Epithelial-mesenchymal status influences how cells deposit fibrillin microfibrils

Here, we show that epithelial-mesenchymal status influences how cells deposit extracellular matrix. Retinal pigmented epithelial (RPE) cells that expressed high levels of E-cadherin and had cell-cell junctions rich in zona occludens (ZO)-1, beta-catenin and heparan sulfate, required syndecan-4 but not fibronectin or protein kinase C alpha (PKC alpha) to assemble extracellular matrix (fibrillin microfibrils and perlecan). In contrast, RPE cells that strongly expressed mesenchymal smooth muscle alpha-actin but little ZO-1 or E-cadherin, required fibronectin (like fibroblasts) and PKC alpha, but not syndecan-4. Integrins alpha 5 beta 1 and/or alpha 8 beta 1 and actomyosin tension were common requirements for microfibril deposition, as was heparan sulfate biosynthesis. TGF beta, which stimulates epithelial-mesenchymal transition, altered gene expression and overcame the dependency on syndecan-4 for microfibril deposition in epithelial RPE cells, whereas blocking cadherin interactions disrupted microfibril deposition. Renal podocytes had a transitional phenotype with pericellular beta-catenin but little ZO-1; they required syndecan-4 and fibronectin for efficient microfibril deposition. Thus, epithelial-mesenchymal status modulates microfibril deposition.