Author:
Vinzenz Marlene,Nemethova Maria,Schur Florian,Mueller Jan,Narita Akihiro,Urban Edit,Winkler Christoph,Schmeiser Christian,Koestler Stefan A.,Rottner Klemens,Resch Guenter P.,Maeda Yuichiro,Small J. Victor
Abstract
Using correlated live cell imaging and electron tomography we found that actin branch junctions in protruding and treadmilling lamellipodia are not concentrated at the front as previously supposed, but link actin filament subsets in which there is a continuum of distances from a junction to the filament plus ends, up to at least 1 µm. When branch sites were observed closely spaced on the same filament their separation was commonly a multiple of the actin helical repeat of 36 nm. Image averaging of branch junctions in the tomograms yielded a model for the in vivo branch at 2.9 nm resolution, which compared closely to that derived for the in vitro actin - Arp2/3 complex. Lamellipodia initiation was monitored in an intracellular wound-healing model and involved branching from the sides of actin filaments oriented parallel to the plasmalemma. Many filament plus ends, presumably capped, terminated behind the lamellipodium tip and localized on the dorsal and ventral surfaces of the actin network. These findings reveal how branching events initiate and maintain a network of actin filaments of variable length and provide the first structural model of the branch junction in vivo. A possible role of filament capping in generating the lamellipodium leaflet is discussed and a mathematical model of protrusion is also presented.
Publisher
The Company of Biologists
Cited by
124 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献