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Role of mitogen-activated protein kinase pathway in prostaglandin F2alpha-induced rat puerperal uterine contraction
1Department of Obstetrics and Gynecology, Osaka University Medical School, Suita-shi, Japan.
Abstract:
In this study, prostaglandin (PG) F2alpha was found to activate mitogen-activated protein (MAP) kinase and MAP kinase kinase (MEK) in cultured rat puerperal uterine myometrial cells. PGF2alpha stimulation also led to an increase in phosphorylation of raf-1, son of sevenless (SOS), and Shc. Furthermore, we examined the mechanism by which PGF2alpha induced MAP kinase phosphorylation. Both pertussis toxin (10 ng/ml), which inactivates Gi/Go proteins, and expression of a peptide derived from the carboxyl terminus of the beta-adrenergic receptor kinase 1 (betaARK1), which specifically blocks signaling mediated by the betagamma subunits of G proteins, blocked the PGF2alpha-induced activation of MAP kinase. Ritodrine (1 microM), which is known to relax uterine muscle contraction, attenuated PGF2alpha-induced tyrosine phosphorylation of MAP kinase. Moreover, to examine the role of MAP kinase pathway in uterine contraction, an inhibitor of MEK activity, PD098059, was used. Although MEK inhibitor had no effect on PGF2alpha-induced calcium mobilization, this inhibitor partially inhibited PGF2alpha-induced uterine contraction. These results provide evidence that PGF2alpha stimulates the MAP kinase signaling pathway in cultured rat puerperal uterine myometrial cells through Gbetagamma protein, suggesting that this new pathway may play an important role in the biological action of PGF2alpha on these cells.
Insights
Prostaglandin F2alpha activates the MAP kinase pathway in uterine cells via Gbetagamma proteins. This pathway partially mediates uterine contractions, revealing a new mechanism for PGF2alpha
Area of Science:
- Cellular signaling
- Reproductive biology
- Molecular pharmacology
Background:
- Prostaglandin F2alpha (PGF2alpha) is a key hormone regulating uterine function.
- The mitogen-activated protein (MAP) kinase pathway is crucial in cellular responses.
- Understanding PGF2alpha signaling in myometrial cells is vital for reproductive health.
Purpose of the Study:
- To investigate the role of the MAP kinase pathway in PGF2alpha-induced uterine myometrial cell activation.
- To elucidate the specific signaling mechanisms involved in PGF2alpha action.
Main Methods:
- Primary cell culture of rat puerperal uterine myometrial cells.
- Stimulation with PGF2alpha and assessment of protein phosphorylation (MAP kinase, raf-1, SOS, Shc).
- Inhibition studies using pertussis toxin, betaARK1 peptide, ritodrine, and PD098059 (MEK inhibitor).
Main Results:
- PGF2alpha activated MAP kinase and MAP kinase kinase (MEK), increasing phosphorylation of raf-1, SOS, and Shc.
- Activation was blocked by pertussis toxin and a betaARK1-derived peptide, indicating Gbetagamma protein involvement.
- Ritodrine attenuated PGF2alpha-induced MAP kinase phosphorylation.
- MEK inhibition partially reduced PGF2alpha-induced uterine contraction but did not affect calcium mobilization.
Conclusions:
- PGF2alpha stimulates the MAP kinase signaling pathway in rat puerperal uterine myometrial cells through Gbetagamma proteins.
- The MAP kinase pathway, activated by PGF2alpha, plays a partial role in uterine contraction.
- This study identifies a novel signaling pathway for PGF2alpha's biological actions in the uterus.