| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2002: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 2001: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Research Abstract |
Mitogen-activated protein (MAP) kinase plays important roles in the establishment of long term potentiation both in vitro and in living animals. MAP kinase is activated in response to a broad range of stimuli including calcium influx through N-methyl-D-aspartate (NMDA) receptor and L-type calcium channel, cAMP, and neurotrophins. To investigate the role of Ras in the activation of MAP kinase and CREB (cAMP response element-binding protein) in hippocampal neurons, we inhibited Ras function by overexpressing a Ras GTPase- activating protein, Gap1m, or dominant negative Ras by means of adenovirus vectors. Gap1m expression almost completely suppressed MAP kinase activation in response to NMDA, calcium ionophore, membrane depolarization, forskolin, and brain-derived neurotrophic factor (BDNF). Dominant negative Ras also showed the similar effects. On the other hand, Rap1 GAP did not significantly inhibit the forskolin-induced activation of MAP kinase. These results demonstrate that Ras transduces signals elicited by a broad range of stimuli to MAP kinase in hippocampal neurons.
We also analyzed Rap1 function in cultured cells. Upon introduction of factors that activated Rap1, enhancement of cell adhesion property was observed. Dominant negative Rap1 blocked this enhancement and dominat active Rap1 strongly activated the cell adhesion, suggenting the role of Rap1 in cell adhesion.
Moreover, we made a gene targeting mouse for Rin, a Ras-like GTPase expressed secifically only in neuronal tissues. This Rin knockout mouse maybe very useful for the functional study of Rin in vivo.
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