Gross Stephane R, Balklava Zita, Griffin Martin
Department of Life Sciences, Nottingham Trent University, Clifton Lane, Nottingham, UK.
J Invest Dermatol. 2003 Aug;121(2):412-23. doi: 10.1046/j.1523-1747.2003.12353.x.
Investigations were undertaken to study the role of the protein cross-linking enzyme tissue transglutaminase in changes associated with the extracellular matrix and in the cell death of human dermal fibroblasts following exposure to a solarium ultraviolet A source consisting of 98.8% ultraviolet A and 1.2% ultraviolet B. Exposure to nonlethal ultraviolet doses of 60 to 120 kJ per m2 resulted in increased tissue transglutaminase activity when measured either in cell homogenates, "in situ" by incorporation of fluorescein-cadaverine into the extracellular matrix or by changes in the epsilon(gamma-glutamyl) lysine cross-link. This increase in enzyme activity did not require de novo protein synthesis. Incorporation of fluorescein-cadaverine into matrix proteins was accompanied by the cross-linking of fibronectin and tissue transglutaminase into nonreducible high molecular weight polymers. Addition of exogenous tissue transglutaminase to cultured cells mimicking extensive cell leakage of the enzyme resulted in increased extracellular matrix deposition and a decreased rate of matrix turnover. Exposure of cells to 180 kJ per m2 resulted in 40% to 50% cell death with dying cells showing extensive tissue transglutaminase cross-linking of intracellular proteins and increased cross-linking of the surrounding extracellular matrix, the latter probably occurring as a result of cell leakage of tissue transglutaminase. These cells demonstrated negligible caspase activation and DNA fragmentation but maintained their cell morphology. In contrast, exposure of cells to 240 kJ per m2 resulted in increased cell death with caspase activation and some DNA fragmentation. These cells could be partially rescued from death by addition of caspase inhibitors. These data suggest that changes in cross-linking both in the intracellular and extracellular compartments elicited by tissue transglutaminase following exposure to ultraviolet provides a rapid tissue stabilization process following damage, but as such may be a contributory factor to the scarring process that results.
开展了多项研究，以探讨蛋白质交联酶组织转谷氨酰胺酶在与细胞外基质相关的变化以及人类皮肤成纤维细胞暴露于由98.8%的紫外线A和1.2%的紫外线B组成的日光浴紫外线A源后细胞死亡过程中所起的作用。当在细胞匀浆中进行测量、通过将荧光素 - 尸胺掺入细胞外基质“原位”测量或通过ε（γ - 谷氨酰）赖氨酸交联的变化来测量时，暴露于每平方米60至120千焦的非致死性紫外线剂量会导致组织转谷氨酰胺酶活性增加。这种酶活性的增加不需要从头合成蛋白质。荧光素 - 尸胺掺入基质蛋白伴随着纤连蛋白和组织转谷氨酰胺酶交联形成不可还原的高分子量聚合物。向培养细胞中添加外源性组织转谷氨酰胺酶以模拟该酶的广泛细胞渗漏，导致细胞外基质沉积增加且基质周转速率降低。细胞暴露于每平方米180千焦会导致40%至50%的细胞死亡，死亡细胞显示细胞内蛋白质有广泛的组织转谷氨酰胺酶交联，且周围细胞外基质的交联增加，后者可能是由于组织转谷氨酰胺酶的细胞渗漏所致。这些细胞显示半胱天冬酶激活和DNA片段化可忽略不计，但保持其细胞形态。相比之下，细胞暴露于每平方米240千焦会导致细胞死亡增加，伴有半胱天冬酶激活和一些DNA片段化。通过添加半胱天冬酶抑制剂，这些细胞的死亡可部分得到挽救。这些数据表明，暴露于紫外线后组织转谷氨酰胺酶引起的细胞内和细胞外区室交联变化提供了损伤后快速的组织稳定过程，但可能是导致瘢痕形成过程的一个促成因素。
