title: Proliferating cell nuclear antigen is required for loading of the SMCX/KMD5C histone demethylase onto chromatin.
abstract: BACKGROUND
  Histone methylation is regulated by a large number of histone methyltransferases and demethylases. The recently discovered SMCX/KMD5C demethylase has been shown to remove methyl residues from lysine 4 of histone H3 (H3K4), and constitutes an important component of the regulatory element-1-silencing transcription factor (REST) protein complex. However, little is known about the cellular mechanisms that control SMCX activity and intracellular trafficking.
  
  
  RESULTS
  In this study, we found that small interfering RNA-mediated knockdown of proliferating cell nuclear antigen (PCNA) resulted in the reduction of the chromatin-bound SMCX fraction. We identified a PCNA-interaction protein motif (PIP box) in the SMCX protein. Using site-directed mutagenesis, we found that the amino acids of the SMCX PIP box are involved in the association of SMCX with PCNA and its interaction with chromatin.
  
  
  CONCLUSIONS
  Our data indicate that the intracellular trafficking of SMCX is controlled by its association with PCNA.
authors: Division of Infectious Diseases - Center for Human Virology, Department of Medicine, Thomas Jefferson University, Philadelphia, PA 19107, USA. rene.daniel@jefferson.edu.
authors: Zhihui
authors: Z
authors: Liang
authors: Marc
authors: M
authors: Diamond
authors: Johanna A
authors: JA
authors: Smith
authors: Matthias
authors: M
authors: Schnell
authors: René
authors: R
authors: Daniel