Table 1.
Enzymes involved in RA synthesis during early organogenesis in mouse.
| Gene | Major sites of expression | Knockout phenotype |
|---|---|---|
| Retinaldehyde Dehydrogenases (oxidation of retinaldehyde to RA) | ||
| Raldh1 | dorsal retina at E9.5 | non-lethal; adults fertile; perioptic mesenchyme defect when Raldh3 also null; protects against obesity in adult |
| Raldh2 | paraxial mesoderm at E7.5; somites; lateral plate mesoderm; optic vesicle mesenchyme; mesonephros; ventral spinal cord | lethal at E9.5; hindbrain and spinal cord defects; small somites with left-right asymmetry; forelimb bud absent; abnormal heart with medial distended cavity; lung and pancreas agenesis; ventral retina defect when Raldh3 also null |
| Raldh3 | lens and nasal placodes at E8.75; retinal pigment epithelium; ventral retina; mesonephros; ventral forebrain | lethal at birth (blockage of nasal passages); ventral retina defect; forebrain striatal defect; perioptic mesenchyme defect when Raldh1 also null |
| Alcohol/Retinol Dehydrogenases (oxidation of retinol to retinaldehyde) | ||
| Adh1 | mesonephros at E9.5; liver; kidney | non-lethal; adults fertile; hypersensitive to vitamin A toxicity; increased retinyl esters |
| Adh3 | ubiquitous from E6.5 to adult | postnatal growth deficiency; adults fertile but smaller litters; hypersensitive to vitamin A deficiency |
| Adh4 | posterior mesoderm at E7.5; craniofacial mesenchyme; stomach | non-lethal; adults fertile; hypersensitive to vitamin A deficiency |
| Rdh1 | widespread at E7.5; liver; kidney | non-lethal; adults fertile; increased weight and adiposity; increased retinyl esters |
| Rdh10 | lateral plate mesoderm at E7.5; somites; floor plate of neural tube | lethal at E13.0; small forelimbs; craniofacial defects; lung agenesis |