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A novel protein, densin, expressed by glomerular podocytes
Heikki Ahola1, Eija Heikkilä, Eva Aström
1Haartman Institute, Department of Bacteriology and Immunology, University of Helsinki, University Central Hospital, PB 63 (Haartmaninkatu 8), Helsinki, Finland.
Journal of the American Society of Nephrology : JASN
|June 24, 2003
Summary
Researchers identified densin, a protein previously thought brain-specific, as a component of the nephrin protein complex in kidney podocytes. This finding suggests densin may play a role in glomerular structure and function.
Area of Science:
- Nephrology
- Molecular Biology
- Cell Biology
Background:
- Podocytes are crucial for glomerular filtration and are implicated in kidney damage.
- The protein complexes interacting with nephrin, a key podocyte structural molecule, are not well understood.
Purpose of the Study:
- To identify novel proteins associated with nephrin in the glomerular filtration slit.
- To investigate the role of densin in podocytes.
Main Methods:
- Immunoprecipitation of glomerular lysates using anti-nephrin antibodies.
- Protein identification via MALDI-TOF mass spectrometry.
- Expression analysis using RT-PCR, immunoblotting, immunocytochemistry, and electron microscopy.
Main Results:
- Densin was identified as a novel nephrin-interacting protein.
- Densin is expressed in glomeruli and cultured podocytes, localizing to the slit diaphragm area.
- Densin exhibits different molecular weights in brain/podocytes (185 kD) versus human glomeruli (210 kD).
Conclusions:
- Densin is a component of the nephrin-associated protein complex in podocytes.
- Densin may play a role in maintaining podocyte shape, polarity, and slit diaphragm organization, similar to its function in neurons.