Evidence that phosphorylation by the mitotic kinase Cdk1 promotes ICER monoubiquitination and nuclear delocalization

• Published in: Experimental cell research Vol. 317; no. 17; pp. 2490 - 2502
• Main Authors: Mémin, Elisabeth, Genzale, Megan, Crow, Marni, Molina, Carlos A.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 15.10.2011; Elsevier BV
• Subjects: 60 APPLIED LIFE SCIENCES; AMP; Animals; CDC2 Protein Kinase - metabolism; Cdk1; CELL NUCLEI; Cell Nucleus - metabolism; CELL PROLIFERATION; Cyclic AMP Response Element Modulator - metabolism; Cytosol - chemistry; Cytosol - metabolism; Gene loci; HeLa Cells; Humans; ICER; Male; Mitosis; NEOPLASMS; Phosphorus content; PHOSPHORYLATION; PROSTATE; Prostatic Neoplasms - metabolism; Prostatic Neoplasms - pathology; Rats; Tumor Cells, Cultured; Ubiquitination; Cdk1; Phosphorylation; Ubiquitination; ICER
• ISSN: 0014-4827; 1090-2422
• DOI: 10.1016/j.yexcr.2011.07.001

In contrast to normal prostatic cells, the transcriptional repressor Inducible cAMP Early Repressor (ICER) is undetected in the nuclei of prostate cancer cells. The molecular mechanisms for ICER abnormal expression in prostate cancer cells remained largely unknown. In this report data is presented demonstrating that ICER is phosphorylated by the mitotic kinase cdk1. Phosphorylation of ICER on a discrete residue targeted ICER to be monoubiquitinated. Different from unphosphorylated, phosphorylated and polyubiquitinated ICER, monoubiquitinated ICER was found to be cytosolic. Taken together, these results hinted on a mechanism for the observed abnormal subcellular localization of ICER in human prostate tumors.