Molecular cloning and functional characterization of the first non-mammalian 26RFa/QRFP orthologue in Goldfish, Carassius auratus.
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.
Liu
Yun
Y
State Key Laboratory of Biocontrol, Institute of Aquatic Economic Animals, and the Guangdong Province Key Laboratory for Aquatic Economic Animals, Sun Yat-Sen University, Guangzhou, China.
Zhang
Yong
Y
Li
Shuisheng
S
Huang
Weiren
W
Liu
Xiaochun
X
Lu
Danqi
D
Meng
Zining
Z
Lin
Haoran
H
D000595:Amino Acid Sequence; D000818:Animals; D001923:Brain Chemistry; D003001:Cloning, Molecular; D018076:DNA, Complementary; D005786:Gene Expression Regulation / Q000502:physiology; D006054:Goldfish; D007031:Hypothalamus / Q000737:chemistry; D036341:Intercellular Signaling Peptides and Proteins; D007986:Luteinizing Hormone / Q000378:metabolism; D009479:Neuropeptides / Q000235:genetics* / Q000502:physiology; D010455:Peptides; D021382:Protein Sorting Signals; D016415:Sequence Alignment
D018076:DNA, Complementary; D036341:Intercellular Signaling Peptides and Proteins; D009479:Neuropeptides; D010455:Peptides; D021382:Protein Sorting Signals; C511787:QRFP peptide; C480638:prepro-26RFa protein, human; D007986:Luteinizing Hormone