title: Post-transcriptional regulation by miR-137 underlies the low abundance of CAR and low rate of bilirubin clearance in neonatal mice.
abstract: OBJECTIVE
  Jaundice, potentially fatal encephalopathy, is common in approximately two-thirds of all well term infants. It is largely due to low expression of constitutive androstane receptor (CAR) in newborns; however, the mechanisms for this low expression were poorly understood.
  
  
  METHODS
  Expression of miR-137 and CAR was compared between neonatal and adult mice and between healthy and a mouse model of obstructive jaundice (OJ) using real-time RT-PCR and Western blot methods. Rate of bilirubin clearance was measured. DNA methylation of miR-137 was analyzed.
  
  
  RESULTS
  Inverse expressions of miR-137 and CAR were consistently observed between newborn and adult mice, with a significantly higher miR-137 level and lower CAR protein and mRNA levels in neonatal liver than in adult liver. Similar reciprocal relationship was found existing between adult OJ mice and healthy control animals with a higher miR-137 level and lower CAR protein and mRNA levels in OJ than in healthy mice. Forced expression of miR-137 in primary hepatocytes repressed CAR protein levels, which was prevented by the inhibitor of miR-137. Knockdown of endogenous miR-137 by its inhibitor increased the rate of bilirubin clearance in OJ mice. Finally, we found that miR-137 was epigenetically over-activated due to hypomethylation in neonatal mice and in adult OJ mice, relative to adult healthy animals.
  
  
  CONCLUSIONS
  Our findings indicate that miR-137 is a repressor of CAR and thus a critical determinant of bilirubin clearance and may be considered a molecular target for the treatment of neonatal hyperbilirubinemia.
authors.affiliation: Department of Pediatrics, Southwest Hospital of the Third Military Medical University, Chongqing 400038, China.
authors.forename: Sheng
authors.initials: S
authors.lastname: Chen
authors.affiliation: Department of Pediatrics, Southwest Hospital of the Third Military Medical University, Chongqing 400038, China. Electronic address: nhhe.tmmu@sohu.com.
authors.forename: Nianhai
authors.initials: N
authors.lastname: He
authors.affiliation: Department of Neonatology, Children's Hospital of Chongqing Medical University, Chongqing 400014, China.
authors.forename: Jialin
authors.initials: J
authors.lastname: Yu
authors.affiliation: Department of Neonatology, Children's Hospital of Chongqing Medical University, Chongqing 400014, China.
authors.forename: Luquan
authors.initials: L
authors.lastname: Li
authors.affiliation: Department of Pediatrics, Southwest Hospital of the Third Military Medical University, Chongqing 400038, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Hu
authors.affiliation: Department of Pediatrics, Southwest Hospital of the Third Military Medical University, Chongqing 400038, China.
authors.forename: Rui
authors.initials: R
authors.lastname: Deng
authors.affiliation: Department of Pediatrics, Southwest Hospital of the Third Military Medical University, Chongqing 400038, China.
authors.forename: Shiming
authors.initials: S
authors.lastname: Zhong
authors.affiliation: Department of Pediatrics, Southwest Hospital of the Third Military Medical University, Chongqing 400038, China.
authors.forename: Leilei
authors.initials: L
authors.lastname: Shen
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001663:Bilirubin / Q000378:metabolism*; D015153:Blotting, Western; D002478:Cells, Cultured; D000090702:Constitutive Androstane Receptor; D005260:Female; D005786:Gene Expression Regulation; D022781:Hepatocytes / Q000166:cytology / Q000378:metabolism*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D035683:MicroRNAs / Q000235:genetics*; D012323:RNA Processing, Post-Transcriptional; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D000090702:Constitutive Androstane Receptor; C551799:MIRN137 microRNA, mouse; D035683:MicroRNAs; D012333:RNA, Messenger; D018160:Receptors, Cytoplasmic and Nuclear; D001663:Bilirubin
keywords: Androstane receptor (CAR); Bilirubin clearance; Hypomethylation; Jaundice; Neonatal hyperbilirubinemia; miR-137