Dissertation/Thesis Abstract

Microspherule Protein Msp58 and Ubiquitin Ligase EDD Form a Stable Complex that Regulates Cell Proliferation
by Benavides, Mario, Ph.D., City University of New York, 2013, 122; 3561768
Abstract (Summary)

A complex molecular network is put into place at specific phases of the cell cycle to prevent unscheduled cell division that could result in malignant cell growth. Emerging evidence shows that still uncharacterized proteins play crucial functions at those cell cycle transition points. Nuclear protein Msp58 and EDD E3 ubiquitin ligase have been implicated in different aspects of cell proliferation and reported to be abnormally expressed in numerous types of cancers. The molecular mechanisms underlying Msp58 and EDD functions, however, are not well understood. The work presented here shows that Msp58 and EDD form a stable protein complex that regulates cell viability and proliferation. Interestingly, knockdown of EDD by RNA interference leads to a significant accumulation of Msp58 protein, which suggests that EDD serves as a negative regulator of Msp58. In addition, our in vivo ubiquitination assays and analyses of various cell lines treated with translational and proteasomal inhibitors demonstrate that Msp58 is regulated post-translationally by the ubiquitin-proteasome pathway. These results imply that EDD ligase activity is involved in this regulatory process. Using flow cytometry analyses and biochemical characterization of Msp58 and/or EDD depleted cells, we show that the Msp58-EDD complex plays important roles in cell cycle progression via the control of cyclin gene expression. In particular, silencing Msp58 and/or EDD alters the protein levels of cyclins B, D and E. Taken together, our data suggest that a set of the biological roles attributed to Msp58 and EDD may be executed in the context of the complex that they form, thereby revealing a novel molecular mechanism for these two proteins to accomplish their functions.

Indexing (document details)
Advisor: Zhong, Hualin
Commitee: Kleiman, Frida, Loayza, Diego, Pinol-Roma, Serafin, Worman, Howard
School: City University of New York
Department: Biology
School Location: United States -- New York
Source: DAI-B 74/09(E), Dissertation Abstracts International
Subjects: Molecular biology, Cellular biology
Keywords: Cell cycle, Cell proliferation, Cyclins, E3 ubiquitin ligase, Microspherule proteins, Nucleoplasm, Ubiquitin-proteasome pathway
Publication Number: 3561768
ISBN: 9781303091056
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