Autophagy and its Regulation in Diabetic Embryopathy

妊娠前糖尿病可导致子代神经管缺陷（NTDs）。即使在最好的产前检查下 尽管如此，糖尿病妇女生育先天缺陷儿童的可能性仍然是非糖尿病妇女的三到四倍。糖尿病引起的NTD对母亲和她的孩子都是重要的公共卫生问题。然而，母体糖尿病致畸性的分子机制仍不清楚。我们最近在母体糖尿病诱导的自噬损伤中发现了一种microRNA介导的应激途径，导致NTD。延长的未折叠蛋白反应（UPR）和内质网（ER）应激在母体糖尿病诱导的NTDs中起关键作用。延长的UPR和自噬损伤之间的分子联系是难以捉摸的。我们发现，沉默主要的UPR传感器IRE 1 α，触发从头自噬体形成，并删除发育中的神经上皮中的Ire 1a基因，拯救自噬，从而防止糖尿病妊娠中的NTD。因此，我们假设母体糖尿病通过ASK 1触发IRE 1 α激活，ASK 1-IRE 1 α信号通过IRE 1 α RNA酶活性抑制发育中神经上皮细胞的自噬，产生XBP 1 s并降解靶向Txnip的miR-17。XBP 1、miR-17-Txnip回路及其串扰介导母体糖尿病的致畸性，导致NTD形成。为了验证我们的假设，我们提出了三个具体目标。目的1将确定ASK 1激活的IRE 1 α是否负责糖尿病胚胎病中的自噬损伤。我们假设母体糖尿病诱导的ASK 1激活通过直接磷酸化触发IRE 1 α激活，并抑制未折叠蛋白的ER相关降解（ERAD）。我们进一步证实，ASK 1-IRE 1 α信号抑制自噬，导致NTD形成。目的2将研究XBP 1 s和miR-17之间的潜在串扰，以及它们在母体糖尿病诱导的自噬损伤和NTD形成中的作用。我们假设IRE 1 α切割XBP 1 mRNA形成XBP 1 s并抑制miR-17的表达，共同导致ATG表达改变，并且XBP 1 s和miR-17受到抑制性调节，导致糖尿病妊娠中发育中的神经上皮细胞和NTD中的自噬损伤。目的3：探讨Txnip是否是IRE 1 α-miR-17通路的靶基因，是否参与糖尿病胚胎病的自噬抑制。我们的假设是Txnip，IRE 1 α-miR-17通路的下游效应子，通过结合并因此使ATG 4在将LC 3-I加工成LC 3-II中的能力丧失来抑制自噬，这是自噬体形成的必要步骤，导致糖尿病妊娠中的细胞失衡和NTD。

Pregestational diabetes induces neural tube defects (NTDs) in the offspring. Even under the best prenatal care, diabetic women are still three- to four-times more likely to have a child with birth defects than nondiabetic women. Diabetes-induced NTDs are significant public health problems for both the mother and her child. Yet, the molecular mechanism underlying the teratogenicity of maternal diabetes is still unclear. We recently discovered a microRNA-mediated stress pathway in maternal diabetes-induced autophagy impairment leading to NTDs. Prolonged unfolded protein response (UPR) and endoplasmic reticulum (ER) stress play critical roles in maternal diabetes-induced NTDs. The molecular link between prolonged UPR and autophagy impairment is elusive. We found that silencing the major UPR sensor, IRE1α, triggered de novo autophagosome formation, and deleting the Ire1a gene in the developing neuroepithelium rescued autophagy thereby preventing NTD in diabetic pregnancy. Therefore, we hypothesize that maternal diabetes triggers IRE1α activation through ASK1 and the ASK1-IRE1α signal inhibits autophagy in the developing neuroepithelium through IRE1α RNase activity by producing XBP1s and degrading miR-17, which targets Txnip. XBP1s, the miR-17-Txnip circuit, and their crosstalk mediate the teratogenicity of maternal diabetes leading to NTD formation. To test our hypothesis, we proposed three Specific Aims. Aim 1 will determine whether ASK1-activated IRE1α is responsible for autophagy impairment in diabetic embryopathy. We hypothesize that maternal diabetes-induced ASK1 activation triggers IRE1α activation via direct phosphorylation and suppresses ER-associated degradation (ERAD) of unfolded proteins. We further posit that the ASK1-IRE1α signal suppresses autophagy leading to NTD formation. Aim 2 will investigate the potential crosstalk between XBP1s and miR-17, and their roles in maternal diabetes-induced autophagy impairment and NTD formation. We hypothesize that IRE1α cleaves XBP1 mRNA to form XBP1s and represses miR-17 expression, collectively resulting in altered ATG expression, and that XBP1s and miR-17 are reciprocally regulated, leading to autophagy impairment in the developing neuroepithelium and NTDs in diabetic pregnancy. Aim 3 will determine whether Txnip is a target gene of the IRE1α-miR-17 pathway and participates in autophagy inhibition in diabetic embryopathy. Our hypothesis is that Txnip, a downstream effector of the IRE1α-miR-17 pathway, represses autophagy by binding to and thus disabling the ability of ATG4 in processing LC3-I in to LC3-II, an essential step for autophagosome formation, leading to cellular imbalance and NTDs in diabetic pregnancy.