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Updated: Nov 28, 2025

Author Spotlight: Detection of Mitophagy in Caenorhabditis elegans and Mammalian Cells Using Organelle-Specific Dyes
Published on: May 19, 2023
Mitochondrial Ca2+ Signaling Is an Electrometabolic Switch to Fuel Phagosome Killing
Philip V Seegren1, Taylor K Downs1, Marta E Stremska2
1Pharmacology Department, University of Virginia, Pinn Hall, 1340 Jefferson Park Avenue, Charlottesville, VA 22908, USA; Carter Immunology Center, University of Virginia, 345 Crispell r. MR-6, Charlottesville, VA 22908, USA.
Abstract:
Phagocytes reallocate metabolic resources to kill engulfed pathogens, but the intracellular signals that rapidly switch the immunometabolic program necessary to fuel microbial killing are not understood. We report that macrophages use a fast two-step Ca2+ relay to meet the bioenergetic demands of phagosomal killing. Upon detection of a fungal pathogen, macrophages rapidly elevate cytosolic Ca2+ (phase 1), and by concurrently activating the mitochondrial Ca2+ (mCa2+) uniporter (MCU), they trigger a rapid influx of Ca2+ into the mitochondria (phase 2). mCa2+ signaling reprograms mitochondrial metabolism, at least in part, through the activation of pyruvate dehydrogenase (PDH). Deprived of mCa2+ signaling, Mcu-/- macrophages are deficient in phagosomal reactive oxygen species (ROS) production and defective at killing fungi. Mice lacking MCU in their myeloid cells are highly susceptible to disseminated candidiasis. In essence, this study reveals an elegant design principle that MCU-dependent Ca2+ signaling is an electrometabolic switch to fuel phagosome killing.
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