Liver X Receptor (LXR) in yellow catfish Pelteobagrus fulvidraco: Molecular characterization, mRNA tissue expression and transcriptional regulation by insulin in vivo and in vitro.
Liver X Receptor (LXR) plays a pivotal role in metabolic regulation in mammals, but little is known about its function in fish. In this study, two lxra isoforms, namely lxra1 and lxra2, were isolated. Their molecular characterization, tissues distribution and transcriptional regulation by insulin in vivo and in vitro were determined. lxrα1 and lxrα2 cDNA covered 2775bp and 3093bp, encoding 446 and 515 amino acid residues, respectively. The protein sequence of yellow catfish lxra included characteristic feature of mammalian lxrs, including the DNA binding (DBD) (containing P-box), ligand binding (LBD) and activation function-2 (AF-2) domains, D-box, and D (hinge) region. Phylogenetic analysis revealed that yellow catfish lxra grouped with lxra of zebrafish but was distant from those of medaka and stickleback. lxrβ clades was absent in teleosts in phylogenetic tree, proving gene loss of lxrβ in teleosts during evolution. The two lxra isoforms (lxra1 and lxra2) mRNAs were ubiquitously expressed in 11 tested tissues. Compared to lxra2, lxra1 mRNA expression was predominant in all tested tissues. The expression of lxrα1 was the highest in testis, then in liver, and the lowest in other tissues. lxrα2 expression was the highest in liver, then in testis, and the lowest in ovary. Insulin significantly stimulated the mRNA expression of lxra1 in vitro and in vivo, while the expression of lxra2 remained unchanged after insulin treatment. The present study serves to increase our understanding into the function of lxra in fish.
Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture of China, Fishery College, Huazhong Agricultural University, Wuhan 430070, China; Freshwater Aquaculture Collaborative Innovative Centre of Hubei Province, Wuhan 430070, China.
Ya-Xiong
YX
Pan
Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture of China, Fishery College, Huazhong Agricultural University, Wuhan 430070, China; Freshwater Aquaculture Collaborative Innovative Centre of Hubei Province, Wuhan 430070, China. Electronic address: luozhi99@mail.hzau.edu.cn.
Zhi
Z
Luo
Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture of China, Fishery College, Huazhong Agricultural University, Wuhan 430070, China; Freshwater Aquaculture Collaborative Innovative Centre of Hubei Province, Wuhan 430070, China.
Mei-Qin
MQ
Zhuo
Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture of China, Fishery College, Huazhong Agricultural University, Wuhan 430070, China; Freshwater Aquaculture Collaborative Innovative Centre of Hubei Province, Wuhan 430070, China.
Wei
W
Hu
Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture of China, Fishery College, Huazhong Agricultural University, Wuhan 430070, China; Freshwater Aquaculture Collaborative Innovative Centre of Hubei Province, Wuhan 430070, China.
Kun
K
Wu
Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture of China, Fishery College, Huazhong Agricultural University, Wuhan 430070, China; Freshwater Aquaculture Collaborative Innovative Centre of Hubei Province, Wuhan 430070, China.
Xi
X
Shi
Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture of China, Fishery College, Huazhong Agricultural University, Wuhan 430070, China; Freshwater Aquaculture Collaborative Innovative Centre of Hubei Province, Wuhan 430070, China.
Yi-Huan
YH
Xu
D000595:Amino Acid Sequence; D000818:Animals; D002397:Catfishes / Q000235:genetics*; D002417:Cattle; D029941:Fish Proteins / Q000235:genetics*; D005786:Gene Expression Regulation / Q000187:drug effects*; D006801:Humans; D007328:Insulin / Q000494:pharmacology*; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D000071518:Liver X Receptors; D008969:Molecular Sequence Data; D057093:Orphan Nuclear Receptors / Q000737:chemistry / Q000235:genetics*; D010802:Phylogeny; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects*
D029941:Fish Proteins; D007328:Insulin; D000071518:Liver X Receptors; C000605213:NR1H3 protein, human; D057093:Orphan Nuclear Receptors; D012333:RNA, Messenger
Insulin; Molecular cloning; Pelteobagrus fulvidraco; Transcriptional regulation; lxra