Heme Oxygenase-1 Localization in the Rat Nephron

Abstract

Background/Aims: Renal tubules undergo oxidative injury in various nephropathies. It is unknown whether tubular cells possess mechanisms to attenuate this form of injury. Heme oxygenase-1 (HO-1), the rate-limiting enzyme in heme catabolism, may provide such a mechanism by reducing levels of free heme, a prooxidant molecule, and by limiting activity of heme-containing prooxidant enzymes. Determination of the distribution of HO-1 in the nephron may identify those segments where HO-1 can afford protection against oxidative injury. Methods: Rats were injected subcutaneously with two different inducers of HO-1: Stannous chloride and cobalt protoporphyrin. At completion of injections, frozen sections of kidneys were stained for HO-1 using a biotin-conjugated monoclonal anti-HO-1 antibody. To identify the origin of tubules staining positive for HO-1, Tetragonolobus purpureas (TP)-derived lectin and Arachnis hypogaea (AH)-derived lectin were applied to sequential sections of the kidney cortex. Results: In rats injected with either HO-1 inducer, HO-1 was immunolocalized in tubules but not in glomeruli. Staining of sequential sections with TP-derived lectin, which binds mainly to proximal tubular cells, was negative in the tubules that stained positive for HO-1. Staining of sequential sections with AH-derived lectin, which binds mainly to distal and collecting tubular cells, was positive in those tubules that were also positive for HO-1. Conclusion: In kidneys of rats injected with inducers of HO-1, distal and collecting tubular cells were identified as the main segments of the nephron that express HO-1. We suggest that the distal nephron, by expressing HO-1, may be less vulnerable to oxidative injury.

Acute renal hemodynamic effects of dimanganese decacarbonyl and cobalt protoporphyrin

“…In the past, CoPP has been conventionally employed in vivo as an inducer of HO activity in the kidney [47,48]. However, in the present study this compound has been used acutely as a HO inhibitor, based on the inhibitory effects on HO activity demonstrated in vitro in renal homogenates, and also supported by the observation that CoPP lowers plasma bilirubin concentration when administered in vivo.…”

Role of Estrogen and Progesterone in the Modulation of CNG-A1 and Na+/K+-ATPase Expression in the Renal Cortex

“…After washing with PBS three times for 5 min at room temperature, the sections were incubated with goat anti-rabbit IgG conjugated to Alexa 586 (AllOlO, Molecular Probes, Carlsbad, CA; dilution 1:200) in PBS for 1 h at room temperature. To verify the localization of antibody staining, biotinylated lectins were used: Dilochos bifiorus lectin (DBA) for staining proximal tubules and collector tubules [30] and Arachis hypogaea lectin (PNA) for distal tubules and collector tubules [31]. Biotinylated lectins 15 ng/mL (DBA, B-1035; PNA, BA-2301-2, Vector Laboratories) were incubated for 2 h at room temperature, washed and incubated with streptavidin conjugated to fluorescein isothiocyanate (FITC; SA-1001, Caltag Laboratories, Burlingame, CA; dilution 1:100) for 1 h at room temperature.…”

Heme oxygenase induction attenuates afferent arteriolar autoregulatory responses

“…Renal HO-2 is localized to epithelial cells of the proximal tubule, thick ascending limb and distal tubule, and connecting tubule, and principal cells of the collecting ducts (20). Renal HO-1 is induced under certain pathological conditions and in response to several agents (19,31,40,41). Acute treatment with hemin stimulates HO activity and increases renal cortical dialysate CO concentration and causes diuresis and natriuresis (37).…”