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Doctoral Dissertation Announcement
Candidate: Derrick S. Hilton
Doctor of Philosophy
Department: Biological Sciences
Title: Exogenous Alpha-Synuclein Induces Cell Death Related Proteins in C6 Oligodendrocyte-like Cells Corresponding to Protein Expression Observed in Multiple System Atrophy
Dr. Charles F. Ide, Chair
Dr. John M. Spitsbergen
Dr. Christine A. Byrd-Jacobs
Dr. Rob R. Eversole
Date: Thursday, June 14, 2012 9:00 a.m. to 11:00 a.m.
1710 Wood Hall
Multiple System Atrophy (MSA) consists of three disorders; Autonomic Dysfunction, Cerebellar Ataxia, and Parkinsonism. In MSA, the protein Alpha-Synuclein (SNCA) appears in the central nervous system as misfolded protein aggregates primarily in oligodendrocytes. This thesis reports the results from studies examining the effect exogenous SNCA has on a cell model; C6 oligodendrocyte-like cells. Treated cells were evaluated using western blot and DNA microarray. In addition the expression of proteins was also evaluated using immunocytochemistry in MSA patients.
C6 cells were shown to take up SNCA when added to the media. SNCA also underwent a truncation when taken up by C6 cells. SNCA induced cell death in C6 cells in a dose dependent manner. SNCA also induced changes in expression of Caspase 3 (CASP3), a marker for apoptosis.
In C6 cells treated with SNCA, two apoptosis related genes, Programmed Cell Death 4 (PDCD4) and Pancreatic Derived Factor (FAM3B) showed changes in protein expression. These changes appeared to correspond to expression of CASP3. In MSA patients, FAM3B, PDCD4 and CASP3 appeared to be expressed in fibers containing myelin basic protein, a marker for oligodendrocytes, suggesting a relationship with the disease.
Cells treated with SNCA undergo changes in gene expression. In cells treated with SNCA, 3 genes were upregulated and 20 genes were downregulated. Many of these genes were related to microtubules, apoptosis and/or the AKT/PI3K/mTOR pathway.
One gene of interest, Hook Homolog 3 (HOOK3), was evaluated via western blot. After treatment with SNCA, HOOK3 protein showed a decrease in expression that confirmed the decrease in gene expression of HOOK3 observed in the DNA microarray. In MSA patients, HOOK3 co-localized with SNCA in the granule cell layer of control patients and decreased in granule cell layer of MSA patients. Interestingly, as HOOK3 and SNCA decreased in the granule cell layer, HOOK3 co-localized with SNCA in the white matter tracks of MSA patients.
Overall these results confirm that C6 cells treated with exogenous SNCA function as a model for MSA. The treatment of SNCA also appeared to influence proteins related to the AKT/PI3K/mTOR pathway, potentially regulating apoptosis.