Dancing in and out of the nucleus: p120(ctn) and the transcription factor Kaiso.
The catenin p120 (hereafter p120(ctn)) was first identified as a Src kinase substrate and subsequently characterized as an Armadillo catenin member of the cell-cell adhesion cadherin-catenin complex. In the past decade, many studies have revealed roles for p120(ctn) in regulating Rho family GTPase activity and E-cadherin stability and turnover, events that occur predominantly at the plasma membrane or in the cytoplasm. However, the recent discovery of the nuclear BTB/POZ-ZF transcription factor Kaiso as a p120(ctn) binding partner, coupled with the detection of p120(ctn) in the nucleus of some cell lines and tumor tissues, suggested that like the classical beta-catenin, p120(ctn) undergoes nucleocytoplasmic trafficking and regulates gene expression. Indeed, p120(ctn) has a classic nuclear localization signal and does traffic to the nucleus. Moreover, nuclear p120(ctn) regulates Kaiso DNA-binding and transcriptional activity, similar to beta-catenin's modulation of TCF/LEF transcription activity. However unlike beta-catenin, p120(ctn) does not appear to be a transcriptional activator. Hence it remains to be determined whether the sole role of nuclear p120(ctn) is regulation of Kaiso or whether p120(ctn) binds and regulates other transcription factors or nuclear proteins.
Daniel
Juliet M
JM
Department of Biology, LSB-331, McMaster University, 1280 Main St. West, Hamilton, ON, Canada L8S 4K1. danielj@mcmaster.ca
D021581:Active Transport, Cell Nucleus; D000818:Animals; D051177:Catenins; D015815:Cell Adhesion Molecules / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism*; D006801:Humans; D008954:Models, Biological; D009369:Neoplasms / Q000378:metabolism; D019913:Nuclear Localization Signals; D010750:Phosphoproteins / Q000378:metabolism*; D021381:Protein Transport; D012097:Repressor Proteins / Q000737:chemistry / Q000378:metabolism; D015398:Signal Transduction; D014157:Transcription Factors / Q000737:chemistry / Q000378:metabolism*; D014158:Transcription, Genetic; D051153:Wnt Proteins / Q000378:metabolism; D016335:Zinc Fingers; D051176:beta Catenin / Q000378:metabolism; D000095002:Delta Catenin
D051177:Catenins; D015815:Cell Adhesion Molecules; D019913:Nuclear Localization Signals; D010750:Phosphoproteins; D012097:Repressor Proteins; D014157:Transcription Factors; D051153:Wnt Proteins; D051176:beta Catenin; D000095002:Delta Catenin; C000722347:CTNND1 protein, human