Interleukin (IL)-1beta is a proinflammatory cytokine implicated in various pathophysiological conditions of the CNS involving NMDA receptor activation. Circumstantial evidence suggests that IL-1beta and NMDA receptors can functionally interact. Using primary cultures of rat hippocampal neurons, we investigated whether IL-1beta affects NMDA receptor function(s) by studying (1) NMDA receptor-induced [Ca2+]i increase and (2) NMDA-mediated neurotoxicity. IL1beta (0.01-0.1 ng/ml) dose-dependently enhances NMDA-induced [Ca2+]i increases with a maximal effect of approximately 45%. This effect occurred only when neurons were pretreated with IL-1beta, whereas it was absent if IL-1beta and NMDA were applied simultaneously, and it was abolished by IL-1 receptor antagonist (50 ng/ml). Facilitation of NMDA-induced [Ca2+]i increase by IL-1beta was prevented by both lavendustin (LAV) A (500 nm) and 4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine (PP2) (1 microm), suggesting an involvement of tyrosine kinases. Increased tyrosine phosphorylation of NMDA receptor subunits 2A and 2B and coimmunoprecipitation of activated Src tyrosine kinase with these subunits was observed after exposure of hippocampal neurons to 0.05 ng/ml IL-1beta. Finally, 0.05 ng/ml IL-1beta increased by approximately 30% neuronal cell death induced by NMDA, and this effect was blocked by both lavendustin A and PP2. These data suggest that IL-1beta increases NMDA receptor function through activation of tyrosine kinases and subsequent NR2A/B subunit phosphorylation. These effects may contribute to glutamate-mediated neurodegeneration.

Background: Members of membrane-bound disintegrin metalloproteinases (ADAMs) were shown to be capable of cleaving amyloid precursor protein (APP) at the ␣cleavage site in different cell systems. One of the candidate ␣-secretases identified in this family is ADAM10. The present study addresses the following major questions: 1) Are the levels of an ␣-secretase candidate (i.e., ADAM10) reduced in accessible cells of Alzheimer Disease (AD) patients? 2) Are ADAM10 levels in the peripheral cells of AD patients related to a concomitant decrease in ␣APPs? Materials and Methods: Western Blot analysis of ADAM10 is performed on platelet homogenates from 33 sporadic AD patients and on 26 age-matched control subjects. Moreover, the levels of ␣-secretase metabolite (␣APPs) are tested both in platelets and cerebrospinal

NMDA receptor, Ca 2ϩ /calmodulin-dependent protein kinase II (␣CaMKII), and postsynaptic density 95 (PSD-95) are three major components of the PSD fraction. Both ␣CaMKII and PSD-95 have been shown previously to bind NR2 subunits of the NMDA receptor complex. The nature and mechanisms of targeting to the NMDA receptor subunits are, however, not completely understood. Here we report that the C-terminal NR2A(S1389-V1464) sequence was sufficient to guarantee the association of both native and recombinant ␣CaMKII and PSD-95. was able to compete with the binding of both native and recombinant ␣CaMKII to the NR2A C-tail. Accordingly, ␣CaMKII(1-325) competes with both the native PSD-95 and the native kinase itself for the binding to NR2A. In addition, Ser/Ala1289 and Ser/Asp1289 point mutations on the unique CaMKII phosphosite of NR2A did not significantly influence the binding of native ␣CaMKII and PSD-95 to the NR2A C-tail. Finally, the association-dissociation of ␣CaMKII and PSD-95 to and from the NR2A C-tail was significantly modulated by activation of NMDA receptor achieved by either pharmacological tools or long-term potentiation induction, underlining the importance of dynamic and reciprocal interactions of NMDA receptor, ␣CaMKII, and PSD-95 in hippocampal synaptic plasticity. Key words: ␣CaMKII; LTP; NMDA; postsynaptic density; PSD-95; synaptic plasticityA mature synapse is capable of modulating its efficacy by means of activity-dependent plasticity events. Such a process might in turn modulate the structural organization of specific synaptic compartment, i.e., the postsynaptic density (PSD), in which clustering of ligand-gated receptors to scaffolding proteins and to enzymes can be dynamically regulated (Ziff, 1997). PSD consists of a complex network of interacting proteins involved in the regulation of synaptic function and modulation of postsynaptic responses. PSDs are enriched in ionotropic AMPA and NMDA glutamate receptors Kennedy, 1997Kennedy, , 1998. NMDA receptors are of major interest because they are involved in synaptogenesis, neuronal circuitry formation, synaptic plasticity, and learning and memory, as well as in the molecular pathogenesis of neurological disorders (Hollmann and Heinemann, 1994;During et al., 2000). NMDA receptors are oligomeric complexes formed by the coassembly of members of three receptor subunit families: NR1, NR2 subfamily (NR2A-D; Hollmann and Heinemann, 1994), and NR3A (Das et al., 1998). Among NR2 subunits, whose expression is developmentally regulated, NR2A is expressed in the adult rat brain in the large majority of synapses (Monyer et al., 1994). Because of its anatomical localization and expression onset, NR2A is likely to play a major role in synaptic plasticity modulating long-term potentiation (LTP) and long-term depression. In fact, animals with C-terminal truncation of postnatally expressed NR1/NR2A heteromeric receptors, but with an intact NR1/NR2B complex, exhibit impaired hippocampal LTP (Sprengel et al., 1998). In PSD, NR2A and NR2B subunits directly interact w...