Misexpression of Wingless-Related MMTV Integration Site 5A in Mouse Mammary Gland Inhibits the Milk Ejection Response and Regulates Connexin43 Phosphorylation
Misexpression of Wingless-Related MMTV Integration Site 5A in Mouse Mammary Gland Inhibits the Milk Ejection Response and Regulates Connexin43 Phosphorylation
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DOI：
10.1095/biolreprod.111.091645
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发表时间：
2011-11-01
影响因子：
3.6
通讯作者：
Serra, Rosa
中科院分区：
文献类型：
--
作者：
Baxley, Sarah E.;Jiang, Wen;Serra, Rosa
无翅相关MMTV整合位点5A（Wnt 5a）是一个非经典的WNT信号转导位点，在小鼠乳腺发育的各个阶段（哺乳期除外）均有表达。使用含有WNT 5A以及WNT 5a-无效组织的缓释丸，我们先前表明WNT 5A起到限制乳腺发育的作用。在这里，我们使用小鼠乳腺肿瘤病毒启动子产生了在乳腺上皮中过表达WNT 5A的转基因小鼠（M5 a小鼠）。泌乳受损的两个高WNT 5A表达线。哺乳缺陷不能用细胞凋亡、谱系分化、乳汁合成或分泌的差异来解释。相反，WNT 5A的错误表达导致催产素反应和乳汁排出失败。注意到M5 a表型与连接蛋白43（Cx43;官方基因符号Gja 1）突变的小鼠表型之间的相似性，我们检查了M5 a小鼠中Cx43的磷酸化和定位。在野生型小鼠中，Cx43在分娩后从磷酸化转变为更低磷酸化的形式。相反，在M5 a小鼠中，Cx43的磷酸化形式在分娩后得以维持。使用非致瘤性乳腺细胞系MCF 10A，我们发现，除了增加Cx43对丝氨酸-368的磷酸化水平外，WNT 5A的异位表达减少或阻断了细胞间转移的染料量。总之，我们提出WNT 5A抑制催产素的反应，并通过调节Cx43功能来防止乳汁排出。
Wingless-related MMTV integration site 5A (Wnt5a) is a noncanonical signaling WNT that is expressed in every stage of mouse mammary gland development except lactation. Using slow release pellets containing WNT5A as well as Wnt5a-null tissue, we previously showed that WNT5A acts to limit mammary development. Here, we generated transgenic mice that overexpress WNT5A in the mammary epithelium using the mouse mammary tumor virus promoter (M5a mice). Lactation was impaired in two high WNT5A-expressing lines. Lactation defects could not be explained by differences in apoptosis, lineage differentiation, milk synthesis, or secretion. Instead, misexpression of WNT5A led to a failure in oxytocin response and milk ejection. Noting the similarity between the M5a phenotype and that of mice with a mutation in connexin43 (Cx43; official gene symbol Gja1), we examined Cx43 phosphorylation and localization in M5a mice. In wild-type mice, Cx43 switched from a phosphorylated to a more hypophosphorylated form after parturition. In contrast, the phosphorylated form of Cx43 was maintained after parturition in M5a mice. Using a nontumorigenic breast cell line, MCF10A, we showed that, in addition to increasing the levels of phosphorylation of Cx43 on serine-368, ectopic expression of WNT5A reduced or blocked the amount of dye transferred between cells. In summary, we propose that WNT5A inhibits the response to oxytocin and prevents milk ejection through regulation of Cx43 function.