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Journal of Endocrinology

Hen, G., Institute of Animal Science, Agricultural Research Organization, Volcani Center, PO Box 6, Bet Dagan 50250, Israel
Einat, P., Consulting and Inventions, Moshe Levi 45A, Nes Ziona 74207, Israel
Rosenblum, C.I., Department of Metabolic Disorders-Diabetes, Merck Research Laboratories, Rahway, NJ 07065, United States
Denver, R.J., Department of Molecular Cellular and Developmental Biology, The University of Michigan, 830 North University Avenue, Ann Arbor, MI 48109-1048, United States
 

We report on the construction of a leptin bioassay based on the activation of chicken leptin receptor in cultured cells. A human embryonic kidney (HEK)-293 cell line, stably transfected with the full-length cDNA of chicken leptin receptor together with a STAT3-responsive reporter gene specifically responded to recombinant human and Xenopus leptins. The observed higher sensitivity of chicken leptin receptor to the former is in agreement with the degree of sequence similarity among these species (about 60 and 38% identical amino acids between humans and chickens, and between humans and Xenopus respectively). The specific activation of signal transduction through the chicken leptin receptor, shown here for the first time, suggests that the transition of Gln209 (implicated in the Gln-to-Pro Zucker fatty mutation in rats) to Glu in chickens does not impair its activity. Analysis of leptin-like activity in human serum samples of obese and lean subjects coincided well with leptin levels determined by RIA. Serum samples ofpre- and post partum cows showed a tight correlation with the degree of adiposity. However, specific activation of the chicken leptin receptor in this assay was not observed with serum samples from broiler or layer chickens (representing fat and lean phenotypes respectively) or with those from turkey. Similar leptin receptor activation profiles were observed with cells transfected with human leptin receptor. Further work is needed to determine whether the lack of leptin-like activity in the chicken serum samples is due to a lack of leptin in this species or simply to a serum level of leptin that is below the detection threshold. © 2008 Society for Endocrinology.
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Monitoring leptin activity using the chicken leptin receptor
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Hen, G., Institute of Animal Science, Agricultural Research Organization, Volcani Center, PO Box 6, Bet Dagan 50250, Israel
Einat, P., Consulting and Inventions, Moshe Levi 45A, Nes Ziona 74207, Israel
Rosenblum, C.I., Department of Metabolic Disorders-Diabetes, Merck Research Laboratories, Rahway, NJ 07065, United States
Denver, R.J., Department of Molecular Cellular and Developmental Biology, The University of Michigan, 830 North University Avenue, Ann Arbor, MI 48109-1048, United States
 

Monitoring leptin activity using the chicken leptin receptor
We report on the construction of a leptin bioassay based on the activation of chicken leptin receptor in cultured cells. A human embryonic kidney (HEK)-293 cell line, stably transfected with the full-length cDNA of chicken leptin receptor together with a STAT3-responsive reporter gene specifically responded to recombinant human and Xenopus leptins. The observed higher sensitivity of chicken leptin receptor to the former is in agreement with the degree of sequence similarity among these species (about 60 and 38% identical amino acids between humans and chickens, and between humans and Xenopus respectively). The specific activation of signal transduction through the chicken leptin receptor, shown here for the first time, suggests that the transition of Gln209 (implicated in the Gln-to-Pro Zucker fatty mutation in rats) to Glu in chickens does not impair its activity. Analysis of leptin-like activity in human serum samples of obese and lean subjects coincided well with leptin levels determined by RIA. Serum samples ofpre- and post partum cows showed a tight correlation with the degree of adiposity. However, specific activation of the chicken leptin receptor in this assay was not observed with serum samples from broiler or layer chickens (representing fat and lean phenotypes respectively) or with those from turkey. Similar leptin receptor activation profiles were observed with cells transfected with human leptin receptor. Further work is needed to determine whether the lack of leptin-like activity in the chicken serum samples is due to a lack of leptin in this species or simply to a serum level of leptin that is below the detection threshold. © 2008 Society for Endocrinology.
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