IGF-I in the bony fish Cottus scorpius: cDNA, expression and differential localization in brain and islets.
The cDNA encoding prepro-insulin-like growth factor (IGF)-I of a teleost, Cottus scorpius, (Scorpaeniformes) was established from liver by RT-PCR and molecular cloning. Typically, the deduced 184 amino acid protein contains a signal peptide, B-, C-, A-, D- and E-domains and all residues necessary for maintenance of tertiary structure. C. scorpius IGF-I shares only approximately 57% identity with C. scorpius insulin in the A-domain and 7% in the B-domain. RT-PCR followed by Southern blotting revealed a transcript in liver, pancreatic islets, stomach, small and large intestine, kidney, gill, testis, ovary, heart and brain indicating paracrine/autocrine actions of locally produced IGF-I. IGF-I- and insulin-immunoreactivities coexisted in the islets, but did not in other sites such as brain. Thus, in contrast to other bony fish, sculpin insulin cells most probably produce IGF-I. The results also challenge the current model of the IGF/insulin evolution.
Division of Neuroendocrinology, Institute of Anatomy, University of Zürich, Switzerland.
D
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Loffing-Cueni
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Schmid
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Graf
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M
Reinecke
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002531:Cerebellum / Q000378:metabolism*; D003545:Cysteine; D005399:Fishes / Q000235:genetics*; D015870:Gene Expression; D007106:Immune Sera; D007150:Immunohistochemistry; D007328:Insulin / Q000032:analysis; D007334:Insulin-Like Growth Factor I / Q000032:analysis* / Q000235:genetics*; D007515:Islets of Langerhans / Q000378:metabolism*; D008099:Liver; D008969:Molecular Sequence Data; D009928:Organ Specificity; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA
D007106:Immune Sera; D007328:Insulin; D012333:RNA, Messenger; D007334:Insulin-Like Growth Factor I; D003545:Cysteine