Localization and activity of lysyl oxidase within nuclei of fibrogenic cells

Lysyl oxidase (EC 1.4.3.13) oxidizes peptidyl lysine to peptidyl aldehyde residues within collagen and elastin, thus initiating formation of the covalent cross-linkages that insolubilize these extracellular proteins. Recent findings raise the possibility that this enzyme may also function intracellularly. The present study provides evidence by immunocytochemical confocal microscopy, Western blot analysis, enzyme assays, and chemical analyses for lysyl oxidase reaction products that this enzyme is present and active within rat vascular smooth muscle cell nuclei. Confocal microscopy indicates its presence within nuclei of 3T3 fibroblasts, as well.

赖氨酰氧化酶（Lysyl oxidase, EC 1.4.3.13）可将胶原蛋白与弹性蛋白内的肽基赖氨酸氧化为肽基醛残基，从而启动共价交联的形成，使这些细胞外蛋白转变为不溶性状态。近期研究发现提示，该酶或许也可在细胞内发挥功能。本研究通过免疫细胞化学共聚焦显微镜检测、蛋白质免疫印迹（Western blot）分析、酶活性测定以及赖氨酰氧化酶反应产物的化学分析，证实该酶存在于大鼠血管平滑肌细胞核内并具有活性。共聚焦显微镜检测结果同样显示，3T3成纤维细胞的细胞核内也存在该酶。