Osteoprotegerin in exosome-like vesicles from human cultured tubular cells and urine.
Urinary exosomes have been proposed as potential diagnostic tools. TNF superfamily cytokines and receptors may be present in exosomes and are expressed by proximal tubular cells. We have now studied the expression of selected TNF superfamily proteins in exosome-like vesicles from cultured human proximal tubular cells and human urine and have identified additional proteins in these vesicles by LC-MS/MS proteomics. Human proximal tubular cells constitutively released exosome-like vesicles that did not contain the TNF superfamily cytokines TRAIL or TWEAK. However, exosome-like vesicles contained osteoprotegerin (OPG), a TNF receptor superfamily protein, as assessed by Western blot, ELISA or selected reaction monitoring by nLC-(QQQ)MS/MS. Twenty-one additional proteins were identified in tubular cell exosome-like vesicles, including one (vitamin D binding protein) that had not been previously reported in exosome-like vesicles. Twelve were extracellular matrix proteins, including the basement membrane proteins type IV collagen, nidogen-1, agrin and fibulin-1. Urine from chronic kidney disease patients contained a higher amount of exosomal protein and exosomal OPG than urine from healthy volunteers. Specifically OPG was increased in autosomal dominant polycystic kidney disease urinary exosome-like vesicles and expressed by cystic epithelium in vivo. In conclusion, OPG is present in exosome-like vesicles secreted by proximal tubular epithelial cells and isolated from Chronic Kidney Disease urine.
Department of Nephrology, Instituto de Investigaciones Sanitarias-Fundación Jiménez Díaz - Universidad Autonoma de Madrid, Madrid, Spain.
Alberto
A
Benito-Martin
Alvaro Conrado
AC
Ucero
Irene
I
Zubiri
Maria
M
Posada-Ayala
Beatriz
B
Fernandez-Fernandez
Pablo
P
Cannata-Ortiz
Maria Dolores
MD
Sanchez-Nino
Marta
M
Ruiz-Ortega
Jesus
J
Egido
Gloria
G
Alvarez-Llamas
Alberto
A
Ortiz
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000595:Amino Acid Sequence; D002460:Cell Line; D000074049:Cytokine TWEAK; D055354:Exosomes / Q000737:chemistry*; D005260:Female; D006801:Humans; D007687:Kidney Tubules, Proximal / Q000166:cytology*; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D053244:Osteoprotegerin / Q000032:analysis* / Q000652:urine*; D051436:Renal Insufficiency, Chronic / Q000652:urine*; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000032:analysis; D048069:Tumor Necrosis Factors / Q000032:analysis
D000074049:Cytokine TWEAK; D053244:Osteoprotegerin; D053221:TNF-Related Apoptosis-Inducing Ligand; C109743:TNFSF12 protein, human; D048069:Tumor Necrosis Factors