During nerve regeneration, extracellular matrix (ECM) directs the rebuilding of the neuromuscular junction. Active zones for neurotransmitter release in the presynaptic plasma membrane appear to be rebuilt following cues of the synaptic ECM. Presumably, transmembrane nerve terminal ECM receptors (nerve terminal anchorage proteins) bind these synaptic ECM cues and form a link to the cytosolic, exocytotic machinery of the nerve terminal. We have identified a potential nerve terminal ECM receptor, a protein complex of 4 proteins and a transmembrane proteoglycan, SV2pg. We call this protein complex the SV2pg complex. The SV2pg complex is a component of the synaptic vesicle membrane and has the properties expected of an ECM receptor. 1) In addition to being part of the synaptic vesicle, this complex is found on the nerve terminal surface in the presynaptic plasma membrane. 2) Subcellular fractionation of electric organ demonstrates that, although most SV2pg is in synaptic vesicles, a significant amount is tightly bound to ECM. 3) We find that the purified SV2pg complex binds to a component of the electric organ ECM extracts. 4) The SV2pg complex binds to laminin. Laminin is a known component of the synaptic ECM and is abundant in electric organ ECM extracts. We propose to test the hypothesis that the SV2pg complex acts as an ECM receptor on the nerve terminal surface: l) We will fully characterize the SV2pg complex and determine how to isolate the components from one another. 2) We will determine whether the SV2pg becomes tightly associated with synaptic ECM during synaptogenesis at the neuromuscular junction. 3) We will determine whether we can block this association during synaptogenesis with antibodies to the SV2pg complex and look at the effects of this blockage on the resulting synaptic structure. 4) We will attempt to isolate the ECM ligand for the SV2pg complex and determine which component of the complex binds the ligand. As mentioned above, this ligand may be laminin. From successful completion of our research we hope to gain some understanding of the molecular events involved in building the synapse during synaptogenesis. In addition, since the SV2pg complex is a synaptic vesicle component and perhaps an ECM receptor, we may elucidate an activity-dependent adhesion mechanism of the synapse.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
2R01NS022367-09A2
Application #
2264482
Study Section
Neurology B Subcommittee 2 (NEUB)
Project Start
1985-07-01
Project End
1998-11-30
Budget Start
1994-12-01
Budget End
1995-11-30
Support Year
9
Fiscal Year
1995
Total Cost
Indirect Cost
Name
University of Washington
Department
Physiology
Type
Schools of Medicine
DUNS #
135646524
City
Seattle
State
WA
Country
United States
Zip Code
98195
Sunderland, W J; Son, Y J; Miner, J H et al. (2000) The presynaptic calcium channel is part of a transmembrane complex linking a synaptic laminin (alpha4beta2gamma1) with non-erythroid spectrin. J Neurosci 20:1009-19
Son, Y J; Scranton, T W; Sunderland, W J et al. (2000) The synaptic vesicle protein SV2 is complexed with an alpha5-containing laminin on the nerve terminal surface. J Biol Chem 275:451-60
Russell, A B; Carlson, S S (1997) Neurexin is expressed on nerves, but not at nerve terminals, in the electric organ. J Neurosci 17:4734-43
Walter, J S; Griffith, P; Sweeney, J et al. (1997) Multielectrode nerve cuff stimulation of the median nerve produces selective movements in a raccoon animal model. J Spinal Cord Med 20:233-43
Robinson, C J; Wurster, R D; Walter, J S (1997) Testing peripheral somatosensory neuroprostheses by recording from raccoon cortex. IEEE Trans Rehabil Eng 5:75-80
Carlson, S S; Iwata, M; Wight, T N (1996) A chondroitin sulfate/keratan sulfate proteoglycan, PG-1000, forms complexes which are concentrated in the reticular laminae of electric organ basement membranes. Matrix Biol 15:281-92
Snow, A D; Nochlin, D; Sekiguichi, R et al. (1996) Identification in immunolocalization of a new class of proteoglycan (keratan sulfate) to the neuritic plaques of Alzheimer's disease. Exp Neurol 138:305-17
Walter, J S; Griffith, P; Scarpine, V et al. (1996) The raccoon as an animal model for upper limb neural prosthetics. J Spinal Cord Med 19:234-41
Walter, J S; McLane, J; Cai, W et al. (1995) Evaluation of a thin-film peripheral nerve cuff electrode. J Spinal Cord Med 18:28-32
Scranton, T W; Iwata, M; Carlson, S S (1993) The SV2 protein of synaptic vesicles is a keratan sulfate proteoglycan. J Neurochem 61:29-44

Showing the most recent 10 out of 14 publications