Author:
WANG YIPING,RANGAN GOPALA K.,TAY YUET-CHING,WANG YAO,HARRIS DAVID C. H.
Abstract
Abstract. The transcription and translation of monocyte chemoattractant protein-1 (MCP-1), a CC chemokine, are increased in proximal tubule epithelial cells (PTC) stimulated with pathophysiologically relevant concentrations of albumin. The purpose of this study was to investigate whether nuclear factor κB (NFκB)/Rel proteins play a role in albumin-induced MCP-1 transcription. Confluent monolayers of rat PTC in primary culture were stimulated with delipidated bovine serum albumin. NFκB, the NFκB inhibitory protein (IκB), and MCP-1 transcription were assessed using electrophoretic mobility shift assays, Western immunoblotting, semiquantitative reverse transcription-PCR, and ribonuclease protection assays. Activation of NFκB by delipidated bovine serum albumin (15 mg/ml) was detectable within 2 h, maximal after 8 h, and maintained for at least 16 h of continuous exposure. Supershift analysis showed that the activated proteins were composed of p50/p50, p50/p65, and p50/c-Rel dimers. dimers. Cytoplasmic IκBα levels were decreased 30 min after stimulation and returned to unstimulated levels by 4 to 8 h. IκBβ levels were decreased at 2 h and there was no recovery until 8 h. Inhibition of NFκB with pharmacologic agents (N-tosyl-phenylalanine chloromethyl ketone and dexamethasone) and an antisense oligonucleotide to the rat p65 subunit of NFκB significantly reduced MCP-1 transcription. The 3.6-kb 5′ flanking region of the rat MCP-1 gene was cloned and sequenced, and two putative κB binding sites were identified within the enhancer region. Therefore, albumin increased NFκB and reduced IκB levels in PTC, and MCP-1 expression was dependent on NFκB activation. It is concluded that the activation of NFκB/Rel proteins modulates chemokine production in PTC in response to albumin and is likely to have an important role in the mediation of tubulointerstitial injury in proteinuric renal disease.
Publisher
American Society of Nephrology (ASN)
Subject
Nephrology,General Medicine
Cited by
122 articles.
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