Filopodial initiation and a novel filament-organizing center, the focal ring.
Filopodial initiation and a novel filament-organizing center, the focal ring.
复制标题
丝状伪足的起始和一个新的丝状组织中心，焦点环。
DOI：
10.1091/mbc.12.8.2378
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发表时间：
2001
影响因子：
3.3
通讯作者：
Tosney,KW
中科院分区：
文献类型：
--
作者：
Steketee,M;Balazovich,K;Tosney,KW
这项研究检查了细丝的起始，并涉及到一个假定的肌动蛋白细丝组织者，焦点环。丝状孢子从面纱中出现时被光学记录下来，面纱是生长锥体的活跃的板层延伸。运动史揭示了三个持续先于丝状突起的事件：细胞质涌入相邻的丝状突起，面纱边缘相密度的局灶性增加，以及转化为丝状突起的根瘤突起。细胞质的内流可能提供了启动所需的物质。在相关的时间推移免疫细胞化学中，这些焦点相密度对应于粘连。这些粘连在丝状基底部持续存在，与随后的运动无关。在相关的时间推移电子显微镜下，这些粘连部位含有一个焦点环(直径12 0 nm的扁平的甜甜圈状结构∼)，带有辐射的肌动蛋白细丝。丝状体的几何形状可以解释相对于相邻的丝状体呈30度角的丝状体突起。提出了一个模型，其中焦点环在启动和稳定丝状伪足方面起着至关重要的作用：1)它们在粘连处锚定肌动蛋白细丝，从而促进张力的发展和丝足的出现；2)“轴向”细丝将焦点环连接到节尖，从而组织纤丝束并确保纤丝束与粘连相交；以及3)“横向”细丝相互连接焦点环和丝状束，从而帮助稳定板层边缘和丝足柄。
This study examines filopodial initiation and implicates a putative actin filament organizer, the focal ring. Filopodia were optically recorded as they emerged from veils, the active lamellar extensions of growth cones. Motile histories revealed three events that consistently preceded filopodial emergence: an influx of cytoplasm into adjacent filopodia, a focal increase in phase density at veil margins, and protrusion of nubs that transform into filopodia. The cytoplasmic influx probably supplies materials needed for initiation. In correlated time lapse-immunocytochemistry, these focal phase densities corresponded to adhesions. These adhesions persisted at filopodial bases, regardless of subsequent movements. In correlated time lapse-electron microscopy, these adhesion sites contained a focal ring (an oblate, donut-shaped structure ∼120 nm in diameter) with radiating actin filaments. Filament geometry may explain filopodial emergence at 30 degree angles relative to adjacent filopodia. A model is proposed in which focal rings play a vital role in initiating and stabilizing filopodia: 1) they anchor actin filaments at adhesions, thereby facilitating tension development and filopodial emergence; 2) “axial” filaments connect focal rings to nub tips, thereby organizing filament bundling and ensuring the bundle intersects an adhesion; and 3) “lateral” filaments interconnect focal rings and filament bundles, thereby helping stabilize lamellar margins and filopodia.