Basic Immunology and PathologyNEPH2 Is Located at the Glomerular Slit Diaphragm, Interacts with Nephrin and Is Cleaved from Podocytes by MetalloproteinasesGerke, Peter*; Sellin, Lorenz‡; Kretz, Oliver†; Petraschka, Daniel*; Zentgraf, Hanswalter§; Benzing, Thomas*; Walz, Gerd* Author Information *Renal Division and†Institute of Anatomy and Cell Biology, University of Freiburg, Freiburg;‡Marienhospital Herne, University of Bochum, Bochum; and§German Cancer Research Center, Heidelberg, Germany Address correspondence to: Dr. Gerd Walz, Renal Division, University Hospital Freiburg, Hugstetter Str. 55, 79106 Freiburg, Germany. Phone: 49-761-270-3250; Fax: 49-761-270-3245; E-mail: [email protected] Received June 4, 2004. Accepted February 26, 2005. Published online ahead of print. Publication date available atwww.jasn.org. Journal of the American Society of Nephrology 16(6):p 1693-1702, June 2005. | DOI: 10.1681/ASN.2004060439 Buy Metrics Abstract The NEPH family comprises three transmembrane proteins of the Ig superfamily interacting with the glomerular slit diaphragm proteins podocin and ZO-1. NEPH1 binds to nephrin, another component of the slit diaphragm, and loss of either partner causes heavy proteinuria. NEPH2, which is strongly conserved among a large number of species, is also expressed in the kidney; however, its function is unknown. The authors raised NEPH2 antisera to demonstrate NEPH2 expression in a variety of mouse tissues, including the kidney and a podocyte cell line. The authors localized the expression of NEPH2 to the glomerular slit diaphragm by electron microscopy and show NEPH2 homodimerization and specific interactions with the extracellular domain of nephrinin vitroandin vivo. NEPH1, however, failed to interact with NEPH2. The authors detected immunoreactive NEPH2 in urine of healthy subjects, suggesting that the extracellular domain is cleaved under physiologic conditions. These findings were confirmedin vitroin podocyte cell culture. Shedding is increased by tyrosine phosphatase inhibitors and diminished by GM6001, an inhibitor of metalloproteinases. Overexpression experiments indicate an involvement of the MT1-matrix metalloproteinase. The results suggest a role for NEPH2 in the organization and/or maintenance of the glomerular slit diaphragm that may differ from the functions of NEPH1 and nephrin. Copyright © 2005 The Authors. Published by Wolters Kluwer Health, Inc. All rights reserved.