The roles of co-chaperone CCRP/DNAJC7 in Cyp2b10 gene activation and steatosis development in mouse livers

PLoS One. 2014 Dec 26;9(12):e115663. doi: 10.1371/journal.pone.0115663. eCollection 2014.


Cytoplasmic constitutive active/androstane receptor (CAR) retention protein (CCRP and also known as DNAJC7) is a co-chaperone previously characterized to retain nuclear receptor CAR in the cytoplasm of HepG2 cells. Here we have produced CCRP knockout (KO) mice and demonstrated that CCRP regulates CAR at multiple steps in activation of the cytochrome (Cyp) 2b10 gene in liver: nuclear accumulation, RNA polymerase II recruitment and epigenetic modifications. Phenobarbital treatment greatly increased nuclear CAR accumulation in the livers of KO males as compared to those of wild type (WT) males. Despite this accumulation, phenobarbital-induced activation of the Cyp2b10 gene was significantly attenuated. In ChIP assays, a CAR/retinoid X receptor-α (RXRα) heterodimer binding to the Cyp2b10 promoter was already increased before phenobarbital treatment and further pronounced after treatment. However, RNA polymerase II was barely recruited to the promoter even after phenobarbital treatment. Histone H3K27 on the Cyp2b10 promoter was de-methylated only after phenobarbital treatment in WT but was fully de-methylated before treatment in KO males. Thus, CCRP confers phenobarbital-induced de-methylation capability to the promoter as well as the phenobarbital responsiveness of recruiting RNA polymerase II, but is not responsible for the binding between CAR and its cognate sequence, phenobarbital responsive element module. In addition, KO males developed steatotic livers and increased serum levels of total cholesterol and high density lipoprotein in response to fasting. CCRP appears to be involved in various hepatic regulations far beyond CAR-mediated drug metabolism.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Aryl Hydrocarbon Hydroxylases / genetics
  • Aryl Hydrocarbon Hydroxylases / metabolism*
  • Cytochrome P450 Family 2
  • Epigenesis, Genetic
  • Fatty Liver / genetics
  • Fatty Liver / metabolism*
  • Heat-Shock Proteins
  • Histones / metabolism
  • Liver / metabolism*
  • Male
  • Mice
  • Molecular Chaperones
  • Phenobarbital / pharmacology
  • Protein Binding
  • Protein Transport
  • RNA Polymerase II / metabolism
  • Receptors, Cytoplasmic and Nuclear / genetics
  • Receptors, Cytoplasmic and Nuclear / metabolism*
  • Response Elements / drug effects
  • Retinoid X Receptor alpha / metabolism
  • Steroid Hydroxylases / genetics
  • Steroid Hydroxylases / metabolism*
  • Transcriptional Activation


  • Dnajc7 protein, mouse
  • Heat-Shock Proteins
  • Histones
  • Molecular Chaperones
  • Receptors, Cytoplasmic and Nuclear
  • Retinoid X Receptor alpha
  • Steroid Hydroxylases
  • Aryl Hydrocarbon Hydroxylases
  • Cyp2b10 protein, mouse
  • Cytochrome P450 Family 2
  • RNA Polymerase II
  • Phenobarbital