Characterization of Lysyl Oxidase: A Fibronectin Dependent Cross Linker of Collagen

Abstract

The extracellular matrix is composed of a complex network of structural and functional proteins, growth factors, and chemical signals that provides surrounding cells with organization and structure. Within the extracellular matrix, fibronectin plays a prominent role through the formation of a mature, insoluble matrix which interacts with numerous proteins including collagen and the enzyme that cross-links it, lysyl oxidase (LOX). While much is known about the interactions between fibronectin and collagen, fibronectin-LOX interactions are currently uncharacterized. Using the NIH 3T3 cell line, we determined a time point in which a stable fibronectin matrix was produced and LOX was secreted into the extracellular space. We also found that the supplementation of ascorbic acid, a chemical which is required for collagen production, significantly increased LOX levels. Additionally, progress was made in the cloning and expression of the active domain of the LOX protein. These initial steps in the establishment of a system for assessing fibronectin-LOX binding interactions will hopefully lead to a greater understanding of the interconnected relationship between fibronectin, LOX, and collagen and facilitate the treatment of disorders of the extracellular matrix.