title: Id4 dependent acetylation restores mutant-p53 transcriptional activity.
abstract: BACKGROUND
  The mechanisms that can restore biological activity of mutant p53 are an area of high interest given that mutant p53 expression is observed in one third of prostate cancer. Here we demonstrate that Id4, an HLH transcriptional regulator and a tumor suppressor, can restore the mutant p53 transcriptional activity in prostate cancer cells.
  
  
  METHODS
  Id4 was over-expressed in prostate cancer cell line DU145 harboring mutant p53 (P223L and V274F) and silenced in LNCaP cells with wild type p53. The cells were used to quantitate apoptosis, p53 localization, p53 DNA binding and transcriptional activity. Immuno-precipitation/-blot studies were performed to demonstrate interactions between Id4, p53 and CBP/p300 and acetylation of specific lysine residues within p53.
  
  
  RESULTS
  Ectopic expression of Id4 in DU145 cells resulted in increased apoptosis and expression of BAX, PUMA and p21, the transcriptional targets of p53. Mutant p53 gained DNA binding and transcriptional activity in the presence of Id4 in DU145 cells. Conversely, loss of Id4 in LNCaP cells abrogated wild type p53 DNA binding and transactivation potential. Gain of Id4 resulted in increased acetylation of mutant p53 whereas loss of Id4 lead to decreased acetylation in DU145 and LNCaP cells respectively. Id4 dependent acetylation of p53 was in part due to a physical interaction between Id4, p53 and acetyl-transferase CBP/p300.
  
  
  CONCLUSIONS
  Taken together, our results suggest that Id4 regulates the activity of wild type and mutant p53. Id4 promoted the assembly of a macromolecular complex involving CBP/P300 that resulted in acetylation of p53 at K373, a critical post-translational modification required for its biological activity.
authors: Ashley E
authors: AE
authors: Knowell
authors: Divya
authors: D
authors: Patel
authors: Derrick J
authors: DJ
authors: Morton
authors: Pankaj
authors: P
authors: Sharma
authors: Shanora
authors: S
authors: Glymph
authors: Center for Cancer Research and Therapeutics Development, Clark Atlanta University, 223 James P, Brawley Dr, SW, Atlanta, GA 30314, USA. jchaudhary@cau.edu.
authors: Jaideep
authors: J
authors: Chaudhary
mesh_terms: D000107:Acetylation; D017209:Apoptosis; D045744:Cell Line, Tumor; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D051796:Inhibitor of Differentiation Proteins / Q000235:genetics / Q000378:metabolism*; D008239:Lysine / Q000378:metabolism*; D008297:Male; D009154:Mutation; D011471:Prostatic Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism*; D050880:p300-CBP Transcription Factors / Q000737:chemistry / Q000378:metabolism*; D000099224:p300-CBP-Associated Factor
chemical_list: D051796:Inhibitor of Differentiation Proteins; D008239:Lysine; D016159:Tumor Suppressor Protein p53; D050880:p300-CBP Transcription Factors; D000099224:p300-CBP-Associated Factor; C490128:ID4 protein, human; C495901:TP53 protein, human