Syntaxins are members of the SNARE complex and play a role in vesicle fusion. In neurons, the most studied syntaxin is syntaxin 1 which is involved in the exocytosis of synaptic vesicles. Distributions and functions of other syntaxin subtypes in the nervous system are not as well defined and can be better understood by identifying the location of each syntaxin subtype in neuronal tissues. Preliminary immunogold electron microscopy has localized syntaxins 1, 3, and 4 to axonal, soma/dendritic, and astroglial plasma membranes, respectively. In parallel to immunoEM studies, my project was to distinguish neuronal versus glial localization of particular syntaxin subtypes by biochemical techniques. Western blots are used to compare the presence of these syntaxins in hippocampal neuronal cultures, which contain a mixture of both neurons and glia, and glial cultures, which contain almost exclusively glial cells. The strategy is validated by analyzing samples with two well-tested antibodies as markers, one specific for an astroglial protein, GFAP, and the other specific for a neuronal protein, CaMKII. Experiments using subtype specific syntaxin antibodies show exclusive presence of syntaxin 1A in neuronal cultures consistent with previous reports. Syntaxin 3 appears to be present in both neuronal and glial cultures. It cannot be unequivocally determined yet whether syntaxin 4 is prominent in neurons or glia because different anti-syntaxin 4 antibodies show inconclusive results. These biochemical results largely complement immunoEM observations for differential localization of syntaxin subtypes in neurons and glia.
Last updated December 14, 2012