Primary human glomerular endothelial cells produce proteoglycans, and puromycin affects their posttranslational modification.
This article describes the possible role of the endothelial cell-surface coat, containing proteoglycans (PGs) with connected glycosaminoglycans (GAGs), in maintaining glomerular permselectivity. Primary human glomerular endothelial cells (HGEC) in culture were treated with the nephrosis-inducing agent puromycin aminonucleoside (PAN). Analysis was made by TaqMan real-time PCR, Western blot analysis, and by metabolic labeling with [(35)S]sulfate. The HGECs express several PGs: syndecan, versican, glypican, perlecan, decorin, and biglycan, which may contribute to the glomerular charge barrier. PAN treatment downregulated both the protein expression (by 25%) and the mRNA expression (by 37 +/- 6%, P < 0.001, n = 8) of versican compared with control. Transferases important for chondroitin and heparan sulfate biosynthesis were also significantly downregulated by PAN, resulting in less sulfate groups, shorter GAG chains, and reduced PG net-negative charge. Moreover, analysis of the cell media after PAN treatment revealed a reduced content of [(35)S]sulfate-labeled PGs (40% of control). We conclude that PAN may cause proteinuria by affecting the endothelial cell-surface layer and not only by disrupting the foot process arrangement of the podocytes. Thus the endothelium may be a more important component of the glomerular barrier than hitherto acknowledged.
Björnson
Anna
A
Dept. of Nephrology, Göteborg Univ., Sahlgrenska Univ. Hospital, SE-413 45 Gothenburg, Sweden. Anna.Bjornson@kidney.med.gu.se
Moses
Jonatan
J
Ingemansson
Annika
A
Haraldsson
Börje
B
Sörensson
Jenny
J
D000328:Adult; D015153:Blotting, Western; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D005944:Glucosamine / Q000493:pharmacokinetics; D006801:Humans; D007678:Kidney Glomerulus / Q000166:cytology / Q000502:physiology*; D011499:Protein Processing, Post-Translational / Q000187:drug effects*; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology*; D011509:Proteoglycans / Q000235:genetics* / Q000378:metabolism; D011691:Puromycin / Q000494:pharmacology*; D012333:RNA, Messenger / Q000032:analysis; D013431:Sulfates; D014166:Transferases / Q000235:genetics / Q000378:metabolism; D014316:Tritium
D011500:Protein Synthesis Inhibitors; D011509:Proteoglycans; D012333:RNA, Messenger; D013431:Sulfates; D014316:Tritium; D011691:Puromycin; D014166:Transferases; D005944:Glucosamine