Paper - Ras in neuron
Arendt T, Heumann R. et al. (2004) Neuronal activation of Ras regulates synaptic connectivity. Eur. J. Neurosci. 19:2953-66
Effects of expression of constitutively active Ras in neurons (synapsin promoter) on morphology, synaptic plasticity of cortical neurons.
[My comments] Roles of Ras-MapK pathway in synaptic plasiticity are still not clear. Many studies have shown LTP and memory are affected by map kinase inactivation. Also, accute expression of dominant negative Ras showed blocking of LTP (Zhu et al.,2000). However, genetic perturbation of Ras showed inconsistent results: both HRas knockout (Manabe et al., 2000) and active-Ras overexpression (above) enhance LTP. Also, because Ras is activated sufficiently by calcium from calcium channels evoked by depolarization ( Dolmetsch et al. 2001, Baldassa S 2003) which usually does not produce LTP, Ras activation is probably not sufficient for producing LTP. BDNF also activates Ras, but usually it is not sufficient to enhance synaptic transmission. Together with the above study, Ras-MapK might act as postsynaptic activity sensor, and enhance the cell reactivity to NMDA-R calcium.
