Commentary: Is the Evidence for Localization of Nephrin on the Slit Diaphragm Rigid?

• Published in: International journal of morphology 2012-12, Vol.30 (4), p.1348-1352
• Main Authors: Hipkaeo, Wiphawi, Suzuki, Ryoji, Abe, Hiroshi, Chaisiwamongkol, Kowit, Kondo, Hisatake
• Format: Article
• Language: eng ; por
• Subjects: ANATOMY & MORPHOLOGY
• ISSN: 0717-9502; 0717-9502
• DOI: 10.4067/S0717-95022012000400016

After careful observation of immuno-electron microscopic findings of the renal glomerular podocyte slit so far published by various authors, it should be noted that no convincing evidence is present for localization of nephrin-immunoreactivity in the slit itself, but that nephrin-immunoreactivity is dominantly localized along the membranes of podocyte pedicles from their tip over a substantial extension. In addition, the notion that the slit diaphragm is composed of strands is compatible with the widely distributed view that the slit strands represent rod-shaped nephrin molecules. However, 3-D findings that the diaphragm is composed of not only strands but also membranous elements have recently demonstrated separately by embedment-free section electron microscopy as well as by frozen/deep-etched replica electron microscopy. It is therefore suggested that the molecular composition of the slit diaphragm remain to be further elucidated, and that it is also necessary to re-consider how nephrin is involved in the renal glomerular filtration based on the exact localization along the podocyte membrane, but not in the slit itself. The present author would welcome any criticism and opinion on his consideration.