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The glomerular slit diaphragm is a modified adherens junction.
Jochen Reiser1, Wilhelm Kriz1, Matthias Kretzler2
1Department of Anatomy and Cell Biology, University of Heidelberg, Germany.
Journal of the American Society of Nephrology : JASN
|January 5, 2000
Summary
The glomerular slit diaphragm functions as an adherens junction, involving P-cadherin and catenins. This finding offers new insights into kidney filtration and associated protein identification.
Area of Science:
- Cell biology
- Nephrology
- Molecular biology
Background:
- The glomerular slit diaphragm, crucial for kidney filtration, shares features with adherens junctions.
- Podocyte foot processes form slit-like structures mimicking in vivo filtration slits.
Purpose of the Study:
- To investigate the molecular composition and structure of the glomerular slit diaphragm.
- To determine if the slit diaphragm functions as an adherens junction.
Main Methods:
- Confocal microscopy and immunogold double labeling electron microscopy to visualize protein localization.
- Reverse transcription-PCR to confirm P-cadherin expression in vitro and in vivo.
- Cultured podocytes used to study cellular structures comparable to filtration slits.
Main Results:
- Zonula occludens-1 (ZO-1) was coexpressed with P-cadherin and catenins (alpha-, beta-, gamma-) in cultured podocytes.
- P-cadherin was detected at the slit diaphragm in association with ZO-1 in situ.
- The slit diaphragm complex lacks vinculin, unlike similar adherens junctions in fibroblasts.
Conclusions:
- The glomerular slit diaphragm is proposed to be an adherens junction composed of P-cadherin, catenins, and ZO-1.
- A P-cadherin-based adherens junction structure explains the zipper-like morphology of the slit diaphragm.
- This study opens avenues for identifying novel slit diaphragm proteins and understanding kidney function.