title: IRS1 and IRS2: molecular characterization, tissue expression and transcriptional regulation by insulin in yellow catfish Pelteobagrus fulvidraco.
abstract: The insulin receptor substrate (IRS) proteins, in particular, IRS1 and IRS2, are the key downstream players of insulin signaling pathway and the regulation of lipid metabolism. In the present study, two genes of IRS (IRS1 and IRS2) were isolated and characterized from yellow catfish Pelteobagrus fulvidraco. Their molecular characterizations, tissue expressions, and transcriptional levels by insulin both in vivo and in vitro were determined. The validated complementary DNAs encoding for IRS1 and IRS2 were 3693 and 3177 bp in length, encoding proteins of 1230 and 1058 amino acid residues, respectively. Similarly to mammals, amino acid sequence alignment revealed that IRSs contained an N-terminal pleckstrin homology (PH) domain, a phosphotyrosine-binding (PTB) domain, and several C-terminal multiple sites of tyrosine phosphorylation. Both IRS1 and IRS2 were widely expressed across the ten tissues (liver, white muscle, spleen, brain, gill, mesenteric fat, anterior intestine, heart, mid-kidney, and ovary), but at the variable levels. Insulin injection at 1 μg/g in vivo significantly stimulated the messenger RNA (mRNA) expression of IRS2, but not IRS1 mRNA expression levels in the liver of yellow catfish after 48 h. In hepatocytes of yellow catfish, insulin incubation significantly stimulated the IRS1 (at a 1000 nM insulin group) and IRS2 (at both 100 and 1000 nM insulin groups) mRNA expressions, which indicated that IRS2 was more sensitive than IRS1 to insulin stimulation in the liver of yellow catfish, and IRS2 played a more important role in mediating insulin's effects on the liver metabolism. The present study serves to increase our understanding into the function of IRS in fish.
authors.affiliation: Key Laboratory of Freshwater Animal Breeding Ministry of Agriculture of P. R. C., Fishery College, Huazhong Agricultural University, Wuhan, 430070, China.|Freshwater Aquaculture Collaborative Innovative Centre of Hubei Province, Wuhan, 430070, China.
authors.forename: Mei-Qin
authors.initials: MQ
authors.lastname: Zhuo
authors.affiliation: Key Laboratory of Freshwater Animal Breeding Ministry of Agriculture of P. R. C., Fishery College, Huazhong Agricultural University, Wuhan, 430070, China.|Freshwater Aquaculture Collaborative Innovative Centre of Hubei Province, Wuhan, 430070, China.
authors.forename: Ya-Xiong
authors.initials: YX
authors.lastname: Pan
authors.affiliation: Key Laboratory of Freshwater Animal Breeding Ministry of Agriculture of P. R. C., Fishery College, Huazhong Agricultural University, Wuhan, 430070, China.|Freshwater Aquaculture Collaborative Innovative Centre of Hubei Province, Wuhan, 430070, China.
authors.forename: Kun
authors.initials: K
authors.lastname: Wu
authors.affiliation: Key Laboratory of Freshwater Animal Breeding Ministry of Agriculture of P. R. C., Fishery College, Huazhong Agricultural University, Wuhan, 430070, China.|Freshwater Aquaculture Collaborative Innovative Centre of Hubei Province, Wuhan, 430070, China.
authors.forename: Yi-Huan
authors.initials: YH
authors.lastname: Xu
authors.affiliation: Key Laboratory of Freshwater Animal Breeding Ministry of Agriculture of P. R. C., Fishery College, Huazhong Agricultural University, Wuhan, 430070, China.|Freshwater Aquaculture Collaborative Innovative Centre of Hubei Province, Wuhan, 430070, China.
authors.forename: Li-Han
authors.initials: LH
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Freshwater Animal Breeding Ministry of Agriculture of P. R. C., Fishery College, Huazhong Agricultural University, Wuhan, 430070, China. luozhi99@mail.hzau.edu.cn.|Freshwater Aquaculture Collaborative Innovative Centre of Hubei Province, Wuhan, 430070, China. luozhi99@mail.hzau.edu.cn.
authors.forename: Zhi
authors.identifier: http://orcid.org/0000-0003-3219-1609
authors.initials: Z
authors.lastname: Luo
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002397:Catfishes / Q000235:genetics*; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D029941:Fish Proteins / Q000235:genetics*; D005786:Gene Expression Regulation / Q000187:drug effects; D022781:Hepatocytes / Q000187:drug effects / Q000378:metabolism; D007328:Insulin / Q000494:pharmacology*; D055504:Insulin Receptor Substrate Proteins / Q000235:genetics*; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism
chemical_list: D018076:DNA, Complementary; D029941:Fish Proteins; D007328:Insulin; D055504:Insulin Receptor Substrate Proteins; D012333:RNA, Messenger
keywords: Insulin; Insulin receptor substrate; Molecular characterization; Pelteobagrus fulvidraco; Tissue expression; Transcriptional regulation