Recombinant Human Apoa-i Gene In Transgenic Mice

Apolipoprotein A-I (apoA-I) is known to be the major protein constituent of HDL and plays a crucial role in the process of reverse cholesterol transport (RCT). Data from various epidemiological studies have shown that plasma HDL-cholesterol (HDL-C) and apoA-I levels are inversely relating to the incidence and mortality of coronary heart disease. In the mammalian species, apoA-I is noticed mostly to be synthesized in liver and small intestine. The mRNA for apoA-I was reported to be 893 nt in length. Mature apoA-I protein is a single polypeptide consisting of 243 ammo acids (Mw=28KD). Human apoA-I gene has been isolated, and sequenced, which is known locating at chromosome 11,1863 bp in length, and consisting of 4 exons and 3 introns. It is important to study the genetic basis for apoA-I synthesis and HDL-C regulation, anyhow, this work is really too complicated if to be studied directly in human beings. The development of transgenic mouse techniques makes the introduction of human gene from outside, and to study the effect of human apoA-I gene on lipid transportation and metabolism processes in vivo possible.Establishment of human apoA-I transgenic animal models have been reported from various laboratories abroad. ApoA-I could selectively raise the HDL-C levels, remodel the HDL particles, i.e. change the composition of apolipoproteins involved, and prevent or postponed the development of experimental atherosclerosis. However, all of these human apoA-I transgenic animals were noticed to be established using natural human apoA-I genes, and its expression sites are confined to those tissues from where expression of human apoA-I occurs naturally. The levels of expression is somewhat difficult to be under control.In this study, mouse metallothionein I (mMT-I) promoter region was selected for introduction which was linked together with the promoter-depleted human apoA-I gene in constructing a recombinant human apoA-I gene, in order to establish a new transgenic mouse model. Owing to the combination of a mMT-I promoter, it makes the recombined human apoA-I gene able to express ubiquitously in various tissue, including liver, kidneys, intestines, pancreas, and brain, and the expression is inducible by using heavy metals or corticosteroids at anytime in choice for further analyzing the dynamic changes of various apolipoproteins as well as to explore certain novel functions of apoA-I.