Leptin resistance is a secondary consequence of the obesity in ciliopathy mutant mice

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 110; no. 19; pp. 7796 - 7801
• Main Authors: Berbari, Nicolas F., Pasek, Raymond C., Malarkey, Erik B., Yazdi, S. M. Zaki, McNair, Andrew D., Lewis, Wesley R., Nagy, Tim R., Kesterson, Robert A., Yoder, Bradley K.
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 07.05.2013; National Acad Sciences
• Subjects: Animals; Arcuate nucleus; Bardet Biedl syndrome; Bardet-Biedl Syndrome - genetics; Bardet-Biedl Syndrome - pathology; Biological Sciences; Body Composition; Cilia; Cilia - pathology; Disease Models, Animal; Drug resistance; Feeding Behavior; Food consumption; Food intake; Genotype & phenotype; Leptin - metabolism; Mice; Mice, Obese; Mice, Transgenic; Motor Activity; Mutation; Neurons; Neurons - metabolism; Obesity; Obesity - genetics; Obesity - metabolism; Obesity - pathology; Phenotype; Phenotypes; Rodents; Signal Transduction; Temperature; Vehicles
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1210192110

Although primary cilia are well established as important sensory and signaling structures, their function in most tissues remains unknown. Obesity is a feature associated with some syndromes of cilia dysfunction, such as Bardet-Biedl syndrome (BBS) and Alström syndrome, as well as in several cilia mutant mouse models. Recent data indicate that obesity in BBS mutant mice is due to defects in leptin receptor trafficking and leptin resistance. Furthermore, induction of cilia loss in leptin-responsive proopiomelanocortin neurons results in obesity, implicating cilia on hypothalamic neurons in regulating feeding behavior. Here, we directly test the importance of the cilium as a mediator of the leptin response. In contrast to the current dogma, a longitudinal study of conditional Ift88 cilia mutant mice under different states of adiposity indicates that leptin resistance is present only when mutants are obese. Our studies show that caloric restriction leads to an altered anticipatory feeding behavior that temporarily abrogates the anorectic actions of leptin despite normalized circulating leptin levels. Interestingly, preobese Bb s 4 mutant mice responded to the anorectic effects of leptin and did not display other phenotypes associated with defective leptin signaling. Furthermore, thermoregulation and activity measurements in cilia mutant mice are inconsistent with phenotypes previously observed in leptin deficient ob/ob mice. Collectively, these data indicate that cilia are not directly involved in leptin responses and that a defect in the leptin signaling axis is not the initiating event leading to hyperphagia and obesity associated with cilia dysfunction.