THE ROLES OF ZINC AND METALLOTHIONEIN IN HEPATOCYTE ANTIOXIDANT DEFENSE By LOUIS LICHTEN A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE

of Thesis Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Science THE ROLES OF ZINC AND METALLOTHIONEIN IN HEPATOCYTE ANTIOXIDANT DEFENSE By Louis Lichten August 2004 Chair: Robert Cousins Major Department: Food Science and Human Nutrition Zinc and metallothionein are involved in cellular antioxidant defense, but the basic mechanisms are not known. Zinc is a biologically redox inert metal, that has been associated with protection from various oxidant producing species. However, zinc induces the cysteine-rich, metal-binding protein, metallothionein, through interaction with the transcription factor MTF-1. Metallothionein may have a role in preventing oxidative stress, by quenching free radicals and other oxidants. Therefore, it is hard to distinguish between protection due to zinc, and protection due to induction of metallothionein. Hence, metallothionein null (KO) mice and metallothionein transgenic (Tg) mice provide a unique opportunity to study altered states of metallothionein expression. These mouse models were used to determine the effects of zinc supplementation and/ or metallothionein gene expression on the susceptibility to oxidative and nitrosative stress. Metallothionein KO mice were significantly less viable than control (CK) mice after