Figure 1.

Characterization of aP2-Cre-ER^T2 transgenic mice. (A) Cre-ER^T2 mRNA is selectively expressed in adipose tissue of aP2-Cre-ER^T2 transgenic mice. Cre-ER^T2 expression was analyzed by RT-PCR on RNA extracted from WAT of a 3-month-old WT mouse and from the indicated tissues of a 3-month-old aP2-Cre-ER^T2(tg/0) transgenic mouse. The PCR products corresponding to Cre-ER^T2 and HPRT mRNA are indicated. (B) After Tam treatment, aP2-Cre-ER^T2 transgenic mice efficiently excise a floxed EGFP cassette in adipocytes. Cryosections of WAT isolated from a 3-month-old Tam-treated aP2-Cre-ER^T2(tg/0) mouse (a), vehicle-treated aP2-Cre-ER^T2(tg/0)/aP2-L-EGFP-L^(tg/0) bigenic mouse (b), and Tam-treated aP2-Cre-ER^T2(tg/0)/aP2-L-EGFP-L^(tg/0) bigenic mouse (c), 30 days after the injection, were analyzed by confocal microscopy. The blue color corresponds to 4′,6-diamidino-2-phenylindole dihydrochloride-stained nuclei, and the green color corresponds to GFP fluorescence. (Scale bar, 20 μm.) (C) Cre-ER^T2 mice selectively excise floxed DNA in adipocytes after Tam treatment. Cre-ER^T2-mediated DNA excision was determined by Southern blot analysis, performed on genomic DNA isolated from organs of 6-month-old aP2-Cre-ER^T2(tg/0)/RXRα^+/af2(I) bigenic mice, 7 days after the last injection of vehicle (lanes 2–12) or Tam (lanes 13–23) or from RXRα^+/af2(II) mouse tail (lane 1). The position of the WT (+), floxed [af2(I)], and recombined [af2(II)] RXRα alleles are indicated. BAT, brown adipose tissue.