title: Co-ordinate regulation of the cystic fibrosis and multidrug resistance genes in cystic fibrosis knockout mice.
abstract: The cystic fibrosis (Cftr and multidrug resistance (Mdr1) genes encode structurally similar proteins which are members of the ABC transporter superfamily. These genes exhibit complementary patterns of expression in vivo, suggesting that the regulation of their expression may be co-ordinated. We have tested this hypothesis in vivo by examining Cftr and Mdr1 expression in cystic fibrosis knockout transgenic mice (Cftr(tm1CAM)). Cftr mRNA expression in Cftr(tm1CAM)/Cftr(tm1CAM) mice was 4-fold reduced in the intestine, as compared with littermate wild-type mice. All other Cftr(tm1CAM)/Cftr(tm1CAM) mouse tissues examined showed similar reductions in Cftr expression. In contrast, we observed a 4-fold increase in Mdr1 mRNA expression in the intestines of neonatal and 3- to 4-week-old Cftr(tm1CAM)/Cftr(tm1CAM) mice, as compared with age-matched +/+ mice, and an intermediate level of Mdr1 mRNA in heterozygous Cftr(tm1CAM) mice. In 10-week-old, Cftr(tm1CAM)/Cftr(tm1CAM) mice and in contrast to the younger mice, Mdr1 mRNA expression was reduced, by 3-fold. The expression of two control genes, Pgk-1 and Mdr2, was similar in all genotypes, suggesting that the changes in Mdr1 mRNA levels observed in the Cftr(tm1CAM)/Cftr(tm1CAM) mice are specific to the loss of Cftr expression and/or function. These data provide further evidence supporting the hypothesis that the regulation Cftr and Mdr1 expression is co-ordinated in vivo, and that this co-ordinate regulation is influenced by temporal factors.
authors.affiliation: Nuffield Department of Clinical Biochemistry, University of Oxford, John Radcliffe Hospital, UK.
authors.forename: A E
authors.initials: AE
authors.lastname: Trezise
authors.forename: R
authors.initials: R
authors.lastname: Ratcliff
authors.forename: T E
authors.initials: TE
authors.lastname: Hawkins
authors.forename: M J
authors.initials: MJ
authors.lastname: Evans
authors.forename: T C
authors.initials: TC
authors.lastname: Freeman
authors.forename: P R
authors.initials: PR
authors.lastname: Romano
authors.forename: C F
authors.initials: CF
authors.lastname: Higgins
authors.forename: W H
authors.initials: WH
authors.lastname: Colledge
mesh_terms: D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics; D018528:ATP-Binding Cassette Transporters / Q000235:genetics; D000818:Animals; D003550:Cystic Fibrosis / Q000235:genetics*; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000235:genetics*; D015342:DNA Probes; D005091:Exons; D005786:Gene Expression Regulation; D019450:Genes, MDR / Q000235:genetics*; D006579:Heterozygote; D006720:Homozygote; D017403:In Situ Hybridization; D007421:Intestine, Small / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000235:genetics; D012260:Ribonucleases / Q000378:metabolism; D012469:Salivary Glands / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D018528:ATP-Binding Cassette Transporters; D015342:DNA Probes; D012333:RNA, Messenger; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; C095122:multidrug resistance protein 3; D012260:Ribonucleases