Author(s): York N, Halbach P, Chiu MA, Bird IM, Pillers DM, Pattnaik BR. Oxytocin (OXT)-stimulated inhibition of Kir7.1 activity is through PIP(2)-dependent Ca(2+) response of the oxytocin receptor in the retinal pigment epithelium in vitro. Cell Signal. 2017 Sep;37:93-102. doi: 10.1016/j.cellsig.2017.06.005. Epub 2017 Jun 8. PMID 28603013
Journal: Cellular Signalling, Volume 37, 09 2017
Oxytocin (OXT) is a neuropeptide that activates the oxytocin receptor (OXTR), a rhodopsin family G-protein coupled receptor. Our localization of OXTR to the retinal pigment epithelium (RPE), in close proximity to OXT in the adjacent photoreceptor neurons, leads us to propose that OXT plays an important role in RPE-retinal communication. An increase of RPE [Ca2+]i in response to OXT stimulation implies that the RPE may utilize oxytocinergic signaling as a mechanism by which it accomplishes some of its many roles. In this study, we used an established human RPE cell line, a HEK293 heterologous OXTR expression system, and pharmacological inhibitors of Ca2+ signaling to demonstrate that OXTR utilizes capacitative Ca2+ entry (CCE) mechanisms to sustain an increase in cytoplasmic Ca2+. These findings demonstrate how multiple functional outcomes of OXT-OXTR signaling could be integrated via a single pathway. In addition, the activated OXTR was able to inhibit the Kir7.1 channel, an important mediator of sub retinal waste transport and K+ homeostasis.