Albumin induces NF-kappaB expression in human proximal tubule-derived cells (IHKE-1).
BACKGROUND
Chronic renal diseases with enhanced glomerular protein filtration are accompanied by tubulointerstitial inflammation and progression to renal function deterioration. Filtered proteins, like albumin, seem to be a pathogenic factor per se in the progression of renal diseases. There is evidence that the nuclear factor kappaB (NF-kappaB) is involved in protein-overload stimulated renal inflammatory pathomechanisms. The aim of this study was to investigate albumin-induced NF-kappaB expression as well as NF-kappaB activity upon long long term exposure to albumin in human proximal tubular cells as only acute albumin-induced NF-kappaB activity has been reported so far.


METHODS
To investigate the hypothesis, that NF-kappaB may be involved in protein-induced renal inflammatory pathomechanisms, we exposed human renal proximal tubule-derived cells (IHKE-1) to bovine serum albumin (BSA: 50 and 500 microg/ml). The NF-kappaB and TNF-alpha specific mRNA expression was detected by RT-PCR. NF-kappaB specific protein expression was analysed by Western blot. Reporter gene assays were performed to determine the NF-kappaB specific activity.


RESULTS
Albumin-exposure induced an increase in NF-kappaB specific mRNA expression, NF-kappaB protein expression and activity. These effects are decreased by the protein kinase C (PKC) inhibitor bisindolylmaleimide I (BIM) and the tyrosine kinase inhibitor herbimycin A. An albumin-induced increase in TNF-alpha specific mRNA expression as biological, inflammatory parameter associated with the albumin-induced NF-kappaB activity was detectable.


CONCLUSIONS
We suggest, that albumin-exposure induces an increase in NF-kappaB and TNF-alpha specific mRNA expression, NF-kappaB specific protein expression and protein activity in renal proximal tubule cells in culture, which is at least in part PKC and tyrosine kinase dependent.
Drumm
Karina
K
Institute of Physiology, University of Wuerzburg, Germany. karina.drumm@mail.uni-wuerzburg.de
Bauer
Boris
B
Freudinger
Ruth
R
Gekle
Michael
M
D000818:Animals; D016227:Benzoquinones; D002417:Cattle; D002478:Cells, Cultured; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D007687:Kidney Tubules, Proximal / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D047029:Lactams, Macrocyclic; D008301:Maleimides / Q000494:pharmacology; D008954:Models, Biological; D016328:NF-kappa B / Q000187:drug effects / Q000378:metabolism*; D011809:Quinones / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D017828:Rifabutin / Q000031:analogs & derivatives; D012710:Serum Albumin, Bovine / Q000494:pharmacology*; D013045:Species Specificity; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
D016227:Benzoquinones; D004791:Enzyme Inhibitors; D007211:Indoles; D047029:Lactams, Macrocyclic; D008301:Maleimides; D016328:NF-kappa B; D011809:Quinones; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D017828:Rifabutin; D012710:Serum Albumin, Bovine; C020754:herbimycin; C070515:bisindolylmaleimide I