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Mapping the ubiquitination sites of the transcriptional repressor ICER
Author(s) -
Woldeamanuel Fanaye Bezunesh,
Crow Marni,
Sebasco Ethan,
Molina Carlos A.
Publication year - 2013
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.27.1_supplement.782.9
Subject(s) - subcellular localization , repressor , ubiquitin , cytosol , lysine , mutant , biology , microbiology and biotechnology , chemistry , biochemistry , transcription factor , gene , amino acid , cytoplasm , enzyme
Inducible cAMP Early Repressor (ICER) is a dominant negative transcriptional repressor that expresses tumor suppressor activity. In cancer cells, ICER is abnormally expressed and becomes modified by ubiquitination. Consequentially, ICER is degraded or re‐localized from the nucleus to the cytosol where it is non‐functional. When ICER is reintroduced into cancer cells, it inhibits the transformed phenotype of cancer cells. The goal of this project is to map the specific ubiquitinated lysines on ICER to define the functional consequences of ICER ubiquitination and cytosolic localization. Eleven mutant forms of ICER were constructed using site‐directed mutagenesis. All lysine residues were substituted to arginine to create an ICER molecule without lysines. Another 10 independent mutants were generated where all but one specific lysine was substituted by arginine. All clones were subcloned in a mammalian expression vector. By using these altered forms of ICER, we have found that ICER is ubiquitinated in several lysines. This data suggested alternative modes of regulating ICER degradation and subcellular localization. The long‐term goal of this project is to identify ways of inhibiting ICER degradation in cancer cells as a new mode for cancer treatment. This project was supported by a grant from the Sokol Institute of Pharmaceutical Sciences, College of Science and Mathematics, Montclair State University.