Combined exposure to Maneb and Paraquat alters transcriptional regulation of neurogenesis-related genes in mice models of Parkinson’s disease
Parkinson's disease (PD) is a multifactorial disease where environmental factors act on genetically predisposed individuals. Although only 5% of PD manifestations are associated with specific mutations, majority of PD cases are of idiopathic origin, where environment plays a prominent role. Concurrent exposure to Paraquat (PQ) and Maneb (MB) in rural workers increases the risk for PD and exposure of adult mice to MB/PQ results in dopamine fiber loss and decreased locomotor activity. While PD is characterized by neuronal loss in the substantia nigra, we previously showed that accumulation of α-synuclein in the limbic system contributes to neurodegeneration by interfering with adult neurogenesis.
We investigated the effect of pesticides on adult hippocampal neurogenesis in two transgenic models: Line 61, expressing the human wild type SNCA gene and Line LRRK2(G2019S), expressing the human LRRK2 gene with the mutation G2019S. Combined exposure to MB/PQ resulted in significant reduction of neuronal precursors and proliferating cells in non-transgenic animals, and this effect was increased in transgenic mice, in particular for Line 61, suggesting that α-synuclein accumulation and environmental toxins have a synergistic effect. We further investigated the transcription of 84 genes with direct function on neurogenesis. Overexpresion of α-synuclein resulted in the downregulation of 12% of target genes, most of which were functionally related to cell differentiation, while LRRK2 mutation had a minor impact on gene expression. MB/PQ also affected transcription in non-transgenic backgrounds, but when transgenic mice were exposed to the pesticides, profound alterations in gene expression affecting 27% of the studied targets were observed in both transgenic lines. Gene enrichment analysis showed that 1:3 of those genes were under the regulation of FoxF2 and FoxO3A, suggesting a primary role of these proteins in the response to genetic and environmental cues.
We report that adult neurogenesis is highly susceptible to multiple “risk factors” for PD, including α-synuclein accumulation, LRRK2 G2019 mutation and exposure to environmental toxins. We identified specific groups of genes that are responsive to each stressor, while uncovering a novel function for Fox transcription factors in PD.
- Combined exposure to Maneb and Paraquat alters transcriptional regulation of neurogenesis-related genes in mice models of Parkinson’s disease
- Open Access
- Available under Open Access This content is freely available online to anyone, anywhere at any time.
- Online Date
- September 2012
- Online ISSN
- BioMed Central
- Additional Links
- Adult neurogenesis
- Parkinson’s disease
- Environmental exposure
- Gene expression
- Gene x environment interactions
- Author Affiliations
- 1. Department of Neuroscience, University of California San Diego, 9500 Gilman Dr., MTF 344, La Jolla, CA, 92093-0624, USA
- 3. Laboratory for Chemistry and Metabolism, Tokyo Metropolitan Institute for Neuroscience, Tokyo, 183-8526, Japan
- 2. Department of Pathology, University of California San Diego, 9500 Gilman Dr., La Jolla, CA, 92093-0624, USA