Glial inflammation and neurodegeneration induced by candoxin, a novel neurotoxin from Bungarus candidus venom: Global gene expression analysis using microarray

Candoxin (PDB #1JGK), a three-finger neurotoxin from Bungarus candidus venom, inhibits post-synaptic neuromuscular and neuronal α7nACh-receptors, and induces delayed cell-death throughout the glial population. When applied to cultured human glial cell lines, candoxin (CDX) induced cell death in a concentration (EC₅₀∼1 μM) and time dependent manner. Results of TUNEL-histochemistry further confirm CDX-induced brain (hippocampus, frontal cortex, and temporal regions) damage when administered intracerebroventricularly (i.c.v) in adult mice. In this study, we explored differential gene expression profiles following exposure of human glial (Hs 683) cell lines to CDX at various time intervals using Affymetrix-GeneChips. By means of MAS and GeneSpring analyses, 105 genes whose expression was significantly (P<0.01) altered by at least 3-fold were selected. Results of the genome analysis reveal that the potential role of CDX at molecular level involves the regulation of genes in signal transduction, ubiquitin-inflammation, mitochondrial-dysfunction, and damage-response pathways. In addition, using QRT-PCR and rationally designed specific CDX-binding peptide (P-NT.II), we identified the genes - IL7R, IL13RA2, IL-1β, TNFRSF12A, GADD45A, CD44 and IFI44 - that might play an important role in CDX-induced glial inflammation, DNA-damage and degeneration. These findings reveal new insight into the molecular mechanisms of glial-driven neurodegeneration after exposure to neurotoxins.