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The interaction between protein kinase A and progesterone on basal and inflammation-induced myometrial oxytocin receptor expression.

ABSTRACT: Our previous work has shown myometrial PKA activity declines in term and twin-preterm labour in association with an increase in the expression of the oxytocin receptor (OTR). Here we investigate the action of cAMP/PKA in basal conditions, with the addition of progesterone (P4) and/or IL-1? to understand how cAMP/PKA acts to maintain pregnancy and whether the combination of cAMP and P4 would be a viable therapeutic combination for the prevention of preterm labour (PTL). Further, given that we have previously found that cAMP enhances P4 action we wanted to test the hypothesis that changes in the cAMP effector system are responsible for the functional withdrawal of myometrial P4 action. Myometrial cells were grown from biopsies obtained from women at the time of elective Caesarean section before the onset of labour. The addition of forskolin, an adenylyl cyclase activator, repressed basal OTR mRNA levels at all doses and P4 only enhanced this effect at its highest dose. Forskolin repressed the IL-1?-induced increase in OTR mRNA and protein levels in a PKA-dependent fashion and repressed IL-1?-activation and nuclear transfer of NF?B and AP-1. P4 had similar effects and the combination P4 and forskolin had greater effects on OTR and NF?B than forskolin alone. While PKA knockdown had no effect on the ability of P4 to repress IL-1?-induced OTR expression it reversed the repressive effect of the combination of P4 and forskolin and resulted in a greater increase than observed with IL-1? alone. These studies suggest that cAMP acts via PKA to repress inflammation-driven OTR expression, but that when PKA activity is reduced, the combination of cAMP and P4 actually enhances the OTR response to inflammation, promoting the onset of labour and suggesting that changes in the cAMP effector system can induce a functional P4 withdrawal.

SUBMITTER: Yulia A

PROVIDER: S-EPMC7707466 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature

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The interaction between protein kinase A and progesterone on basal and inflammation-induced myometrial oxytocin receptor expression.

Yulia Angela A Varley Alice J AJ Singh Natasha N Lei Kaiyu K Tribe Rachel M RM Johnson Mark R MR

PloS one 20201201 12

Our previous work has shown myometrial PKA activity declines in term and twin-preterm labour in association with an increase in the expression of the oxytocin receptor (OTR). Here we investigate the action of cAMP/PKA in basal conditions, with the addition of progesterone (P4) and/or IL-1β to understand how cAMP/PKA acts to maintain pregnancy and whether the combination of cAMP and P4 would be a viable therapeutic combination for the prevention of preterm labour (PTL). Further, given that we hav ...[more]

PMID: 33259490

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Project description:Study hypothesisMyometrial explants represent a superior model compared with cell culture models for the study of human myometrial progesterone (P4) signalling in parturition.Study findingGene expression analysis showed myometrial explants closely resemble the in vivo condition and the anti-inflammatory action of P4 is not lost with labour onset.What is known alreadyCirculating P4 levels decline before the onset of parturition in most animals, but not in humans. This has led to the suggestion that there is a functional withdrawal of P4 action at the myometrial level prior to labour onset. However, to date, no evidence of a loss of P4 function has been provided, with studies hampered by a lack of a physiologically relevant model.Study design, samples/materials, methodsMyometrial biopsies obtained at Caesarean section were dissected into explants after a portion was immediately snap frozen (t = 0). Microarray analysis was used to compare gene expression of t = 0 with paired (i) explants, (ii) passage 4 myometrial cell cultures or (iii) the hTERT myometrial cell line. Western blotting and chemokine/cytokine assays were used to study P4 signalling in myometrial explants.Main results and the role of chanceGene expression comparison of t = 0 to the three models demonstrated that explants more closely resemble the in vivo status. At the protein level, explants maintain both P4 receptor (PR) and glucocorticoid receptor (GR) levels versus t = 0 whereas cells only maintain GR levels. Additionally, treatment with 1 µM P4 led to a reduction in interleukin-1 (IL-1) β-driven cyclooxygenase-2 in explants but not in cells. P4 signalling in explants was PR-mediated and associated with a repression of p65 and c-Jun phosphorylation. Furthermore, the anti-inflammatory action of P4 was maintained after labour onset.Limitations/reasons for cautionThere is evidence of basal inflammation in the myometrial explant model.Wider implications of the findingsMyometrial explants constitute a novel model to study P4 signalling in the myometrium and can be used to further elucidate the mechanisms of P4 action in human labour.Large scale dataData deposited at http://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?token=gvmpggkurbgxfqf&acc=GSE77830.Study funding and competing interestThis work was supported by grants from the Joint Research Committee of the Westminster Medical School Research Trust, Borne (No. 1067412-7; a sub-charity of the Chelsea and Westminster Health Charity) and the Imperial NIHR Biomedical Research Centre. The views expressed are those of the author(s) and not necessarily those of the NHS or the Department of Health. The authors have no conflict of interest.

Dataset Information

The interaction between protein kinase A and progesterone on basal and inflammation-induced myometrial oxytocin receptor expression.

Publications

The interaction between protein kinase A and progesterone on basal and inflammation-induced myometrial oxytocin receptor expression.

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