Journal of Lipid Research, Vol 36, 1463-1473, Copyright © 1995 by Lipid Research, Inc.
Overexpression of human apolipoprotein A-I in transgenic rats and the hyperlipoproteinemia associated with experimental nephrosis
BF Burkey, D France, H Wang, X Ma, B Brand, C Abuhani, MR Diffenderfer, JB Marsh, JR Paterniti Jr and EA Fisher
Department of Metabolic Diseases, Sandoz Research Institute, Sandoz Pharmaceuticals Corporation, East Hanover, NJ 07936, USA.
Hyperlipoproteinemia contributes both to kidney disease progression and the
development of atherosclerosis. Elevated high density lipoprotein
cholesterol and apolipoprotein A-I (apoA-I) serum levels are independent
factors protective against the atherosclerotic process. We examined the
effects in a transgenic rat model of human apoA-I expression on the
hyperlipoproteinemia and edema after puromycin aminonucleoside-induced
nephrosis in three groups of animals: low line (TgR[hAI]low, human plasma
apoA-I = 16.0 mg/dl); high line (TgR[hAI]high, 284 mg/dl); and
non-transgenic litter mates (TgR[hAI]non). Nephrosis increased total plasma
apoA-I levels 2-fold in TgR[hAI]non rats (75 vs. 162 mg/dl) and 4-fold in
the TgR[hAI]low (97 vs. 458 mg/dl) and TgR[hAI]high rats (356 vs. 1,346
mg/dl). In both transgenic lines, this increase was due mainly to
elevations of serum human apoA-I. The hepatic steady-state levels of rat
apoA-I mRNA increased 5- to 7-fold in all three groups, while human apoA-I
mRNA levels increased 21- and 65-fold in the low and high expressing
groups, respectively, indicating a different degree of responsiveness of
the rat and human genes. While nephrotic TgR[hAI]non and TgR[hAI]low rats
showed severe hyperlipoproteinemia and edema, much lower levels of edema
and of serum triglycerides, phospholipids, and cholesterol were seen in the
TgR[hAI]high group. Urinary excretion of apoA-I, phospholipids, and
cholesterol was significantly increased in the TgR[hAI]high group,
indicating this as one possible mechanism for the relatively lower serum
levels of these lipids. We conclude that the human apoA-I gene is
responsive to nephrosis and that human apoA-I- transgenic rats with this
syndrome provide an animal model for the study of human high density
lipoprotein and apoA-I metabolism.