Molecular cloning of prepro-thyrotropin-releasing hormone cDNAs from the common carp Cyprinus carpio and goldfish Carassius auratus

Yasuhiro Aoki, Miho Takahashi, Tomohiro Masuda, Toshiro Tsukamoto, Masayuki Iigo, Tadashi Yanagisawa

Research output: Contribution to journalArticle

Abstract

To expand our knowledge on the evolution of prepro-thyrotropin-releasing hormone (ppTRH) from fish to tetrapods, sequences of ppTRH cDNAs from two cyprinid teleosts, the common carp Cyprinus carpio and goldfish Carassius auratus, were determined. Degenerate primers were designed based on the conserved regions between the zebrafish ppTRH sequence identified from the zebrafish EST database and the sockeye salmon ppTRH sequence, and PCR amplification was performed. Full-length ppTRHs were confirmed from ppTRH cDNAs obtained by 5′- and 3′-rapid amplification of cDNA ends. The common carp ppTRH cDNA encodes 187 amino acids including 6 copies of the TRH progenitor sequence (Lys/Arg-Arg-Gln-His-Pro-Gly-Lys/Arg-Arg), whereas the goldfish ppTRH cDNA encodes 231 amino acids including 8 copies of the TRH progenitor sequence. The molecular phylogenetic analysis of the ppTRH sequences reflected the predicted pattern of species classification. The common carp, goldfish, and zebrafish ppTRHs have some unique characteristics. The common carp and zebrafish ppTRHs are smaller than that of the goldfish mainly due to the absence of 29 and 17 consecutive amino acids, respectively. The deleted region includes one or two TRH progenitor sequences flanked by some glutamate residues, similar to the glutamate-rich regions of human ppTRH. Hydropathy profiles showed that the presence of a TRH progenitor sequence in the C-terminal hydrophilic region is a characteristic of teleosts and human ppTRHs. These observations may provide clues to a better understanding of the molecular evolution of ppTRH.

Original languageEnglish (US)
Pages (from-to)84-92
Number of pages9
JournalGeneral and Comparative Endocrinology
Volume141
Issue number1
DOIs
StatePublished - Mar 2005

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Keywords

  • Common carp
  • Goldfish
  • Molecular evolution
  • Prepro-thyrotropin-releasing hormone

ASJC Scopus subject areas

  • Animal Science and Zoology
  • Endocrinology

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