Differential Expression of Retinoic Acid-Synthesizing (RALDH) Enzymes During Fetal Development and Organ Differentiation in the Mouse

The study examined the expression of retinoic acid-synthesizing enzymes Raldh1, Raldh2, and Raldh3 during mouse fetal development and organ differentiation. Raldh1 was prominently expressed in the lung, stomach, intestine, and specific brain structures postnatally, while Raldh2 was found in the kidney nephrogenic zone and mesenchyme of various organs. Raldh3 was specific to the intestinal lamina propria and certain epithelial tissues. Additionally, Raldh1 was highly expressed in ventral mesencephalic cells, including the substantia nigra, until adulthood, and Raldh3 was found in the lateral ventricle septal fork and the superficial layer of the posterior cerebral cortex at postnatal stages. In developing hair follicles, Raldh3 was expressed at the base of the follicles at 5 days post-partum, with Raldh1 coexpressed at weaker levels, but these patterns were not observed at 3 weeks post-partum. The distinct expression patterns indicated a regulated requirement for retinoic acid synthesis in various differentiating organs, highlighting their roles in organogenesis and tissue differentiation.