CLONING OF A CDNA-ENCODING RAT ALDEHYDE DEHYDROGENASE WITH HIGH-ACTIVITY FOR RETINAL OXIDATION

Retinoic acid (RA), an important regulator of cell differentiation, is biosynthesized from retinol via retinal by a two-step oxidation proce ss, We previously reported the purification and partial amino acid (aa ) sequence of a rat kidney aldehyde dehydrogenase (ALDH) isozyme that catalyzed the oxidation of 9-cis and all-trans retinal to correspondin g RA with high efficiency [Labrecque et al. Biochem. J. 305 (1995) 681 -684]. A rat kidney cDNA library was screened using a 291-bp PCR produ ct generated from total kidney RNA using a pair of oligodeoxyribonucle otide primers matched with the aa sequence. The full-length rat kidney ALDH cDNA contains a 2315-bp (501 aa) open reading frame (ORF), The a a sequence of rat kidney ALDH is 89, 96 and 87% identical to that of t he rat cytosolic ALDH, the mouse cytosolic ALDH and human cytosolic AL DH, respectively, Northern blot and RT-PCR-mediated analysis demonstra ted that rat kidney ALDH is strongly expressed in kidney, lung, testis , intestine, stomach and trachea, but weakly in the liver.