title: Cloning and characterization of class 1 and class 2 insulin-like growth factor-I mRNA in Songliao black pig.
abstract: Insulin-like growth factor-I (IGF-I) plays a fundamental role in postnatal mammalian growth, development, and metabolism. The mammalian IGF-I gene contains at least six exons from which several different mRNAs are transcribed. In this study, IGF-I mRNA in Songliao black pig liver was investigated using RLM-RACE. Using a 3'-RACE technique, we determined that all mRNA transcripts lacked exon 5 sequence and contained only exon 6 sequence. Using a 5'-RACE technique, we investigated the presence of class 1 and class 2 IGF-I mRNAs. In several other species, the class 1 and class 2 IGF-I polypeptides are generated from mRNAs containing exon 1 or exon 2, respectively. Both class 1 and class 2 IGF-I mRNAs were identified in Songliao black pig liver. Transcription is initiatated upstream of exons 1 and 2 at multiple dispersed start sites to yield two distinct IGF-I mRNA transcript classes which differ in the precursor peptides predicted from their individual leader sequences. Tissue distribution of Songliao black pig class 1 and class 2 IGF-I mRNA was investigated by real-time RT-PCR. Both classes of IGF-I mRNA were expressed in a variety of tissues, however, class 1 IGF-I mRNA was more abundant than class 2 in all tissues.
authors.affiliation: Laboratory Animal Center, Jilin University, 5333 of Xi'an Road, Changchun, Jilin 130062, P.R. China.
authors.forename: Shuqi
authors.initials: S
authors.lastname: Xiao
authors.forename: Shuang
authors.initials: S
authors.lastname: Li
authors.forename: Jiabao
authors.initials: J
authors.lastname: Zhang
authors.forename: Shumin
authors.initials: S
authors.lastname: Zhang
authors.forename: Lisheng
authors.initials: L
authors.lastname: Dai
authors.forename: Yonghua
authors.initials: Y
authors.lastname: Bao
authors.forename: Ning
authors.initials: N
authors.lastname: Jiang
authors.forename: Yan
authors.initials: Y
authors.lastname: Gao
authors.forename: Zhongli
authors.initials: Z
authors.lastname: Zhao
authors.forename: Delin
authors.initials: D
authors.lastname: Mo
authors.forename: Yaosheng
authors.initials: Y
authors.lastname: Chen
authors.forename: Zhihui
authors.initials: Z
authors.lastname: Zhao
mesh_terms: D000818:Animals; D003001:Cloning, Molecular / Q000379:methods; D005091:Exons; D007334:Insulin-Like Growth Factor I / Q000235:genetics*; D016133:Polymerase Chain Reaction / Q000379:methods; D012333:RNA, Messenger / Q000235:genetics*; D034421:Sus scrofa; D014018:Tissue Distribution
chemical_list: D012333:RNA, Messenger; D007334:Insulin-Like Growth Factor I