title: The characterization of prepro-insulin-like growth factor-1 Ea-2 expression and insulin-like growth factor-1 genes (devoid 81 bp) in the zebrafish (Danio rerio).
abstract: In this study, we cloned zebrafish (Danio rerio) IGF-1 cDNA and gene from zebrafish brain cDNA library and adult zebrafish genomic library, respectively. Based on two cDNAs sequence with different length of 5'- and 3'-untranslated region (5UTR and 3UTR) and one nucleotide difference at glutamine (A9, CAG) of A domain represented at IGF-1 sequence. One of zebrafish IGF-1 genes named as IGF-1a gene. The zebrafish IGF-1a gene spanned approximately 15 kb and is divided into five exons. The results of IGF-1 cDNA and genomic Southern blotting, all indicated that the zebrafish have more than one IGF-1 gene. The genomic organization of zebrafish IGF-1a gene in an exon is devoid of 81 bp segment which is located at 3' end of exon 3 encoded 27 amino acid of E domain. The segment of 27 amino acid exists in known teleost IGF-1 genes but is absent in zebrafish IGF-1 gene. The E domain of zebrafish IGF-1 Ea-2 is encoded by 3' end of exon 3 (16 amino acid), full of exon 4 (12 amino acid) and exon 5 (19 amino acid). The sequence data revealed the zebrafish IGF-1a gene encoded IGF-1a Ea-2 mRNA. In combination RT-PCR with Southern blotting, zebrafish IGF-1 genes abundantly expressed IGF-1 Ea-2 mRNA in all tested adult tissues and developmental stages of embryo. The IGF-1 Ea-2 mRNA was first detected during embryo development from blastula stage to hatching, during yolk absorption and at feeding. All these findings suggest that the expression of pro-IGF-1 Ea-2 is not controlled by alternative splicing but alternative gene usage in the zebrafish.
authors.affiliation: Graduate Institute of Life Sciences, National Defense Medical Center, 114, Taipei, Taiwan.
authors.forename: M H
authors.initials: MH
authors.lastname: Chen
authors.forename: G
authors.initials: G
authors.lastname: Lin
authors.forename: H
authors.initials: H
authors.lastname: Gong
authors.forename: C
authors.initials: C
authors.lastname: Weng
authors.forename: C
authors.initials: C
authors.lastname: Chang
authors.forename: J
authors.initials: J
authors.lastname: Wu
mesh_terms: D020413:3' Untranslated Regions; D020121:5' Untranslated Regions; D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D004625:Embryo, Nonmammalian; D005091:Exons; D018507:Gene Expression Regulation, Developmental; D007334:Insulin-Like Growth Factor I / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D020033:Protein Isoforms / Q000235:genetics; D011498:Protein Precursors / Q000235:genetics* / Q000378:metabolism; D017421:Sequence Analysis; D013002:Somatomedins / Q000235:genetics*; D015027:Zebrafish / Q000196:embryology / Q000235:genetics* / Q000254:growth & development; D029961:Zebrafish Proteins
chemical_list: D020413:3' Untranslated Regions; D020121:5' Untranslated Regions; D020033:Protein Isoforms; D011498:Protein Precursors; D013002:Somatomedins; D029961:Zebrafish Proteins; C431139:igf1 protein, zebrafish; C093199:preproinsulin-like growth factor I; D007334:Insulin-Like Growth Factor I