic metazoan cells: the loss of asymmetric distribution of plasma membrane phosphatidylserine, plasma membrane blebbing, chromatin condensation and margination, and DNA fragmentation. Simultaneous overexpression of Bcl-X(L) prevents these changes. We demonstrate that Bax triggers phenotypic alterations in yeast strongly resembling those it causes in metazoan apoptotic cells.


Asunto(s)
Apoptosis , Proteínas Proto-Oncogénicas/fisiología , Saccharomyces cerevisiae/metabolismo , Animales , Membrana Celular/metabolismo , Membrana Celular/ultraestructura , Núcleo Celular/metabolismo , Núcleo Celular/ultraestructura , Cromatina/metabolismo , Fragmentación del ADN , Técnicas de Transferencia de Gen , Etiquetado Corte-Fin in Situ , Indoles , Mamíferos/genética , Microscopía Electrónica , Fosfatidilserinas/metabolismo , Proteínas Proto-Oncogénicas/genética , Proteínas Proto-Oncogénicas c-bcl-2/genética , Proteínas Proto-Oncogénicas c-bcl-2/fisiología , Saccharomyces cerevisiae/citología , Saccharomyces cerevisiae/genética , Proteína X Asociada a bcl-2 , Proteína bcl-X
4.
Comput Appl Biosci ; 11(2): 133-9, 1995 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-7620984

RESUMEN

This paper describes an algorithm for calculating the photoperiod length (daylength as intercepted by plants) with special emphasis on its use in models describing plant growth and development. The ability to calculate simply and exactly the length of the day for different locations is essential not only for the models describing photoperiodic effects on plant development but also for the simulation of the daily sum of the produced photosynthates or the calculation of the average daily temperature. Two previously published algorithms for calculation of photoperiod length were compared with ours, based on the system of equations describing movement of earth around the sun. The curve gained when plotting daylengths calculated by our algorithm against a particular date is asymmetrical with respect to daylength in equinoxes, while the curve showing the data calculated by both compared algorithms is apparently symmetrical. The differences between our algorithm and the other two algorithms increase with increasing latitude: at 50 degrees N they are in the range of 6.9-13.8 min. We have also demonstrated an effect of location height, geographical longitude and a year on calculated daylength of a particular day.


Asunto(s)
Algoritmos , Fotoperiodo , Luz , Fotosíntesis , Fenómenos Fisiológicos de las Plantas , Plantas/efectos de la radiación
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