activity-dependent shedding of the nmda receptor glycine binding site by matrix metalloproteinase 3 a putative mechanism of postsynaptic plasticity活动依赖性脱落nmda受体甘氨酸结合位点的基质金属蛋白酶3假定的突触后可塑性的机制.pdfVIP

Activity-Dependent Shedding of the NMDA Receptor Glycine Binding Site by Matrix Metalloproteinase 3: A PUTATIVE Mechanism of Postsynaptic Plasticity 1. 2. 2 2 2 Thorsten Pauly , Miriam Ratliff , Eweline Pietrowski , Rainer Neugebauer , Andrea Schlicksupp , 2 2 Joachim Kirsch , Jochen Kuhse * 1 Department of Anatomy and Cellular Neurobiology, University of Ulm, Ulm, Germany, 2 Department of Anatomy and Cell Biology, University of Heidelberg, Heidelberg, Germany Abstract Functional and structural alterations of clustered postsynaptic ligand gated ion channels in neuronal cells are thought to contribute to synaptic plasticity and memory formation in the human brain. Here, we describe a novel molecular mechanism for structural alterations of NR1 subunits of the NMDA receptor. In cultured rat spinal cord neurons, chronic NMDA receptor stimulation induces disappearance of extracellular epitopes of NMDA receptor NR1 subunits, which was prevented by inhibiting matrix metalloproteinases (MMPs). Immunoblotting revealed the digestion of solubilized NR1 subunits by MMP-3 and identified a fragment of about 60 kDa as MMPs-activity-dependent cleavage product of the NR1 subunit in cultured neurons. The expression of MMP-3 in the spinal cord culture was shown by immunoblotting and immunofluorescence microscopy. Recombinant NR1 glycine binding protein was used to identify MMP-3 cleavage sites within the extracellular S1 and S2-domains. N-terminal sequencing and site-directed mutagenesis revealed S542 and L790 as two putative major MMP-3 cleavage sites of the NR1 subunit. In conclusion, our data indicate that MMPs, and in partic