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 exper- iments were conducted to investigate potential pathways or mechanisms by which Cd may contribute to cataract formation and ocular disease. Zebrafish larvae (72, 96, and 120 hours post fertilization), adult zebrafish (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 zebrafish larvae and RNA sequencing (RNA-Seq) for adult zebrafish and HLE cells. Gene Ontology (GO) enrichment analysis for the zebrafish 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 zebrafish exposure (50 μM Cd for 4 hours) enriched the “embryonic eye morphogenesis” gene set and significant genes involved in enrichment (tcf7l1a, pitx2, fzd8a, sfrp5, lmx1bb, mfap2, six3b, lum, phactr4b, and foxc1a) were down-regulated. GSEA for the 10-month female zebrafish (50 μM Cd for 4 hours) enriched the “photoreceptor cell differentiation” gene set and significant 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 zebrafish 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 setting the foundation for identification of the molecular mechanisms contributing to ocular diseases.
We haven’t been travelling much this year, but our collaborators have been busy!
Dearborn, D.C., A.B. Gager, A.G. McArthur, M.E. Gilmour, E. Mandzhukova, R.A. Mauck. 2017. How to get diverse MHC genotypes without disassortative mating. Presentation at the 2017 Annual Meeting of the Society for Integrative and Comparative Biology, New Orleans, Louisiana.
McLean, M., D. Theriault, M. Kelley, B.A. Lago, A.G. McArthur, & L. Williams. 2017. Role of Nfe2 and pro-oxidant exposure in inner ear development in zebrafish. Presentation at the Society of Toxicology 56rd Annual Meeting, Baltimore, Maryland.
Williams, L.M., B.A. Lago, A.G. McArthur, A.R. Raphenya, N. Pray, N. Saleem, S. Salas, K. Paulson, R.S. Mangar, Y. Liu, A.H. Vo, & J.A. Shavit. 2017. The transcription factor, Nuclear factor, erythroid 2 (Nfe2), is a regulator of the oxidative stress response during Danio rerio development. Presentation at the Society of Toxicology 56rd Annual Meeting, Baltimore, Maryland.
Winsor, G.L., C. Bertelli, K.K. Tsang, B. Alcock, A.G. McArthur, & F.S.L. Brinkman. 2017. Pseudomonas Genome Database 2017: Improved gene/AMR/VF/genomic island annotations, comparative genome analyses, and a platform for facilitating public health genomic epidemiology. Presentation at the 16th International Conference on Pseudomonas, Liverpool, United Kingdom.
This month we say farewell to Briony Lago as she returns to her undergraduate studies in Chemical Biology at McMaster. Briony joined us as part of her Chemical Biology Co-Op program and worked on both human muscle atrophy and zebrafish toxicology transcriptome studies, as well a curation of the Comprehensive Antibiotic Resistance Database. Her publications are below, with more on the way. Briony was also awarded a 2016 IIDR Summer Student Fellowship for her work. Good luck Briony!
- Jia, B., A.R. Raphenya, B. Alcock, N. Waglechner, P. Guo, K.K. Tsang, B.A. Lago, B.M. Dave, S. Pereira, A.N. Sharma, S. Doshi, M. Courtot, R. Lo, L.E. Williams, J.G. Frye, T. Elsayegh, D. Sardar, E.L. Westman, A.C. Pawlowski, T.A. Johnson, F.S.L. Brinkman, G.D. Wright, & A.G. McArthur. 2017. CARD 2017: expansion and model-centric curation of the Comprehensive Antibiotic Resistance Database. Nucleic Acids Research, 45, D566-573.
- Williams, L.M, B.A. Lago, A.G. McArthur, A.R. Raphenya, N. Pray, N. Saleem, S. Salas, K. Paulson, R.S. Mangar, Y. Liu, A.H. Vo, & J.A. Shavit. 2016. The transcription factor, Nuclear factor, erythroid 2 (Nfe2), is a regulator of the oxidative stress response during Danio rerio development. Aquatic Toxicology, 180, 141-154.
Three of our undergraduate students gave poster presentations in the last month. Arjun Sharma (Biochemistry & Biomedical Sciences 3rd year) outlined his work on developing the Comprehensive Antibiotic Resistance Database’s (arpcard.mcmaster.ca) CARD*Shark text mining algorithms at the Michael G. DeGroote Institute for Infectious Disease Research (IIDR) Trainee Day while Kirill Pankov (Biomedical Discovery & Commercialization 4th year) presented the results of his summer NSERC Undergraduate Student Research Award (USRA) research in the Laboratory of Dr. Joanna Wilson into the origin of Cnidarian P450 enzymes, work he is continuing in our lab as part of his thesis research. Mohammad Khan (Biomedical Discovery & Commercialization 4th year), a thesis student in the Laboratory of Dr. Eric Brown that collaborates with our group, also presented a poster at IIDR Trainee Day on his work on chemical-genetic interaction database design.
Sharma, A.N., S. Doshi, A.R. Raphenya, B. Alcock, B.M. Dave, B.A. Lago, K.K. Tsang, & A.G. McArthur. 2016. CARDShark: Computer-assisted biocuration of the Comprehensive Antibiotic Resistance Database. Poster presentation at the 2016 Michael G. DeGroote Institute for Infectious Disease Research (IIDR) Trainee Day, Hamilton, Ontario, Canada.
Pankov, K., A.G. McArthur & J.Y. Wilson. 2016. The Cytochrome P450 (CYP) superfamily in the Cnidarian phylum. Poster presentation at the 2016 Undergraduate Student Research Awards (USRA) Poster Session, Hamilton, Ontario, Canada.
Khan, M.A., S. French, B. Aubie, A.G McArthur & E.D. Brown. 2016. Challenging common screening filters through analysis of a chemical-genetic screening database. Poster presentation at the 2016 Michael G. DeGroote Institute for Infectious Disease Research (IIDR) Trainee Day, Hamilton, Ontario, Canada.
Development is a complex and well-defined process characterized by rapid cell proliferation and apoptosis. At this stage in life, a developmentally young organism is more sensitive to toxicants as compared to an adult. In response to pro-oxidant exposure, members of the Cap’n’Collar (CNC) basic leucine zipper (b-ZIP) transcription factor family (including Nfe2 and Nfe2-related factors, Nrfs) activate the expression of genes whose protein products contribute to reduced toxicity. Here, we studied the role of the CNC protein, Nfe2, in the developmental response to pro-oxidant exposure in the zebrafish (Danio rerio). Following acute waterborne exposures to diquat or tert-buytlhydroperoxide (tBOOH) at one of three developmental stages, wildtype (WT) and nfe2 knockout (KO) embryos and larvae were morphologically scored and their transcriptomes sequenced. Early in development, KO animals suffered from hypochromia that was made more severe through exposure to pro-oxidants; this phenotype in the KO may be linked to decreased expression of alas2, a gene involved in heme synthesis. WT and KO eleutheroembryos and larvae were phenotypically equally affected by exposure to pro-oxidants, where tBOOH caused more pronounced phenotypes as compared to diquat. Comparing diquat and tBOOH exposed embryos relative to the WT untreated control, a greater number of genes were up-regulated in the tBOOH condition as compared to diquat (tBOOH: 304 vs diquat: 148), including those commonly found to be differentially regulated in the vertebrate oxidative stress response (OSR) (e.g. hsp70.2, txn1, and gsr). When comparing WT and KO across all treatments and times, there were 1170 genes that were differentially expressed, of which 33 are known targets of the Nrf proteins Nrf1 and Nrf2. More specifically, in animals exposed to pro-oxidants a total of 968 genes were differentially expressed between WT and KO across developmental time, representing pathways involved in coagulation, embryonic organ development, body fluid level regulation, erythrocyte differentiation, and oxidation-reduction, amongst others. The greatest number of genes that changed in expression between WT and KO occurred in animals exposed to diquat at 2h post fertilization (hpf). Across time and treatment, there were six genes (dhx40, cfap70, dnajb9b, slc35f4, spi-c, and gpr19) that were significantly up-regulated in KO compared to WT and four genes (fhad1, cyp4v7, nlrp12, and slc16a6a) that were significantly down-regulated. None of these genes have been previously identified as targets of Nfe2 or the Nrf family. These results demonstrate that the zebrafish Nfe2 may be a regulator of both primitive erythropoiesis and the OSR during development.
Kara Tsang (graduate, McMaster BDC) – Kara did her BiomedDC 4A15 thesis in the lab, focused on Pseudomonas resistome prediction and cystic fibrosis-associated metagenomic sequencing and starts September 2016 as MSc student in the area of clinical AMR analytics, particularly metagenomics. Her work will be part of our recently funded Genome Canada grants, as well as part of McMaster’s clinical genome sequencing efforts.
Krishna Srinivasan (graduate, McMaster Biology) – Krishna just finished his undergraduate degree in McMaster’s Biology department, with a thesis in environmental toxicology. He starts as a MSc student September 2016, collaborating with the Jenny lab (UAlabama) on our recently funded NIH grant examining the role of MTF-1 in lens development and cataractogenesis.
CIHR (G. Steinberg, McMaster University, Canada) Gene Environment Team on Brown/beige Adipose Tissue (GET_BAT). In this project we will conduct studies in cells, mice and humans to examine how agricultural and food processing practices may regulate brown adipose tissue metabolic activity directly or indirectly by altering the billions of bacteria that reside within our gastrointestinal tract.
NIH/NIEHS (M. Jenny, University of Alabama, USA) The role of MTF-1 as a mediator of ocular toxicity. The major goals of this project are to characterize the role of MTF-1 in regulating genes involved in eye development.
NIH/NIEHS (A. Timme-Laragy, University of Massachusetts Amherst) Activation of Nrf2 during embryonic development: mechanisms and consequences. Examining the possible regulatory role of Nrf2 in early embryonic development, with emphasis upon molecular responses to oxidative stress.
Briony Lago has joined the lab as part of her McMaster Chemical Biology Co-Op program. She will be working on our ‘Omic’ Responses & Inactivity in Aging project (a collaboration with colleagues in Kinesiology & Chemistry, see here) as well as our collaboration with Bates College on the role of Nfe2 in the oxidative stress response during zebrafish development (see here).