In PSD-95, Dig, ZO-1/DIg-homologous region (PDZ) 3-truncated mutant mice in which LTD could not be induced but LTP was found to be enhanced, we found a subtle, yet preferential displacement of synaptic N-methyl-D-aspartate
receptor subunit 2B (NR2B) subunits in lateral regions of the synapse without affecting changes in the localization of N-methyl-D-aspartate WZB117 clinical trial receptor subunit 2A (NR2A) subunits. In persistent inhibitory alpha CaMKII Thr305 substituted with Asp in alpha-isoform of calcium-calmodulin kinase II (T305D) mutant mice with severely impaired LTP but stable LTD expression, we found a selective reduction of NR2A subunits at both the synapse and throughout the cytoplasm of the spine without any effect on the NR2B subunit. In an experiment of mutual exclusivity, neither PSD-95 nor aCaMKII localization was found to be affected by mutations to the corresponding PSD protein suggesting that they are functionally independent of the other in the regulation of NR2A- and NR2B-containing NMDARs preceding synaptic activity. Consequently, there may exist at least two distinct PSD-95 and alpha CaMKII-specific
NMDAR complexes involved in mediating LTP and LTD through opposing signal transcluction pathways in synapses of the hippocampus. The contrasting phenotypes of the PSD-95 and alpha CaMKII mutant mice further establish the prospect of an independent and, possibly, competing mechanism check details for the regulation of NMDAR-dependent bidirectional synaptic plasticity. (C) 2008 IBRO. Published by Elsevier Ltd. All rights reserved.”
“Introduction: Atherosclerotic plaque microvessels are associated with plaque hemorrhage and rupture. The mechanisms underlying plaque angiogenesis are largely unknown. Angiopoietin (Ang)-1 and -2 are ligands of the endothelial receptor Tie-2. Ang-1 induces formation of stable vessels, whereas Ang-2 destabilizes the interaction between endothelial cells and their support cells. We studied the expression
patterns of Ang-1 and -2 in relation to plaque microvessels. Methods and Results: Carotid endarterectomy specimens were studied (n = 100). Microvessel density (MVD) was correlated with the however presence of macrophages and with a (fibro) atheromatous plaque phenotype. A negative correlation was observed between Ang-1 expression and MVD. A positive correlation was observed between the ratio of Ang-2/Ang-1 and MVD. Ang-2 expression was correlated with matrix metalloproteinase-2 (MMP-2) activity. Immunohistochemical staining of Ang-1 was observed in smooth muscle cells, whereas Ang-2 was detected in endothelial cells, smooth muscle cells and macrophages. Conclusions: In plaques with high MVD, the local balance between Ang-1 and Ang-2 is in favor of Ang-2. Plaque Ang-2 levels are associated with MMP-2 activity.