This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Fibrosis is characterized by the accumulation of extracellular components such as fibrillar collagens and lysyl oxidase (LOX). This natural process can be beneficial during wound healing but it can also be damaging as evident in pulmonary disorders and progressive heart disease. We set out to identify proteins that interact with the LOX protein family of amine oxidases to gain a better picture of how these proteins are involved during fibrosis. We identified several target proteins that potentially interact with LOX and the LOX-like protein (LOXL) using the yeast two-hybrid system. These interactions were confirmed using qualitative and quantitative binding assays and co-localizations to the extracellular matrix. One such target, fibronectin, was shown to interact with LOX outside the catalytic domains of the mature enzyme with a dissociation constant of 2.5 nM, comparable to type I collagen and tropoelastin. LOX activity was significantly reduced in mouse embryonic fibroblasts lacking fibronectin, presumably resulting from inefficient activation by BMP-1 as shown by Western blot and activity assays. These results suggest that the interaction between LOX and fibronectin can influence the collagen matrix and mediate fibrotic processes. We are also examining the interactions between LOXL and six other matrix proteins, including fibronectin, that can also have an effect during fibrosis. Results from these studies will elucidate how extracellular proteins contribute to fibrotic processes and how they can be modified.
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