Identification of Novel Targets of the Human Cell Cycle Regulatory Protein Cdc34
Annual summary 1 Jul 96-30 Jun 99
BAYLOR COLL OF MEDICINE HOUSTON TX
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The goal of this project was to understand the role of human ubiquitin-conjugating enzyme UBC, hCdc34 in normal and malignant mammary cells. To elucidate the mode of hCdc34 action in human cells, we used a genetic assay called two-hybrid cloning to identify proteins that interact with hCdc34, screening 1.5 million human cDNAs. Thirty cDNA clones found to be active in this assay were isolated and analyzed. Four of these clones are previously known regulators of meiosis and spermatogenesis, including two that belong to the bZIP family of transcriptional repressors, and one has distinct role in sister chromatid cohesion and DNA double strand break repair. We have authenticated the two-hybrid interactions by clearly demonstrating the targeting of three repressors of cAMP-induced transcription, hICERII gamma, hATF5 and CREM beta by hCdc34 and a structurally similar UBC enzyme, hRad6B for ubiquitin-proteasome mediated proteolysis Pati et. al., 1999, Mol Cell Biol 19 5001-13. This study provides novel information that stability of specific mammalian transcription factors is the result of complex targeting by multiple UBC enzymes, and may have far reaching physiologic implications in cAMP-inducible gene regulation which governs diverse cellular processes including cell cycle and oncogenesis. These results will also be critical to designing new therapeutic strategies that could modulate the activity of the Cdc34 enzyme to prevent the growth andor genesis of breast tumor.
- Genetic Engineering and Molecular Biology
- Medicine and Medical Research