Transgenic mice with overexpression of human scavenger receptor A on endothelial cells

Objectives To establish a new transgenic mouse model for determining the fu nction and role of human scavenger receptor A (SR-A) in atherosclerosis in vivo. Methods Human scavenger receptor minigene-driven mouse tie-1 promoter was c onstructed and confirmed by endonuclease digestion and sequence analysis. T ransgenic mice were generated via the microinjection method. PCR and Southe rn blot were used to screen the positive transgenic mice. RT-PCR and immuno histochemical analysis were used to detect the level and location of human SR-A I expression in transgenic mice. The activity of human SR-A I was dete rmined by morphologic observation of aortic endothelial cells of transgenic mice under transmission electron microscopy. Results The electrophoresis assay showed the expected 4 fragments of 0.9 kb , 1.1 kb, 1.2 kb and 4.2 kb in the Sma I digest and 2 fragments of 0.8 kb a nd 6.7 kb in Bgl R digest of plasmids pTie-1/hSR-A. The fragment sequence o f tie-1 promoter and human SR-A cDNA in plasmids pTie-1/hSR-A was correct a nd no ATG before the translation initiation sites of human SR-A was found b y sequence analysis. 561 injected and surviving embryos with the purified h uman SR-A minigene were implanted into the oviducts of 19 ICR pseudopregnan t mice. Among the 54 surviving pups from 13 foster mothers, 7 were identifi ed by PCR and Southern blot analysis. The results of RT-PCR and immunohisto chemical analysis showed human SR-A was specifically expressed on vascular endothelial cells of the aorta and renal artery, as well as hepatic sinusoi dal endothelial cells in transgenic mice. Transmmion electron microscope (T EM) of aorta of transgenic mice showed that a large number of vesicles, mul tivesicle bodies and swollen mitochondria filled the plasma of endothelial cells. Conclusions A transgenic mouse model with overexpression of human SR-A in e ndothelial cells was successfully established. The transgene was integrated and transmitted into the chromosome of transgenic mice. Tie-1 promoter con trolled the transgene to express in endothelial cells in mice. Pinocytic ac tivity of aortic endothelial cells in transgenic mice was higher than that of C57BL/6J mice. Our studies will provide a new transgenic model for inves tigation of atherosclerosis and functions of human SR-A.