title: New inducible genetic method reveals critical roles of GABA in the control of feeding and metabolism.
abstract: Currently available inducible Cre/loxP systems, despite their considerable utility in gene manipulation, have pitfalls in certain scenarios, such as unsatisfactory recombination rates and deleterious effects on physiology and behavior. To overcome these limitations, we designed a new, inducible gene-targeting system by introducing an in-frame nonsense mutation into the coding sequence of Cre recombinase (nsCre). Mutant mRNAs transcribed from nsCre transgene can be efficiently translated into full-length, functional Cre recombinase in the presence of nonsense suppressors such as aminoglycosides. In a proof-of-concept model, GABA signaling from hypothalamic neurons expressing agouti-related peptide (AgRP) was genetically inactivated within 4 d after treatment with a synthetic aminoglycoside. Disruption of GABA synthesis in AgRP neurons in young adult mice led to a dramatic loss of body weight due to reduced food intake and elevated energy expenditure; they also manifested glucose intolerance. In contrast, older mice with genetic inactivation of GABA signaling by AgRP neurons had only transient reduction of feeding and body weight; their energy expenditure and glucose tolerance were unaffected. These results indicate that GABAergic signaling from AgRP neurons plays a key role in the control of feeding and metabolism through an age-dependent mechanism. This new genetic technique will augment current tools used to elucidate mechanisms underlying many physiological and neurological processes.
authors.affiliation: Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030;
authors.forename: Fantao
authors.initials: F
authors.lastname: Meng
authors.affiliation: Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030;
authors.forename: Yong
authors.initials: Y
authors.lastname: Han
authors.affiliation: Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA 52242;
authors.forename: Dollada
authors.initials: D
authors.lastname: Srisai
authors.affiliation: Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Haifa 32000, Israel;
authors.forename: Valery
authors.initials: V
authors.lastname: Belakhov
authors.affiliation: Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030;
authors.forename: Monica
authors.initials: M
authors.lastname: Farias
authors.affiliation: Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030;
authors.forename: Yong
authors.initials: Y
authors.lastname: Xu
authors.affiliation: Department of Biochemistry, University of Washington, Seattle, WA 98195; Howard Hughes Medical Institute, University of Washington, Seattle, WA 98195 qiw@bcm.edu palmiter@uw.edu.
authors.forename: Richard D
authors.initials: RD
authors.lastname: Palmiter
authors.affiliation: Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Haifa 32000, Israel;
authors.forename: Timor
authors.initials: T
authors.lastname: Baasov
authors.affiliation: Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030; qiw@bcm.edu palmiter@uw.edu.
authors.forename: Qi
authors.initials: Q
authors.lastname: Wu
mesh_terms: D054369:Agouti-Related Protein / Q000172:deficiency / Q000235:genetics / Q000502:physiology; D000818:Animals; D004734:Energy Metabolism / Q000235:genetics* / Q000502:physiology*; D005247:Feeding Behavior / Q000502:physiology*; D005818:Genetic Engineering; D005968:Glutamate Decarboxylase / Q000172:deficiency / Q000235:genetics / Q000502:physiology; D007031:Hypothalamus / Q000502:physiology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D015398:Signal Transduction; D005680:gamma-Aminobutyric Acid / Q000502:physiology*
chemical_list: D054369:Agouti-Related Protein; C515199:Agrp protein, mouse; D005680:gamma-Aminobutyric Acid; D005968:Glutamate Decarboxylase; C402565:glutamate decarboxylase 1; C401141:glutamate decarboxylase 2
keywords: AgRP neurons; GABA; eating disorders; feeding behavior; inducible gene knockout