Department of Laboratory Medicine & Pathobiology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada M5S 1A8.
Lombardi Comprehensive Cancer Center, Departments of Oncology and Medicine, Georgetown University, Washington, DC, USA.
Dev Biol. 2014 Jul 15;391(2):219-29. doi: 10.1016/j.ydbio.2014.04.007. Epub 2014 Apr 21.
Mesenchymal dysplasia (mes) mice harbour a truncation in the C-terminal region of the Hh-ligand receptor, Patched-1 (mPtch1). While the mes variant of mPtch1 binds to Hh-ligands with an affinity similar to that of wild type mPtch1 and appears to normally regulate canonical Hh-signalling via smoothened, the mes mutation causes, among other non-lethal defects, a block to mammary ductal elongation at puberty. We demonstrated previously Hh-signalling induces the activation of Erk1/2 and c-src independently of its control of smo activity. Furthermore, mammary epithelial cell-directed expression of an activated allele of c-src rescued the block to ductal elongation in mes mice, albeit with delayed kinetics. Given that this rescue was accompanied by an induction in estrogen receptor-alpha (ERα) expression and that complex regulatory interactions between ERα and c-src are required for normal mammary gland development, it was hypothesized that expression of ERα would also overcome the block to mammary ductal elongation at puberty in the mes mouse. We demonstrate here that conditional expression of ERα in luminal mammary epithelial cells on the mes background facilitates ductal morphogenesis with kinetics similar to that of the MMTV-c-src(Act) mice. We demonstrate further that Erk1/2 is activated in primary mammary epithelial cells by Shh-ligand and that this activation is blocked by the inhibitor of c-src, PP2, is partially blocked by the ERα inhibitor, ICI 182780 but is not blocked by the smo-inhibitor, SANT-1. These data reveal an apparent Hh-signalling cascade operating through c-src and ERα that is required for mammary gland morphogenesis at puberty.
间充质发育不良（mes）小鼠携带 Hh 配体受体 Patched-1（mPtch1）C 末端区域的截断。虽然 mes 变体的 mPtch1 与野生型 mPtch1 结合 Hh 配体的亲和力相似，并且似乎通过 smoothened 正常调节经典的 Hh 信号传导，但 mes 突变导致，除了其他非致死性缺陷外，青春期乳腺导管伸长受阻。我们之前证明 Hh 信号传导独立于其对 smo 活性的控制诱导 Erk1/2 和 c-src 的激活。此外，乳腺上皮细胞定向表达激活的 c-src 等位基因可挽救 mes 小鼠中导管伸长的阻滞，尽管动力学延迟。鉴于这种挽救伴随着雌激素受体-α（ERα）表达的诱导，并且 ERα 和 c-src 之间的复杂调节相互作用是正常乳腺发育所必需的，因此假设 ERα 的表达也会克服 mes 小鼠青春期乳腺导管伸长的阻滞。我们在这里证明，在 mes 背景下的腔上皮乳腺上皮细胞中条件表达 ERα 可促进导管形态发生，动力学与 MMTV-c-src(Act) 小鼠相似。我们进一步证明 Shh 配体激活原代乳腺上皮细胞中的 Erk1/2，并且这种激活被 c-src 的抑制剂 PP2 阻断，被 ERα 抑制剂 ICI 182780 部分阻断，但不受 smo 抑制剂 SANT-1 阻断。这些数据揭示了一种明显的 Hh 信号级联，通过 c-src 和 ERα 发挥作用，这是青春期乳腺形态发生所必需的。
