Are Intermediate Filament Proteins Involved in Gene Expression?-猫眼课题宝

中间丝蛋白是否参与基因表达？

DOI：

发表时间：

1985

期刊：

Annals of the New York Academy of Sciences

影响因子：

5.2

通讯作者：

中科院分区：

综合性期刊3区

文献类型：

作者：

P. Traub

自从20世纪60年代中期发现中间纤维(IF)以来，它们一直被认为是细胞骨架的组成部分，并在脊椎动物细胞中发挥结构作用。这一概念主要基于间接免疫荧光和电子显微镜揭示的它们在细胞质中的三维分布特征，以及它们在生理离子条件下的高度不溶性。此外，IFs已被证明与各种亚细胞结构有关，其中许多结构是膜结合的，但也与许多酶系统和其他细胞质成分有关。对这些主要是微观观察的解释最终得出了这样一个假设，即IF作为细胞空间的机械积分器发挥作用。然而，最近的实验表明，IF在脊椎动物细胞中发挥的作用比迄今推测的要微妙得多。显微注射针对IF蛋白的抗体导致IF网络的崩溃，而不影响先前提出的由细胞质延伸的IF介导的细胞活动。“-‘~在脊椎动物的早期胚胎发生期间，某些细胞类型不表达IF蛋白，这也是令人惊讶的。’”‘’在一些在体外培养的细胞中也观察到了同样的情况。20，2‘因此，从这些观察来看，脊椎动物细胞质中IF网络的延伸并不是细胞正常功能的必要条件，无论是在原位还是在体外。在寻找IFs在脊椎动物细胞中的替代功能时，可以假设不是细丝本身，而是它们的亚单位蛋白负责细胞的重要功能；细丝可能只代表亚单位蛋白质的一种储存和运输形式，作为翻译后修饰的多肽，在细胞内外信号的反应下从细丝中释放出来。本通讯试图根据最近的体外研究结果来举例说明这种可能性，即至少非上皮源性的IF蛋白是核酸结合蛋白22-28，并且容易受到钙激活的Pr~-Teinase的有限处理。

Since the discovery of intermediate filaments (IFs) in the middle 1960s,'-' they have been supposed to be constituents of the cytoskeleton and to play a structural role in vertebrate cells. This notion is mainly based on their characteristic three-dimensional distribution in the cytoplasm as revealed by indirect immunofluorescence and electron microscopy and by their high insolubility under physiological ionic conditions. In addition, IFs have been shown to be associated with a variety of subcellular structures many of which are membrane-bounded, but also with a number of enzyme systems and other cytoplasmic constituents. The interpretation of these, mostly microscopic, observations culminated in the hypothesis that IFs function as mechanical integrators of cellular space.""' However, recent experimentation has demonstrated that IFs play a more subtle role in vertebrate cells than hitherto presumed. Microinjection of antibodies specifically directed against IF proteins leads to the collapse of the IF meshworks without affecting cellular activities previously proposed to be mediated by cytoplasmically extended IFs."-'~ It is also striking that during early embryogenesis of vertebrates certain cell types do not express IF proteins.'"'' The same situation is observed in a number of cells propagated in vitro.20,2' It thus appears from these observations that the extension of IF networks in the cytoplasm of vertebrate cells is not a necessary prerequisite for proper cell functioning, neither in situ nor in vitro. In search for an alternative functional role of IFs in vertebrate cells, it might be assumed that not the filaments as such but their subunit proteins are in charge of vital cellular functions; the filaments might only represent a storage and transportation form of subunit proteins that, as posttranslationally modified polypeptides, are released from the filaments in response to intraand extracellular signals. The present communication attempts to exemplify this possibility on the basis of the recent in vitro findings that at least the IF proteins of non-epithelial origin are nucleic acid-binding proteins22-28 and susceptible to limited processing by Ca2+-activated pr~teinases.~~-"