Lysyl Oxidase Activates the Transcription Activity of Human Collagene III Promoter

Abstract

Lysyl oxidase is an extracellular enzyme that controls the maturation of collagen and elastin. Lysyl oxidase and collagen III often show similar expression patterns in fibrotic tissues. Therefore, we investigated the influence of lysyl oxidase overexpression on the promoter activity of human COL3A1 gene. Our results showed that when COS-7 cells overexpressed the mature form of lysyl oxidase, the activity of the human COL3A1 promoter was increased up to an average of 12 times when tested by luciferase reporter assay. The effect was specific, because other promoters were not affected. Moreover, lysyl oxidase effect was abolished by ␤-aminopropionitrile, a specific inhibitor of its catalytic activity. Electrophoretic mobility shift assay showed a binding activity in the region from ؊101 to ؊77 that was significantly increased by lysyl oxidase overexpression. The binding was specifically competed by the cold probe, and the mutagenesis of this region abolished both the binding activity in gel retardation and lysyl oxidase stimulation of COL3A1 promoter in transfection experiments. We identified the binding activity as Ku antigen in its two components: Ku80 and Ku70. This study suggests a new coordinated mechanism by which lysyl oxidase might control the development of fibrosis.

Autocrine Growth Factor Regulation of Lysyl Oxidase Expression in Transformed Fibroblasts

“…Mature lysyl oxidase enzyme has been reported to be taken up by cells and translocated to the nucleus of some cells, where it influences the transcription of type III collagen (67)(68)(69). It has been suggested that lysyl oxidase could interact with histones (70), known in vitro substrates of purified lysyl oxidase (71), and thereby possibly directly or indirectly regulate gene transcription.…”

Ku Represses the HIV-1 Transcription

“…The most extensively studied sequence, NRE1, is located in the MMTV LTR region and is capable of specific binding to the Ku heterodimer complex (18,22). The GR-MMTV NRE1 element was shown to be, in vitro, the highest affinity Ku DNA binding site.…”

“…Ku has been shown to be involved in the transcriptional regulation of different genes such as the late UL38 promoter of HSV-1 (35), the promoter of human COL3A1 gene (18), and the human U1 snRNA gene. Furthermore, it has been suggested that Ku may act as a transcriptional repressor in the context of the expression of retroviral elements either endogenous such as the intracisternal A particle (20) or exogenous as the GR strain of MMTV (36) and the HTLV (21).…”

“…Second, Ku may recruit and activate the kinase at specific sites (4). Putative Ku-specific binding sites were proposed in a variety of genes such as c-myc r (16), the transferrin receptor (17), collagen III (18), the U1 snRNA (19), and also in retroviral sequences, notably in the long terminal repeat (LTR) sequences of intracisternal A particle (20), HTLV-1 (21,22), and mouse mammary tumor virus (MMTV) (4). In the latter two cases, these sequences were suggested to be involved in the negative regulation of transcription.…”

Lysyl Oxidase Oxidizes Cell Membrane Proteins and Enhances the Chemotactic Response of Vascular Smooth Muscle Cells

“…Nevertheless, the limited view of LOX function pertained until the striking observation was made that LOX acted as a suppressor of ras-induced carcinogenesis (9,10). Subsequently, LOX has been implicated in a number of novel biological functions, including the regulation of the promoter activity of collagen type III (11), the control of cell adhesion and growth (12), the metastatic phenotype of certain tumors in adult animals (13,14), and gene regulation (15). Of additional interest is the finding that the mature extracellular catalyst can be found within the nuclei of fibrogenic vascular smooth muscle cells and fibroblasts (16,17).…”