Elevated oxidized glutathione in cystinotic proximal tubular epithelial cells.
Cystinosis, the most frequent cause of inborn Fanconi syndrome, is characterized by the lysosomal cystine accumulation, caused by mutations in the CTNS gene. To elucidate the pathogenesis of cystinosis, we cultured proximal tubular cells from urine of cystinotic patients (n = 9) and healthy controls (n = 9), followed by immortalization with human papilloma virus (HPV E6/E7). Obtained cell lines displayed basolateral polarization, alkaline phosphatase activity, and presence of aminopeptidase N (CD-13) and megalin, confirming their proximal tubular origin. Cystinotic cell lines exhibited elevated cystine levels (0.86 +/- 0.95 nmol/mg versus 0.09 +/- 0.01 nmol/mg protein in controls, p = 0.03). Oxidized glutathione was elevated in cystinotic cells (1.16 +/- 0.83 nmol/mg versus 0.29 +/- 0.18 nmol/mg protein, p = 0.04), while total glutathione, free cysteine, and ATP contents were normal in these cells. In conclusion, elevated oxidized glutathione in cystinotic proximal tubular epithelial cell lines suggests increased oxidative stress, which may contribute to tubular dysfunction in cystinosis.
Wilmer
Martijn J G
MJ
Laboratory of Pediatrics and Neurology, Radboud University Nijmegen Medical Centre, The Netherlands.
de Graaf-Hess
Adriana
A
Blom
Henk J
HJ
Dijkman
Henry B P M
HB
Monnens
Leo A
LA
van den Heuvel
Lambertus P
LP
Levtchenko
Elena N
EN
D000255:Adenosine Triphosphate / Q000378:metabolism; D018826:CD13 Antigens / Q000378:metabolism; D002478:Cells, Cultured; D003553:Cystine / Q000378:metabolism; D003554:Cystinosis / Q000378:metabolism / Q000473:pathology*; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism*; D019803:Glutathione Disulfide / Q000378:metabolism*; D006801:Humans; D007687:Kidney Tubules, Proximal / Q000378:metabolism / Q000473:pathology*; D026561:Low Density Lipoprotein Receptor-Related Protein-2 / Q000378:metabolism
D026561:Low Density Lipoprotein Receptor-Related Protein-2; D003553:Cystine; D000255:Adenosine Triphosphate; D018826:CD13 Antigens; D019803:Glutathione Disulfide