Purkinje cell degeneration (pcd) mice are characterized by the postnatal death of virtually all cerebellar Purkinje cells beginning at 15 to 18 days of age, and all the Purkinje cells are almost gone by 30 days. A moderate ataxia appears by 22 to 24 days in pcd mutant. In addition, pcd mutant exhibits a slow degeneration of retinal photoreceptor cells and mitral cells in the olfactory bulb. And the male mutant has a sperm abnormality. Although pcd phenotypes are caused by mutations in ATP/GTP binding protein 1 (Agtpbpl) gene, the molecular pathway involved in Purkinje cell degeneration is poorly understood. In this study, we investigated the gene expression profiling using DNA microarray analysis between wildtype and pcd mutant mice at the age of postnatal day 20 which is before the appearance of clear phenotypic abnormalities. As a result, we identified 300 differentially expressed genes between wildtype and pcd mutant mice. Majority of them were involved in metabolism and cellular physiological process. Wildtype and mutant animals were classified into two different groups based on the expression patterns. To confirm the results, semi-quantitative RT-PCR was carried out. The genes identified in this study will provide directions and target molecules for future studies. On the other hand, in order to explore the possible molecular pathways underlying pcd phenotypes, we performed yeast two-hybrid system using three different length fragments of Agtpbpl as baits to screen mouse brain cDNA libraries to identify the interacting proteins with AgtpbpL 22 different cDNAs of 57 positive clones were identified from the screening result. ^transformations and bioinformatics analysis revealed that 6 proteins might interact with AgtpbpL 15 of 57 clones were sequenced and confirmed with cotransformation as same protein named SNAP25-associated proteins (Snapiri), which is involved into neurotransmitter release process. Further study and comprehensive analysis have to be done to confirm the interactions between Agtpbpl and 6 possible proteins in mammals to clarify the mutation mechanism inpcd mice.
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