High Glucose Increases Lysyl Oxidase Expression and Activity in Retinal Endothelial Cells: Mechanism for Compromised Extracellular Matrix Barrier Function
نویسندگان
چکیده
OBJECTIVE In diabetes, retinal vascular basement membrane (BM) undergoes significant thickening and compromises vessel function including increased vascular permeability, a prominent lesion of early diabetic retinopathy. In this study we determined whether altered expression and activity of lysyl oxidase (LOX), a cross-linking enzyme, may compromise vascular basement membrane functional integrity under high-glucose (HG) conditions. RESEARCH DESIGN AND METHODS Rat retinal endothelial cells (RRECs) grown in normal (5 mmol/l) or HG (30 mmol/l glucose) medium for 7 days were assessed for expression of LOX and proLOX by Western blot analysis and LOX enzyme activity. To determine whether HG alters cellular distribution patterns of LOX and proLOX, immunostaining with respective antibodies was performed. Similarly, cells grown in normal or HG medium were subjected to both LOX inhibition with β-aminopropionitrile (BAPN) and by small interfering RNA knockdown, and respectively examined for cell monolayer permeability. Additionally, retinas of streptozotocin (STZ)-induced diabetic rats were analyzed to determine if diabetes altered LOX expression. RESULTS Western blot analysis revealed significantly increased LOX and proLOX expression in cells grown in HG medium compared with those grown in normal medium. The increased LOX level was strikingly similar to LOX upegulation in the diabetic retinas. In cells grown in HG medium, LOX activity and cell monolayer permeability was significantly increased, as were LOX and proLOX immunostaining. Small interfering RNA- or BAPN-induced-specific blockage of LOX expression or activity, respectively, reduced cell monolayer permeability. CONCLUSIONS HG-induced increased LOX expression and activity compromises barrier functional integrity, a prominent lesion of diabetic retinopathy.
منابع مشابه
Lysyl oxidase and endothelial dysfunction: mechanisms of lysyl oxidase down-regulation by pro-inflammatory cytokines.
Lysyl oxidase (LOX) plays a pivotal role in extracellular matrix (ECM) maturation. Furthermore, novel biological functions has been ascribed to LOX, among them cell differentiation, migration, transformation and regulation of gene expression. In this context, it has been suggested that abnormalities of LOX expression could underlie the development of multiple pathological processes including ca...
متن کاملTransformation and expression of Penicillium funicolusum glucose oxidase gene in yeast
Glucose oxidase is an important enzyme hydrolyzing for its hydrolyzing activity on glucos. It possesses and has a wide board of applications in different industries such as bakery, pharmaceutical, plant pathology and biosensors. In this study, yeast (Saccharomyces cerevisiae) was transformed successfully by the glucose oxidase gene (gox) obtained from Penicillium funicolusum. The secreted gluco...
متن کاملInhibition of Lysyl Oxidases Improves Drug Diffusion and Increases Efficacy of Cytotoxic Treatment in 3D Tumor Models.
Tumors are characterized by a rigid, highly cross-linked extracellular matrix (ECM), which impedes homogeneous drug distribution and potentially protects malignant cells from exposure to therapeutics. Lysyl oxidases are major contributors to tissue stiffness and the elevated expression of these enzymes observed in most cancers might influence drug distribution and efficacy. We examined the effe...
متن کاملDownregulation of Lysyl Oxidase Protects Retinal Endothelial Cells From High Glucose–Induced Apoptosis
Purpose To investigate the effect of reducing high glucose (HG)-induced lysyl oxidase (LOX) overexpression and increased activity on retinal endothelial cell apoptosis. Methods Rat retinal endothelial cells (RRECs) were grown in normal (N) or HG (30 mM glucose) medium for 7 days. In parallel, RRECs were grown in HG medium and transfected with LOX small interfering RNA (siRNA), scrambled siRNA...
متن کاملHypoxia-induced ROS signaling is required for LOX up-regulation in endothelial cells.
The adaptive response of endothelial cells to hypoxia involves a substantial remodeling of extracellular matrix (ECM). In endothelial cells hypoxia up-regulates lysyl oxidase (LOX), a key enzyme in ECM assembly, relevant to vascular homeostasis. However, the mechanism underlying this response has not been established. Hypoxia up-regulated LOX expression in endothelial cells (HUVEC and BAEC) and...
متن کامل