Bowles Center for Alcohol Studies, University of North Carolina, Chapel Hill, North Carolina.
Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, North Carolina.
Birth Defects Res. 2017 Jan 20;109(1):49-54. doi: 10.1002/bdra.23571.
While pharmacological activation of the Hedgehog (HH) signaling pathway may have therapeutic benefits for developmental and adult diseases, its teratogenic potential is of concern. The membrane molecule Smoothened (SMO) transduces HH signaling and can be acutely modulated by antagonists and agonists. The objective of the current experiments was to determine how maternal treatment with the Smo agonist, SAG, affects the developing limb.
Pregnant C57BL/6J mice received a single injection of SAG (15, 17, or 20 mg/kg, i.p.) or its vehicle on gestational day (GD) 9.25, the time of limb bud induction. Embryos were examined on GD 15 for gross dysmorphology and skeletal staining was performed to visualize the number and type of digits on the fore- and hindlimbs. Additionally, in situ hybridization was performed 4 hr after GD 9.25 SAG administration to determine SAG's effects on Gli1 and Gli2 mRNA expression.
The most prevalent effect of SAG was the dose-dependent induction of pre-axial polydactyly; defects ranged from a broad thumb to the duplication of two finger-like digits on the preaxial side of the thumb. The highest SAG dose was effective in ca. 80% of the embryos and increased Gli1 and Gli2 mRNA expression in the limb bud, with Gli1 mRNA being the most upregulated.
Preaxial polydactyly can be caused in the developing embryo by acute maternal administration of a Smo agonist that activates HH signaling. These results are consistent with the preaxial polydactyly induced in developmental disorders associated with mutations in HH signaling genes.Birth Defects Research 109:49-54, 2017. © 2016 Wiley Periodicals, Inc.
尽管 Hedgehog（HH）信号通路的药理学激活可能对发育和成人疾病具有治疗益处，但它的致畸潜力令人担忧。膜分子 Smoothened（SMO）转导 HH 信号，并且可以被激动剂和拮抗剂急性调节。目前实验的目的是确定母体用 SMO 激动剂 SAG 处理如何影响发育中的肢体。
妊娠 C57BL/6J 小鼠在妊娠第 9.25 天（肢体芽诱导时）接受 SAG（15、17 或 20mg/kg，ip）或其载体的单次注射。在 GD 15 检查胚胎的大体畸形，并进行骨骼染色以显示前肢和后肢的手指数量和类型。此外，在 GD 9.25 后 SAG 给药后 4 小时进行原位杂交，以确定 SAG 对 Gli1 和 Gli2 mRNA 表达的影响。
SAG 最常见的作用是剂量依赖性诱导前轴多趾畸形;缺陷范围从宽拇指到拇指前轴侧两个指状指的复制。最高剂量的 SAG 在大约 80%的胚胎中有效，并增加了肢体芽中的 Gli1 和 Gli2 mRNA 表达，其中 Gli1 mRNA 的表达上调最明显。
急性母体给予激活 HH 信号的 SMO 激动剂可在发育中的胚胎中引起前轴多趾畸形。这些结果与与 HH 信号基因突变相关的发育障碍引起的前轴多趾畸形一致。出生缺陷研究 109：49-54，2017。© 2016 Wiley Periodicals，Inc.
