UC San Diego

Drug sensitization is thought to arise through changes in transcription, modification of signaling, and synaptic transmission. A novel rat gene, mrt1, may contribute to this neuronal plasticity as it is upregulated during sensitization. Mrt1 contains a PX domain which classifies it as a sorting nexins- thus mrt1 is also called SNX27. In addition, SNX27 also has a PDZ domain which has been demonstrated to interact with and mediate GIRK channel trafficking. To explore this interaction and the role that SNX27 may play in sensitization it is necessary to localize SNX27 expression. Using a novel SNX27 antibody I had three aims for my Masters project. First, to characterize the specificity of the antibody. Second, to characterize SNX27 expression in the brain, particularly in the hippocampus. Third, to correlate this expression back to an interaction with GIRK channels. The SNX27 antibody demonstrated good specificity for SNX27 protein. SNX27 was found to be ubiquitously expressed in nearly all regions of the brain, with particularly noticeable expression in the hippocampus. SNX27 was expressed in the principle cells of the DG, CA3, and CA1; as well as in glia throughout the hippocampus. Colocalization studies suggested possible SNX27 expression in cell bodies, dendrites, and axons. Perisomatic punctate expression was also seen, suggesting a vesicular localization of SNX27. GIRK3 expression was mostly axonal and did not correlate well with SNX27 expression. However, punctate GIRK3 expression was seen in cells displaying similar SNX27 expression, alluding to possible overlap in GIRK3 and SNX27 vesicular expression