Expression of hypoxia-inducible factor-1alpha and -2alpha in hypoxic and ischemic rat kidneys.

Abstract

Oxygen tensions in the kidney are heterogeneous, and their changes presumably play an important role in renal physiologic and pathophysiologic processes. A family of hypoxia-inducible transcription factors (HIF) have been identified as mediators of transcriptional responses to hypoxia, which include the regulation of erythropoietin, metabolic adaptation, vascular tone, and neoangiogenesis. In vitro, the oxygen-regulated subunits HIF-1alpha and -2alpha are expressed in inverse relationship to oxygen tensions in every cell line investigated to date. The characteristics and functional significance of the HIF response in vivo are largely unknown. High-amplification immunohistochemical analyses were used to study the expression of HIF-1alpha and -2alpha in kidneys of rats exposed to systemic hypoxia bleeding anemia, functional anemia (0.1% carbon monoxide), renal ischemia, or cobaltous chloride (which is known to mimic hypoxia). These treatments led to marked nuclear accumulation of HIF-1alpha and -2alpha in different renal cell populations. HIF-1alpha was mainly induced in tubular cells, including proximal segments with exposure to anemia/carbon monoxide, in distal segments with cobaltous chloride treatment, and in connecting tubules and collecting ducts with all stimuli. Staining for HIF-1alpha colocalized with inducible expression of the target genes heme oxygenase-1 and glucose transporter-1. HIF-2alpha was not expressed in tubular cells but was expressed in endothelial cells of a small subset of glomeruli and in peritubular endothelial cells and fibroblasts. The kidney demonstrates a marked potential for upregulation of HIF, but accumulation of HIF-1alpha and HIF-2alpha is selective with respect to cell type, kidney zone, and experimental conditions, with the expression patterns partly matching known oxygen profiles. The expression of HIF-2alpha in peritubular fibroblasts suggests a role in erythropoietin regulation.

• Authors: Christian Rosenberger, Stefano Mandriota, Jan Steffen Jürgensen, Michael S Wiesener, Jan H Hörstrup, Ulrich Frei, Peter J Ratcliffe, Patrick H Maxwell, Sebastian Bachmann, Kai-Uwe Eckardt
• Journal: Journal of the American Society of Nephrology : JASN (J Am Soc Nephrol) Vol. 13 Issue 7 Pg. 1721-32 (Jul 2002) ISSN: 1046-6673 [Print] United States
• PMID: 12089367 (Publication Type: Comparative Study, Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Basic Helix-Loop-Helix Transcription Factors
• DNA-Binding Proteins
• Glucose Transporter Type 1
• Hif1a protein, rat
• Hypoxia-Inducible Factor 1
• Hypoxia-Inducible Factor 1, alpha Subunit
• Monosaccharide Transport Proteins
• Nuclear Proteins
• Protein Isoforms
• Slc2a1 protein, rat
• Trans-Activators
• Transcription Factors
• endothelial PAS domain-containing protein 1
• Cobalt
• Carbon Monoxide
• Heme Oxygenase (Decyclizing)
• Heme Oxygenase-1
• cobaltous chloride
• Oxygen

Topics

• Animals
• Basic Helix-Loop-Helix Transcription Factors
• Carbon Monoxide (pharmacology)
• Cobalt (pharmacology)
• DNA-Binding Proteins (metabolism)
• Gene Expression
• Glucose Transporter Type 1
• Heme Oxygenase (Decyclizing) (genetics)
• Heme Oxygenase-1
• Hypoxia (metabolism)
• Hypoxia-Inducible Factor 1
• Hypoxia-Inducible Factor 1, alpha Subunit
• Ischemia (metabolism)
• Kidney (drug effects, metabolism)
• Male
• Monosaccharide Transport Proteins (genetics)
• Nuclear Proteins (metabolism)
• Oxygen (pharmacology)
• Phlebotomy
• Protein Isoforms (metabolism)
• Rats
• Rats, Sprague-Dawley
• Renal Circulation
• Staining and Labeling
• Trans-Activators (metabolism)
• Transcription Factors