CRH Acts on CRH-R1 and -R2 to Differentially Modulate the Expression of Large-Conductance Calcium-Activated Potassium Channels in Human Pregnant Myometrium

Abstract

CRH has been implicated to play a key role in the control of human pregnancy and parturition. Large-conductance potassium channels (BKCa) play a pivotal role in the modulation of uterine contractility during pregnancy. The objectives of the present study were to investigate the effect of CRH on BKCa expression in human pregnant myometrial cells. Myometrial tissues were collected at cesarean section from pregnant women not-in-labor (TNL) or in-labor (TL) at term, and myocytes were isolated and cultured. CRH was identified in human pregnant myometrium and mainly expressed in myometrial myocytes. Cultured myometrial cells were able to secrete CRH. In TNL myometrial cells, CRH treatment increased the expression of BKCa α- and β-subunits. CRH receptor type 1 (CRH-R1) antagonist, antalarmin, decreased whereas CRH receptor type 2 (CRH-R2) antagonist, astressin2b, increased the expression of BKCa. CRH-R2 small interfering RNA (siRNA) caused an increase, but CRH-R1 siRNA resulted in a decrease, in BKCa expression. In contrast to TNL cells, CRH exhibited an opposite effect on BKCa expression in TL myometrial cells, i.e. decreased BKCa expression. Antalarmin enhanced but astressin2b reduced BKCa expression. CRH-R2 siRNA decreased whereas CRH-R1 siRNA increased BKCa expression. 1,3-Dihydro-1-[2-hydroxy-5-(trifluoromethyl)phenyl]-5-(trifluoromethyl)-2H-benzimidazol-2-one significantly inhibited the frequency of spontaneous contractions of myometrial strips, and this effect was significantly decreased in TL strips compared with TNL ones. Our data suggest that CRH-R1 and CRH-R2 show differential regulation of BKCa expression. These effects mediated by CRH-R1 and CRH-R2 are changed after the onset of labor. This leads us to suggest that CRH may fine-tune myometrial contractility by modulating the expression of BKCa during pregnancy and labor.

Prostaglandin F2α regulates the expression of uterine activation proteins via multiple signalling pathways

“…Our previous study has shown that PGF2A robustly stimulates PTGS2 and OTR expression in cultured HMSMCs which were isolated from lower segment (Xu et al 2011). In the present study, it was also shown that PGF2A at 10 K6 M significantly enhanced PTGS2 and OTR expression in HMSMCs.…”

“…This study was approved by the specialty committee on ethics of biomedicine research, Second Military Medical University, Shanghai, China, and informed consent was obtained from all the patients who participated in this study. HMSMCs were cultured as described previously (Xu et al 2011). Briefly, myometrial pieces were incubated with phenol-red-free DMEM, containing 1 mg/ml collagenase type II (Invitrogen), and 1 mg/ml deoxyribonuclease I (Invitrogen) at 37 8C for 45 min.…”

Centrally acting drug moxonidine decreases reactive oxygen species via inactivation of the phosphoinositide-3 kinase signaling in the rostral ventrolateral medulla in hypertensive rats

“…A standard procedure for total RNA extraction and quantitative real-time RT-PCR was carried out as described previously [24]. Total RNA was prepared using Trizol reagent (Life Technologies, Carlsbad, California, USA).…”

BK Channels Regulate Myometrial Contraction by Modulating Nuclear Translocation of NF-κB

“…This has raised the important question of how activity of this channel is regulated. Several mechanisms have been suggested, including changes in transcript or protein expression (21,35), alternative splicing (36), association with caveolar domains (37), association with accessory subunits (38), and functional coupling with ß-adrenergic receptors (39,40). Interestingly, the gene that encodes the BK channel has an NF-B binding site in the 5Ј-flanking sequence of the promoter (41); thus, we envisioned that we would see an increase in BK channel expression in the presence of LPS.…”