FIGURE 10.

Effects of expression of the PDZK1[Tyr³⁸⁸ → Ala]transgene on hepatic SR-BI protein levels (A) and plasma lipoprotein cholesterols (B and C) in WT and PDZK1 KO mice. A, liver lysates (∼30 μg of protein) from mice with the indicated genotypes, with (+) or without (−) the PDZK1[Tyr³⁸⁸ → Ala]Tg (substitution in the PDZ4 domain), were analyzed by immunoblotting, and bands representing PDZK1 (∼70 kDa) and SR-BI (∼82 kDa) were visualized by chemiluminescence. ϵ-COP (∼34 kDa) was used as a loading control. Note the faint SR-BI band in the nontransgenic PDZK1 KO lane. Replicate experiments with multiple exposures and sample loadings were used to determine the relative levels of expression of SR-BI. B, plasma samples were harvested from mice with the indicated genotypes and PDZK1[Tyr³⁸⁸ → Ala]transgene. Total plasma cholesterol levels were determined in individual samples by enzymatic assay, and mean values from the indicated numbers of animals (n) are shown for each genotype. Independent WT and KO control animals for each founder line were generated to ensure that the mixed genetic backgrounds for experimental and control mice were matched. * indicates the nontransgenic KO plasma cholesterol levels were statistically significantly different from those plasma cholesterol levels of WT (p < 0.0001). ** indicates PDZK1 KO ([Tyr³⁸⁸ → Ala]Tg) plasma cholesterol levels were statistically significantly different from those plasma cholesterol levels of nontransgenic PDZK1 KO mice (p < 0.0001). WT, WT ([Tyr³⁸⁸ → Ala]Tg), and KO ([Tyr³⁸⁸ → Ala]Tg) plasma cholesterol levels were not statistically significantly different. C, plasma samples (described in panel B) from individual animals were size fractionated by FPLC, and the total cholesterol content of each fraction was determined by an enzymatic assay. The chromatograms are representative of multiple individually determined profiles. Approximate elution positions of native VLDL, IDL/LDL, and HDL particles are indicated by brackets and determined as previously described (7).