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Date of Award

5-2009

Document Type

Campus Access

Degree Name

Doctor of Philosophy (PhD)

Degree Program

Animal Biotechnology and Biomedical Sciences

First Advisor

Barbara A. Osborne

Second Advisor

Juan Anguita

Third Advisor

Pablo Visconti

Subject Categories

Cell Biology | Molecular Biology

Abstract

Nur77, an orphan nuclear receptor, plays a key role in T cell apoptosis. As a transcription factor, Nur77 is assumed to exert its functions by driving the expression of target genes. However, Nur77 targets in T cell apoptosis are unknown. In cancer cell lines, Nur77 can induce apoptosis through the intrinsic apoptotic pathway but it remains controversial how Nur77 kills T cells. In this study, we provide biochemical, pharmacological and genetic evidence demonstrating that Nur77 induces apoptosis through the activation of the intrinsic pathway in T cells. We also show that Nur77 is a physiological substrate of the MEK-ERK-RSK-cascade. Specifically, we demonstrate that RSK phosphorylate Nur77 at serine 354 and this modulates Nur77 nuclear export and intracellular translocation during T cell death. Our data reveal that Nur77 phosphorylation and mitochondrial targeting, regulated by RSK, may define a role for the MEK1/2-ERK1/2 cascade in T cell apoptosis.

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