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Mobilização da calmodulina e da neurogranina depende da variação da concentração de cálcio
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Abstract(s)
A calmodulina (CaM) e neurogranina (Ng) são duas proteínas expressas em células nervosas, localizadas maioritariamente no soma e no núcleo em células do hipocampo. Foi detetado que existia uma mobilização da calmodulina e da neurogranina do soma para as dendrites quando era induzido uma variação da concentração de cálcio, pela adição de um agente quelante (EGTA). Sabendo que a concentração intracelular de cálcio é de 100 nM, pela relação da intensidade de fluorescência com a concentração de cálcio, verificou-se que houve uma redução de 40 nM da concentração intracelular de cálcio em cortes tratados com EGTA durante 15 minutos. Estas proteínas são necessárias em grandes quantidades durante a atividade neuronal na zona das dendrites para ativar os enzimas dependentes de cálcio\calmodulina. A CaM regula uma serie de processos biológicos como por exemplo na regulação da ativação das cinases Ca2+/CaM-dependentes e pela sua grande afinidade com o cálcio. Para obter um conhecimento mais avançado sobre a interação destas duas proteínas analisou-se se estas respondem a estímulos de alta frequência de uma forma coordenada. Verificou-se que apos estímulo existia uma mobilização da CaM e da Ng para os dendrites indicando que a CaM e Ng são necessárias na zona dos dendrites durante atividade neuronal. Em estudos em células sem a capacidade de expressar a Ng a CaM não era mobilizada com a mesma eficácia registada em células normais que expressam a Ng. Verificou-se também que a mobilização da CaM também depende da ativação de recetores NMDA já que na presença do inibidor AP5 a mobilização não foi tão eficaz como em condições normais. Concluiu-se que a mobilidade da CaM e da Ng da soma para as dendrites depende da variação da concentração de cálcio e que esta mesma mobilização dá-se também numa situação de estímulo eletrofisiológico.
Calmodulin (CaM) and neurogranina (Ng) are two proteins expressed in nerve cells, primarily localized in the soma and nucleus in cells in the hippocampus. It was detected that there was a mobilization of calmodulin and neurogranina from the soma to the dendrites when was induced a variation of calcium concentration by the addition of a chelating agent (EGTA). Knowing the intracellular calcium concentration is 100 nM, by the ratio of fluorescence intensity is possible to estimate the concentration of calcium, It was found that the concentration intracellular of calcium decreases 40 nM in slices treated with EGTA for 15 min. These proteins are required in large quantities during neuronal activity in the area of dendrites to activate the enzymes calcium-calmodulin dependents. The CaM regulates a number of biological processes such as the regulation of activation of kinases Ca2 + / CaM-dependents and its high affinity for calcium. For a more advanced knowledge about the interaction of these two proteins examined whether these stimuli respond to high frequency in a coordinated way. It was found that after stimulation there was a mobilization of CaM and Ng for the dendrites indicating that CaM and Ng are needed in the area of dendrites during neuronal activity. In studies on cells lacking the ability to express Ng, the CaM was not mobilized as effectively recorded in normal cells with expression of Ng. It was also found that mobilization of CaM also depends on activation of NMDA receivers since the presence of the inhibitor AP5, the mobilization of CaM was not as effective as under normal conditions. It was concluded that the mobility of CaM and Ng sum for the dendrites depends on the variation of the concentration of calcium mobilization and that the same occurs also in a situation electrophysiological stimulus.
Calmodulin (CaM) and neurogranina (Ng) are two proteins expressed in nerve cells, primarily localized in the soma and nucleus in cells in the hippocampus. It was detected that there was a mobilization of calmodulin and neurogranina from the soma to the dendrites when was induced a variation of calcium concentration by the addition of a chelating agent (EGTA). Knowing the intracellular calcium concentration is 100 nM, by the ratio of fluorescence intensity is possible to estimate the concentration of calcium, It was found that the concentration intracellular of calcium decreases 40 nM in slices treated with EGTA for 15 min. These proteins are required in large quantities during neuronal activity in the area of dendrites to activate the enzymes calcium-calmodulin dependents. The CaM regulates a number of biological processes such as the regulation of activation of kinases Ca2 + / CaM-dependents and its high affinity for calcium. For a more advanced knowledge about the interaction of these two proteins examined whether these stimuli respond to high frequency in a coordinated way. It was found that after stimulation there was a mobilization of CaM and Ng for the dendrites indicating that CaM and Ng are needed in the area of dendrites during neuronal activity. In studies on cells lacking the ability to express Ng, the CaM was not mobilized as effectively recorded in normal cells with expression of Ng. It was also found that mobilization of CaM also depends on activation of NMDA receivers since the presence of the inhibitor AP5, the mobilization of CaM was not as effective as under normal conditions. It was concluded that the mobility of CaM and Ng sum for the dendrites depends on the variation of the concentration of calcium mobilization and that the same occurs also in a situation electrophysiological stimulus.
Description
Projeto final da licenciatura, Bioquímica, Faculdade de Ciências e Tecnologia da Universidade do Algarve, 2012
Keywords
Neurogranina Neurónios Cálcio