Two novel sites of expression of NADPH cytochrome P450 reductase during murine embryogenesis: Limb mesenchyme and developing olfactory neuroepithelia

While all cells in eukaryotic organisms probably express the gene encoding NADPH cytochrome P450 reductase, we identified two novel sites which have t he highest local concentrations of P450 reductase transcripts during murine embryogenesis. One site is in developing limbs, including lateral limb bud mesenchyme and condensing mesenchyme in the footplate which will form prec artilage. A second site is in primitive neuroepithelia, including future ol factory epithelia and olfactory lobes of the brain. These high, local conce ntrations of P450 reductase transcripts revealed by in situ hybridization w ere transient and most prominent between embryonic (E) days 12.5-15.5. They cannot be explained by the known functions for P450 reductase. The precurs or nature of the highest reductase-expressing cells suggests that different iation-specific mechanisms regulate P450 reductase gene transcription durin g organogenesis. The data suggest this multifunctional protein might serve an important role in the formation of precartilage models from condensing l imb mesenchyme and in the early development of joints that will form at app osed surfaces of these models. (C) 1999 Wiley-Liss, Inc.