Laminin-5 and hemidesmosomes: role of the alpha 3 chain subunit in hemidesmosome stability and assembly.
Laminin-5 and hemidesmosomes: role of the alpha 3 chain subunit in hemidesmosome stability and assembly.
复制标题
DOI：
--
复制
发表时间：
1996-10
影响因子：
4
通讯作者：
Scott E. Baker;S. Hopkinson;M. Fitchmun;G. Andreason;Francine Frasier;George;Plopper;Vito Quaranta;Jonathan C. R. Jones
中科院分区：
文献类型：
--
作者：
Scott E. Baker;S. Hopkinson;M. Fitchmun;G. Andreason;Francine Frasier;George;Plopper;Vito Quaranta;Jonathan C. R. Jones
半桥粒是复杂的大分子结构，整合了细胞外基质和上皮细胞的细胞骨架的元素。为了表征半桥粒中的细胞-基质相互作用，我们利用了 804G 细胞，该细胞具有在体外组装半桥粒的不寻常能力。在我们的研究过程中，我们制备了一组针对大鼠层粘连蛋白-5（构成 804G 基质的主要结构元件）的单克隆抗体。其中一种称为 CM6，可识别大鼠层粘连蛋白 5 的 150 kDa α 链，并结合完整层粘连蛋白 5 分子的球状 (G) 结构域（通过旋转阴影测定）。 CM6 抗体扰乱 804G 细胞中形成的半桥粒。特别是，在 804G 细胞与 CM6 抗体孵育 1 小时内，层粘连蛋白 5 和 α 6 β 4 整合素的共定位消失，到 2 小时时，半桥粒抗体产生的染色主要出现在核周区的细胞质中。从超微结构上看，CM6 抗体首先似乎诱导半桥粒与底层基质分离。接下来，基底细胞表面的部分内陷形成囊泡，其面向细胞质的表面被仍与角蛋白中间丝相连的半桥粒所覆盖。锚定丝延伸到囊泡的内部隔室中。我们还研究了 CM6 抗体对模型系统的影响，其中 804G 细胞基质诱导人角质形成细胞中半桥粒的从头组装。该过程涉及半桥粒相关整联蛋白 α 6 β 4 的质膜重组以及其他半桥粒成分（例如 230 kDa 大疱性类天疱疮抗原）的重新分布。用CM6抗体预处理804G基质可阻断半桥粒成分的质膜重组并抑制半桥粒形成。我们的研究表明，层粘连蛋白 5 α 链的 G 结构域在半桥粒组装的成核以及半桥粒结构完整性的维持中发挥着至关重要的作用。
Hemidesmosomes are complex macromolecular structures which integrate elements of the extracellular matrix and the cytoskeleton of epithelial cells. To characterize cell-matrix interactions in the hemidesmosome, we have made use of 804G cells which possess the unusual ability to assemble hemidesmosomes in vitro. During the course of our studies, we have raised a set of monoclonal antibodies against rat laminin-5, the major structural element comprising 804G matrix. One of these, termed CM6, recognizes the 150 kDa alpha chain of rat laminin-5 and binds the globular (G) domain of intact laminin-5 molecules as determined by rotary shadowing. CM6 antibodies perturb formed hemidesmosomes in 804G cells. In particular, within 1 hour of incubation of 804G cells with CM6 antibodies, colocalization of laminin-5 and alpha 6 beta 4 integrin is lost and by 2 hours, staining generated by hemidesmosomal antibodies appears primarily cytoplasmic in the perinuclear zone. Ultrastructurally, CM6 antibodies first appear to induce detachment of hemidesmosomes from the underlying matrix. Next, portions of the basal cell surface invaginate to form vesicles whose cytoplasmic-facing surface is coated with hemidesmosomes still associated with keratin intermediate filaments. Anchoring filaments extend into the inside compartment of the vesicles. We have also studied the impact of CM6 antibodies on a model system in which the matrix of 804G cells induces de novo assembly of hemidesmosomes in human keratinocytes. This process involves the plasma membrane reorganization of the hemidesmosome associated integrin alpha 6 beta 4 as well as a redistribution of other hemidesmosome components such as the 230 kDa bullous pemphigoid antigen. Pretreatment of 804G matrix with CM6 antibodies blocks such plasma membrane reorganization of hemidesmosome components and inhibits hemidesmosome formation. Our studies indicate a crucial role for the G domain of the alpha chain of laminin-5 in both nucleation of hemidesmosome assembly as well as maintenance of hemidesmosome structural integrity.