Role of integrin-linked kinase in epithelial-mesenchymal transition in crescent formation of experimental glomerulonephritis.
BACKGROUND
Glomerular parietal epithelial-mesenchymal transition (EMT) is a key event in crescent formation of glomerulonephritis (GN). Integrin-linked kinase (ILK) is an integrin cytoplasmic-binding protein that has been implicated in the regulation of cell adhesion, extracellular matrix organization and EMT. Transforming growth factor-beta (TGF-beta) is involved in the induction and progression of EMT in several tissues.


METHODS
To investigate whether ILK is involved in the crescent formation in GN, we studied the expression of ILK protein and activity in crescentic GN induced in Wistar Kyoto (WKY) rats. In addition, we investigated whether transforming growth factor-beta1 (TGF-beta1) could induce glomerular EMT and ILK by using cultured parietal epithelial cell (PEC).


RESULTS
The expression of ILK was strongly induced in cellular crescents at day 7 and followed by a decrease in fibrocellular crescents at day 28. ILK-expressing cells in cellular crescents were double-positive for protein gene product 9.5 (PEC marker), alpha-smooth muscle actin (alpha-SMA, myofibroblasts marker) and TGF-beta1, indicating a possible contribution of ILK and TGF-beta1 to EMT in crescent formation in GN. Consistent with the finding of histological ILK expression in crescents, western blot and kinase activity assay showed an increase in both ILK protein and activity, peaking at day 7 of GN (3.7- and 3.5-fold of control, respectively). The expression of ILK increased to 3.1-fold of control when EMT was induced in cultured PEC by TGF-beta1.


CONCLUSIONS
The present results provide the first evidence that expression and activity of ILK are increased in cellular crescents of experimental GN. Enhanced expression and activity of ILK, possibly by TGF-beta1, is associated with the induction of EMT by PEC and thereby, may participate in the formation of cellular crescents in GN.
Shimizu
Maki
M
Department of Pediatrics, The Institute of Health Bioscience, The University of Tokushima Graduate School, Kuramoto-cho-3-chome, Tokushima 770-8503, Japan.
Kondo
Shuji
S
Urushihara
Maki
M
Takamatsu
Masanori
M
Kanemoto
Katsuyoshi
K
Nagata
Michio
M
Kagami
Shoji
S
D000818:Animals; D015153:Blotting, Western; D002448:Cell Adhesion / Q000502:physiology*; D002478:Cells, Cultured; D004195:Disease Models, Animal; D018450:Disease Progression; D004847:Epithelial Cells / Q000201:enzymology / Q000473:pathology; D005921:Glomerulonephritis / Q000201:enzymology / Q000473:pathology*; D007150:Immunohistochemistry; D007678:Kidney Glomerulus / Q000378:metabolism / Q000473:pathology; D008297:Male; D008648:Mesoderm / Q000201:enzymology / Q000473:pathology; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D051381:Rats; D011921:Rats, Inbred WKY; D016212:Transforming Growth Factor beta / Q000378:metabolism; D053773:Transforming Growth Factor beta1; D000099200:Scaffold Protein ILK
D017346:Protein Serine-Threonine Kinases; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D000099200:Scaffold Protein ILK; C508962:Tgfb1 protein, rat