Changes in Rat Liver Proteome Following Acute In Vivo Iron Overload

Abstract

The mammalian liver is a primary site for iron processing. Excess iron consumption or iron uptake/storage disorders alter hepatic gene expression and correlate with various liver diseases. The general patterns of change in the hepatic proteome following acute iron overload, however, are poorly understood. To address this, we injected rats with iron dextran to induce liver iron accumulation. After 24, 48, and 96 hours post‐injection, whole livers were isolated and flash‐frozen. Liver non‐heme iron levels increased 30‐fold at all post‐injection times. Liver proteins were solubilized from frozen liver powders with thiourea‐containing buffer and subjected to two‐dimensional gel electrophoresis. Digital spot quantitation of gel images and analysis of protein tryptic digests by MALDI‐TOF/TOF mass spectrometry identified 38 proteins whose expression changed ≥ 1.5 fold following acute iron overload. The majority of identified proteins increased during iron overload including urea cycle enzymes and various enzymes involved in anti‐oxidant defense, lipid metabolism, and mitochondrial ATP formation. Fewer proteins decreased during iron overloading and included specific lipid binding proteins. These results provide a foundation for more detailed analyses on the sequential patterns of changes in liver protein expression during acute iron overload. (Support: NIH DK‐61984)