Fructose inhibits compensatory increases in renal expression of the 1,25(OH)₂D₃ metabolizing enzyme CYP27B1 induced by dietary Ca²⁺deficiency in mice.

(A) mRNA expression levels of renal CYP27B1 (1α-hydroxylase) and CYP24A1 (24-hydroxylase). (B) The protein abundance of CYP27B1 and CYP24A1, using β-actin as a reference. (C) mRNA expression levels of renal TRPV6, CaBP28k, CaBP9k and PMCA1. Nor  =  normal; G  =  glucose; F  =  fructose. All mRNA expression level data were analyzed by real-time PCR using EF1α as a reference and normalized to levels in mice fed glucose and normal Ca²⁺ diet. Data are means ± SEM (n = 5–6 per group). Differences (P<0.05) among means are indicated by differences in superscript letters, as analyzed by 1-way ANOVA LSD. Thus, within a gene of interest, bars with superscript “a” are > bars with “b” which in turn > bars with “c”. Dietary fructose inhibits compensatory increases in renal expression of Ca²⁺ transporters and 1,25(OH)₂D₃ metabolizing enzymes induced by dietary Ca²⁺-deficiency.