Congenital malformations occur in up to 10% of babies born to diabetic women. Optimal glycemiccontrol is difficult to achieve and maintain, and even transient exposure to hyperglycemia can causemalformations. This project is formulated on the basis of our strong preliminary data. We have found 1)hyperglycemia impairs autophagy and increases the accumulation of defective mitochondria,dysfunctional proteins and swollen endoplasmic reticulum (ER) in the developing neuroepithelium; 2) thenon-toxic autophagy activator, trehalose, reverses hyperglycemia-induced autophagy impairment andneural tube defects (NTDs); 3) PKCa gene deletion, a p70S6K1 inhibitor, an ER chaperone (4-PBA) andoverexpression of sirtuin 2 (SIRT2) histone deacetylase in the neural tube, all reduce hyperglycemia-induced NTDs; 4) both p70S6K1 inhibitor and SIR2 overexpression restore levels of the autophagymarker, LC3-II. We test a novel hypothesis that maternal diabetes-induced autophagy impairmentcauses NTD formation by disrupting cellular homeostasis leading to ER stress and apoptosis, andthat maternal hyperglycemia activates p70S6K1 resulting in autophagy impairment. Restoration ofautophagy by trehalose prevents hyperglycemia-induced NTDs. In addition, reduced SIRT2 andSIRT6 expression mediates the effect of p70S6K1.
Aim 1 will determine whether trehalose preventshyperglycemia-induced NTDs by correcting autophagy impairment that causes ER stress andapoptosis. We hypothesize that maternal diabetes induces aberrant changes of Atg1 and Sqsmt1expression, which regulate autophagy, leading to autophagy impairment which induces apoptosis andNTDs, and reversal of autophagy impairment by trehalose, will restore cellular homeostasis and thusprevent diabetes-induced NTDs.
Aim 2 will investigate the activation mechanism and the role ofp70S6K1 in autophagy impairment and NTD formation in diabetic embryopathy. Our workinghypothesis is that PKCa activates p70S6K1 which causes autophagy impairment, an increase in DNA-methyltransferases (DNMTs) and a decrease in SIRT 2 and 6 gene expression leading to NTD formation.
Aim 3 will determine the underlying mechanism and the role of reduced sirt2 and sirt6 geneexpression in autophagy impairment that leads to diabetic embryopathy. We will test the hypothesisthat promoter hypermethylation and subsequent reduced transcription factor binding activities cause sirt2and sirt6 gene reduction which lead to autophagy impairment by modulating the expression of Atg1 andSqsmt1 via deacetylation of Foxo transcription factors. Our studies will provide mechanistic evidence forautophagy, ER stress, p70S6K1 and SIRT2/6 as targets for therapeutic interventions.

Public Health Relevance

Nearly two million American women at reproductive ages have diabetes and this number will be double by 2030. Maternal diabetes is a significant risk factor for structural birth defects. Diabetic women under modern preconceptional care are still three to four times more likely to have a child with birth defects than non-diabetic women. Diabetes-induced birth defects remain significant maternal-fetal health problems. In this proposal, we employ two complementary models, the type I and type II diabetic embryopathy, to delineate the mechanisms underlying diabetes-induced neural tube defects (NTDs). In a series of mechanistic studies, we will test the novel hypothesis that autophagy impairment is responsible for apoptosis leading to NTDs, and that activation of the PKCa-p70S6K1-SIRT2/6 pathway causes autophagy impairment in diabetic embryopathy. This project will provide a mechanistic basis for exploring the non-toxic autophagy activator, trehalose, p70S6K1 inhibitors, endoplasmic reticulum chemical chaperones and specific SIRT2 and SIRT6 activators as new prevention strategies against diabetes- induced NTDs.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
High Priority, Short Term Project Award (R56)
Project #
1R56DK095380-01A1
Application #
8536445
Study Section
Pregnancy and Neonatology Study Section (PN)
Program Officer
Jones, Teresa L Z
Project Start
2012-09-21
Project End
2014-08-31
Budget Start
2012-09-21
Budget End
2014-08-31
Support Year
1
Fiscal Year
2012
Total Cost
$149,999
Indirect Cost
$52,280
Name
University of Maryland Baltimore
Department
Obstetrics & Gynecology
Type
Schools of Medicine
DUNS #
188435911
City
Baltimore
State
MD
Country
United States
Zip Code
21201
Gu, Hui; Yu, Jingwen; Dong, Daoyin et al. (2016) High Glucose-Repressed CITED2 Expression Through miR-200b Triggers the Unfolded Protein Response and Endoplasmic Reticulum Stress. Diabetes 65:149-63
Wang, Fang; Reece, E Albert; Yang, Peixin (2015) Oxidative stress is responsible for maternal diabetes-impaired transforming growth factor beta signaling in the developing mouse heart. Am J Obstet Gynecol 212:650.e1-11
Wang, Fang; Wu, Yanqing; Gu, Hui et al. (2015) Ask1 gene deletion blocks maternal diabetes-induced endoplasmic reticulum stress in the developing embryo by disrupting the unfolded protein response signalosome. Diabetes 64:973-88
Gu, Hui; Yu, Jingwen; Dong, Daoying et al. (2015) The miR-322-TRAF3 circuit mediates the pro-apoptotic effect of high glucose on neural stem cells. Toxicol Sci 144:186-96
Yang, Peixin; Reece, E Albert; Wang, Fang et al. (2015) Decoding the oxidative stress hypothesis in diabetic embryopathy through proapoptotic kinase signaling. Am J Obstet Gynecol 212:569-79
Wang, Fang; Reece, E Albert; Yang, Peixin (2015) Advances in revealing the molecular targets downstream of oxidative stress-induced proapoptotic kinase signaling in diabetic embryopathy. Am J Obstet Gynecol 213:125-34
Wu, Yanqing; Wang, Fang; Fu, Mao et al. (2015) Cellular Stress, Excessive Apoptosis, and the Effect of Metformin in a Mouse Model of Type 2 Diabetic Embryopathy. Diabetes 64:2526-36
Wu, Yanqing; Wang, Fang; Reece, E Albert et al. (2015) Curcumin ameliorates high glucose-induced neural tube defects by suppressing cellular stress and apoptosis. Am J Obstet Gynecol 212:802.e1-8
Wang, Fang; Reece, E Albert; Yang, Peixin (2013) Superoxide dismutase 1 overexpression in mice abolishes maternal diabetes-induced endoplasmic reticulum stress in diabetic embryopathy. Am J Obstet Gynecol 209:345.e1-7
Yang, Peixin; Li, Xuezheng; Xu, Cheng et al. (2013) Maternal hyperglycemia activates an ASK1-FoxO3a-caspase 8 pathway that leads to embryonic neural tube defects. Sci Signal 6:ra74

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