No description available.

No description available.

Haa1 is a transcription factor that adapts Saccharomyces cerevisiae cells to weak organic acid stresses by activating the expression of various genes. How Haa1 is activated by weak acids is not clear. This study proposes that Hrr25 is an important regulator of cellular adaptation to weak acid stress by inhibiting Haa1 through phosphorylation. YRO2, one of the targets of Haa1, shows increase in expression during stationary phase. This increase is due to basal activity of Haa1 and another, unknown, transcription factor. This study proposes that Gsm1 is another transcription factor that regulates YRO2 expression in the stationary phase. Finally, the mechanism of regulation of YRO2 by Haa1 is largely unknown. This study identifies two possible Haa1-medated cis-acting elements in the YRO2 promoter.

A doença de Alzheimer (DA) é uma desordem neurodegenerativa progressiva, caracterizada pela perda de neurônios corticais e subcorticais. Padrões patológicos da doença de Alzheimer incluem a presença de lesões neurofibrilares que consistem no acúmulo da proteína ?- amilóide e dos emaranhados neurofibrilares, decorrentes da hiperfosforilação da proteína Tau. Apenas dois grupos principais de fármacos são utilizados para o tratamento da DA, os inibidores colinesterásicos e antagonistas do receptor N-metil-D-aspartato. Entretanto, a fosforilação de proteínas pelas proteínas cinases constituem um dos principais mecanismos pelos quais as células se utilizam para regular seu metabolismo e demais funções e desequilíbrios nestas atividades estão relacionados a uma infinidade de doenças. O número elevado de isoformas de proteínas cinases 1 (CK1) encontradas na DA e sua associação em marcadores de lesões neurodegenerativas indicam sua participação nas etapas finais da degeneração, comum tanto à DA quanto a outras desordens neurodegenerativas. A abordagem da proteína CK1 como alvo terapêutico para a DA é promissora uma vez que os compostos usuais utilizados para diminuir a produção de ?-amilóide também bloqueiam a quebra de outras proteínas, causando graves efeitos colaterais. Cada vez mais as ferramentas de bioinformática vêm sendo utilizadas como auxílio na redução de custos e tempo para as pesquisas. Dentre estas técnicas destaca-se a triagem virtual, que reúne um conjunto de técnicas utilizadas de forma sequencial com o objetivo de selecionar compostos protótipos para os alvos desejados. Neste trabalho, foram utilizadas técnicas de triagem virtual baseada em ligantes e estrutura, a partir de uma base de 500 mil compostos, selecionando 35 compostos com perfil de atividade inibitória para a enzima CK1. Destes, os compostos 24, 25, 36, 39 41 e 42 apresentaram resultados significativos com relação ao potencial de inibição da enzima CK1?. Entre aqueles que já foram submetidos a ensaios de inibição enzimática, 25 apresentou seletividade para CK1?, com 40% de inibição. Para aqueles compostos com melhor potencial de inibição à concentração de 10 ?M será determinado o IC50 e uma extensa análise dos resultados será realizada futuramente. / Alzheimer\'s disease (AD) is a progressive neurodegenerative disorder characterized by loss of cortical and subcortical neurons. Pathological patterns of Alzheimer\'s disease include the presence of neurofibrillary lesions consisting of the accumulation of amyloid-? protein and the neurofibrillary tangles, resulting of hyperphosphorylated Tau protein. Only two major groups of drugs are used for treatment of AD, cholinesterase inhibitors and antagonists of Nmethyl- D-aspartate receptor. The phosphorylation of proteins by protein kinases constitute one of the major mechanisms which cells use to regulate their metabolism and imbalances in these activities are related to a series of diseases. The high number of isoforms of protein kinase 1 (CK1) found in AD and its association with neurodegenerative markers of indicate their participation in the final stages of degeneration, common to both AD and other neurodegenerative disorders. The approach of CK1 protein as a therapeutic target for AD is promising as the usual compounds used to reduce the production of amyloid-? also block the breakdown of other proteins, causing severe side effects. Increasingly, bioinformatics tools have been used as an aid in reducing costs and time to research. Among these techniques highlights the virtual screening, which includes a set of techniques used sequentially with the aim of select compounds prototypes for the desired target. Ligand and structure-based virtual screening techniches from a 500 thousand database resulted in 35 selected with inhibitory profile for CK1 enzyme were used in this study. The compounds 24, 25, 36, 39 41 and 42 had significan potential for CK1? enzyme inhibition. Among those submitted to enzyme inhibition assays, compound 25 showed selectivity for CK1? , with 40 % inhibition. For those compounds with the best inhibitory concentration at 10 mM and the IC50 will be given an extensive analysis of the results will be held in the future .

A doença de Alzheimer (DA) é uma desordem neurodegenerativa progressiva, caracterizada pela perda de neurônios corticais e subcorticais. Padrões patológicos da doença de Alzheimer incluem a presença de lesões neurofibrilares que consistem no acúmulo da proteína ?- amilóide e dos emaranhados neurofibrilares, decorrentes da hiperfosforilação da proteína Tau. Apenas dois grupos principais de fármacos são utilizados para o tratamento da DA, os inibidores colinesterásicos e antagonistas do receptor N-metil-D-aspartato. Entretanto, a fosforilação de proteínas pelas proteínas cinases constituem um dos principais mecanismos pelos quais as células se utilizam para regular seu metabolismo e demais funções e desequilíbrios nestas atividades estão relacionados a uma infinidade de doenças. O número elevado de isoformas de proteínas cinases 1 (CK1) encontradas na DA e sua associação em marcadores de lesões neurodegenerativas indicam sua participação nas etapas finais da degeneração, comum tanto à DA quanto a outras desordens neurodegenerativas. A abordagem da proteína CK1 como alvo terapêutico para a DA é promissora uma vez que os compostos usuais utilizados para diminuir a produção de ?-amilóide também bloqueiam a quebra de outras proteínas, causando graves efeitos colaterais. Cada vez mais as ferramentas de bioinformática vêm sendo utilizadas como auxílio na redução de custos e tempo para as pesquisas. Dentre estas técnicas destaca-se a triagem virtual, que reúne um conjunto de técnicas utilizadas de forma sequencial com o objetivo de selecionar compostos protótipos para os alvos desejados. Neste trabalho, foram utilizadas técnicas de triagem virtual baseada em ligantes e estrutura, a partir de uma base de 500 mil compostos, selecionando 35 compostos com perfil de atividade inibitória para a enzima CK1. Destes, os compostos 24, 25, 36, 39 41 e 42 apresentaram resultados significativos com relação ao potencial de inibição da enzima CK1?. Entre aqueles que já foram submetidos a ensaios de inibição enzimática, 25 apresentou seletividade para CK1?, com 40% de inibição. Para aqueles compostos com melhor potencial de inibição à concentração de 10 ?M será determinado o IC50 e uma extensa análise dos resultados será realizada futuramente. / Alzheimer\'s disease (AD) is a progressive neurodegenerative disorder characterized by loss of cortical and subcortical neurons. Pathological patterns of Alzheimer\'s disease include the presence of neurofibrillary lesions consisting of the accumulation of amyloid-? protein and the neurofibrillary tangles, resulting of hyperphosphorylated Tau protein. Only two major groups of drugs are used for treatment of AD, cholinesterase inhibitors and antagonists of Nmethyl- D-aspartate receptor. The phosphorylation of proteins by protein kinases constitute one of the major mechanisms which cells use to regulate their metabolism and imbalances in these activities are related to a series of diseases. The high number of isoforms of protein kinase 1 (CK1) found in AD and its association with neurodegenerative markers of indicate their participation in the final stages of degeneration, common to both AD and other neurodegenerative disorders. The approach of CK1 protein as a therapeutic target for AD is promising as the usual compounds used to reduce the production of amyloid-? also block the breakdown of other proteins, causing severe side effects. Increasingly, bioinformatics tools have been used as an aid in reducing costs and time to research. Among these techniques highlights the virtual screening, which includes a set of techniques used sequentially with the aim of select compounds prototypes for the desired target. Ligand and structure-based virtual screening techniches from a 500 thousand database resulted in 35 selected with inhibitory profile for CK1 enzyme were used in this study. The compounds 24, 25, 36, 39 41 and 42 had significan potential for CK1? enzyme inhibition. Among those submitted to enzyme inhibition assays, compound 25 showed selectivity for CK1? , with 40 % inhibition. For those compounds with the best inhibitory concentration at 10 mM and the IC50 will be given an extensive analysis of the results will be held in the future .

Ces dernières années, les méthodes hybrides QM/MM combinant la mécanique quantique (QM) et la mécanique moléculaire (MM) se sont revélées des méthodes de choix pour l'étude de systèmes chimiques et biochimiques contenant plus d'une centaine d'atomes. Nous avons mis en évidence les apports et difficultés liés à leur utilisation à travers des systèmes variés: modélisation de ligands phosphines, réactivité d'une protéine de type acide phosphatase pourpre, modélisation de l'interaction protéine-ligand.

Thesis (Ph.D.)--University of Alabama at Birmingham, 2007. / Title from first page of PDF file (viewed on June 25, 2009). Includes bibliographical references.

Thesis (Ph. D.)--University of Virginia, 2007. / Title from title page. Includes bibliographical references. Also available online through Digital Dissertations.

Thesis (Ph.D.) -- University of Texas Southwestern Medical Center at Dallas, 2005. / Not embargoed. Vita. Bibliography: 105-114.

Pregnenolone (PREG), the precursor of all neurosteroids, is synthesized in the nervous system from cholesterol and recent clinical studies indicate that reduced cognitive symptoms of schizophrenia correlate with elevated serum levels of pregnenolone sulfate (PregS), its immediate sulfated metabolite. PregS fulfills most of the classical criteria for an endogenous modulator of excitatory synaptic transmission, including: presence in nervous tissue at physiologically relevant concentrations, potentiation of N-methyl-D-aspartate receptor (NMDAR) mediated synaptic activity, and a mechanism for its inactivation. As NMDAR hypoactivity has been implicated in the pathophysiology of schizophrenia, defects in neurosteroid metabolism might play a role in its associated cognitive dysfunction. PregS improves memory performance in rodents and augments long-term potentiation (LTP), an electrophysiological correlate of synaptic plasticity that is stabilized by phosphorylation of the cAMP response element binding protein (CREB). We have previously demonstrated that PregS at low picomolar (pM) concentrations increases intracellular Ca2+ and CREB via synaptic NMDARs. Therefore, we hypothesized that low pM concentrations of PregS might potentiate spontaneous excitatory postsynaptic currents (sEPSCs) and promote molecular events underlying synaptic plasticity. Here, using whole-cell patch clamp recordings, we report that PregS enhances the frequency of sEPSCs of cultured hippocampal neurons by about 2-fold while not altering their amplitude or passive membrane properties. This suggests that PregS acts presynaptically by increasing the frequency of neurotransmitter release or postsynaptically by activating silent synapses. We then investigated the hypothesis that PregS increases α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) and NMDAR subtypes at synapses as a molecular switch for this enhancement. We measured receptor redistribution and phosphorylation using fluorescence imaging and Western blot technology. The results demonstrate that PregS (50pM, 10min): (1) Increases AMPAR (GluA1)/PSD95 colocalization (dependent on L-type voltage-gated Ca+2 channel and synaptic NMDAR activity), and increases phosphorylation of GluA1 at serine-831/845; (2) Increases casein kinase 2 (CK2) dependent surface NMDAR2A (GluN2A) but not GluN1 or GluN2B; and (3) Increases GluN2B serine-1480 phosphorylation. The results show that PregS increases the frequency of excitatory synaptic transmission and increases surface/synaptic AMPARs and surface GluN2A (but not GluN1 or GluN2B) NMDARs, shifting the molecular composition of young glutamatergic synapses toward the adult GluN2A enriched synaptic phenotype.