Cell B E品 370v37 04 Figure 5. 370A Reduces the Size of the Mammary Fat Pad and Increases Mammary Gland Branch Density iD) Whole mount preparations of stained mammary glands. (A)Gland area(dotted line)and fat pad area(dashed line) are quantified from the main lactiferous duct(arrow head). Representative images are shown of 370v(B), 370v/370A (C), and 370A (D). (E and F) Average branch density (+sEM)(E and mean fat pad area(SEM)()are shown. Significance levels by ANOVA post hoc tests: p<0.05(),p<0.01(), p<0.001("). See also Table S5. escued the reduction in eccrine gland number of d heterozy- 370A is not sufficient to cause a significant change in either gotes. The finding that 370A mice have reduced fat pads reveals Meibomian or mammary gland size. Our results suggest the a hereto unappreciated role for Ectodysplasin signaling in regu- magnitude of the effects exerted by the 370A allele are more Dtem2:的 vel of change in Ectodysplasin signaling. This inference shifts The differences between the 370A knockin mouse phenotypes the discussion of potential adaptive consequences of 370 and those of loss- and gain-of-function models emphasize the toward other ectodermal appendages, which were affected in advantage of a more accurate mouse model. a dramatic change our model. This highlights the importance of employing as close hair size and shape and a disordered hair coat are observed a genetic mouse model as possible as a proxy for studying hen Ectodysplasin signaling is strongly augmented in Edar human genetic variation. transgenic mice carrying multiple copies of the wild-type Edar gene(Mou et aL, 2008)or in K14-Eda-A1 transgenic mice(Cui Pleiotropic Effects and Potential Selective Forces et al., 2003; Mustonen et aL., 2003). In contrast, the changes Favoring the 370A Allele directly attributable to the 370A allele are in the same direction, Our study provides evidence that 370A was selected in East but a smooth hair coat with subtle changes in hair size is observed. Asia, but the question of which of its observed pleiotropic pheno- everal of the other phenotypes observed in stronger gain-of- types were adaptations and which were exaptations remains. function models are not detected in 370A mice. In particular, One possibility is that selection favored individuals with an Cell 152, 691-702, February 14, 2013(2013 Elsevier Inc. 697rescued the reduction in eccrine gland number of dlj heterozy￾gotes. The finding that 370A mice have reduced fat pads reveals a hereto unappreciated role for Ectodysplasin signaling in regu￾lating the formation not only of the mammary gland, in which EDAR is expressed (Pispa et al., 2003), but also of the surrounding mesenchymal support tissue. The differences between the 370A knockin mouse phenotypes and those of loss- and gain-of-function models emphasize the advantage of a more accurate mouse model. A dramatic change in hair size and shape and a disordered hair coat are observed when Ectodysplasin signaling is strongly augmented in Edar transgenic mice carrying multiple copies of the wild-type Edar gene (Mou et al., 2008) or in K14-Eda-A1 transgenic mice (Cui et al., 2003; Mustonen et al., 2003). In contrast, the changes directly attributable to the 370A allele are in the same direction, but a smooth hair coat with subtle changes in hair size is observed. Several of the other phenotypes observed in stronger gain-of￾function models are not detected in 370A mice. In particular, 370A is not sufficient to cause a significant change in either Meibomian or mammary gland size. Our results suggest the magnitude of the effects exerted by the 370A allele are more modest than those modeled to date, and that a different subset of ectodermal appendages may be preferentially sensitive to this level of change in Ectodysplasin signaling. This inference shifts the discussion of potential adaptive consequences of 370A toward other ectodermal appendages, which were affected in our model. This highlights the importance of employing as close a genetic mouse model as possible as a proxy for studying human genetic variation. Pleiotropic Effects and Potential Selective Forces Favoring the 370A Allele Our study provides evidence that 370A was selected in East Asia, but the question of which of its observed pleiotropic pheno￾types were adaptations and which were exaptations remains. One possibility is that selection favored individuals with an Figure 5. 370A Reduces the Size of the Mammary Fat Pad and Increases Mammary Gland Branch Density (A–D) Whole mount preparations of stained mammary glands. (A) Gland area (dotted line) and fat pad area (dashed line) are quantified from the main lactiferous duct (arrow head). Representative images are shown of 370V (B), 370V/370A (C), and 370A (D). (E and F) Average branch density (±SEM) (E) and mean fat pad area (±SEM) (F) are shown. Significance levels by ANOVA post hoc tests: p < 0.05 (*), p < 0.01 (**), p < 0.001 (***). See also Table S5. Cell 152, 691–702, February 14, 2013 ª2013 Elsevier Inc. 697