Endotoxemia alters tight junction gene and protein expression in the kidney

Am J Physiol Renal Physiol. 2012 Sep 15;303(6):F821-30. doi: 10.1152/ajprenal.00023.2012. Epub 2012 Jul 11.

Abstract

Intact tight junctional (TJ) proteins are required for tubular ion transport and waste excretion. Disruption of TJs may contribute to a decreased glomerular filtration rate in acute kidney injury (AKI) via tubular backleak. The effect of LPS-mediated AKI on murine TJs has not been studied extensively. We hypothesized LPS endotoxin administration to mice would disrupt tubular TJ proteins including zonula occludens-1 (ZO-1), occludin, and claudins. ZO-1 and occludin immunofluorescence 24 h post-LPS revealed a marked change in localization from the usual circumferential fencework pattern to one with substantial fragmentation. Renal ZO-1 expression was significantly reduced 24 h after LPS (decrease of 56.1 ± 7.4%, P < 0.001), with subsequent recovery. ZO-1 mRNA expression was increased 24 h post-LPS (4.34 ± 0.87-fold, P = 0.0019), suggesting disruption of ZO-1 protein is not mediated by transcriptional regulation, but rather by degradation or changes in translation. Similarly, claudin-4 protein expression was decreased despite elevated mRNA. LPS administration resulted in dephosphorylation of occludin and fragmented tubular redistribution. Protein expression of claudin-1, and -3 was increased after LPS. ZO-1, occludin, and claudin-1, -3, and -4 gene expression were increased 48 h after LPS, suggesting a renal response to strengthen TJs following injury. Interestingly, reduced mRNA expression was found only for claudin-8. This study provides further support that LPS-induced AKI is associated with structural injury and is not merely due to hemodynamic changes.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Acute Disease
  • Animals
  • Endotoxemia / chemically induced
  • Endotoxemia / genetics
  • Endotoxemia / metabolism*
  • Gene Expression Regulation
  • Kidney / metabolism*
  • Kidney / pathology
  • Lipopolysaccharides / toxicity
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Tight Junction Proteins / genetics
  • Tight Junction Proteins / metabolism*
  • Tight Junctions / genetics
  • Tight Junctions / metabolism*
  • Tight Junctions / pathology

Substances

  • Lipopolysaccharides
  • Tight Junction Proteins