Human enhancer of invasion 10 (HEI10), a novel ring finger protein that alters mitotic progression through regulation of cyclin B levels / Garabet G. Toby.

Format:

Book

Manuscript

Microformat

Thesis/Dissertation

Author/Creator:

Toby, Garabet G.

Contributor:

Golemis, Erica A., advisor.

University of Pennsylvania.

Language:

English

Subjects (All):

Penn dissertations--Cell and molecular biology.

Cell and molecular biology--Penn dissertations.

Cell and Molecular Biology.

Academic Dissertations as Topic.

Medical Subjects:

Cell and Molecular Biology.

Academic Dissertations as Topic.

Local Subjects:

Penn dissertations--Cell and molecular biology.

Cell and molecular biology--Penn dissertations.

Physical Description:

xi, 120 pages : illustrations (some color) ; 29 cm

Production:

2003.

Summary:

The misregulation of cell division is at the basis of a number of diseases including tumor formation in cancer. The process of cellular division is highly conserved in eukaryotes, and is dependent upon the function of proteins that are centrally involved in specification of cell cycle and cell morphology. Therefore, isolating new regulators of cell cycle progression and cell shape will identify genes that are potential targets for therapeutic agents. In a functional screen in the yeast S. cerevisiae, the human HEI10 (H&barbelow;uman E&barbelow;nhancer of I&barbelow;nvasion, clone 10) protein was identified from a HeLa cDNA library based on its ability to promote yeast agar invasion and filamentation. This phenotype is manifested by elongation of the cells and depends on the regulation of the cell cycle at the G2/M transition. HEI10 expression in yeast imposes a delay in mitotic entry. Through two-hybrid screening, the mitotic cyclin B1 and an E2 ubiquitin-conjugating enzyme were isolated as HEI10-interacting proteins. The HEI10 sequence includes a divergent RING finger motif (characteristic of E3 ubiquitin ligases), and Cdc2/cyclin binding and phosphorylation sites. Mutation of these sequences alters HEI10-dependent yeast phenotypes. In vertebrates, addition of HEI10 inhibits nuclear envelope breakdown and mitotic entry. Mechanistically, HEI10 expression reduces cyclin B levels in cycling Xenopus eggs, and reduces levels of the cyclin B ortholog Clb2p in yeast. HEI10 is itself a specific in vitro substrate of purified cyclin B/cdc2, with a TPVR motif as primary phosphorylation site. Finally, HEI10 is itself ubiquitinated in egg extracts, and is also auto-ubiquitinated in vitro . These and other points lead to a model in which HEI10 defines a divergent class of E3 ubiquitin ligase, functioning in progression through G2/M.

Notes:

Supervisor: Erica A. Golemis.

Thesis (Ph.D. in Cell and Molecular Biology) -- University of Pennsylvania, 2003.

Includes bibliographical references.

Local Notes:

University Microfilms order no.: 3095953.

OCLC:

244973226