Title

Interaction of CreP with PP1c in the Unfolded Protein Response of Human Cells

Poster Number

52

Lead Author Major

Pre-Dentistry

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

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Apr 20th, 1:00 PM Apr 20th, 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.