TY - JOUR T1 - Enzymatic conversion of retinaldehyde to retinoic acid by cloned murine cytosolic and mitochondrial aldehyde dehydrogenases. JF - Molecular Pharmacology JO - Mol Pharmacol SP - 88 LP - 96 VL - 46 IS - 1 AU - M Chen AU - C Achkar AU - L J Gudas Y1 - 1994/07/01 UR - http://molpharm.aspetjournals.org/content/46/1/88.abstract N2 - It has previously been reported that retinaldehyde can be converted to retinoic acid by cytosolic aldehyde dehydrogenase (AHD-2) in liver extracts [Biochem. Pharmacol. 42: 1279-1285 (1991)]. To determine which enzyme(s) carried out this reaction in murine embryonic stem cells, two aldehyde dehydrogenases were cloned; the AHD-2 gene was cloned from a liver cDNA library, and a closely related gene, AHD-M1, was cloned from an embryonic F9 cell cDNA library by conserved oligonucleotide sequence screening. AHD-M1 contained an open reading frame of 1554 base pairs, which encoded 517 amino acids. The AHD-M1 gene encoded a protein with a putative amino acid sequence that was 94% and 97% identical to the mitochondrial aldehyde dehydrogenases of human and rat, respectively, and thus we have cloned the murine cDNA for this enzyme for the first time. The AHD-M1 cDNA was only 64% identical to AHD-2. Northern analysis showed that AHD-M1 mRNA was constitutively expressed in F9 and P19 embryonic teratocarcinoma stem cells and in AB1 embryonic stem cells. There was a 3-5-fold retinoic acid-associated increase in the amount of this mRNA during the differentiation of F9 cells into parietal endoderm. In contrast, we could not detect the expression of AHD-2 mRNA in AB1, P19, or F9 cells, even though the F9 cells could convert retinaldehyde to retinoic acid. When the AHD-M1 and AHD-2 cDNAs were inserted into the expression vector pSG5 and transfected into cultured COS cells, 3-5-fold and 100-fold increases, respectively, in the conversion of [3H]retinaldehyde to [3H]retinoic acid could be detected by high performance liquid chromatographic assay. We conclude that both enzymes are capable of converting retinaldehyde to retinoic acid in intact COS cells. AHD-2 is more active than AHD-M1 in this conversion, but AHD-2 is not the enzyme responsible for this conversion in F9 embryonic stem cells. ER -