Figure 2. Systemic loss of Kif3a and/or Tg737 from adult mice results in a hyperphagia-induced obesity phenotype.

(A) Images of Kif3a-cKO (left) and Kif3a-cWT (right) females 16 weeks after administration of tamoxifen. These littermates were of equivalent weight at time of injection. (B) Tg737-cKO (left) and Tg737-cWT (right) females are also shown 16 weeks after tamoxifen administration. (C,D) Body weight analysis of (C) Kif3a-cWT and Kif3a-cKO and (D) Tg737-cWT and Tg737-cKO males and females after tamoxifen administration (week zero). The number of Kif3a-cKO and Kif3a-cWT females analyzed in this study changed at week 6 when several of the mice were used to evaluate fat pad and organ weight masses. Animals were 8–12 weeks of age at the time of initial tamoxifen administration. (E,F) Weekly food intake analysis of (E) Kif3a-cKO and Kif3a-cWT males and (F) Tg737-cKO and Tg737-cWT males after initial tamoxifen administration (week 0). Several animals were euthanized in the course of the experiment for body composition and histological analyses. Kif3a-cWT controls that were not induced with tamoxifen are also shown in blue (E). (G) Body weight analysis in pair feeding studies of Kif3a-cKO males after administration of tamoxifen. Separate groups of Kif3a-cWT males were tested with or without tamoxifen to assess changes due to tamoxifen administration. (H) Kif3a-cWT and Kif3a-cKO males were administered tamoxifen and were diet restricted to 4.0 g/day for 8 subsequent weeks. At 8 weeks, all mice were then fed ad libitum (* = p≤0.05, indicates the initial point of significant deviation between controls and mutants).