title: RNA expressions of AHR, ARNT and CYP1B1 are influenced by AHR Arg554Lys polymorphism.
abstract: OBJECTIVE
  The aryl hydrocarbon receptor (AHR) is a ligand activated transcription factor that together with Aryl Hydrocarbon Receptor Nuclear Translocator (ARNT) controls the expression of Xenobiotic metabolising enzymes (XME) such as CYP1B1. In the absence of exogenous ligands, AHR is supposed to be involved in promotion of cell cycle progression. Polymorphisms of the AHR gene are suggested to be associated with susceptibility to cancer. Because of its critical role in xenobiotic induced toxicity and carcinogenesis as well as its ligand independent relevance we investigated the effects of AHR Arg554Lys Polymorphism on gene expression level of the AHR, ARNT and CYP1B1.
  
  
  METHODS
  Detection of the AHR Arg554Lys polymorphism of the AHR gene was performed by rapid capillary PCR with melting curve analysis. The quantitative Real-Time PCR (qRT-PCR) of AHR, ARNT and CYP1B1 mRNAs was carried out in white blood cells from 287 Caucasians. Calculations of expression were made with the 2(-ΔΔCT) method.
  
  
  RESULTS
  The relative AHR mRNA expression revealed significant differences between the two homozygote AHR genotypes Arg554Arg (11.0±1.0; n=228) and Lys554Lys (0.6±0.4; n=3; p<0.001). Also significant differences were seen between the heterozygote genotype Arg554Lys (13.0±3.0; n=40) and the homozygote Lys554Lys genotype (0.6±0.4; n=3; p<0.001). These differences above were replicated significantly in the relative mRNA expression of ARNT and CYP1B1. Comparing the determined CT-values, a correlation coefficient of R=0.748 for AHR and ARNT, R=0.626 for ARNT and CYP1B1 as well as R=0.533 for AHR and CYP1B1 was calculated.
  
  
  CONCLUSIONS
  Our findings suggest that the homozygote variant genotype of AHR Lys554Lys is associated with a significantly lower AHR, ARNT and CYP1B1 mRNA expression.
authors: Institut und Poliklinik für Arbeits- und Sozialmedizin, Justus-Liebig-Universität, Aulweg 129, D-35392 Giessen, Germany. Simone.Helmig@arbmed.med.uni-giessen.de
authors: Simone
authors: S
authors: Helmig
authors: Jens Udo
authors: JU
authors: Seelinger
authors: Juliane
authors: J
authors: Döhrel
authors: Joachim
authors: J
authors: Schneider
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019943:Amino Acid Substitution / Q000235:genetics*; D001189:Aryl Hydrocarbon Hydroxylases / Q000235:genetics* / Q000378:metabolism; D051784:Aryl Hydrocarbon Receptor Nuclear Translocator / Q000235:genetics* / Q000378:metabolism; D065633:Cytochrome P-450 CYP1B1; D005260:Female; D005786:Gene Expression Regulation; D005787:Gene Frequency / Q000235:genetics; D005838:Genotype; D006801:Humans; D008297:Male; D008875:Middle Aged; D020641:Polymorphism, Single Nucleotide / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D018336:Receptors, Aryl Hydrocarbon / Q000235:genetics* / Q000378:metabolism; D055815:Young Adult
chemical_list: D012333:RNA, Messenger; D018336:Receptors, Aryl Hydrocarbon; D051784:Aryl Hydrocarbon Receptor Nuclear Translocator; D001189:Aryl Hydrocarbon Hydroxylases; C585496:CYP1B1 protein, human; D065633:Cytochrome P-450 CYP1B1