Departmental Papers (Dental)
Stimulation of TLR3 Triggers Release of Lysosomal ATP in Astrocytes and Epithelial Cells That Requires TRPML1 Channels
Date of this Version
Article number 5726
Cross-reactions between innate immunity, lysosomal function, and purinergic pathways may link signaling systems in cellular pathologies. We found activation of toll-like receptor 3 (TLR3) triggers lysosomal ATP release from both astrocytes and retinal pigmented epithelial (RPE) cells. ATP efflux was accompanied by lysosomal acid phosphatase and beta hexosaminidase release. Poly(I:C) alkalinized lysosomes, and lysosomal alkalization with bafilomycin or chloroquine triggered ATP release. Lysosomal rupture with glycyl-L-phenylalanine-2-naphthylamide (GPN) eliminated both ATP and acid phosphatase release. Secretory lysosome marker LAMP3 colocalized with VNUT, while MANT-ATP colocalized with LysoTracker. Unmodified membrane-impermeant 21-nt and "non-targeting" scrambled 21-nt siRNA triggered ATP and acid phosphatase release, while smaller 16-nt RNA was ineffective. Poly(I:C)-dependent ATP release was reduced by TBK-1 block and in TRPML1-/- cells, while TRPML activation with ML-SA1 was sufficient to release both ATP and acid phosphatase. The ability of poly(I:C) to raise cytoplasmic Ca2+ was abolished by removing extracellular ATP with apyrase, suggesting ATP release by poly(I:C) increased cellular signaling. Starvation but not rapamycin prevented lysosomal ATP release. In summary, stimulation of TLR3 triggers lysosomal alkalization and release of lysosomal ATP through activation of TRPML1; this links innate immunity to purinergic signaling via lysosomal physiology, and suggests even scrambled siRNA can influence these pathways. © 2018 The Author(s).
Beckel, J., Gómez, N. M., Lu, W., Campagno, K. E., Nabet, B., Albalawi, F., Lim, J. C., & Boesze-Battaglia, K. (2018). Stimulation of TLR3 Triggers Release of Lysosomal ATP in Astrocytes and Epithelial Cells That Requires TRPML1 Channels. Scientific Reports, 8 (1), Article number 5726-. http://dx.doi.org/10.1038/s41598-018-23877-3
Date Posted: 08 December 2022
This document has been peer reviewed.