Redox regulation of HIF-1alpha levels and HO-1 expression in renal medullary interstitial cells.

Abstract

The present study hypothesized that superoxide (O2(-)*) importantly contributes to the regulation of hypoxia-inducible factor (HIF)-1alpha expression at posttranscriptional levels in renal medullary interstitial cells (RMICs) of rats. By Western blot analysis, it was found that incubation of RMICs with O2(-)* generators xanthine/xanthine oxidase and menadione significantly inhibited the hypoxia- or CoCl(2)-induced increase in HIF-1alpha levels and completely blocked the increase in HIF-1alpha levels induced by ubiquitin-proteasome inhibition with CBZ-LLL in the nuclear extracts from these cells. Under normoxic conditions, a cell-permeable O2(-)* dismutase (SOD) mimetic, 4-hydroxyl-tetramethylpiperidin-oxyl (TEMPOL) and PEG-SOD, significantly increased HIF-1alpha levels in RMICs. Two mechanistically different inhibitors of NAD(P)H oxidase, diphenyleneiodonium and apocynin, were also found to increase HIF-1alpha levels in these renal cells. Moreover, introduction of an anti-sense oligodeoxynucleotide specific to NAD(P)H oxidase subunit, p22(phox), into RMICs markedly increased HIF-1alpha levels. In contrast, the OH* scavenger tetramethylthiourea had no effect on the accumulation of HIF-1alpha in these renal cells. By Northern blot analysis, scavenging or dismutation of O2(-)* by TEMPOL and PEG-SOD was found to increase the mRNA levels of an HIF-1alpha-targeted gene, heme oxygenase-1. These results indicate that increased intracellular O2(-)* levels induce HIF-1alpha degradation independently of H(2)O(2) and OH* radicals in RMICs. NAD(P)H oxidase activity may importantly contribute to this posttranscriptional regulation of HIF-1alpha in these cells under physiological conditions.

• Authors: Zhi-Zhang Yang, Andrew Y Zhang, Fu-Xian Yi, Pin-Lan Li, Ai-Ping Zou
• Journal: American journal of physiology. Renal physiology (Am J Physiol Renal Physiol) Vol. 284 Issue 6 Pg. F1207-15 (Jun 2003) ISSN: 1931-857X [Print] United States
• PMID: 12595275 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• DNA, Complementary
• Free Radical Scavengers
• Hypoxia-Inducible Factor 1, alpha Subunit
• Leupeptins
• Oligodeoxyribonucleotides, Antisense
• Reactive Oxygen Species
• Transcription Factors
• carbobenzoxy-leucyl-leucyl-leucine
• Cobalt
• Vitamin K 3
• Xanthine Oxidase
• NADPH Oxidases
• cobaltous chloride

Topics

• Animals
• Blotting, Northern
• Blotting, Western
• Cell Hypoxia (physiology)
• Cell Nucleus (metabolism)
• Cell Separation
• Cobalt (pharmacology)
• DNA, Complementary (biosynthesis, genetics)
• Free Radical Scavengers (pharmacology)
• Hypoxia-Inducible Factor 1, alpha Subunit
• Kidney Medulla (cytology, drug effects, metabolism)
• Leupeptins (pharmacology)
• Male
• NADPH Oxidases (metabolism)
• Oligodeoxyribonucleotides, Antisense (pharmacology)
• Oxidation-Reduction
• Rats
• Rats, Wistar
• Reactive Oxygen Species (metabolism)
• Transcription Factors (biosynthesis)
• Transcriptional Activation
• Vitamin K 3 (pharmacology)
• Xanthine Oxidase (pharmacology)