The Research Of Gene Transcriptional Regulation By Histone Binding Protein NRDc

Histone methylation is an important component of epigenetic regulation, which can regulate gene expression and participate in a variety of biological processes. We find a novel H3K4me2-binding protein NRDc during the identification of proteins which can specifically bind to different histone methylations. NRDc is a member of M16family metalloendopeptidase, which cleaves substrates upstream of Arg or Lys in basic pairs in vitro. At the cell surface, NRDc binds heparin-binding epidermal growth factor-like growth factor (HB-EGF) and enhances HB-EGF-induced cell migration. Most of the mouses which are knocked out NRDc died in48hours, and development of nervous system delayed.In this study, we find that NRDc is the first protein which binds specifically H3K4me2and it can regulate gene transcription. NRDc binds specifically H3K4me2peptide both in vivo and in vitro contrast with the peptides of unmodified H3, H3K4mel and H3K4me3. Mass Spectrometry analysis showed that NRDc interact with NCoR/SMRT-HDAC3complex, and this interaction is directly related to HDAC3. Then, we use NRDc (-/-) and NRDc (-/-FL) cell lines to do microarray experiment, and we identified some target genes by NRDc through this assay. We found that the expression level of NRDc’s target genes is significantly higher in knock out cells, which showed that NRDc repress the expression of these target genes. We found the region which NRDc binds to through chromatin immunoprecipitation experiment. NCoR and HDAC3also bind to these target genes more significantly, and the level of acetylation is lower.In general, our study provides a working model for how NRDc mediates transcriptional repression. NRDc can bind to its target genes through H3K4me2binding activity. The chromatin associated NRDc recruits NCoR/SMRT-HDAC3complex, which repress transcription through histone deacetylation.