P2X7 Receptor Triggers Lysosomal Leakage Through Calcium Mobilization in a Mechanism Dependent on Pannexin-1 Hemichannels.

Stephanie Alexia Cristina Silva Santos,Newton G Castro,Luiz Eduardo Baggio Savio,Júlia Costa De Sousa,Pedro Muanis Persechini,Marcelo Felippe Santiago,Fernando Ariel Genta,Robson Coutinho-Silva,Victória Gabriela Bello-Santos,Bianca Monteiro Henriques-Santos,Eleonora Kurtenbach

doi:10.3389/fimmu.2022.752105

Abstract

The P2X7 receptor is a critical purinergic receptor in immune cells. Its activation was associated with cathepsin release into macrophage cytosol, suggesting its involvement in lysosomal membrane permeabilization (LMP) and leakage. Nevertheless, the mechanisms by which P2X7 receptor activation induces LMP and leakage are unclear. This study investigated cellular mechanisms associated with endosomal and lysosomal leakage triggered by P2X7 receptor activation. We found that ATP at 500 μM and 5 mM (but not 50 μM) induced LMP in non-stimulated peritoneal macrophages. This effect was not observed in P2X7-deficient or A740003-pretreated macrophages. We found that the P2X7 receptor and pannexin-1 channels mediate calcium influx that might be important for activating specific ion channels (TRPM2 and two-pore channels) on the membranes of late endosomes and lysosomes leading to LMP leakage and consequent cathepsin release. These findings suggest the critical role of the P2X7 receptor in inflammatory and infectious diseases via lysosomal dysfunction.

Highlights

Endosomes are membrane-surrounded organelles that transport extracellular macromolecules in eukaryotic cells [1]
We investigated the effect of extracellular adenosine-5’triphosphate disodium salt hydrate (ATP) (50 mM, 500 mM, and 5 mM) on non-stimulated peritoneal macrophage late endosome and endolysosome stability
500 mM (p < 0.001) and 5 mM ATP (p < 0.0001) treatments significantly decreased the number of late endosomes/endolysosomes marked with Lucifer Yellow (LY) (Figure 1A, representative images; Figure 1C, quantification), suggesting that P2X7 receptor activation mediates lysosomal leakage

Summary

Introduction

Endosomes are membrane-surrounded organelles that transport extracellular macromolecules in eukaryotic cells [1]. Plasma cell membrane invaginations originate primary endocytic vesicles that deliver their contents to early endosomes in the cytoplasm. The late endosomes can fuse with lysosomes to form a transient hybrid organelle called the endolysosome [1]. Larger particles such as pathogens and apoptotic cells are usually internalized by. P2X7 Receptor Triggers Lysosomal Leakage phagocytosis—a receptor-mediated cell mechanism of engulfment and uptake of particles within a plasma membrane-derived vesicle. These vesicles called phagosomes can fuse with lysosomes forming phagolysosomes [2]

Methods

Results

Conclusion