Pregnancy Reprograms Large-Conductance Ca ²⁺ -Activated K ⁺ Channel in Uterine Arteries

Abstract

The large conductance Ca2+-activated K+ (BKCa) channel is of critical importance in pregnancy-mediated increase in uterine artery vasodilation and blood flow. The present study tested the hypothesis that active DNA demethylation plays a key role in pregnancy-induced reprogramming and upregulation of BKCa channel β1 subunit (BKβ1) in uterine arteries. Uterine arteries were isolated from non-pregnant and near-term pregnant sheep. Pregnancy significantly increased the expression of ten-eleven translocation methylcytosine dioxygenase 1 (TET1) in uterine arteries. A half-palindromic estrogen response element was identified at the TET1 promoter and estrogen treatment increased TET1 promoter activity and TET1 expression in uterine arteries. In accordance, pregnancy and steroid hormone treatment resulted in demethylation of BKβ1 promoter by increasing 5hmC and decreasing 5mC at the CpG in the Sp1-380 binding site that is of critical importance in the regulation of the promoter activity and BKβ1 expression. Inhibition of TET1 with fumarate significantly decreased BKβ1 expression in uterine arteries of pregnant animals and blocked steroid hormone-induced upregulation of BKβ1. Functionally, fumarate treatment inhibited pregnancy and steroid hormone-induced increases in BKCa channel current density and BKCa channel-mediated relaxations. In addition, fumarate blocked pregnancy and steroid hormone-induced decrease in pressure-dependent myogenic tone of the uterine artery. The results demonstrate a novel mechanism of estrogen-mediated active DNA demethylation in reprogramming of BKCa channel expression and function in the adaption of uterine circulation during pregnancy.

SIRT1 increases cardiomyocyte binucleation in the heart development

“…To silence the SIRT1 gene, siRNAs designed to specifically knock down rat SIRT1 or siRNA negative controls were purchased from Dharmacon (Lafayette, CO). Cell transfection was performed with HiPerfect transfection reagent (Qiagen, Valencia, CA) following the manufacturer's recommendations, as described previously [ 60 ]. Briefly, the mixture of target or negative siRNAs, Briefly, the mixture of target or negative siRNAs, HiPerfect transfection reagent, and Minimum Essential Media I (Thermo Fisher, Waltham, MA) was prepared and incubated for 10 minutes at room temperature.…”

Influence of Estrogens on Uterine Vascular Adaptation in Normal and Preeclamptic Pregnancies

“…This type of Ca 2+ release, termed sparks, activates BK Ca channels, causing spontaneous transient outward currents (STOCs), and hyperpolarizing currents ( Figure 2) [119]. Estrogenic modulation of BK Ca activity is mediated by DNA demethylation, which upregulates the BKβ1 subunit and increases BK Ca channels activity [120].…”

BKCa participates in E2 inducing endometrial adenocarcinoma by activating MEK/ERK pathway

“…The altered expressions or activation of BKCa may lead to changes of intracellular calcium and membrane potential resulting in dysfunction of cells and organs. BKCa was revealed as an important molecule in regulating contraction/relaxation of muscle cells [ 8 ], neurotransmission in the brain, and metabolism, proliferation, migration, and gene expression [ 9 ]. Although it has been described in some types of cancer cell, such as osteosarcoma [ 10 ], breast cancer [ 11 ] and gastric cancer [ 12 ], little is known about the functions of BKCa in uterus.…”