title: Complementary expression patterns of retinoid acid-synthesizing and -metabolizing enzymes in pre-natal mouse inner ear structures.
abstract: Retinoic acid (RA) plays a pivotal role in patterning and differentiation of the embryonic inner ear. Despite its documented effects during embryonic development, the cellular sites that synthesize or metabolize RA in the inner ear have yet to be determined. Here we describe the distribution of three synthesizing enzymes, retinaldehyde dehydrogenases 1, 2 and 3 (RALDH1, RALDH2 and RALDH3) and two catabolizing enzymes (CYP26A1 and CYP26B1) in the mouse inner ear at embryonic day 18.5 when active cell differentiation is underway. Two detection methods, radioactive and non-radioactive in situ hybridization, were employed to elucidate the tissue distribution and cellular localization of these enzymes, respectively. All of the five enzymes examined, with the exception of CYP26A1, were expressed in both vestibular and cochlear end organs. While expression of the three RALDHs was observed in various cell types, CYP26B1 expression was found only in supporting cells of the vestibular and cochlear end organs. In the cochlea, expression domains of RALDH1-3 and CYP26B1 were complementary to one another. These results reveal specific tissue- and cellular expression patterns of RA synthesizing and catabolizing enzymes in the pre-natal inner ear, and suggest that a precise control of RA concentrations in various cell types of the inner ear is achieved by the balance between RALDHs and CYP26B1 activities.
authors.affiliation: Institut Clinique de la Souris, 1, rue Laurent Fries, B.P. 10142, 67404 Illkirch, France. romand@igbmc.u-strasbg.fr
authors.forename: Raymond
authors.initials: R
authors.lastname: Romand
authors.forename: Karen
authors.initials: K
authors.lastname: Niederreither
authors.forename: Suzan
authors.initials: S
authors.lastname: Abu-Abed
authors.forename: Martin
authors.initials: M
authors.lastname: Petkovich
authors.forename: Valérie
authors.initials: V
authors.lastname: Fraulob
authors.forename: Eri
authors.initials: E
authors.lastname: Hashino
authors.forename: Pascal
authors.initials: P
authors.lastname: Dollé
mesh_terms: D000445:Aldehyde Oxidoreductases / Q000235:genetics / Q000378:metabolism; D000818:Animals; D002454:Cell Differentiation / Q000502:physiology; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics / Q000378:metabolism; D007758:Ear, Inner / Q000196:embryology* / Q000378:metabolism; D004798:Enzymes / Q000235:genetics* / Q000378:metabolism; D015870:Gene Expression; D020869:Gene Expression Profiling; D017403:In Situ Hybridization; D051379:Mice; D050697:Retinal Dehydrogenase; D000072516:Retinoic Acid 4-Hydroxylase; D014212:Tretinoin / Q000378:metabolism*
chemical_list: D004798:Enzymes; D014212:Tretinoin; D003577:Cytochrome P-450 Enzyme System; C000607080:Cyp26a1 protein, mouse; C000607081:Cyp26b1 protein, mouse; D000072516:Retinoic Acid 4-Hydroxylase; D000445:Aldehyde Oxidoreductases; D050697:Retinal Dehydrogenase