Filensin and phakinin form a novel type of beaded intermediate filaments and coassemble de novo in cultured cells.
Filensin and phakinin form a novel type of beaded intermediate filaments and coassemble de novo in cultured cells.
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DOI：
10.1083/jcb.132.4.643
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发表时间：
1996-02
影响因子：
7.8
通讯作者：
Georgatos, SD
中科院分区：
文献类型：
--
作者：
Goulielmos, G;Gounari, F;Remington, S;Muller, S;Haner, M;Aebi, U;Georgatos, SD
晶状体的纤维细胞拥有一种独特的细胞骨架系统，称为“串珠链细丝”（BFs）。BFs由两种新近发现的中间丝蛋白（IF） filensin和phakinin组成。为了研究这些异聚干扰素的组织和组装，我们进行了一系列体外聚合研究和转染实验。由纯化的纤维蛋白和phakinin组装的细丝在低角度旋转阴影下表现出19-21纳米的周期性特征。然而，定量质量/长度（MPL）测量表明，纤维素/phakinin细丝包括两个不同的可分离成分：核心细丝和周围细丝部分。与非均匀组织一致，通过扫描透射电子显微镜（STEM）对未固定和未染色的标本进行可视化显示，中心灯丝的存在被规则间隔的12-15纳米直径的珠子装饰。我们的数据表明，丝状核由phakinin组成，phakinin表现出自组装成丝束的趋势，而珠状核含有filensin/phakinin异聚物。当在培养细胞中短暂表达时，filenxin和phakinin共聚并形成丝状结构。在无IF的SW13细胞中进行的实验表明，体内晶状体特异性蛋白的共组装不需要预先存在的IF系统。在上皮细胞MCF-7中，新生形成的细丝似乎从不同的病灶生长，并组织成厚的纤维层，排列在质膜和核膜上。然而，在CHO和sv40转化的晶状体上皮细胞（两者都是成纤维细胞样）中，纤维组装产生径向网络，与内源性波形蛋白IFs共分布。这些观察结果证明，由晶状体特异性IF蛋白形成的细丝在结构上不同于普通的细胞质IF。此外，研究结果表明，体内纤维蛋白/phakinin丝的空间排列受宿主特异性因子的调节。这些因素可能涉及细胞骨架网络（例如，波形蛋白干扰素）和/或与细胞膜相关的特定位点。
The fiber cells of the eye lens possess a unique cytoskeletal system known as the "beaded-chain filaments" (BFs). BFs consist of filensin and phakinin, two recently characterized intermediate filament (IF) proteins. To examine the organization and the assembly of these heteropolymeric IFs, we have performed a series of in vitro polymerization studies and transfection experiments. Filaments assembled from purified filensin and phakinin exhibit the characteristic 19-21-nm periodicity seen in many types of IFs upon low angle rotary shadowing. However, quantitative mass-per-length (MPL) measurements indicate that filensin/phakinin filaments comprise two distinct and dissociable components: a core filament and a peripheral filament moiety. Consistent with a nonuniform organization, visualization of unfixed and unstained specimens by scanning transmission electron microscopy (STEM) reveals the the existence of a central filament which is decorated by regularly spaced 12-15-nm-diam beads. Our data suggest that the filamentous core is composed of phakinin, which exhibits a tendency to self-assemble into filament bundles, whereas the beads contain filensin/phakinin hetero-oligomers. Filensin and phakinin copolymerize and form filamentous structures when expressed transiently in cultured cells. Experiments in IF-free SW13 cells reveal that coassembly of the lens-specific proteins in vivo does not require a preexisting IF system. In epithelial MCF-7 cells de novo forming filaments appear to grow from distinct foci and organize as thick, fibrous laminae which line the plasma membrane and the nuclear envelope. However, filament assembly in CHO and SV40-transformed lens- epithelial cells (both of which are fibroblast-like) yields radial networks which codistribute with the endogenous vimentin IFs. These observations document that the filaments formed by lens-specific IF proteins are structurally distinct from ordinary cytoplasmic IFs. Furthermore, the results suggest that the spatial arrangement of filensin/phakinin filaments in vivo is subject to regulation by host- specific factors. These factors may involve cytoskeletal networks (e.g., vimentin IFs) and/or specific sites associated with the cellular membranes.
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DOI：
10.1083/jcb.122.6.1323
发表时间：
1993-09
期刊：
The Journal of cell biology
影响因子：
--
作者：
Ching GY;Liem RK
通讯作者：
Liem RK
影响因子：
5.6
作者：
HISANAGA, S;HIROKAWA, N
通讯作者：
HIROKAWA, N
影响因子：
7.8
作者：
ALBERS, K;FUCHS, E
通讯作者：
FUCHS, E
影响因子：
2.9
作者：
AEBI, U;HANER, M;ENGEL, A
通讯作者：
ENGEL, A
影响因子：
2
作者：
IRELAND, M;MAISEL, H
通讯作者：
MAISEL, H