DOI: 10.1369/jhc.4A6489.2005 Volume 53 (4): 533-541, 2005 Copyright ©The Histochemical Society, Inc. Mitochondrial Expression of Arginase II in Male and Female Rat Inner Medullary Collecting Ducts
Laboratoire de Physiopathologie Métabolique et Rénale, Institut National de la Santé et de la Recherche Médicale (INSERM) (OL) and Centre Commun d'Imagerie Laennec (CeCIL) (SB,SP), Université Claude Bernard, Faculté de Médecine Lyon R.T.H. Laennec, Lyon, France Correspondence to: Dr. Olivier Levillain, Université Claude Bernard, Faculté de Médecine Lyon R.T.H. Laennec, Laboratoire de Physiopathologie Métabolique et Rénale, INSERM U 499, 7, rue G. Paradin, 69372 Lyon Cedex 08, France. E-mail: Olivier.Levillain{at}laennec.univ-lyon1.fr Microdissected rat proximal straight tubules (PST) and inner medullary collecting ducts (IMCD) highly produce urea from L-arginine, supporting the expression of the mitochondrial arginase II. However, IMCD contain a very low density of mitochondria compared with PST. Recently, arginase II has been localized by immunohistochemistry in rat PST but not IMCD. This study was designed to verify whether rat IMCD express arginase II and to identify its subcellular localization. We developed an antibody raised against arginase II that allowed the detection of a band of 38 kDa corresponding to arginase II on immunoblots. In male and female rat kidneys, Western blot analyses revealed that arginase II was highly expressed in the inner medulla (IM), the outer stripe of the outer medulla (osOM), and the deep cortex. Immunocytochemistry demonstrated that arginase II was homogeneously expressed in IMCD. Proteins of the cytosolic and mitochondrial fractions extracted from osOM and IM and analyzed by Western blot showed that 86% of arginase II was associated with mitochondria. The molecular weight of arginase II was similar in the cytosolic and mitochondrial fractions. Immunoelectron microscopy confirmed the presence of arginase II in the mitochondria of IMCD. In conclusion, arginase II is expressed in mitochondria of male and female rat IMCD. (J Histochem Cytochem 53:533541, 2005)
Key Words: renal zones Western blot cytosol mitochondria electron microscopy
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