Figure 4
CaMKII-dependent regulation of Rap1 activity. (a) Quantification of active Rap1 and active Ras immunoreactivity in the dendrites of CaMKIIα KI or wild-type neurons. Data are presented as the mean ± SEM, (neurons at 21–22 DIV, Rap1; n = 42 and 27 cells from 4 independent cultures of wild-type and CaMKIIα KI hippocampi, Ras; n = 32 and 33 cells from 5 independent cultures of wild-type and CaMKIIα KI hippocampi), *p < 0.05, t-test. (b) Immunoreactivity of active Rap1 in the dendrites of hippocampal neurons at 22–23 DIV and immunostaining for the presynaptic marker vGluT1 or the postsynaptic marker synGAP. Active Rap1-positive punctae are either colocalized with (arrows) or separated from (arrowheads) the synaptic markers. Bar, 5 µm. (c) Immunocytochemistry of KN93-treated neurons exposed to the anti-active Rap1 antibody. The intensity of active-Rap1 punctae at synGAP-positive postsynaptic sites was lower in neurons treated with KN93 (arrows). Bar, 5 µm. (d) Quantification of active Rap1 immunoreactivity at synGAP-positive postsynaptic sites indicates that Rap1 activity is negatively regulated by KN93. Data are presented as the mean ± SEM, (neurons at 20–22 DIV, n = 22 cells from 3 independent cultures for both control (KN92) and KN93 treatment), ***p < 0.001, t-test.
