Caveolae are plasma membrane invaginations that contain a variety of signal transduction molecules and receptors for
growth factors and
cytokines. This study was performed to examine the in vivo expression and localization of
caveolin-1 in kidneys from 19 children who underwent surgery release of ureteropelvic junction obstruction (UPJO) in relation to renal function and degree of tubulointerstitial
fibrosis. Renal biopsies were carried out at the time of surgery for obstruction release. Kidney tissue from children of similar age removed because of
carcinoma was used as control. Expression of
caveolin-1 at the
protein level in renal tissue and urine was demonstrated in patients with
technetium 99 m labeled
diethylene triamine pentaacetate ((99)
Tc DTPA) renal scan 28.8+/-2% and increased tubular interstitial
fibrosis in seven patients at the time of obstruction release. Colocalization staining of AT(1)
angiotensin II receptor with
caveolin-1 in basolateral membrane of epithelial tubule cells, enhanced AT(1) messenger
ribonucleic acid (
mRNA) and decreased
endothelial nitric oxide synthase (eNOS), were shown in these patients. In contrast, absence of association of
caveolin-1 with AT(1) receptor expression in proximal and collecting tubule membranes with AT(1) receptor
mRNA and eNOS
mRNA expression near control were demonstrated in 12 patients, with (99)
Tc DTPA renal scan 39.7+2.1% and no evidence of tubulointerstitial
fibrosis. From our results, the role of
caveolin-1 as
a factor contributing to the severity of the tubulointerstitial process resulting from obstructive nephropathy could be suggested.