Plasma apolipoprotein B-48, hepatic apolipoprotein B mRNA editing and apolipoprotein B mRNA editing catalytic subunit-1 mRNA levels are altered in zinc-deficient rats

Apolipoprotein B (apoB) exists as two major isoforms and serves as an oblig atory component of lipid-rich plasma lipoprotein particles. Apolipoprotein B mRNA editing is a zinc-dependent, site-specific cytidine deamination that determines whether the apoB-100 or apoB-48 isoform is synthesized. The obj ective of this work was to examine whether dietary zinc levels affect apoB mRNA editing in vivo, adult male Sprague-Dawley rats were randomly assigned to zinc-deficient (ZD, <0.5 mg Zn/kg diet), zinc-adequate (ZA, 30 mg Zn/kg diet) or zinc-replenished (ZDA, ZD rats fed the ZA diet for last 2 d) diet ary groups for 18 d. The ratio of plasma apolipoprotein B-48 (apoB-48) to t otal apoB was significantly lower in zinc-deficient compared with zinc-adeq uate rats. Primer extension analysis indicated a modest but significant red uction in hepatic apoB mRNA editing in ZD rats compared with that of the ZA group. In ZDA rats, hepatic apoB mRNA editing and the percentage of plasma apoB-48 to total apoB were not different from ZA rats. The mRNA abundance of hepatic apobec-1 (apoB mRNA editing catalytic subunit 1) was significant ly lower in ZD and ZDA rats than in ZA rats. In summary, the plasma ratio o f apoB-48 to total apoB protein as well as hepatic apoB mRNA editing and he patic apobec-1 mRNA levels were reduced in rats consuming a zinc-deficient diet. These data suggest that one or more components of apoB metabolism may be influenced by dietary zinc status.