Abstract
Background
Obesity, the condition of excessive accumulation of fat is a poorly understood disorder and is a risk factor for type II diabetes, hypertension, and hyperlipidaemia. Recently, a putative mouse obese gene was cloned and its product, termed ob protein, was shown to be involved in the regulation of body weight.
Materials and Methods
Bacterial and insect cells were used for expression of recombinant mouse ob protein. Amino-terminal sequence analysis and site-directed mutagenesis were used to identify and characterize the mature form of ob protein. Genetically obese mice and wild-type rats were used to determine the biological activity of ob protein.
Results
Mouse ob protein is synthesized as a precursor molecule, the mature form of which was found in mouse serum. Biochemical analysis identified the processing site in the ob precursor molecule and an intramolecular disulfide bond in the mature form that is necessary for activity. Reduction of food intake and weight gain after administration of ob protein to genetically obese mice and wild-type rats is reversible.
Discussion
This study demonstrates that ob protein is a secreted satiety factor which regulates body weight and reduces food intake even in animals with no genetic body weight abnormalities. The failure of ob protein to effect these parameters in db/db mice supports the hypothesis that these mice are deficient in a signaling molecule that normally responds to the ob protein.
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Acknowledgments
The authors thank Ross Okamura (UCSF) for mouse fat tissue, Jon Strich, Frank Marcus, and Bob Drummond for help in protein production and purification, and Frank Masur and Surinder Kaur for mass spectroscopy and N-terminal sequence analysis. We thank Leah Conroy for expert assistance in growth of insect cells. We also thank Laurie Stephens, Mike Cardone, Filippo Randazzo, David Duhl, and Jaime Escobedo for helpful discussions.
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Contributed by F. E. Cohen Cohen on September 21, 1995.
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Giese, K., Fantl, W.J., Vitt, C. et al. Reduction of Food Intake and Weight Gain by the ob Protein Requires a Specific Secondary Structure and Is Reversible. Mol Med 2, 50–58 (1996). https://doi.org/10.1007/BF03402202
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DOI: https://doi.org/10.1007/BF03402202