A nonsense mutation in mouse Adamtsl2 causes uterine hypoplasia and an irregular estrous cycle

The spontaneous mutation stubby (stb) in mice causes chondrodysplasia and male infertility due to impotence through autosomal recessive inheritance. In this study, we conducted linkage analysis to localize the stb locus within a 1.6 Mb region on mouse chromosome 2 and identified a nonsense mutation in Adamtsl2 of stb/stb mice. Histological analysis revealed disturbed endochondral ossification with a reduced hypertrophic chondrocyte layer and stiff skin with a thickened dermal layer. These phenotypes are similar to those observed in humans and mice with ADAMTSL2/Adamtsl2 mutations. Moreover, stb/stb female mice exhibited severe uterine hypoplasia at 5 weeks of age and irregular estrous cycles at 10 weeks of age. In normal mice, Adamtsl2 was more highly expressed in the ovary and pituitary gland than in the uterus, and this expression was decreased in stb/stb mice. These findings suggest that Adamtsl2 may function in these organs rather than in the uterus. Thus, we analyzed Gh expression in the pituitary gland and plasma estradiol and IGF1 levels, which are required for the development of the female reproductive tract. There was no significant difference in Gh expression and estradiol levels, whereas IGF1 levels in stb/stb mice were significantly reduced to 54-59% of those in +/+ mice. We conclude that Adamtsl2 is required for the development of the uterus and regulation of the estrous cycle in female mice, and decreased IGF1 may be related to these abnormalities.