Characterization of the human PKD2 transgenic mouse line (PKD2tg). A: Human PKD2 mRNA expression versus endogenous Pkd2 mRNA expression in different organs/tissues of PKD2tg (light gray bars) mice and their wild-type (WT; dark gray bars) littermates, determined by quantitative PCR. All quantitative PCR results were normalized to the glyceraldehyde-3-phosphate dehydrogenase (GAPDH) expression. B: Proteins extracted from the same organs/tissues of PKD2tg mice and their wild-type littermates were analyzed by Western blot with an anti- polycystin (PC)-2 antibody (hPKD2-Cp). Markedly higher PC2 expression is detected in the organs/tissues of PKD2tg mice than in those of their wild-type littermates. β-Actin was used as an internal loading control. C: Quantitative analysis of the densitometry values of the Western blot analyses. At least three transgenic mice or their wild-type littermates were tested. D–Q: IHC analysis (IHC) (D–J) and immunofluorescence (IF) (K–Q) staining with the hPKD2-Cp antibody to detect PC2 in the kidneys of 12-month-old PKD2tg transgenic mice and their wild-type littermates. A Pkd2-null embryonic kidney (embryonic day 14.5, E14.5) was used as a negative control. Obvious positive labeling (arrows) is seen in both the PKD2tg and wild-type–littermate kidneys, but it is much stronger in the PKD2tg kidney (arrows in D versus E and in K versus L). There is no positive signal in the Pkd2-null embryonic kidney (F and M). IHC (G and H) and IF (N and O) staining analyses were used for examine the liver of these mice. Stronger positive staining (arrows in G versus H and N versus O) is detected in the PKD2tg liver than in the wild-type–littermate liver. Similar IHC and IF staining results were obtained in the pancreas of these mice (arrows in I versus J and in P versus Q). R: Kaplan-Meier survival analysis of wild-type and PKD2tg mice. No difference in survival rate is seen between the wild-type and PKD2tg mice up to 12 months of age (n = 25 per genotype). Data presented as means ± SD (A and C). Scale bars: 50 μm (D–J); 100 μm (K–Q). cy, cyst; M, months.