Migrating human neutrophils exhibit dynamic spatiotemporal variation in membrane lipid organization.
Migrating human neutrophils exhibit dynamic spatiotemporal variation in membrane lipid organization.
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DOI：
10.1165/rcmb.2009-0286oc
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发表时间：
2010-10
影响因子：
6.4
通讯作者：
R. G. Sitrin;T. M. Sassanella;Jeffrey J Landers;H. Petty
中科院分区：
文献类型：
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作者：
R. G. Sitrin;T. M. Sassanella;Jeffrey J Landers;H. Petty
质膜内高度有序的鞘脂富集脂筏微域（lrm）据称是专门的信号平台。白细胞迁移被认为需要LRM重新分配，但是在细胞移动过程中原位LRM的研究进展有限。利用改进的环境敏感探针的光谱位移成像方法，laurdan（表示为广义极化函数），实时绘制了人类多形核中性粒细胞（PMNs）迁移过程中的质膜顺序（即膜双层脂质的紧密排列）。形态学极化的PMNs在尾足部表现出明显的LRM簇，在每个例子中，膜顺序振荡的平均周期分别为37.0±1.46和149.9±9.0秒（P < 0.01）。LRM聚集体在非极化细胞的点状和簇状分布中也被证实，在极化pmn的板足上也有短暂的聚集体。细胞极化并不伴随着膜序的整体增加。甲基-β-环糊精破坏LRM对细胞速度有较小的负面影响，但它消除了向FMLP或白三烯B趋化梯度的定向偏迁移(4)。lrm的破坏还导致Rac 1/2 GTPase和GM3神经节苷脂从片足基向外重新分布，以及多个假足同时或快速连续延伸，而不是形成明确的前缘。因此，我们证明迁移pmn的质膜顺序是动态变化的，在尾足动物中始终可见明显的振荡。这些发现巩固了原位快速重组lrm的存在，并支持lrm在趋化素反应中的作用。
Highly ordered sphingolipid-enriched lipid raft microdomains (LRMs) within plasma membranes purportedly function as specialized signaling platforms. Leukocyte migration is believed to entail LRM redistribution, but progress in studying LRMs in situ during cell movement has been limited. By using an improved method for imaging the spectral shift of the environmentally sensitive probe, laurdan (expressed as a generalized polarization function), the plasma membrane order (i.e., tight packing of membrane bilayer lipids) of human polymorphonuclear neutrophils (PMNs) was mapped in real time during migration. Morphologically polarized PMNs exhibited prominent LRM clusters at the uropod, where in every instance membrane order was found to oscillate with mean periodicities of 37.0 ± 1.46 and 149.9 ± 9.0 seconds (P < 0.01). LRM aggregates were also demonstrated in punctate and clustered distributions of nonpolarized cells and transiently at the lamellipodia of polarized PMNs. Cellular polarization was not accompanied by an overall increase in membrane order. LRM disorganization with methyl-β-cyclodextrin had small negative effects on cell velocity, but it abrogated directionally biased migration toward chemotactic gradients of FMLP or leukotriene B(4). LRMs disruption also caused redistribution of Rac 1/2 GTPase and GM3 ganglioside away from the lamellipodium, as well as extension of multiple pseudopods simultaneously or in rapid succession, rather than formation of a defined leading edge. Thus, we demonstrate that the plasma membrane order of migrating PMNs changes dynamically, with prominent oscillations consistently seen at the uropod. These findings solidify the existence of rapidly reorganizing LRMs in situ and support a role for LRMs in chemotaxin responsiveness.