Co-expression of CYP27B1 enzyme with the 1.5 kb CYP27B1 promoter-luciferase transgene in the mouse

The renal enzyme 25-hydroxyvitamin D la-hydroxylase (CYP2713 1), responsible for the synthesis of circulating. 1,25-dihydroxyvitamin D (1,25D), is also expressed in a number of non-renal tissues. The regulation of CYP27B 1 expression by the short flanking promoter outside the kidney is, however, largely unknown. We have used a transgenic mice expressing the 1.5 kb promoter of the human CYP27B 1 gene fused to the firefly luciferase gene in order to investigate tissue-specific CYP27B 1 expression. These transgenic animals demonstrated co-localised luciferase and endogenous CYP27B 1 expression in kidney proximal convoluted tubular cells. Strong co-expression of luciferase and CYP27B 1 also occurred in neurons and Purkinje cells of the cerebellum and in Leydig and Sertoli cells of the testes. Other tissues to exhibit CYP27B 1-promoter directed luciferase activity included lung, prostate, trabecular bone and jejunum as well as the choroid epithelium. The tissue specific changes in luciferase activity were age-related. These findings demonstrate that the proximal 1.5 kb 5' flanking region of the CYP27B I gene directs the expression of CYP27B 1 in a number of known and novel tissues in a specific manner. Crown Copyright (c) 2008 Published by Elsevier Ireland Ltd. All rights reserved.