Fig. 1.

Premature aging phenotypes in testicular nuclear receptor 4 (TR4)^−/− mice. A: 1-yr survival rate between TR4^+/+, TR4^+/−, and TR4^−/− mice (n = 74 for TR4^+/+ and TR4^+/− mice, n = 77 for TR4^−/− mice). B: general appearance of TR4^−/− [knockout (KO)] mice. Gray hair and hunchback were seen in 6-mo-old TR4^−/− female mice compared with age-matched TR4^+/+ [wild-type (WT)] mice. C: extramedullary hematopoiesis in 6-mo-old TR4^−/− mice liver. D: radiograph of 3- and 6-mo-old TR4^−/− and TR4^+/+ mice showed skeletal abnormalities in aging TR4^−/− mice. Six-month-old TR4^−/− mice display curvature of the spinal column (kyphosis). Pictures from B–D are the representative pictures from ≥3 pairs of WT and KO mice. E: dual-energy X-ray absorptiometry scan analyses of young (2–4 mo; n = 4) and old male TR4^−/− mice (n = 5) at the age of 6–7 mo compared with age/sex-matched TR4^+/+ mice. Differences in bone mineral density (BMD) of a particular sex and genotypes were analyzed by Student's t-test *P < 0.05.