Pax6 influences expression patterns of genes involved in neurodegeneration

Background: Pax6, a highly conserved multifunctional transcription factor, has been critical for neurogenesis and neuronal plasticity. It is presumed that if level of Pax6 approaches either low or null, critical genes responsible for maintaining functional status of neurons or glia would be modulated. Purpose: Therefore, it has been intended to explore possibility of either direct or indirect influence of Pax6 in neurodegeneration. Methods: The cell lines having origin of murine embryonic fibroblast (Pax6-non expressing, NIH3T3-cell line), murine neuroblastoma (Pax6-expressing brain-derived, Neuro-2a-cell line), and human glioblastomaastrocytoma (U87MG) were cultured and maintained in a CO2 incubator at 37 degrees C and 5% CO2 in DMEM containing 10% fetal bovine serum. The knockdown of endogenous Pax6 in Neuro-2a cells was achieved through siRNA based gene knock-down approach. The efficiency and validation of knock-down was done by real time PCR. The knock-down of Pax6 was successfully achieved. Results: The levels of expression of transcripts of some of the proposed putative markers of neurodegeneration like Pax6, S100 beta, GFAP, BDNF, NGN2, p73 alpha, p73 delta, LDH, SOD, and Catalase were analyzed in Pax6 knockdown condition for analysis of role of Pax6 in neurodegeneration. Since the Pax6 has been proposed to bind to promoter sequences of catalase, and catalase suppresses TGF beta, relative lower levels of catalase in Neuro-2a and U-87MG as compared to NIH-3T3 indicates a possible progressive dominant negative impact of Pax6. However, presence of SOD and LDH indicates alternative protective mechanism. Conclusion: Presence of BDNF and TGFa indicates association between them in glioblastoma-astrocytoma. Therefore, Pax6 seems to be involved directly with p53 and TGF beta mediated pathways and indirectly with redox-sensitive pathway regulation. The neurodegenerative markers S100 beta, GFAP, BDNF, NGN2, p73a, p73d, observed downregulated in Pax6 knockdown condition suggest Pax6-mediated regulation of these markers. Observations enlighten Pax6-mediated influences on cascades of genes involved in growth, differentiation and maturation of neurons and glia.