Molecular cloning and functional characterization of the first non-mammalian 26RFa/QRFP orthologue in Goldfish, Carassius auratus

Mol Cell Endocrinol. 2009 May 6;303(1-2):82-90. doi: 10.1016/j.mce.2009.01.009. Epub 2009 Jan 22.


In this study, we used data mining approach to predict 26RFa/QRFP precursors from fish, amphibian, reptile and avian species and subsequently cloned a 26RFa/QRFP precursor cDNA from goldfish brain based on the predicted sequences information. The goldfish 26RFa/QRFP precursor cDNA encoded a propeptide of 168 amino acids (aa) with predicted signal peptide of 30 aa at N-terminal and putative mature peptides, including 26RFa (26 aa) and 7RFa (7 aa) located at the C-terminal. Multiple sequence alignment showed almost all of the 26RFa/QRFP mature peptides possessed KGGFXFRF-amide motifs (X=G, S, A or N) at their C-terminus, and the last three residues FRF were fully conserved across vertebrates, indicating that the evolutionary pressure has exerted to conserve several C-terminal amino acid residues among the known and predicted 26RFa/QRFP precursors. Real-time PCR revealed that 26RFa/QRFP gene was expressed abundantly in goldfish hypothalamus, optic tectum-thalamus and testis. The regulation of goldfish hypothalamic 26RFa/QRFP gene expression by negative energy balance and putative role of goldfish 26RFa/QRFP in the control of luteinizing hormone (LH) release were studied. Hypothalamic 26RFa/QRFP gene expression was pronouncedly increased at 4 days after food deprivation. Furthermore, intraperitoneal (IP) injection of synthesized goldfish 26RFa/QRFP at a dose of 1 microg/g bodyweight significantly increased serum LH levels at 1h. However, LH levels were not significantly changed by IP injection of goldfish 26RFa/QRFP at lower dosage or at other time points (3 and 6 h), or by incubation of goldfish primary cell cultures. These results suggested that goldfish 26RFa/QRFP shared some similar features with its mammalian counterparts and partly exerted the regulatory function in energy homeostasis and hypothalamic-pituitary-gonadal (HPG) axis as observed in mammalian species.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Brain Chemistry
  • Cloning, Molecular
  • DNA, Complementary
  • Gene Expression Regulation / physiology
  • Goldfish
  • Hypothalamus / chemistry
  • Intercellular Signaling Peptides and Proteins
  • Luteinizing Hormone / metabolism
  • Neuropeptides / genetics*
  • Neuropeptides / physiology
  • Peptides
  • Protein Sorting Signals
  • Sequence Alignment


  • DNA, Complementary
  • Intercellular Signaling Peptides and Proteins
  • Neuropeptides
  • Peptides
  • Protein Sorting Signals
  • QRFP peptide
  • prepro-26RFa protein, human
  • Luteinizing Hormone