All animal experimental protocols approved by Animal Care Committee of the Toronto Centre of Phenogenomics conformed to the standards of the Canadian Council on Animal Care. Irx3-deficient (Irx3KO) mice 47 and Ins2-Cre mice 48 were described previously. Rosa26EnR-Irx3 conditional transgenic mice (EnR-Irx3) was generated using pROSA26PA gene-targeting vector as previously described 49. Mice were maintained on 12-hour light/dark cycles and provided with food and water ad libitum. For diet-induced obesity studies, 8 week old male mice were subjected to 45% high-fat diet (Research Diets) for 10 weeks. Body weight was measured every week from 4 to 18 weeks of age, and body composition was analyzed using a EchoMRI device (Echo Medical Systems) at 18 weeks of age. Body mass index (BMI) was calculated by dividing body weight (g) by body length (mm) squared (BMI = body weight/body length2).
