title: Distribution of messenger RNAs for aldehyde dehydrogenase 1, aldehyde dehydrogenase 2, and aldehyde dehydrogenase 5 in human tissues.
abstract: BACKGROUND
  The distribution of aldehyde dehydrogenases in human tissues is incompletely understood, in part because of technical limitations of gel electrophoretic and other enzyme assay methods used previously and because of the instability of the enzymes. Since these enzymes participate in detoxification of endogenous and exogenous compounds, including ethanol, their tissue distribution may be relevant to the toxicology of a number of substances and to the medical consequences of alcoholism.
  
  
  METHODS
  The abundance of mRNA for aldehyde dehydrogenase 1 (ALDH1), aldehyde dehydrogenase 2 (ALDH2), and aldehyde dehydrogenase 5 (ALDH5) was determined by Northern blotting using poly A+ RNA from 16 adult human tissues and 5 fetal tissues.
  
  
  RESULTS
  The highest levels of ALDH1 mRNA were found in liver, kidney, muscle, and pancreas. ALDH2 and ALDH5 were expressed in a larger number of tissues than ALDH1, with highest levels in liver, kidney, muscle, and heart. Fetal heart, brain, liver, lung, and kidney expressed ALDH2 and ALDH5, while ALDH1 was present mainly in fetal liver, kidney, and lung.
  
  
  CONCLUSIONS
  The results are in general agreement with the distribution of enzymes studied in a limited number of tissues in the past, with the exception that the ALDH1 activity reported to exist in heart and brain may, in fact, be ALDH5. The only mRNA detected in placenta was that for ALDH5. This study extends the knowledge of the expression of these enzymes to several tissues not previously studied and establishes the tissue distribution of the new enzyme ALDH5.
authors.affiliation: Department of Medicine, Indiana University School of Medicine, Indianapolis 46202-5121, USA.
authors.forename: M J
authors.initials: MJ
authors.lastname: Stewart
authors.forename: K
authors.initials: K
authors.lastname: Malek
authors.forename: D W
authors.initials: DW
authors.lastname: Crabb
mesh_terms: D000328:Adult; D000444:Aldehyde Dehydrogenase / Q000235:genetics*; D000071396:Aldehyde Dehydrogenase, Mitochondrial; D015152:Blotting, Northern; D015342:DNA Probes; D005333:Fetus; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology; D006801:Humans; D007527:Isoenzymes / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics*; D014018:Tissue Distribution
chemical_list: D015342:DNA Probes; D007527:Isoenzymes; D012333:RNA, Messenger; C096127:ALDH2 protein, human; D000444:Aldehyde Dehydrogenase; D000071396:Aldehyde Dehydrogenase, Mitochondrial