Intersection of the mTOR/p70S6K1 signaling and the HIPPO-Yap tissue organizer in neurulation and diabetic embryopathy

总结 妊娠前糖尿病可导致神经管缺陷（NTDs）。有六千万育龄妇女 （18-44岁），约300万美国女性糖尿病患者。即使在最好的情况下 尽管产前护理，患有糖尿病的妇女生下出生缺陷的孩子的可能性仍然是患有糖尿病的妇女的三到四倍， 没有糖尿病的女性揭示糖尿病诱导的NTDs的潜在机制对于 了解其发病机制，提供潜在的干预靶点。是相关蛋白（雅普）， 转录辅激活因子，决定身体和器官的大小，并调节细胞凋亡，增殖， 分化我们发现，无论是条件性KO的雅普或转基因（Tg）过表达的组成性 神经上皮中特异性的活性雅普（CA-雅普）导致NTD形成。我们最近公布的数据 证明mTOR（雷帕霉素的机制靶点）下游激酶p70 S6 K1之一被激活 母亲糖尿病和它的缺乏加重糖尿病胚胎病。此外，mTOR抑制剂 雷帕霉素预防糖尿病胚胎病。HIPPO-Yap通路和mTOR通路均诱导细胞凋亡。 和组织生长。因此，我们假设母体糖尿病激活mTOR-p70 S6 K1， 通过磷酸化激活HIPPO激酶Lats 1拮抗雅普，选择性增加 翻译并破坏内质网（ER）稳态，导致NTD。Lats 1失活 雅普通过磷酸化，破坏平面细胞极性（PCP），导致失败的神经形成。到 为了验证我们的假设，我们提出以下目标。具体目标1。确定主要mTOR是否 下游效应子p70 S6 K1通过磷酸化雅普上游激酶Lats 1抵消雅普活性 糖尿病胚胎病我们将研究母体糖尿病是否激活mTOR效应子p70 S6 K1， 它与支架蛋白Merlin和Lats 1形成三级复合物，在两个细胞中触发Lats 1磷酸化， 以前未鉴定的位点，Thr 255和Thr 262，导致雅普失活。具体目标2。以确定 HIPPO信号激酶Lats 1激活是否导致糖尿病患者神经管缺陷 胚胎病我们将测试母体糖尿病是否诱导Lats 1在新位点磷酸化， 随后是导致雅普和NTD形成抑制的典型磷酸化位点。具体 目标3。为了研究微调的雅普活性对神经胚形成的关键作用及其失调如何破坏神经胚的形成， 糖尿病胚胎病的平面细胞极性。我们将评估雅普活动在 神经形成和恢复雅普活性可改善糖尿病胚胎病变。我们将进一步评估， 微调的雅普活性在神经形成期间维持PCP基因表达。

SUMMARY Pregestational diabetes induces neural tube defects (NTDs). There are 60 million women of reproductive age (18-44 years old) worldwide, and approximately 3 million American women with diabetes. Even under the best prenatal care, women with diabetes are still three- to four-times more likely to have a child with birth defects than women without diabetes. Unraveling the mechanism underlying diabetes-induced NTDs is critical for understanding its pathogenesis and providing potential intervention targets. Yes-associated protein (Yap), a transcriptional co-activator, determines body and organ size and regulates cell apoptosis, proliferation, and differentiation. We found that either conditional KO of Yap or transgenic (Tg) overexpression of constitutively active Yap (CA-Yap) specifically in the neuroepithelium resulted in NTD formation. Our recently published data demonstrate that one of the mTOR (mechanistic target of rapamycin) downstream kinase p70S6K1 is activated by maternal diabetes and its deficiency alleviates diabetic embryopathy. Furthermore, the mTOR inhibitor rapamycin prevents diabetic embryopathy. Both the HIPPO-Yap pathway and the mTOR pathway induce cell and tissue growth. Thus, we hypothesize that maternal diabetes activates mTOR-p70S6K1, which antagonizes Yap by activating the HIPPO kinase Lats1 through phosphorylation, selectively increases translation and disrupts endoplasmic reticulum (ER) homeostasis, leading to NTDs. Lats1 inactivates Yap through phosphorylation that disrupts the planar cell polarity (PCP) leading to failed neurulation. To test our hypothesis, we propose the following aims. Specific Aim 1. determine whether the major mTOR downstream effector p70S6K1 counteracts Yap activity by phosphorylating Yap upstream kinase Lats1 in diabetic embryopathy. We will examine whether maternal diabetes-activated the mTOR effector p70S6K1, which forms a tertiary complex with the scaffold protein Merlin and Lats1, triggers Lats1 phosphorylation in two previously unidentified sites, Thr255 and Thr262, leading to Yap inactivation. Specific Aim 2. To determine whether the HIPPO signaling kinase Lats1 activation leads to neural tube defects in diabetic embryopathy. We will test whether maternal diabetes induces Lats1 phosphorylation at new sites and subsequent the canonical phosphorylation sites which leads to suppression of Yap and NTD formation. Specific Aim 3. To investigate how fine-tuned Yap activity is critical for neurulation and its dysregulation disrupts planar cell polarity in diabetic embryopathy. We will assess that Yap activity is tightly controlled during neurulation and restoring Yap activity can ameliorate diabetic embryopathy. We will further evaluate whether fine-tuned Yap activity maintains PCP gene expression during neurulation.