N‐sulfation of Cell Surface Heparan Sulfate Glycosaminoglycans is Critical for Podocyte‐Matrix Interactions

Abstract

Podocytes adhere to the glomerular basement membrane via cell surface receptors which include heparan sulfate (HS) proteoglycans (PG). Podocytes unable to assemble HS glycosaminoglycan chains have defective cell attachment and spreading, and cytoskeletal disruption in vitro and in vivo. The current report explores the importance of heparan sulfation in regulating podocyte cell‐matrix interactions, using an immortalized podocyte cell line having the genomic deletion of N‐deacetylase/ N‐sulfotransferase 1 (NDST1), the enzyme responsible for N‐sulfation of HS. Compared to wild type podocytes, mutant podocytes attached, spread and migrated less efficiently in assays than control cells. In the process of cell‐matrix interaction, the mutant cells showed decreased clustering of syndecan 4, the cell surface HSPG involved in focal adhesion formation, and decreased recruitment of PKCα, α‐actinin 4, vinculin, and pFAK to focal adhesions. Cell surface integrin expression and integrin activation/signaling was significantly diminished in the mutant cells. These results serve to highlight the critical role of HS N‐sulfation in regulating the ability of podocytes to interact with the extracellular matrix.Grant Funding Source: NIDDK RO1‐DK07786