Casein kinase 2 inhibition impairs spontaneous and oxytocin‐induced contractions in late pregnant mouse uterus.

New Findings: <bold>What is the central question of this study?</bold> Does the inhibition of the protein kinase casein kinase 2 (CK2) alter the uterine contractility? <bold>What is the main finding and its importance?</bold> Inhibition of CK2 impaired the spontaneous and oxytocin‐induced contractility in late pregnant mouse uterus. This finding suggests that CK2 is a novel pathway mediating oxytocin‐induced contractility in the uterus and thus opens up the possibility for this class of drugs to be developed as a new class of tocolytics. Abstract: The protein kinase casein kinase 2 (CK2) is a ubiquitously expressed serine or threonine kinase known to phosphorylate a number of substrates. The aim of this study was to assess the effect of CK2 inhibition on spontaneous and oxytocin‐induced uterine contractions in 19 day pregnant mice. The CK2 inhibitor CX‐4945 elicited a concentration‐dependent relaxation in late pregnant mouse uterus. CX‐4945 and another selective CK2 inhibitor, apigenin, also inhibited the oxytocin‐induced contractile response in late pregnant uterine tissue. Apigenin also blunted the prostaglandin F2α response, but CX‐4945 did not. Casein kinase 2 was located in the lipid raft fractions of the cell membrane, and disruption of lipid rafts was found to reverse its effect. The results of the present study suggest that CK2, located in lipid rafts of the cell membrane, is an active regulator of spontaneous and oxytocin‐induced uterine contractions in the late pregnant mouse. [ABSTRACT FROM AUTHOR]