Role of Smad3 in the hormonal modulation of in vivo wound healing responses

Smad3 is involved in mediating intracellular signaling by members of the transforming growth factor-beta superfamily and plays a critical role in the cellular proliferation, differentiation, migration, and elaboration of matrix pivotal to cutaneous wound healing. Cross-talk between Smad3 and hormone signaling in vitro has been suggested as an important control mechanism regulating cell activities; however, its relevance in vivo is unknown. Here we report that Smad3 plays a role in androgen-mediated inhibition of wound healing but not in the responses to estrogen modulation in vivo. Both wild-type and Smad3 null female mice exhibited delayed healing following ovariectomy, which could be reversed by estrogen replacement. By contrast, castration accelerated healing in wild-type male mice and was reversible by exogenous androgen treatment. Intriguingly, modulation of androgen levels resulted in no discernible perturbation in the healing response in the Smad3 null mice. Mutant monocytes could be lipopolysaccharide stimulated to produce specific pro-inflammatory agents (macrophage monocyte inhibitory factor) in a fashion similar to wild-type cells, but exhibited a muted response to androgen-mediated stimulation while maintaining a normal response to estrogen-induced macrophage inhibitory factor inhibition. These data suggest that Smad3 plays a role in mediating androgen signaling during the normal wound healing response and implicate Smad3 in the modulation of inflammatory cell activity by androgens.