Differential expression of nephrin in acquired human proteinuric diseases.
BACKGROUND
The slit-diaphragm protein nephrin is an essential component of the glomerular filtration barrier. It is not clear whether renal injury in patients with acquired proteinuric diseases is associated with altered regulation of the nephrin gene or protein.


METHODS
We examined expression patterns of nephrin protein and messenger RNA (mRNA) in renal biopsy specimens from patients with minimal lesion (n = 7), focal segmental glomerulosclerosis (FSGS; n = 14), or membranous nephropathy (MN; n = 7) and controls (n = 8) by immunohistochemistry, immunoelectron microscopy, in situ hybridization, and polymerase chain reaction (PCR) amplification of nephrin complementary DNA.


RESULTS
In normal kidney, nephrin staining showed a diffuse interrupted linear pattern along the glomerular basement membrane (GBM). Nephrin staining in minimal lesion specimens showed a finely granular pattern along the GBM and was positive in cell bodies of visceral glomerular epithelial cells. Nephrin staining was most disrupted in FSGS specimens. Immunoelectron microscopy showed that nephrin-specific gold particles were almost absent in effaced foot processes in proteinuric patients. An in situ hybridization study showed significantly decreased nephrin mRNA-expressing cells in cases of FSGS and MN compared with controls. Reverse-transcription PCR showed significantly lower levels of nephrin mRNA in cases of FSGS and MN than controls, but no significant difference between minimal lesion cases and controls. Relative levels of glomerular nephrin mRNA correlated inversely with percentage of glomeruli with sclerosis in proteinuric diseases.


CONCLUSIONS
These results suggest that nephrin-expression patterns in proteinuric diseases are different according to the specific glomerular disease or severity of glomerular damage.
Kim
Byoung Kwon
BK
Department of Pathology, Seoul National University College of Medicine, Seoul, Korea.
Hong
Hye Kyoung
HK
Kim
Ji Hoon
JH
Lee
Hyun Soon
HS
D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D005260:Female; D005786:Gene Expression Regulation / Q000235:genetics; D006801:Humans; D007150:Immunohistochemistry; D017403:In Situ Hybridization / Q000379:methods; D007674:Kidney Diseases / Q000235:genetics* / Q000378:metabolism*; D007678:Kidney Glomerulus / Q000737:chemistry / Q000293:injuries / Q000473:pathology / Q000648:ultrastructure; D008297:Male; D008565:Membrane Proteins; D016253:Microscopy, Immunoelectron; D008875:Middle Aged; D014176:Protein Biosynthesis; D011506:Proteins / Q000235:genetics* / Q000276:immunology; D011507:Proteinuria / Q000235:genetics* / Q000378:metabolism*; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods
D008565:Membrane Proteins; D011506:Proteins; D012333:RNA, Messenger; C113267:nephrin