Interaction of CreP with PP1c in the Unfolded Protein Response of Human Cells
Poster Number
52
Format
Poster Presentation
Faculty Mentor Name
Doug Weiser
Faculty Mentor Department
Biological Sciences
Abstract/Artist Statement
When the amount of unfolded proteins in the endoplasmic reticulum exceeds the folding capacity available, the consequent ER stress activates the unfolded protein response (UPR). Excessive stress can lead to cell death (apoptosis), so the UPR is physiologically significant to cell and tissue survival. As a response, the cell phosphorylates the eukaryotic translation initiation factor alpha subunit (eIF2 alpha) on serine 51 to inhibit protein translation. Two proteins, GADD34 and CReP, function as negative feedback inhibitors to suppress UPR. Stress-induced GADD34 dephosphorylation of eIF2 alpha differs from CReP phosphatase activity, which constitutively regulates basal levels of eIF2 alpha phosphorylation in unstressed cells. Both proteins complex with phosphatase PP1c to bind and dephosphorylate eIF2 alpha. Past work on GADD34 has identified domains present on the C-terminus of the protein that are necessary for binding PP1c. Not much is currently known about the necessary domains for PP1c-binding in CReP. Point mutations were made within the amino acid sequence of the conserved region of CReP, allowing us to study which regions of the protein must be present for PP1c binding. We have been working with HEK293T cancer cells, performing transfections with the gene encoding regulatory CreP. Treatment of the cells with stress-inducing thapsigargin drug led to production of protein, and the treatments were then analyzed by Western blotting. Through this, we hope to learn more about CReP’s role in mediating stress resistance, within the wider context of understanding prevention of human diseases like cancer, diabetes, and neurodegenerative disorders.
Location
DeRosa University Center, Ballroom
Start Date
20-4-2013 1:00 PM
End Date
20-4-2013 3:00 PM
Interaction of CreP with PP1c in the Unfolded Protein Response of Human Cells
DeRosa University Center, Ballroom
When the amount of unfolded proteins in the endoplasmic reticulum exceeds the folding capacity available, the consequent ER stress activates the unfolded protein response (UPR). Excessive stress can lead to cell death (apoptosis), so the UPR is physiologically significant to cell and tissue survival. As a response, the cell phosphorylates the eukaryotic translation initiation factor alpha subunit (eIF2 alpha) on serine 51 to inhibit protein translation. Two proteins, GADD34 and CReP, function as negative feedback inhibitors to suppress UPR. Stress-induced GADD34 dephosphorylation of eIF2 alpha differs from CReP phosphatase activity, which constitutively regulates basal levels of eIF2 alpha phosphorylation in unstressed cells. Both proteins complex with phosphatase PP1c to bind and dephosphorylate eIF2 alpha. Past work on GADD34 has identified domains present on the C-terminus of the protein that are necessary for binding PP1c. Not much is currently known about the necessary domains for PP1c-binding in CReP. Point mutations were made within the amino acid sequence of the conserved region of CReP, allowing us to study which regions of the protein must be present for PP1c binding. We have been working with HEK293T cancer cells, performing transfections with the gene encoding regulatory CreP. Treatment of the cells with stress-inducing thapsigargin drug led to production of protein, and the treatments were then analyzed by Western blotting. Through this, we hope to learn more about CReP’s role in mediating stress resistance, within the wider context of understanding prevention of human diseases like cancer, diabetes, and neurodegenerative disorders.