To understand the effects of global Cyp27a1 and Cyp3a4 gene deletions on bile acid synthesis

The overall goal of the project is to generate a potential mouse model for Cerebrotendinous Xanthomatosis (CTX), a rare autosomal recessive bile synthesis disorder. Patients with this disorder were found to have mutations in Cyp27a1 gene, which results in deficiency of the enzyme sterol 27-hydroxylase. This loss leads to inhibition of cholesterol being converted into bile acids. Global deletion of Cyp27a1 in mice showed none of the CTX phenotype and do not accumulate bile alcohols. As livers of these mice show tremendous upregulation of Cyp3a4, so we hypothesized that it may have "detoxified’ the intermediates and therefore presented a normal phenotype. For answering this, we made double KO mice with Cyp27a1-/- and Cyp3a cluster (Cyp3a13/57/16/41/44/11/25/59) and found no phenotype till 6 months of age. Total RNA was isolated from liver of one mouse in each group. Cyp27a1 KO, Cyp3a4 KO, Cyp27a1-Cyp3a4 DKO mouse livers were compared to WT mouse.