Hidden Disease Susceptibility and Sexual Dimorphism in the Heterozygous Knockout of Cyp51 from Cholesterol Synthesis

We examined the genotype-phenotype interactions of Cyp51(+/-) mice carrying one functional allele of lanosterol 14 alpha-demethylase from cholesterol biosynthesis. No distinct developmental or morphological abnormalities were observed by routine visual inspection of Cyp51(+/-) and Cyp51(+/+) mice and fertility was similar. We further collected a large data-set from female and male Cyp51(+/-) mice and controls fed for 16 weeks with three diets and applied linear regression modeling. We used 3 predictor variables (genotype, sex, diet), and 39 response variables corresponding to the organ characteristics (7), plasma parameters (7), and hepatic gene expression (25). We observed significant differences between Cyp51(+/-) and wildtype mice in organ characteristics and blood lipid profile. Hepatomegaly was observed in Cyp51(+/-) males, together with elevated total and low-density lipoprotein cholesterol. Cyp51(+/-) females fed high-fat, high-cholesterol diet were leaner and had elevated plasma corticosterone compared to controls. We observed elevated hepatocyte apoptosis, mitosis and lipid infiltration in heterozygous knockouts of both sexes. The Cyp51(+/-) females had a modified lipid storage homeostasis protecting them from weight-gain when fed high-fat high-cholesterol diet. Malfunction of one Cyp51 allele therefore initiates disease pathways towards cholesterol-linked liver pathologies and sex-dependent response to dietary challenge.