Myosin va bound to phagosomes binds to F-actin and delays microtubule-dependent motility
Myosin va bound to phagosomes binds to F-actin and delays microtubule-dependent motility
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DOI：
10.1091/mbc.12.9.2742
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发表时间：
2001-09-01
影响因子：
3.3
通讯作者：
Kuznetsov, SA
中科院分区：
文献类型：
--
作者：
Al-Haddad, AH;Shonn, MA;Kuznetsov, SA
我们建立了一个基于光学显微镜的测定，重建从小鼠巨噬细胞中纯化的吞噬体在体外预组装的F-肌动蛋白的结合。小鼠巨噬细胞的内源性肌球蛋白Va和鸡脑的外源性肌球蛋白Va都能刺激吞噬体-F-肌动蛋白的相互作用。肌球蛋白Va与吞噬体的关联与它们以ATP调节的方式结合F-肌动蛋白的能力相关，并且肌球蛋白Va的抗体特异性地阻断ATP敏感的吞噬体与F-肌动蛋白的结合。在正常小鼠和稀释致死自发突变纯合子小鼠（肌球蛋白Va null）中观察到骨髓巨噬细胞吞噬体从外周细胞到中心的摄取和逆行运输。然而，在稀释致死的巨噬细胞中，吞噬体在核周区域的积累比正常巨噬细胞快两倍。运动分析显示跳跃吞噬体运动与暂时逆转的方向在正常的巨噬细胞，而几乎没有逆转的方向，观察到在稀释致死的巨噬细胞。这些观察结果表明，肌球蛋白Va。介导吞噬体与F-肌动蛋白的结合，导致微管依赖性逆行吞噬体向细胞中心运动的延迟。我们提出了一个“拮抗/合作机制”来解释跳跃吞噬体运动的细胞中心在正常的巨噬细胞。
We established a light microscopy-based assay that reconstitutes the binding of phagosomes purified from mouse macrophages to preassembled F-actin in vitro. Both endogenous myosin Va from mouse macrophages and exogenous myosin Va from chicken brain stimulated the phagosome-F-actin interaction. Myosin Va association with phagosomes correlated with their ability to bind F-actin in an ATP-regulated manner and antibodies to myosin Va specifically blocked the ATP-sensitive phagosome binding to F-actin. The uptake and retrograde transport of phagosomes from the periphery to the center of cells in bone marrow macrophages was observed in both normal mice and mice homozygous for the dilute-lethal spontaneous mutation (myosin Va null). However, in dilute-lethal macrophages the accumulation of phagosomes in the perinuclear region occurred twofold faster than in normal macrophages. Motion analysis revealed saltatory phagosome movement with temporarily reversed direction in normal macrophages, whereas almost no reversals in direction were observed in dilute-lethal macrophages. These observations demonstrate that myosin Va. mediates phagosome binding to F-actin, resulting in a delay in microtubule-dependent retrograde phagosome movement toward the cell center. We propose an "antagonistic/cooperative mechanism" to explain the saltatory phagosome movement toward the cell center in normal macrophages.