title: Phosphorylation-dependent regulation of stability and transforming potential of ETS transcriptional factor ESE-1 by p21-activated kinase 1.
abstract: Differential phosphorylation of transcription factors by signal transduction pathways play an important role in regulation of gene expression and functions. ESE-1 is an epithelium-specific ETS transcription factor that transforms human breast epithelial cells through a serine- and aspartic acid-rich domain (SAR) by an unknown cytoplasmic mechanism. Here we found that a signaling kinase, p21-activated kinase-1 (Pak1), interacts with and phosphorylates ESE-1. Interestingly, Pak1 selectively phosphorylates ESE-1 at Ser(207), which is located within the SAR domain. A S207A substitution in ESE-1 reduced its ability to transform breast cancer cells. We also found that ESE-1 is a labile protein and by interacting with F-box-binding protein beta-TrCP, undergoes ubiquitin-dependent proteolysis. Intriguingly, Pak1 phosphorylation inactive mutant ESE1-S207A is more unstable than either wild-type ESE-1 or its Pak1 phosphorylation mimetic mutant, i.e. ESE1-S207E. These findings provide novel insights into the mechanism of transformation potential of ESE-1 and discovered that ESE-1 functions are coordinately regulated by Pak1 phosphorylation and beta-TrCP-dependent ubiquitin-proteasome pathways.
authors.affiliation: Department of Molecular and Cellular Oncology, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030, USA.
authors.forename: Bramanandam
authors.initials: B
authors.lastname: Manavathi
authors.forename: Suresh K
authors.initials: SK
authors.lastname: Rayala
authors.forename: Rakesh
authors.initials: R
authors.lastname: Kumar
mesh_terms: D045744:Cell Line, Tumor; D002471:Cell Transformation, Neoplastic / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D005260:Female; D006801:Humans; D020125:Mutation, Missense; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational / Q000235:genetics; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary / Q000235:genetics; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D050783:Proto-Oncogene Proteins c-ets; D015398:Signal Transduction / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D044844:beta-Transducin Repeat-Containing Proteins / Q000235:genetics / Q000378:metabolism*; D054462:p21-Activated Kinases
chemical_list: C471644:BTRC protein, human; D004268:DNA-Binding Proteins; C105529:ELF3 protein, human; D011518:Proto-Oncogene Proteins; D050783:Proto-Oncogene Proteins c-ets; D014157:Transcription Factors; D044844:beta-Transducin Repeat-Containing Proteins; C515903:PAK1 protein, human; D017346:Protein Serine-Threonine Kinases; D054462:p21-Activated Kinases