A screening campaign in sea urchin egg homogenate as a platform for discovering modulators of NAADP-dependent Ca2+ signaling in human cells. (November 2018)

• Record Type: Journal Article
• Authors: Gunaratne, Gihan S.; Johns, Malcolm E.; Hintz, Hallie M.; Walseth, Timothy F.; Marchant, Jonathan S.
• Is Part Of: Cell calcium. Volume 75(2018)
• Page Start: 42
• Page End: 52
• Publication Date: 2018-11
• Subjects: NAADP -- Ca2+release -- Drug screening -- Endosomes -- Lysosomes; Calcium -- Metabolism -- Periodicals; Vertebrates -- Physiology -- Periodicals; Calcium -- Physiological effect -- Periodicals; Cell physiology -- Periodicals; Calcium in the body -- Periodicals; 572.516
• DOI: 10.1016/j.ceca.2018.08.002
• Languages: English
• ISSNs: 0143-4160

Abstract

Graphical abstract: Highlights: Nicotinic acid adenine dinucleotide phosphate (NAADP) releases Ca 2+ from acidic organelles. Modulators of NAADP signaling are useful research tools with potential therapeutic value. A sea urchin egg homogenate screen yielded novel inhibitors of NAADP-evoked Ca 2+ release. These inhibitors were also effective blockers of NAADP action in a human cell line. Abstract: The Ca 2+ mobilizing second messenger nicotinic acid adenine dinucleotide phosphate (NAADP) regulates intracellular trafficking events, including translocation of certain enveloped viruses through the endolysosomal system. Targeting NAADP-evoked Ca 2+ signaling may therefore be an effective strategy for discovering novel antivirals as well as therapeutics for other disorders. To aid discovery of novel scaffolds that modulate NAADP-evoked Ca 2+ signaling in human cells, we have investigated the potential of using the sea urchin egg homogenate system for a screening campaign. Known pharmacological inhibitors of NAADP-evoked Ca 2+ release (but not cADPR- or IP3 -evoked Ca 2+ release) in this invertebrate system strongly correlated with inhibition of MERS-pseudovirus infectivity in a human cell line. A primary screen of 1534 compounds yielded eighteen 'hits' exhibiting >80% inhibition of NAADP-evoked Ca 2+ release. A validation pipeline for these candidates yielded seven drugs that inhibited NAADP-evoked Ca 2+ release without depleting acidic Ca 2+ stores in a human cell line. These candidates displayed a similar penetrance of inhibition in both the sea urchin system and the human cell line, and the extent of inhibition of NAADP-evoked Ca 2+ signals correlated well with observed inhibition of infectivity of a Middle East Respiratory syndrome coronavirus (MERS-CoV) pseudovirus. These experiments support the potential of this simple, homogenate system for screening campaigns to discover modulators of NAADP, cADPR and IP3 -dependent Ca 2+ signaling with potential therapeutic value.