Revisiting the role of calcium in phagosome formation and maturation

Abstract

Like other membrane receptor-mediated responses, execution of phagocytosis requires the transduction of signals to cytoplasmic effectors. Signaling in this case is particularly complex as the process involves not only the formation of phagosomes but also their subsequent maturation and resolution. Transient increases in cytosolic calcium, which mediate a variety of other transduction pathways, also feature prominently in phagocytosis. However, despite intensive study over the course of nearly 30 years, the occurrence, source, and functional relevance of such calcium bursts remain the subject of debate. Here, we have attempted to consolidate the information that was reviewed in the past with more recent studies in an effort to shed some light on the existing controversies. K E Y W O R D Sfluorescence, calcium, phagocytosis, phagosome maturation, membrane fusion summarized in Table 1 upward of 80% of the studies reported that an elevation in [Ca 2+ ] cyt accompanied phagosome formation. Yet a significant

Better Together: Current Insights Into Phagosome-Lysosome Fusion

“…The lipid composition of phagosomes, the actin cytoskeleton, the vacuolar-type ATPase (V-ATPase) and calcium signaling play important roles during phagosome maturation. Here, we will only discuss the phosphoinositide lipids and the controversial role of actin and the V-ATPase in PL biogenesis, as calcium signaling has been extensively reviewed elsewhere ( 101 ).…”

Determinants of Phagosomal pH During Host-Pathogen Interactions

“…Besides Na + and K + , (phago)lysosomes also store Ca 2+ (Westman et al, 2019). Lysosomes are thought to accumulate Ca 2+ , at least in part, via Ca 2+ /H + exchange; accordingly, V-ATPase inhibition using well-established pharmacological agents impairs Ca 2+ loading.…”

Lysosome Fusion Maintains Phagosome Integrity during Fungal Infection

“…Fusion of lysosomes with phagosomes is thought to require Ca 2+ (although discrepancies exist; Nunes and Demaurex, 2010;Westman et al, 2019b). We hypothesized that the phagosomal expansion required to accommodate C. albicans growth similarly requires cytosolic Ca 2+ ([Ca 2+ ] cyt ) transients.…”