Developmental expression of cytochrome CYP26B1 (P450RAI-2) in human cephalic tissues.

Expression levels of cytochrome CYP26B1, which is involved in the specific all-trans-RA inactivation, were evaluated in human cephalic tissues at gestational days 57-110 and exhibited values approximately 10-fold higher than later gestational days 112-224 and adult tissues. CYP26B1 mRNA levels in the adult cerebellum were approximately 2-fold higher than in the adult whole brain tissue. Considered together, these data suggest a unique role for CYP26B1 during human brain development.

Patterns of CYP26 expression in human prenatal cephalic and hepatic tissues indicate an important role during early brain development.

CYP26 (P450RAI) catalyzes catabolic retinoic acid (RA) hydroxylation and thereby appears to play a critical role in retinoid signaling pathways during development. In this study, a quantitative competitive reverse transcriptase-polymerase chain reaction (RT-PCR) assay was developed for evaluation of CYP26 message levels in human prenatal tissues. Statistical analyses of transcription levels in 12 prenatal human brains and six prenatal human livers demonstrated good sensitivity and reproducibility.

Expression of cytochrome P450RAI (CYP26) in human fetal hepatic and cephalic tissues.

PCR amplifications with two sets of degenerate primers that were targeted to CYP26-specific regions were performed with cDNAs from human fetal liver and brain as templates. PCR products were purified, cloned, sequenced and analyzed with the BLAST program. Our results revealed expression of CYP26 in both human fetal liver and brain.