Structural, biochemical, and expression analysis of two distinct insulin-like growth factor I receptors and their ligands in zebrafish

Maures, T., Chan, S.-J., Xu, B., Sun, H., Ding, J., and Duan, C.
Endocrinology   143(5): 1858-1871 (Journal)
Registered Authors
Chan, Shu Jin, Duan, Cunming
MeSH Terms
  • Amino Acid Sequence
  • Animals
  • Cloning, Molecular
  • DNA Primers
  • DNA, Complementary/biosynthesis
  • DNA, Complementary/genetics
  • Gene Expression Regulation, Developmental/genetics*
  • Growth/genetics*
  • Growth/physiology
  • Immunohistochemistry
  • In Situ Hybridization
  • Insulin-Like Growth Factor I/biosynthesis
  • Insulin-Like Growth Factor I/genetics
  • Insulin-Like Growth Factor II/biosynthesis
  • Insulin-Like Growth Factor II/genetics
  • Larva/metabolism
  • Ligands
  • Molecular Sequence Data
  • Peptides/chemical synthesis
  • RNA, Messenger/biosynthesis
  • RNA, Messenger/genetics
  • Receptor, IGF Type 1/biosynthesis*
  • Receptor, IGF Type 1/chemistry
  • Receptor, IGF Type 1/genetics*
  • Receptor, Insulin/biosynthesis
  • Receptor, Insulin/genetics
  • Reverse Transcriptase Polymerase Chain Reaction
  • Somatomedins/biosynthesis
  • Somatomedins/genetics
  • Tissue Distribution
  • Zebrafish
  • Zebrafish Proteins/biosynthesis
  • Zebrafish Proteins/genetics
11956169 Full text @ Endocrinology
We have cloned and characterized cDNAs encoding the zebrafish IGF ligands and receptors. Sequence comparison showed that the primary structures of zebrafish IGF-I, IGF-II, and IGF-I receptors (IGF-IRs) have been highly conserved in vertebrates. In contrast to the presence of a single IGF-IR gene in mammals, two distinct IGF-IR genes, termed igf-1ra and igf-1rb, were found in zebrafish. Structural and phylogenetic analyses indicated that both genes are orthologous to the human igf-1r gene. Immunoprecipitation studies with specific antibodies showed that both IGF-IR genes are expressed and both receptors bind to IGFs and des(1-3)IGF-I, but not to insulin. The spatio-temporal expression patterns of the two IGF-IRs and their ligands were determined using a combination of RT-PCR, whole mount in situ hybridization, and immunocytochemistry. Transcripts for both IGF-I and -II mRNAs were found throughout embryogenesis in a ubiquitous manner. In adult tissues, IGF-I mRNA was more abundant in liver and testis, and its level was increased after GH treatment, whereas IGF-II mRNA was not regulated by GH. IGF-IRa and IGF-IRb mRNAs and proteins were expressed in overlapping spatial domains, but exhibited distinct temporal expression patterns. In particular, the relative level of IGF-IRa mRNA was low during early embryogenesis and increased in the hatched larva, whereas the situation was reversed for IGF-IRb mRNA. In adult zebrafish, the overall tissue distribution patterns of the two IGF-IRs were similar, but there were differences in their cellular localization and relative abundance in defined cells/regions. The differential expression pattern of IGF-IRa and IGF-IRb suggest that they may play distinct roles in regulating the growth and development of zebrafish.
Genes / Markers
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Mutations / Transgenics
Human Disease / Model
Sequence Targeting Reagents
Engineered Foreign Genes