Diamine oxidase and catalase are expressed in the same cells but are present in different subcellular compartments in porcine kidney

Abstract

IntroductionDiamine oxidase (DAO; EC 1.4.3.6) catalyzes the oxidative deamination of histamine and other biogenic amines in a reaction that produces the corresponding aldehyde as well as ammonia and hydrogen peroxide [1]. Hydrogen peroxide is a highly reactive compound and may cause cellular damage if not scavenged appropriately [2]. Therefore, we reasoned that the hydrogen peroxide producing and degrading enzymes might be co-localized in mammalian tissues and analyzed the cellular and subcellular distribution of DAO and of catalase (EC 1.11.1.6), the major hydrogen peroxide scavenging enzyme [3]. Materials and methodsPorcine kidney specimens were prepared immediately post mortem and fixed in 4% buffered paraformaldehyde for 24 h at 4°C. The specimens were then embedded in paraffin and sections of 5 to 25 mm were cut. The sections were dewaxed in xylene, rehydrated in ethanol, and incubated with antibodies specific for DAO and for catalase. DAO was detected with a rabbit polyclonal anti-DAO antibody (1: 2000 dilution) [4] followed by incubation with fluorescein isothiocyanate (FITC)-conjugated swine anti-rabbit immunoglobulins (1:50 dilution) (Dako, Glostrup, Denmark). Catalase was detected with a mouse monoclonal anti-catalase antibody (1:200 dilution) [5] followed by incubation with tetramethylrhodamine isothiocyanate (TRITC)-conjugated goat antimouse immunoglobulins (1:50 dilution) (Sigma, St. Louis, MO, USA). All antibodies were diluted in 50 mM Tris hydrochloride pH 7.5/ 150 mM NaCl/1% bovine serum albumin and sections were washed with 50 mM Tris hydrochloride pH 7.5/150 mM NaCl/0.05% Tween 20. DNA was stained with 4,6-diamidino-2-phenylindole (DAPI, 1 mg/l) to visualize cell nuclei. The sections were mounted with fluorescence mounting medium (Dako) and analyzed with a Leica TCS 4D confocal laser scanning fluorescence microscope. False-color images of individual optical sections and projections as well as stereo views with depths ranging from 5 to 20 mm were prepared by digital image processing, using the Leica ScanWare TM software. Results and discussionLittle attention has previously been paid to the fact that diamine oxidase and related amine oxidases in addition to inactivating primary amines also produce hydrogen peroxide, a compound dangerous for cells due to its oxidative potential and as a precursor of oxygen radicals [2]. Our interest in the fate of this potentially harmful reaction product prompted us to use antibodies specific for DAO [4] and for catalase [5], the major hydrogen peroxide scavenging enzyme, to investigate the cellular and subcellular localisation of these enzymes and to ask whether they are co-localized in porcine kidney.Interestingly, we found DAO and catalase to be expressed in the same cells, namely in proximal tubular epithelial cells (Fig. 1). Both enzymes showed decreasing levels of expression from the outer cortex towards the medulla. However, the proteins were present in different subcellular compartments. In agreement with earlier work [6], we found DAO to be present in sm...

Immunohistochemical Localization of Histamine N-Methyltransferase in Guinea Pig Tissues

“…Concerning the alternative pathway of histamine catabolism, involving diamine oxidase, few immunohistochemical data are available. Although Schwelberger et al (1998Schwelberger et al ( ,1999 reported the presence of DAO in the intestine and proximal tubules in pig kidney, the immunohistochemical localization in other tissues remains unclear. Beaven (1982) suggested that the localization of DAO was restricted to the intestine, kidney, thymus, and placenta.…”

“…Although there exist two main catabolic pathways for histamine in tissues, methylation by histamine N -methyltransferase (HMT; EC 2.1.1.8.) and oxidative deamination by diamine oxidase (DAO; EC 1.4.3.6) (Beaven 1982), information on the relative importance of each pathway to the catabolism of histamine in tissue as well as the cellular localization of these enzymes (Fukuda et al 1986;Schwelberger et al 1999) is limited.…”

Amine oxidases and monooxygenases in the in vivo metabolism of xenobiotic amines in humans: has the involvement of amine oxidases been neglected?

“…Diamine oxidase (DAO), which is an SSAO, is above all expressed in intestine, kidney and placenta. Its subcellular localization has been defined in porcine small intestine and kidney, where it is present in plasma‐membrane‐associated vesicles [59,60]. Lysyl oxidase is unique amongst the SSAO family of enzymes: although it is sensitive to SSAO inhibitors, its cofactor appears to be lysine tyrosylquinone rather than topaquinone (TPQ) [58].…”

Toward Oral Supplementation of Diamine Oxidase for the Treatment of Histamine Intolerance

“…The intolerance results from an imbalance between the uptake of histamine and the histamine-degrading enzyme diamine oxidase (DAO) (EC 1.4.3.22) [5]. Human DAO is a secretory enzyme that is located mainly in the small intestinal mucosa and the kidneys [3,6,7]. This enzyme catalyzes the oxidative deamination of histamine or other biogenic amines to the corresponding aldehydes, ammonia, and hydrogen peroxide [8].…”