Annexin A1 is a new functional linker between actin filaments and phagosomes during phagocytosis

Abstract

Remodelling of the actin cytoskeleton plays a key role in particle internalisation and the phagosome maturation processes. Actin-binding proteins (ABPs) are the main players in actin remodelling but the precise role of these proteins in phagocytosis needs to be clarified. Annexins, a group of ABPs, are known to be present on phagosomes. Here, we identified annexin A1 as a factor that binds to isolated latex bead phagosomes (LBPs) in the presence of Ca2+ and facilitates the F-actin–LBP interaction in vitro. In macrophages the association of endogenous annexin A1 with LBP membranes was strongly correlated with the spatial and temporal accumulation of F-actin at the LBP. Annexin A1 was found on phagocytic cups and around early phagosomes, where the F-actin was prominently concentrated. After uptake was completed, annexin A1, along with F-actin, dissociated from the nascent LBP surface. At later stages of phagocytosis annexin A1 transiently concentrated only around those LBPs that showed transient F-actin accumulation (‘actin flashing’). Downregulation of annexin A1 expression resulted in impaired phagocytosis and actin flashing. These data identify annexin A1 as an important component of phagocytosis that appears to link actin accumulation to different steps of phagosome formation.

Proteomic analysis of porcine mesenteric lymph-nodes after Salmonella typhimurium infection

“…Moreover, annexin A1 (ANXA1), which was initially related to anti-inflammatory functions [29], appears to be involved in controlling association of F-actin with phagosomes thereby affecting phagosome formation. ANXA1 binds to, bundles and colocalizes with F-actin during phagocytic cup formation and on mature phagosomes [30]. Intriguingly, this protein exhibited the most prominent increase of abundance in the porcine MLN after infection.…”

Caspase-1–mediated pathway promotes generation of thromboinflammatory microparticles

“…This pathway also released various soluble proteins into the extracellular space ( Figure 2F), including cytoskeleton-associated proteins and annexins 1 and 5 (Supplemental Table 1), which are known to interact with the MP components actin and PS (38,39).…”

Effect of Cardiopulmonary Bypass on Annexin A1 Expression in Peripheral Blood Mononuclear Cells of Children with Congenital Heart Disease

“…Mass spectrometry was performed in these 12 proteins and difference was found in only one protein (Annexin A1) (Figure 2). Annexin A1 is an important protein regulating inflammation and plays critical roles in the generation of inflammatory metabolites and the adhesion between neutrophils/monocytes and endothelial cells (5,6). Thus, the Annexin A1 expression was further confirmed by the Western blot assay.…”