PhD Defence for Ahmad Abd-El-Aziz, PhD Environmental Sciences

Wednesday, October 13th, 10:00 AM in the Health Sciences Building Room 106 or by web conference

Title: Proteomic Evidence for a Plausible Epigenetic Effect on Equine Cell Differentiation Under Heat Stress

Abstract:

To learn about the potential effects of extreme heat, which can be a consequence of climate change, the effects of heat as a proxy for climate stress on a cell’s gene expression were investigated. In particular, the aim of this thesis was to determine the impact of heat stress on cell differentiation in an equine stem cell model through the outcome of heat stress on the proteome, which is the complete set of proteins expressed by an organism. The proteins identified could then be used to ascertain whether new biomarkers of chronic heat stress will emerge or whether we will identify potential targets for future treatment. 

Proteomic analysis was performed using mass spectrometry to compare relative protein abundances among three cell types, mesenchymal stem cells (MSCs), osteoblasts, and adipocytes, cultured at two temperatures, 37°C and 42°C.  The survival of the cells was validated using cell staining and observation of the cellular differentiation process and the heat stress was validated by Western Blotting, using an anti-Hsp90 antibody to quantify Hsp90 elevation in response to elevated cell culture temperature. All cell lines survived at 42°C, and all showed a higher level of HSP90 expression as well, showing that cell culture at 42°C had a physiological effect on the cells.  Furthermore, not only were the proteins’ relative abundances dependent on cell type and the application of heat stress individually, but many proteins only differed in relative abundance among the three cell types when cultured at different temperatures, showing a cell type-specific response to heat stress.  Many of these proteins were involved in cell-signalling pathways such as Notch and Wnt signalling, which are known to regulate cell development in vitro and embryonic development in vivo.  If the effects on the proteome were a result of epigenetic mechanisms, then the altered proteome during differentiation may have long-term effects. 

Future research is required to investigate the potential epigenetic changes in these cells, such as changes in DNA methylation in select genes.  This cell-culture model of cell differentiation could also be applied to test the impact of other forms of stress, such as inflammatory stress caused by biological mediators, on cell development, or on other cell lines, such as human cells

In-person attendance is welcome with masks required. Members of the UPEI community and the general public are welcome. Seating is limited. If attending via the web is preferred, please contact the Graduate Studies Coordinator at gsc@upei.ca for the web link to the web conference.