Document Detail

Predominant expression of monoamine oxidase B isoform in rabbit renal proximal tubule: regulation by I2 imidazoline ligands in intact cells.
MedLine Citation:
PMID:  9106629     Owner:  NLM     Status:  MEDLINE    
Previous studies have shown that a subpopulation of the catecholamine-degrading enzymes monoamine oxidase (MAO) A and B holds a previously unknown regulatory site, the I2-imidazoline binding site (I2BS). In the present work, we characterized the isoforms of monoamine oxidases expressed in the rabbit renal proximal tubule, defined their relationship with I2BS, and investigated the ability of I2BS ligands to inhibit enzyme activity in intact cells. Two findings indicate that MAO-B is the predominant isoform expressed in the renal proximal tubule cells: 1) Western blot performed with an anti-MAO-A/MAO-B polyclonal antiserum revealed a single 55-kDa band corresponding to MAO-B; 2) enzyme assays showed an elevated MAO-B activity ([14C]beta-phenylethylamine oxidation: Vmax = 1.31 +/- 0.41 nmol/min/mg protein), whereas MAO-A activity was only detectable ([14C]5-HT oxidation: Vmax = 80.3 +/- 19 pmol/min/mg protein). Photoaffinity labeling with the I2BS ligand [125I]2-(3-azido-4-iodophenoxy)-methylimidazoline revealed a single 55-kDa band, which indicates that MAO-B of the renal proximal tubule cells holds the I2 imidazoline binding site. [3H]Idazoxan binding studies and enzyme assays showed that, in intact cells, I2BS ligands bind to and inhibit MAO-B. Indeed, the increase in the accessibility of intracellular compartment by cell permeabilization did not enhance [3H]idazoxan binding, which indicates that, in intact cells, intracellular I2BS are fully occupied by imidazoline ligands. In addition, enzyme assays showed that incubation of proximal tubule cells with imidazoline ligands leads to a complete, dose-dependent inhibition of MAO activity. These data show the predominant expression of MAO-B in rabbit renal proximal tubule and its regulation by imidazoline ligands in intact cells.
C Gargalidis-Moudanos; A Remaury; N Pizzinat; A Parini
Related Documents :
3100369 - Evidence for existence of polyol pathway in cultured rat mesangial cells.
474709 - Metaplastic and mitotic activity of the ischemic (endocrine) kidney in experimental ren...
16060389 - Prevention of neomycin-induced nephrotoxic event in pig proximal tubular epithelial cel...
22308909 - The thread-protective cell, a new cell performing multiple tasks.
2835539 - Glomerular epithelial, mesangial, and endothelial cell lines from transgenic mice.
12393089 - Macula densa neuronal nitric oxide synthase.
20873809 - High-performance photoelectrochemical cells from ionic liquid electrolyte in methyl-ter...
23900309 - Glycosylation of tyrosinase is a determinant of melanin production in cultured melanoma...
7686949 - Phosphorylation of cd20 in cells from a hairy cell leukemia cell line. evidence for inv...
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Molecular pharmacology     Volume:  51     ISSN:  0026-895X     ISO Abbreviation:  Mol. Pharmacol.     Publication Date:  1997 Apr 
Date Detail:
Created Date:  1997-05-06     Completed Date:  1997-05-06     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  0035623     Medline TA:  Mol Pharmacol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  637-43     Citation Subset:  IM    
Institut National de la Santé et de la Recherche Médicale U388, Centre Hospitalier Universitaire Rangueil, Toulouse, France.
Export Citation:
APA/MLA Format     Download EndNote     Download BibTex
MeSH Terms
Binding Sites
Blotting, Western
Idazoxan / metabolism
Imidazoline Receptors
Kidney Cortex / enzymology
Kidney Tubules, Proximal / enzymology*
L-Lactate Dehydrogenase / metabolism
Monoamine Oxidase / biosynthesis*,  metabolism
Monoamine Oxidase Inhibitors / pharmacology
Receptors, Drug / metabolism*
Reg. No./Substance:
0/Imidazoline Receptors; 0/Ligands; 0/Monoamine Oxidase Inhibitors; 0/Receptors, Drug; 10028-17-8/Tritium; 79944-58-4/Idazoxan; EC Dehydrogenase; EC Oxidase

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

Previous Document:  p53 and WAF1 are induced and Rb protein is hypophosphorylated during cell growth inhibition by the t...
Next Document:  Selective up-regulation of alpha1a-adrenergic receptor protein and mRNA in brown adipose tissue by n...