Graduate Seminar Series: Molecular Stream
Graduate Seminar Series for the Institute of Biomedical Engineering (BME). This day is for molecular stream presenters.
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Presentation Title: Towards a Live-Cell Fluorescent Biosensor to Image Beta-cell Endoplasmic Reticulum Stress
Abstract: Endoplasmic Reticulum (ER) stress is caused by an accumulation of misfolded proteins. When unmitigated, it results in metabolic dysfunction and apoptosis, and is a key mechanism responsible for the progression of beta-cell failure leading to Type 2 Diabetes. In response to protein misfolding, a transmembrane stress-sensing protein called IRE1α can activate the Unfolded Protein Response (UPR). In the early stages of the UPR, protein translation is attenuated to allow for refolding and repair. If unsuccessful, degradation of protein and RNA begins, and apoptosis may be triggered. To measure the dynamics of ER stress in living beta-cells, we are developing a genetically encoded sensor based on IRE1α. This sensor uses a fluorescent protein-tagged IRE1α, which homo-oligomerizes to dimeric and tetrameric conformations under early and chronic ER stress, respectively. These conformational changes can be quantified through changes in the fluorescent polarization ratio of the sensor. To validate this sensor, we have demonstrated the sensor responds to chemical and physiological (high glucose) stress induction in a rat beta-cell line (INS-1E) and mouse islets. Preliminary data suggest that UPR-associated XBP1 mRNA splicing is highly correlated with sensor response. Furthermore, individual cells with the highest sensor response (correlating to late-stage UPR) show elevated levels of pro-apoptotic protein TXNIP. These data are consistent with a working sensor that can be used to investigate ER stress dynamics in beta-cells.
Supervisor Name: Jonathan Rocheleau
Year of Study: 2
Program of Study: PhD
Zoom link: https://us02web.zoom.us/j/89610372821?pwd=azd4SCtYVWtreVovaGNPV1c2NGY2Zz09
Meeting ID: 896 1037 2821
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