The human macrophage sodium channel NaV1.5 regulates mycobacteria processing through organelle polarization and localized calcium oscillations

• Published in: FEMS immunology and medical microbiology Vol. 63; no. 3; pp. 319 - 327
• Main Authors: Carrithers, Lisette M., Hulseberg, Paul, Sandor, Matyas, Carrithers, Michael D.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01-12-2011; Blackwell
• Subjects: Acidification; Bacteriology; BCG; Biological and medical sciences; Calcium (mitochondrial); Calcium Signaling; Calcium signalling; Cell activation; Cells, Cultured; endosomes; Endosomes - metabolism; Endosomes - microbiology; Fundamental and applied biological sciences. Psychology; Gene Knockdown Techniques; Humans; Infection; macrophage; Macrophages; Macrophages - immunology; Macrophages - metabolism; Macrophages - microbiology; Microbiology; Miscellaneous; Mitochondria; Mitochondria - metabolism; Mycobacterium; Mycobacterium bovis - immunology; Na super(+)/Ca super(2+)-exchanging ATPase; NAV1.5 Voltage-Gated Sodium Channel; Organelles; Phagocytosis; Phagosomes; Polarization; Signal transduction; Sodium channels (voltage-gated); Sodium Channels - genetics; Sodium Channels - metabolism; voltage‐gated sodium channel; phagocytosis; macrophage; voltage-gated sodium channel; calcium signaling; Human; Mycobacterium; Calcium; Inorganic element; Regulation(control); Immunology; Sodium; Mycobacteriales; Mycobacteriaceae; Bacteria; Actinomycetes; Phagocytosis; Macrophage
• ISSN: 0928-8244; 1574-695X
• DOI: 10.1111/j.1574-695X.2011.00853.x

Abstract
Phagocytosis and intracellular processing of mycobacteria by macrophages are complex cellular processes that require spatial and temporal coordination of particle uptake, organelle movement, activation of signaling pathways, and channel-mediated ionic flux. Recent work demonstrated that human macrophage NaV1.5, an intracellular voltage-gated sodium channel expressed on late endosomes, enhances endosomal acidification and phagocytosis. Here, using bacillus Camille-Guerin (BCG) as a model of mycobacterial infection, we examined how this channel regulates phagocytosis and phagosome maturation in human macrophages. Knockdown of NaV1.5 reduced high capacity uptake of labeled BCG. BCG-containing, NaV1.5-expressing cells demonstrated localization of NaV1.5 and Rab-7 positive endosomes and mitochondria to periphagosome regions that was not observed in NaV1.5-deficient cells. Knockdown of the channel reduced the initial calcium response following bacterial challenge and prevented the generation of prolonged and localized calcium oscillations during phagosome maturation. Inhibition of the mitochondrial Na+/Ca2+ exchanger also prevented prolonged calcium oscillations during phagosome maturation. These results suggest that NaV1.5 and mitochondrial-dependent calcium signaling regulate mycobacteria phagocytosis and phagosome maturation in human macrophages through spatial-temporal coordination of calcium signaling within a unique subcellular region.