title: Effects of high glucose on integrin activity and fibronectin matrix assembly by mesangial cells.
abstract: The filtration unit of the kidney is the glomerulus, a capillary network supported by mesangial cells and extracellular matrix (ECM). Glomerular function is compromised in diabetic nephropathy (DN) by uncontrolled buildup of ECM, especially type IV collagen, which progressively occludes the capillaries. Increased levels of the ECM protein fibronectin (FN) are also present; however, its role in DN is unknown. Mesangial cells cultured under high glucose conditions provide a model system for studying the effect of elevated glucose on deposition of FN and collagen IV. Imaging of mesangial cell cultures and analysis of detergent-insoluble matrix show that, under high glucose conditions, mesangial cells assembled significantly more FN matrix, independent of FN protein levels. High glucose conditions induced protein kinase C-dependent β1 integrin activation, and FN assembly in normal glucose was increased by stimulation of integrin activity with Mn(2+). Collagen IV incorporation into the matrix was also increased under high glucose conditions and colocalized with FN fibrils. An inhibitor of FN matrix assembly prevented collagen IV deposition, demonstrating dependence of collagen IV on FN matrix. We conclude that high glucose induces FN assembly, which contributes to collagen IV accumulation. Enhanced assembly of FN might facilitate dysregulated ECM accumulation in DN.
authors.affiliation: Department of Molecular Biology, Princeton University, Princeton, NJ 08544.
authors.forename: Charles G
authors.initials: CG
authors.lastname: Miller
authors.affiliation: Division of Nephrology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232Department of Cancer Biology, Vanderbilt University Medical Center, Nashville, TN 37232Department of Medicine, Veterans Affairs Medical Center, Nashville, TN 37212.
authors.forename: Ambra
authors.initials: A
authors.lastname: Pozzi
authors.affiliation: Division of Nephrology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232Department of Cancer Biology, Vanderbilt University Medical Center, Nashville, TN 37232Department of Medicine, Veterans Affairs Medical Center, Nashville, TN 37212Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, TN 37232.
authors.forename: Roy
authors.initials: R
authors.lastname: Zent
authors.affiliation: Department of Molecular Biology, Princeton University, Princeton, NJ 08544 jschwarz@princeton.edu.
authors.forename: Jean E
authors.initials: JE
authors.lastname: Schwarzbauer
mesh_terms: D002478:Cells, Cultured; D024141:Collagen Type IV / Q000378:metabolism; D003928:Diabetic Nephropathies / Q000378:metabolism*; D005109:Extracellular Matrix / Q000378:metabolism*; D016326:Extracellular Matrix Proteins / Q000378:metabolism; D005353:Fibronectins / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D016023:Integrins / Q000378:metabolism; D050527:Mesangial Cells / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: D024141:Collagen Type IV; D016326:Extracellular Matrix Proteins; D005353:Fibronectins; D016023:Integrins; D005947:Glucose