Phosphorylation status of nephrin in human membranous nephropathy.
BACKGROUND
We recently reported that nephrin, a major slit-diaphragm protein, is phosphorylated at Y1204 and Y1228 in normal human glomeruli and that phosphorylation decreased significantly in minimal-change nephrosis. These results indicate that phosphorylation of nephrin is important for maintenance of normal podocyte morphology and function. On the other hand, phosphorylation of nephrin was reportedly increased in certain animal models of glomerular injury.


METHODS
We performed immunofluorescent and immunoelectron staining of phosphorylated nephrin in human kidney biopsy specimens of membranous nephropathy (MN) to investigate whether phosphorylation of nephrin was altered in human MN and whether it correlated with MN staging.


RESULTS
Although aberrant localization of phosphorylated nephrin was detected using immunoelectron microscopy in stage I MN, a decrease in the immunofluorescent intensity of phosphorylated nephrin was not observed in stage I, and only a slight decrease was seen in stages II, III, and IV compared with controls. No significant correlation between nephrin phosphorylation and proteinuria was observed.


CONCLUSIONS
Nephrin phosphorylation was not significantly decreased in the early stage of MN.
Ohashi
Teiko
T
Department of Medicine, Kidney Center, Tokyo Women's Medical University, 8-1 Kawada-cho, Shinjuku-ku, Tokyo, 162-8666, Japan.
Uchida
Keiko
K
Asamiya
Yukari
Y
Tsuruta
Yuki
Y
Ohno
Mayuko
M
Horita
Shigeru
S
Nitta
Kosaku
K
D000368:Aged; D005455:Fluorescent Antibody Technique; D015433:Glomerulonephritis, Membranous / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D007678:Kidney Glomerulus / Q000378:metabolism* / Q000473:pathology / Q000648:ultrastructure; D008565:Membrane Proteins / Q000378:metabolism*; D016253:Microscopy, Immunoelectron; D008875:Middle Aged; D010766:Phosphorylation; D011507:Proteinuria / Q000378:metabolism; D014443:Tyrosine / Q000378:metabolism
D008565:Membrane Proteins; C113267:nephrin; D014443:Tyrosine