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A. Giddabasappa, W. Xiao, B. Xu, S. Mukherjee, S. Chaney, M. Brooks, R. Khanna, A. Swaroop, D. A. Fox; Gene Profiling and Patterning in the Mouse Retina During Gestational Lead Exposure (GLE). Invest. Ophthalmol. Vis. Sci. 2008;49(13):3086. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
GLE increases and prolongs the proliferation of retinal progenitor cells, which results in an increase in late-born rods and bipolar cells, but not Müller glial cells in adult retina [ARVO 2007]. The molecular mechanisms responsible for this novel retinal phenotype are unknown. Our goals were to identify the genes, clusters and signaling pathways specific for the novel phenotypic changes observed in the adult GLE retinas.
C57BL/6 female mice were exposed to water or lead throughout gestation (E) and until postnatal day (PN) 10: a period equivalent to human gestation. RNA from E16.5, E18.5, PN2, PN6 and PN10 C57BL/6 control and GLE retinas was isolated and gene expression was analyzed by Affymetrix mouse genome array. Stringent threshold and statistical procedures were used to identify differentially expressed genes in control [ARVO 2007] and GLE retinas and then to compare these data sets. A real-time qPCR SuperArray custom microarray was used to validate and extend these results. Pathway analysis was performed using Ariadne’s Pathway Studio software.
Control and GLE retinas had 4, 899 and 5,144 differentially expressed genes, respectively. These were sorted into five distinct clusters based on their differential pattern and level of expression. Clusters 2, 3 and 5 were upregulated and clusters 1 and 4 were downregulated. Significant cluster-specific changes between control and GLE retinas were found at selected days in clusters 2, 3 and 4. In cluster 4, Gene Ontology analysis showed that genes associated with the cell cycle were significantly upregulated at PN6 in the GLE retinas. Pathway analysis of these differentially expressed genes with Ariadne’s software revealed CDC2 as the major hub, and CCND1 and CCNB1 as minor hubs. SuperArray analysis validated and extended these results by revealing upregulation of Cdc2, Ccnd1 and Ccnb1 and other cell cycle genes at E18.5, PN2 and PN6 in GLE retinas.
The combination of cluster, pathway and SuperArray results reveal that genes associated with the regulation of cell cycle were significantly upregulated during GLE. These results are consistent with our developmental (E16.5 to PN10) BrdU and Ki67 confocal data. Future studies will examine the spatiotemporal protein expression of these cell cycle genes and their regulators with immunoblots and immunohistochemistry.
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