Discovery and functional characterization of leptin and its receptors in Japanese quail (Coturnix japonica).
Leptin is an important endocrine regulation factor of food intake and energy homeostasis in mammals; however, the existence of a poultry leptin gene (LEP) is still debated. Here, for the first time, we report the cloning of a partial exon 3 sequence of LEP (qLEP) and four different leptin receptor splicing variants, including a long receptor (qLEPRl) and three soluble receptors (qLEPR-a, qLEPR-b and qLEPR-c) in Japanese quail (Coturnix japonica). The qLEP gene had high GC content (64%), which is similar to other reported avian leptin genes. The encoded qLEP protein possessed the conserved pair of cysteine residues that are required to form a lasso knot for full biological activity, but shared relatively low identities with LEPs of other vertebrates. The translated qLEPRl protein contained 1143 amino acids and shared high amino acid sequence identity with a chicken homolog (89% identity). qLEPRl also contained all the motifs, domains, and basic tyrosine residues that are conserved in the LEPRl proteins of other vertebrates. qRT-PCR analysis showed that LEP and the four LEPR variants were expressed extensively in all tissues examined; the expression levels of LEP were relatively high in hypothalamus, skeletal muscle, and pancreas, while the expression levels of the LEPRs were highest in the pituitary. Compared with the expression levels of juvenile qLEP and total qLEPR (including all LEPR variants), the expression levels of mature qLEP and total qLEPR were up-regulated in the hypothalamus and pituitary, and down-regulated in the ovary. The expressions of LEP/LEPR increased when fasting and decreased when refeeding in the brain and peripheral tissues of juvenile quail, which suggested that the LEP/LEPR system modulated food intake and energy expenditure, although, unlike in mammals, LEP may actually act to inhibit food intake during fasting, at least in juvenile quail. The results indicate that qLEP and qLEPR have unique expression patterns and that the encoded proteins play important roles in the regulation of reproduction and energy status in Japanese quail.
College of Animal Science and Veterinary Medicine, Henan Agricultural University, Zhengzhou 450002, China.
Dandan
D
Wang
College of Animal Science and Veterinary Medicine, Henan Agricultural University, Zhengzhou 450002, China.
Chunlin
C
Xu
College of Animal Science and Veterinary Medicine, Henan Agricultural University, Zhengzhou 450002, China.
Taian
T
Wang
College of Animal Science and Veterinary Medicine, Henan Agricultural University, Zhengzhou 450002, China.
Hong
H
Li
College of Animal Science and Veterinary Medicine, Henan Agricultural University, Zhengzhou 450002, China.
Yanmin
Y
Li
College of Animal Science and Veterinary Medicine, Henan Agricultural University, Zhengzhou 450002, China.
Junxiao
J
Ren
College of Animal Science and Veterinary Medicine, Henan Agricultural University, Zhengzhou 450002, China; Henan Innovative Engineering Research Center of Poultry Germplasm Resource, Henan Agricultural University, Zhengzhou 450002, China; International Joint Research Laboratory for Poultry Breeding of Henan, Henan Agricultural University, Zhengzhou 450002, China.
Yadong
Y
Tian
College of Animal Science and Veterinary Medicine, Henan Agricultural University, Zhengzhou 450002, China; Henan Innovative Engineering Research Center of Poultry Germplasm Resource, Henan Agricultural University, Zhengzhou 450002, China; International Joint Research Laboratory for Poultry Breeding of Henan, Henan Agricultural University, Zhengzhou 450002, China.
Zhuanjian
Z
Li
College of Animal Science and Veterinary Medicine, Henan Agricultural University, Zhengzhou 450002, China; Institute of Animal Husbandry and Veterinary Medicine, Henan Academy of Agricultural Sciences, Zhengzhou 450002, China.
Yuping
Y
Jiao
College of Animal Science and Veterinary Medicine, Henan Agricultural University, Zhengzhou 450002, China; Henan Innovative Engineering Research Center of Poultry Germplasm Resource, Henan Agricultural University, Zhengzhou 450002, China; International Joint Research Laboratory for Poultry Breeding of Henan, Henan Agricultural University, Zhengzhou 450002, China. Electronic address: xtkang2001@263.net.
Xiangtao
X
Kang
College of Animal Science and Veterinary Medicine, Henan Agricultural University, Zhengzhou 450002, China; Henan Innovative Engineering Research Center of Poultry Germplasm Resource, Henan Agricultural University, Zhengzhou 450002, China; International Joint Research Laboratory for Poultry Breeding of Henan, Henan Agricultural University, Zhengzhou 450002, China. Electronic address: Xjliu2008@hotmail.com.
Xiaojun
X
Liu
D000367:Age Factors; D000595:Amino Acid Sequence; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism; D003001:Cloning, Molecular; D003370:Coturnix / Q000378:metabolism; D004435:Eating / Q000235:genetics; D005091:Exons; D005260:Female; D007031:Hypothalamus / Q000378:metabolism*; D020738:Leptin / Q000235:genetics / Q000378:metabolism*; D010053:Ovary / Q000378:metabolism*; D010902:Pituitary Gland / Q000378:metabolism*; D054411:Receptors, Leptin / Q000235:genetics / Q000378:metabolism*
D002352:Carrier Proteins; D020738:Leptin; D054411:Receptors, Leptin
Alternative splicing; Gene cloning; LEPR; Leptin; Physiological function; Quail