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Darlene A Dartt, Jeffrey Bair, Markus Olsen, Robin Hodges, Tor Paaske Utheim, Charles N Serhan; Comparison of Signaling Pathways used by the Specialized Pro-Resolving Mediators Maresin1- and Maresin-2 to Regulate Conjunctival Goblet Cell Function . Invest. Ophthalmol. Vis. Sci. 2019;60(9):6260.
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Purpose: We previously determined that the specialized pro-resolving mediator (SPM) maresin-1 (MaR1) stimulates conjunctival goblet cell secretion using the phospholipase (PL)C dependent pathway. Our purpose is to determine if maresin-2 (MaR2) uses the same signaling pathways as MaR1.
Methods: Goblet cells were cultured from pieces of rat conjunctiva. Intracellular Ca2+concentration ([Ca2+]i) was measured using fura2/AM in cultured rat conjunctival goblet cells stimulated by agonists and antagonists. After incubation of goblet cells with agonists and antagonists high moleculular weight glycoconjugate secretion was determined using an enzyme-linked lectin assay (ELLA).
Results: Treatment with MaR2 increased [Ca2+]iand secretion above basal levels in a concentration dependent manner. Increase in [Ca2+]istimulated by both MaR1 and MaR2 were blocked by LY29311, a BLT-1 receptor inhibitor suggesting that MaR1 and MaR2 both activated the BLT1 receptor. Stimulation with MaR1 attenuated the [Ca2+]i response to MaR2, but, MaR2 did not block the MaR1 response suggesting that MaR1 activated a second receptor or MaR1 and 2 interacted with overlapping regions on the BLT1 receptor. As with MaR1, the MaR2 increase in [Ca2+]iwas dependent on intracellular Ca2+stores as the effect and was inhibited by the [Ca2+]istore inhibitor thapsigargin, but persisted in the absence of extracellular Ca2+. MaR1 and MaR2 use another common downstream effector as increases in [Ca2+]istimulated by either were blocked by the protein kinase C (PKC) inhibitor Ro31749. In contrast, MaR1, but not MaR2 stimulated increase in [Ca2+]i was blocked by the PLC inhibitor U73122 and MaR2, but not MaR1 stimulated [Ca2+]iresponse was blocked by H89 an inhibitor protein kinase A (PKA), a component of the cAMP dependent pathway.
Conclusions: We conclude that in conjunctival goblet cells the MaR2 increases in [Ca2+]iand stimulates secretion. MaR2 and MaR1 use different, but overlapping, signaling pathways to increase [Ca2+]i.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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