The mechanism and role of transient F-actin recruitment, or F-actin ‘flashes’, on phagosomes remains enigmatic. Here we provide a comprehensive characterization of F-actin flashing dynamics on phagosomes, including receptor and signaling involvement. F-actin flashes predominate during the integrin-driven complement receptor (CR)-mediated phagocytosis. F-actin flashes begin shortly after internalization and persist on phagosomes for approximately 3 minutes before disassembling and reassembling several times within the first hour. Strikingly, the appearance of F-actin flashes on phagosomes coincides with morphological deformation, lysis and occasional fission of internalized red blood cells. The cadence of flashes depends on particle stiffness, and the F-actin networks on phagosomes are enriched in mechanosensitive components including focal adhesion proteins, RhoA and actomyosin. Inhibiting Arp2/3 and myosin IIA activity significantly reduces the frequency at which phagosome cargo becomes deformed during transient F-actin accumulation. At later time points, post-F-actin flashing, enhanced degradation of phagosome contents is observed, compared with non-flashing phagosomes. Taken together, these data suggest that actomyosin-driven phagosome contractions serve to disrupt malleable particles physically, a process akin to mastication, to enhance later enzymatic digestion.

吞噬体上瞬时 F-肌动蛋白募集或 F-肌动蛋白“闪光”的机制和作用仍然是个谜。在这里，我们提供了吞噬体上 F-肌动蛋白闪烁动力学的全面表征，包括受体和信号传导参与。F-肌动蛋白闪光在整合素驱动的补体受体（CR）介导的吞噬作用中占主导地位。F-肌动蛋白在内化后不久开始闪烁，并在吞噬体上持续约 3 分钟，然后在第一个小时内多次分解和重新组装。引人注目的是，吞噬体上 F-肌动蛋白闪光的出现与内化红细胞的形态变形、裂解和偶尔裂变相一致。闪光的节奏取决于颗粒的刚度，吞噬体上的 F-肌动蛋白网络富含机械敏感成分，包括粘着斑蛋白、RhoA 和肌动球蛋白。抑制 Arp2/3 和肌球蛋白 IIA 活性可显着降低瞬时 F-肌动蛋白积累期间吞噬体货物变形的频率。在稍后的时间点，与非闪烁的吞噬体相比，在 F-肌动蛋白闪烁后，观察到吞噬体内容物的降解增强。总而言之，这些数据表明肌动球蛋白驱动的吞噬体收缩有助于物理破坏可塑颗粒，这是一个类似于咀嚼的过程，以增强随后的酶促消化。