Claudin-6 localized in tight junctions of rat podocytes.
Tight junctions rarely exist in podocytes of the normal renal glomerulus, whereas they are the main intercellular junctions of podocytes in nephrosis and in the early stage of development. Claudins have been identified as tight junction-specific integral membrane proteins. Those of podocytes, however, remain to be elucidated. In the present study, we investigated the expression and localization of claudin-6 in the rat kidney, especially in podocytes. Western blot analysis and RT-PCR revealed that the neonatal kidney expressed much higher levels of claudin-6 than the adult kidney. Immunofluorescence microscopy showed intense claudin-6 staining in most of the tubules and glomeruli in neonates. The staining in tubules declined distinctly in adults, whereas staining in glomeruli was well preserved during development. Claudin-6 in glomeruli was distributed along the glomerular capillary wall and colocalized with zonula occludens-1. The staining became conspicuous after kidney perfusion with protamine sulfate (PS) to increase tight junctions in podocytes. Immunoelectron microscopy showed that immunogold particles for claudin-6 were accumulated at close cell-cell contact sites of podocytes in PS-perfused kidneys, whereas a very limited number of immunogold particles were detected, mainly on the basal cell membrane and occasionally at the slit diaphragm and close cell-cell contact sites in normal control kidneys. In puromycin aminonucleoside nephrosis, immunogold particles were also found mainly at cell-contact sites of podocytes. These findings indicate that claudin-6 is a transmembrane protein of tight junctions in podocytes during development and under pathological conditions.
Zhao
Linning
L
Department of Structural Pathology, Institute of Nephrology, Niigata University Graduate School of Medical and Dental Sciences, 1-757 Asahimachi-dori, Niigata, Japan.
Yaoita
Eishin
E
Nameta
Masaaki
M
Zhang
Ying
Y
Cuellar
Lino Munoz
LM
Fujinaka
Hidehiko
H
Xu
Bo
B
Yoshida
Yutaka
Y
Hatakeyama
Katsuyoshi
K
Yamamoto
Tadashi
T
D000818:Animals; D000831:Animals, Newborn; D002462:Cell Membrane / Q000378:metabolism / Q000648:ultrastructure; D057167:Claudins; D005260:Female; D007678:Kidney Glomerulus / Q000378:metabolism / Q000473:pathology / Q000648:ultrastructure; D008565:Membrane Proteins / Q000378:metabolism*; D009401:Nephrosis / Q000139:chemically induced / Q000378:metabolism / Q000473:pathology; D010750:Phosphoproteins / Q000378:metabolism; D050199:Podocytes / Q000166:cytology / Q000378:metabolism* / Q000648:ultrastructure; D011692:Puromycin Aminonucleoside; D051381:Rats; D011921:Rats, Inbred WKY; D019108:Tight Junctions / Q000378:metabolism* / Q000648:ultrastructure; D062826:Zonula Occludens-1 Protein
D057167:Claudins; D008565:Membrane Proteins; D010750:Phosphoproteins; C569044:Tjp1 protein, rat; D062826:Zonula Occludens-1 Protein; D011692:Puromycin Aminonucleoside; C122101:claudin 6