title: Regulation of rDNA transcription by proto-oncogene PELP1.
abstract: BACKGROUND
  Proline-, glutamic acid-, and leucine-rich protein (PELP1) is a novel nuclear receptor coregulator with a multitude of functions. PELP1 serves as a scaffolding protein that couples various signaling complexes with nuclear receptors and participates as a transcriptional coregulator. Recent data suggest that PELP1 expression is deregulated in hormonal cancers, and that PELP1 functions as a proto-oncogene; however, the mechanism by which PELP1 promotes oncogenesis remains elusive.
  
  
  RESULTS
  Using pharmacological inhibitors, confocal microscopy and biochemical assays, we demonstrated that PELP1 is localized in the nucleolus and that PELP1 is associated with the active ribosomal RNA transcription. Cell synchronization studies showed that PELP1 nucleolar localization varies and the greatest amount of nucleolar localization was observed during S and G2 phases. Using pharmacological compounds and CDK site mutants of PELP1, we found that CDK's activity plays an important role on PELP1 nucleolar localization. Depletion of PELP1 by siRNA decreased the expression of pre-rRNA. Reporter gene assays using ribosomal DNA (pHrD) luc-reporter revealed that PELP1WT but not PELP1MT enhanced the expression of reporter. Deletion of nucleolar domains abolished PELP1-mediated activation of the pHrD reporter. ChIP analysis revealed that PELP1 is recruited to the promoter regions of rDNA and is needed for optimal transcription of ribosomal RNA.
  
  
  CONCLUSIONS
  Collectively, our results suggest that proto-oncogene PELP1 plays a vital role in rDNA transcription. PELP1 modulation of rRNA transcription, a key step in ribosomal biogenesis may have implications in PELP1-mediated oncogenic functions.
authors.affiliation: Department of Obstetrics and Gynecology, and Cancer Therapy and Research Center, University of Texas Health Science Center, San Antonio, Texas, United States of America.
authors.forename: Vijay K
authors.initials: VK
authors.lastname: Gonugunta
authors.forename: Binoj C
authors.initials: BC
authors.lastname: Nair
authors.forename: Rajib
authors.initials: R
authors.lastname: Rajhans
authors.forename: Gangadhara R
authors.initials: GR
authors.lastname: Sareddy
authors.forename: Sujit S
authors.initials: SS
authors.lastname: Nair
authors.forename: Ratna K
authors.initials: RK
authors.lastname: Vadlamudi
mesh_terms: D021581:Active Transport, Cell Nucleus; D002453:Cell Cycle; D002466:Cell Nucleolus / Q000378:metabolism; D056970:Co-Repressor Proteins / Q000737:chemistry / Q000378:metabolism*; D018844:Cyclin-Dependent Kinases / Q000378:metabolism; D004275:DNA, Ribosomal / Q000235:genetics*; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D010766:Phosphorylation; D011401:Promoter Regions, Genetic / Q000235:genetics; D017434:Protein Structure, Tertiary; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins / Q000737:chemistry / Q000378:metabolism*; D014157:Transcription Factors / Q000737:chemistry / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D056970:Co-Repressor Proteins; D004275:DNA, Ribosomal; C000715470:MAS1 protein, human; C438485:PELP1 protein, human; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins; D014157:Transcription Factors; D018844:Cyclin-Dependent Kinases