Indiana University-Purdue University Indianapolis (IUPUI) / The MDM2-p53 feedback loop is a well-characterized pathway. p53 is a
transcription factor and regulates the transcriptional expression of genes that
encode proteins responsible for cellular senescence, cell cycle arrest,
apoptosis, and DNA repair. Various cellular stresses can result in p53
activation, including hypoxia, DNA damage by agents such as UV or IR,
oncogenic signaling, nucleotide depletion and nucleolar stress from
perturbation of ribosomal biogenesis. Under normal conditions, MDM2’s role in
the pathway is to inhibit p53 function by directly binding to this protein and
facilitating its ubiquitylation and 26S proteasome-mediated degradation.
Under stressful cellular conditions, certain proteins interact with and rescue
MDM2’s inhibition of p53. For example, upon exposure to small amounts of
Actinomycin D, rRNA transcript synthesis is stalled resulting in the release of
various ribosomal proteins including RPL5, RPL11 and RPL23; each of which
has been shown to bind MDM2 within its central acidic domain and inhibit its
ability to destabilize p53. Although the RPL5 binding region of MDM2 have
been mapped in prior investigations, the MDM2-binding region(s) of RPL5
have yet to be characterized.
By employing RPL5 deletion mutagenesis and in vitro GST-fusion
protein-protein association assays with purified proteins, this dissertation
attempts to elucidate those regions of RPL5 that may interact with MDM2.
Normalizing RPL5-WT to 1.00, our study reveals that the basic N and C-terminals
of RPL5 appear to bind with MDM2 while RPL5’s central region
displays negligible binding to the central acidic domain of MDM2. Also, the
possible meanings of these RPL5 MDM2 binding domains are discussed along
with their utilization in potential future applications.
| Identifer | oai:union.ndltd.org:IUPUI/oai:scholarworks.iupui.edu:1805/2203 |
| Date | 20 July 2010 |
| Creators | Plummer, Kevin D. |
| Contributors | Lu, Hua, Goebl, Mark, 1958-, Hurley, Thomas D., 1961- |
| Source Sets | Indiana University-Purdue University Indianapolis |
| Language | en_US |
| Detected Language | English |
| Type | Thesis |
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