title: The N-reductive system composed of mitochondrial amidoxime reducing component (mARC), cytochrome b5 (CYB5B) and cytochrome b5 reductase (CYB5R) is regulated by fasting and high fat diet in mice.
abstract: The mitochondrial amidoxime reducing component mARC is the fourth mammalian molybdenum enzyme. The protein is capable of reducing N-oxygenated structures, but requires cytochrome b5 and cytochrome b5 reductase for electron transfer to catalyze such reactions. It is well accepted that the enzyme is involved in N-reductive drug metabolism such as the activation of amidoxime prodrugs. However, the endogenous function of the protein is not fully understood. Among other functions, an involvement in lipogenesis is discussed. To study the potential involvement of the protein in energy metabolism, we tested whether the mARC protein and its partners are regulated due to fasting and high fat diet in mice. We used qRT-PCR for expression studies, Western Blot analysis to study protein levels and an N-reductive biotransformation assay to gain activity data. Indeed all proteins of the N-reductive system are regulated by fasting and its activity decreases. To study the potential impact of these changes on prodrug activation in vivo, another mice experiment was conducted. Model compound benzamidoxime was injected to mice that underwent fasting and the resulting metabolite of the N-reductive reaction, benzamidine, was determined. Albeit altered in vitro activity, no changes in the metabolite concentration in vivo were detectable and we can dispel concerns that fasting alters prodrug activation in animal models. With respect to high fat diet, changes in the mARC proteins occur that result in increased N-reductive activity. With this study we provide further evidence that the endogenous function of the mARC protein is linked with lipid metabolism.
authors.affiliation: Department of Pharmaceutical and Medicinal Chemistry, Christian-Albrechts-Universität zu Kiel, Kiel, Germany.
authors.forename: Heyka H
authors.initials: HH
authors.lastname: Jakobs
authors.affiliation: Department of Genetics, Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, Warsaw, Poland.
authors.forename: Michal
authors.initials: M
authors.lastname: Mikula
authors.affiliation: Department of Pharmaceutical and Medicinal Chemistry, Christian-Albrechts-Universität zu Kiel, Kiel, Germany.
authors.forename: Antje
authors.initials: A
authors.lastname: Havemeyer
authors.affiliation: Department of Genetics, Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, Warsaw, Poland.
authors.forename: Adriana
authors.initials: A
authors.lastname: Strzalkowska
authors.affiliation: Department of Genetics, Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, Warsaw, Poland.
authors.forename: Monika
authors.initials: M
authors.lastname: Borowa-Chmielak
authors.affiliation: Department of Genetics, Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, Warsaw, Poland.
authors.forename: Artur
authors.initials: A
authors.lastname: Dzwonek
authors.affiliation: Department of Genetics, Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, Warsaw, Poland.
authors.forename: Marta
authors.initials: M
authors.lastname: Gajewska
authors.affiliation: Department of Genetics, Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, Warsaw, Poland; Department of Gastroenterology and Hepatology, Medical Center for Postgraduate Education, Warsaw, Poland.
authors.forename: Ewa E
authors.initials: EE
authors.lastname: Hennig
authors.affiliation: Department of Genetics, Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, Warsaw, Poland; Department of Gastroenterology and Hepatology, Medical Center for Postgraduate Education, Warsaw, Poland.
authors.forename: Jerzy
authors.initials: J
authors.lastname: Ostrowski
authors.affiliation: Department of Pharmaceutical and Medicinal Chemistry, Christian-Albrechts-Universität zu Kiel, Kiel, Germany.
authors.forename: Bernd
authors.initials: B
authors.lastname: Clement
mesh_terms: D000818:Animals; D001550:Benzamidines / Q000378:metabolism; D045744:Cell Line, Tumor; D042966:Cytochrome-B(5) Reductase / Q000378:metabolism*; D015786:Cytochromes b5 / Q000378:metabolism*; D059305:Diet, High-Fat; D004789:Enzyme Activation; D005215:Fasting; D006801:Humans; D006963:Hyperphagia / Q000378:metabolism; D050356:Lipid Metabolism; D008297:Male; D051379:Mice; D024101:Mitochondrial Proteins / Q000378:metabolism*; D010088:Oxidoreductases / Q000378:metabolism*
chemical_list: D001550:Benzamidines; D024101:Mitochondrial Proteins; C053561:benzamidoxime; D015786:Cytochromes b5; D010088:Oxidoreductases; D042966:Cytochrome-B(5) Reductase; C032157:benzamidine