Hypoxia during gestation is a common stress to maternal cardiovascular homeostasis and causes aberrant uterine vascular hemodynamics and an increased risk of preeclampsia and abnormal fetal development. Recent studies in sheep have demonstrated that chronic hypoxia during gestation causes a significant decrease in estrogen receptor 1 (ER1) expression in uterine arteries, and inhibits the steroid hormone-mediated adaptation of myogenic tone in uterine arteries in pregnancy. However, the molecular mechanisms remain poorly understood. Our preliminary studies suggest that chronic hypoxia increases promoter methylation of the ER1 gene in the uterine artery. DNA methylation is a chief mechanism in epigenetic modification of gene expression patterns. Although methylation of the ER1 promoter has been reported to occur as a direct function of physiological regulation in several tissue types and as part of a pathological progression of numerous types of cancerous tissues, little is known about the epigenetic regulation of ER1 gene expression pattern in vascular smooth muscle and its functional consequences. The proposed studies will address these major gaps in our knowledge and test the hypothesis that chronic hypoxia during gestation causes aberrant promoter methylation and ER1 gene repression resulting in heightened myogenic tone of the uterine artery in pregnancy.
Three specific aims are proposed to determine whether: 1) long-term high altitude hypoxia during gestation increases the promoter methylation resulting in ER1 gene repression, 2) prolonged hypoxia has direct causal effects on the heightened promoter methylation and ER1 gene repression, and 3) hypoxia- mediated promoter methylation and ER1 gene repression inhibit the steroid hormone-mediated adaptation of pressure-dependent myogenic tone in the uterine arteries in pregnancy. The results will not only significantly advance our knowledge of the molecular mechanisms underlying aberrant uteroplacental circulation and hence improve our understanding of the pregnancy complications associated with hypoxia, but also provide exciting novel insights into the epigenetic mechanisms regulating ER1 gene expression patterns in vascular smooth muscle and hence a comprehensive understanding of the role of ER1 in the estrogen-mediated protective effect of vascular function in general.

Public Health Relevance

Hypoxia during gestation is a common stress to maternal cardiovascular homeostasis and increases the risk of preeclampsia and fetal intrauterine growth restriction. The proposed studies will provide new insights into the molecular mechanisms underlying aberrant uteroplacental circulation caused by hypoxia in pregnancy and suggest new direction in the clinical management of the pregnancy complications associated with hypoxia, thereby reducing perinatal morbidity while improving maternal health and neonatal outcome.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL110125-03
Application #
8473271
Study Section
Special Emphasis Panel (ZRG1-EMNR-P (02))
Program Officer
Mitchell, Megan S
Project Start
2011-08-18
Project End
2016-05-31
Budget Start
2013-06-01
Budget End
2014-05-31
Support Year
3
Fiscal Year
2013
Total Cost
$353,430
Indirect Cost
$115,430
Name
Loma Linda University
Department
Other Basic Sciences
Type
Schools of Medicine
DUNS #
009656273
City
Loma Linda
State
CA
Country
United States
Zip Code
92350
Zhu, Ronghui; Huang, Xiaohui; Hu, Xiang-Qun et al. (2014) Gestational hypoxia increases reactive oxygen species and inhibits steroid hormone-mediated upregulation of Ca(2+)-activated K(+) channel function in uterine arteries. Hypertension 64:415-22
Chen, Man; Dasgupta, Chiranjib; Xiong, Fuxia et al. (2014) Epigenetic upregulation of large-conductance Ca2+-activated K+ channel expression in uterine vascular adaptation to pregnancy. Hypertension 64:610-8
Xiao, Daliao; Zhu, Ronghui; Zhang, Lubo (2014) Gestational hypoxia up-regulates protein kinase C and inhibits calcium-activated potassium channels in ovine uterine arteries. Int J Med Sci 11:886-92
Ma, Qingyi; Xiong, Fuxia; Zhang, Lubo (2014) Gestational hypoxia and epigenetic programming of brain development disorders. Drug Discov Today 19:1883-96
Xiao, DaLiao; Dasgupta, Chiranjib; Li, Yong et al. (2014) Perinatal nicotine exposure increases angiotensin II receptor-mediated vascular contractility in adult offspring. PLoS One 9:e108161
Zhu, Ronghui; Xiao, DaLiao; Zhang, Lubo (2013) Potassium channels and uterine vascular adaptation to pregnancy and chronic hypoxia. Curr Vasc Pharmacol 11:737-47
Chen, Man; Xiong, Fuxia; Zhang, Lubo (2013) Promoter methylation of Egr-1 site contributes to fetal hypoxia-mediated PKC? gene repression in the developing heart. Am J Physiol Regul Integr Comp Physiol 304:R683-9
Zhu, Ronghui; Hu, Xiang-Qun; Xiao, Daliao et al. (2013) Chronic hypoxia inhibits pregnancy-induced upregulation of SKCa channel expression and function in uterine arteries. Hypertension 62:367-74
Li, Yong; Xiao, Daliao; Yang, Shumei et al. (2013) Promoter methylation represses AT2R gene and increases brain hypoxic-ischemic injury in neonatal rats. Neurobiol Dis 60:32-8
Paradis, Alexandra; Zhang, Lubo (2013) Role of endothelin in uteroplacental circulation and fetal vascular function. Curr Vasc Pharmacol 11:594-605

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