Processing of laminin-5 and its functional consequences: role of plasmin and tissue-type plasminogen activator.
Processing of laminin-5 and its functional consequences: role of plasmin and tissue-type plasminogen activator.
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DOI：
10.1083/jcb.141.1.255
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发表时间：
1998-04-06
期刊：
影响因子：
--
通讯作者：
Jones JC
中科院分区：
文献类型：
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作者：
Goldfinger LE;Stack MS;Jones JC
某些培养细胞（例如大鼠上皮细胞系804 G和人乳腺上皮细胞MCF-10A）的细胞外基质的层粘连蛋白-5组分能够在将其他细胞接种在其上时使称为半桥粒的细胞-基质粘附装置的组装成核。这些基质也阻碍细胞运动。相比之下，细胞接种到层粘连蛋白-5丰富的基质pp 126上皮细胞不能组装半桥粒，是能动的。为了理解这些矛盾的现象，我们使用一组层粘连蛋白-5亚基特异性抗体，比较了804 G和MCF-10A细胞分泌的异源三聚体层粘连蛋白-5与pp 126细胞分泌的层粘连蛋白-5的形式。pp 126细胞分泌的层粘连蛋白-5 α3亚基的分子量为190 kD，而804 G和MCF-10A细胞分泌的层粘连蛋白-5 α3亚基的分子量为160 kD。在不明显影响层粘连蛋白5 β和γ链的酶浓度下，纤溶酶可将pp 126细胞层粘连蛋白5的190 kD α3链特异性蛋白水解为160 kD物质。在纤溶酶处理后，pp 126细胞层粘连蛋白-5不仅阻碍细胞运动，而且变得有能力进行半桥粒的成核组装。纤溶酶可能在处理层粘连蛋白-5亚基中发挥重要作用的可能性得到了免疫荧光分析的支持，该分析表明MCF-10A和pp 126细胞的细胞外基质中层粘连蛋白-5和纤溶酶原共定位。而组织型纤溶酶原激活剂（tPA），它将纤溶酶原纤溶酶，共分布与层粘连蛋白-5在MCF-10A基质，tPA是不存在于pp 126细胞外基质。用外源性tPA处理pp 126富含层粘连蛋白-5的细胞外基质导致层粘连蛋白-5 α3链从190至160 kD的蛋白水解。此外，纤溶酶原和tPA在体外结合层粘连蛋白-5。总之，我们提供的证据表明，层粘连蛋白-5是一种多功能的蛋白质，可以在某些情况下作为一个运动，并在其他时间作为一个粘附因子。在培养的细胞中，这种功能转换似乎依赖于tPA和纤溶酶原，并受其调节。
The laminin-5 component of the extracellular matrices of certain cultured cells such as the rat epithelial cell line 804G and the human breast epithelial cell MCF-10A is capable of nucleating assembly of cell– matrix adhesive devices called hemidesmosomes when other cells are plated upon them. These matrices also impede cell motility. In contrast, cells plated onto the laminin-5–rich matrices of pp126 epithelial cells fail to assemble hemidesmosomes and are motile. To understand these contradictory phenomena, we have compared the forms of heterotrimeric laminin-5 secreted by 804G and MCF-10A cells with those secreted by pp126 cells, using a panel of laminin-5 subunit-specific antibodies. The α3 subunit of laminin-5 secreted by pp126 cells migrates at 190 kD, whereas that secreted by 804G and MCF-10A cells migrates at 160 kD. The pp126 cell 190-kD α3 chain of laminin-5 can be specifically proteolyzed by plasmin to a 160-kD species at enzyme concentrations that do not apparently effect the laminin-5 β and γ chains. After plasmin treatment, pp126 cell laminin-5 not only impedes cell motility but also becomes competent to nucleate assembly of hemidesmosomes. The possibility that plasmin may play an important role in processing laminin-5 subunits is supported by immunofluorescence analyses that demonstrate colocalization of laminin-5 and plasminogen in the extracellular matrix of MCF-10A and pp126 cells. Whereas tissue-type plasminogen activator (tPA), which converts plasminogen to plasmin, codistributes with laminin-5 in MCF-10A matrix, tPA is not present in pp126 extracellular matrix. Treatment of pp126 laminin-5–rich extracellular matrix with exogenous tPA results in proteolysis of the laminin-5 α3 chain from 190 to 160 kD. In addition, plasminogen and tPA bind laminin-5 in vitro. In summary, we provide evidence that laminin-5 is a multifunctional protein that can act under certain circumstances as a motility and at other times as an adhesive factor. In cells in culture, this functional conversion appears dependent upon and is regulated by tPA and plasminogen.