Expression of retinoic acid 4-hydroxylase (CYP26) during mouse and Xenopuslaevis embryogenesis

Retinoids are important signal molecules during vertebrate embryonic develo pment and their synthesis as well as catabolism should therefore be strictl y regulated. The retinoic acid (RA) 4-hydroxylase, belonging to the cytochr ome P450 family CYP26, is an enzyme catalyzing the 4-hydroxylation of RA, t hereby regulating RA homeostasis. Here we describe the temporal and spatial expression patterns of mouse (mCYP26) and Xenopus laevis (xCYP26) homologu es. In mouse, expression is detected in uterine crypt, around differentiati ng cartilage, several regions of the head, regions of the pharynx, the neur al retina, and several regions of the trunk. In Xenopus, Northern blot anal ysis shows presence of xCYP26 transcripts before the MBT and an increased e xpression level during gastrulation. Whole-mount in situ hybridization show s a specific expression pattern arising at onset of gastrulation, with a ri ng around the blastopore. By mid gastrulation there is an anterior and a po sterior expression domain, each of which gets more complex later in develop ment. There are some important similarities and differences in expression p attern between Xenopus and mouse. (C) 1999 Elsevier Science Ireland Ltd. Al l rights reserved.