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).
Adenosine Triphosphate, Animals, Astrocytes, Autophagy, Biomarkers, Calcium, Cells, Cultured, Epithelial Cells, Hydrogen-Ion Concentration, Lysosomes, Mice, RNA, Small Interfering, Toll-Like Receptor 3, Transient Receptor Potential Channels, adenosine triphosphate, biological marker, calcium, Mcoln1 protein, mouse, small interfering RNA, toll like receptor 3, transient receptor potential channel, animal, astrocyte, autophagy, cell culture, epithelium cell, genetics, lysosome, metabolism, mouse, pH
Beckel, J. M., Gómez, N. M., Lu, W., Campagno, K. E., Nabet, B., Albalawi, F., Lim, J. C., Boesze-Battaglia, K., & Mitchell, C. H. (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: 09 February 2023
This document has been peer reviewed.