Tribulo Paula, Leão Beatriz Caetano da Silva, Lehloenya Khoboso C, Mingoti Gisele Zoccal, Hansen Peter J
Department of Animal Sciences, D.H. Barron Reproductive and Perinatal Biology Research Program, and Genetics Institute, University of Florida, Gainesville, Florida, USA.
School of Veterinary Medicine, Laboratory of Reproductive Physiology, UNESP-Universidade Estadual Paulista, Araçatuba, São Paulo, Brazil and Post-Graduation Program in Veterinary Medicine, School of Agrarian and Veterinarian Sciences, Department of Animal Reproduction, UNESP-Universidade Estadual Paulista, Jaboticabal, São Paulo, Brazil.
Biol Reprod. 2017 Jun 1;96(6):1129-1141. doi: 10.1093/biolre/iox048.
The specific role of WNT signaling during preimplantation development remains unclear. Here, we evaluated consequences of activation and inhibition of β-catenin (CTNNB1)-dependent and -independent WNT signaling in the bovine preimplantation embryo. Activation of CTNNB1-mediated WNT signaling by the agonist 2-amino-4-(3,4-(methylenedioxy)benzylamino)-6-(3-methoxyphenyl)pyrimidine (AMBMP) and a glycogen synthase kinase 3 inhibitor reduced development to the blastocyst stage. Moreover, the antagonist of WNT signaling, dickkopf-related protein 1 (DKK1), alleviated the negative effect of AMBMP on development via reduction of CTNNB1. Based on labeling for phospho c-Jun N-terminal kinase, there was no evidence that DKK1 activated the planar cell polarity (PCP) pathway. Inhibition of secretion of endogenous WNTs did not affect development but increased number of cells in the inner cell mass (ICM). In contrast, DKK1 did not affect number of ICM or trophectoderm (TE) cells, suggesting that embryo-derived WNTs regulate ICM proliferation through a mechanism independent of CTNNB1. In addition, DKK1 did not affect the number of cells positive for the transcription factor yes-associated protein 1 (YAP1) involved in TE formation. In fact, DKK1 decreased YAP1. In contrast, exposure of embryos to WNT family member 7A (WNT7A) improved blastocyst development, inhibited the PCP pathway, and did not affect amounts of CTNNB1. Results indicate that embryo-derived WNTs are dispensable for blastocyst formation but participate in regulation of ICM proliferation, likely through a mechanism independent of CTNNB1. The response to AMBMP and WNT7A leads to the hypothesis that maternally derived WNTs can play a positive or negative role in regulation of preimplantation development.
WNT信号通路在植入前胚胎发育过程中的具体作用尚不清楚。在此，我们评估了激活和抑制牛植入前胚胎中β-连环蛋白（CTNNB1）依赖性和非依赖性WNT信号通路的后果。激动剂2-氨基-4-（3,4-（亚甲二氧基）苄基氨基）-6-（3-甲氧基苯基）嘧啶（AMBMP）和糖原合酶激酶3抑制剂激活CTNNB1介导的WNT信号通路会降低发育至囊胚阶段的比例。此外，WNT信号通路的拮抗剂Dickkopf相关蛋白1（DKK1）通过降低CTNNB1减轻了AMBMP对发育的负面影响。基于磷酸化c-Jun氨基末端激酶的标记，没有证据表明DKK1激活了平面细胞极性（PCP）通路。抑制内源性WNTs的分泌不影响发育，但增加了内细胞团（ICM）中的细胞数量。相反，DKK1不影响ICM或滋养外胚层（TE）细胞的数量，这表明胚胎来源的WNTs通过独立于CTNNB1的机制调节ICM增殖。此外，DKK1不影响参与TE形成的转录因子Yes相关蛋白1（YAP1）阳性细胞的数量。事实上，DKK1降低了YAP1。相反，将胚胎暴露于WNT家族成员7A（WNT7A）可改善囊胚发育，抑制PCP通路，且不影响CTNNB1的量。结果表明，胚胎来源的WNTs对于囊胚形成并非必需，但可能通过独立于CTNNB1的机制参与ICM增殖的调节。对AMBMP和WNT7A的反应导致这样一种假设，即母体来源的WNTs在植入前发育的调节中可以发挥正向或负向作用。
