Vision is a crucial aspect of life for humans and animals. Impaired vision can lead
to reduced quality of life along with other complications. Cataracts are a leading
cause of impaired vision and blindness worldwide. Cataracts develop as a process of
aging, although several environmental and lifestyle factors increase the risk of this
disease. The toxic metal cadmium (Cd) has been associated with cataract formation
and other ocular diseases such as macular degeneration. Cadmium exposure experiments
were conducted to investigate potential pathways or mechanisms by which
Cd may contribute to cataract formation and ocular disease. Zebra fish larvae (72,
96, and 120 hours post fertilization), adult zebra sh (6-month male, 10-month male,
and 10-month female) and the B3 human lens epithelial (HLE) cell line were acutely
exposed to varying concentrations of Cd. Transcriptomic changes relative to control
(0 μM Cd) were determined using microarray analysis for zebra sh larvae and
RNA sequencing (RNA-Seq) for adult zebra sh and HLE cells. Gene Ontology (GO)
enrichment analysis for the zebra sh larvae exposure (50 μM Cd for 4 or 8 hours)
enriched the "retina development in camera-type eye" term, and genes involved in
enrichment (dnmt1, ccna2, fen1, mcm3 and slbp) were down-regulated. Gene set
enrichment analysis (GSEA) for the 10-month male zebra sh exposure (50 μM Cd
for 4 hours) enriched the "embryonic eye morphogenesis" gene set and signi ficant
genes involved in enrichment (tcf7l1a, pitx2, fzd8a, sfrp5, lmx1bb, mfap2, six3b, lum,
phactr4b, and foxc1a) were down-regulated. GSEA for the 10-month female zebra sh
(50 μM Cd for 4 hours) enriched the "photoreceptor cell differentiation" gene set and
signi cant genes involved in enrichment (odc1, thrb, and ush2a) were up-regulated.
GO enrichment analysis for up-regulated genes in the HLE cell exposure (10 μM Cd
for 4 hours) enriched the terms "eye development" (22 genes) and "lens development
in camera-type eye" (CITED2, SKIL, CRYAB, SLC7A11, TGFB2, EPHA2, BCAR3,
WNT5B, and BMP4). These results show cadmium is capable of altering transcription
of eye-related genes in both zebra sh and human models, which may contribute
to the formation of ocular disease. Many of these genes are involved in lens and
retina development, yet they are also associated with diseases in these eye structures.
Future studies could assess the consequences of altered transcription of these genes
which could help elucidate the mechanisms of these changes and the overall effect of
cadmium exposure on ocular disease. Ultimately, our study characterized the regulation
of eye-related genes in response to Cd exposure and provided valuable knowledge
laying the foundation for identi fication of the molecular mechanisms contributing to
ocular diseases. / Thesis / Master of Science (MSc) / The eye is a sphere-like organ which is important for visualizing your surroundings. It is composed of many different structures such as the cornea, lens and retina. Many eye diseases have been characterized by abnormalities in eye structures; for example, a cataract occurs when the lens becomes cloudy and unable to focus light while macular degeneration is defined by progressive deterioration of the retinal macula region. While these diseases can occur through the natural aging process, certain environmental factors can increase risk. Exposure to cadmium, a toxic heavy metal which causes negative effects in animals, has shown to be associated with eye disease like cataracts and macular degeneration. In order to expand on this knowledge, we exposed both zebrafish and human lens cells to cadmium. By utilizing different experimental methods such as microarray analysis and RNA sequencing, eye-related genes which were affected by cadmium were revealed. Identifying the relationship between eye diseases, cadmium and gene expression will help identify the mechanism by which cadmium contributes to eye disease formation.
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/24128 |
| Date | January 2018 |
| Creators | Srinivasan, Krishna |
| Contributors | McArthur, Andrew, Biochemistry and Biomedical Sciences |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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