title: p300 alters keratinocyte cell growth and differentiation through regulation of p21(Waf1/CIP1).
abstract: BACKGROUND
  p300 functions as a transcriptional co-activator to regulate many cellular responses such as cell growth, transformation, development and differentiation. It has been shown to affect the transcriptional activity of p53 which regulates p21(Waf1/CIP1) expression, however, the role of p300 in differentiation remains unclear.
  
  
  RESULTS
  Knockdown of p300 protein with short hairpin RNA (shRNA) molecules delays human neonatal foreskin keratinocyte (HFKs) differentiation. Moreover, depletion of p300 increases the proliferative capacity of HFKs, extends the life span of cells and allows differentiated HFKs to re-enter the cell cycle. Studies indicate that depletion of p300 down-regulates the acetylation and expression of p53, and chromatin immunoprecipitation (ChIP) analysis shows that induction of p21(Waf1/CIP1) in early differentiation is a result of p300 dependent activation of p53 and that depletion of p21(Waf1/CIP1) results in the delay of differentiation and a phenotype similar to p300 depletion.
  
  
  CONCLUSIONS
  p300 has a direct role in the control of cell growth and differentiation in primary epithelial cells, and p21(Waf1/CIP1) is an important mediator of these p300 functions.
authors.affiliation: Centre for Cancer Research and Cell Biology, Queen's University Belfast, Belfast, United Kingdom.
authors.forename: Ping-Pui
authors.initials: PP
authors.lastname: Wong
authors.forename: Adam
authors.initials: A
authors.lastname: Pickard
authors.forename: Dennis J
authors.initials: DJ
authors.lastname: McCance
mesh_terms: D002454:Cell Differentiation; D002455:Cell Division; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000502:physiology*; D006801:Humans; D049490:Systems Biology; D050880:p300-CBP Transcription Factors / Q000502:physiology*
chemical_list: C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; D050880:p300-CBP Transcription Factors