Zinc is an essential micronutrient that is required to maintain health. Zinc transporters control absorption and elimination of dietary zinc and cellular functions. This project is focused on ZIP14, a zinc transporter that responds to proinflammatory stimuli produced by dietary factors, infection and injury. ZIP14, through its zinc transporting capacity has roles in control of cellular signaling pathways, e.g. protein kinases, protein phosphatases and transcription factor regulation. During this project we identified key aspects of the phenotype resulting from knockout of Zip14 in mice. These include: defective liver regeneration, diminished intestinal barrier function with low grade chronic inflammation and increased levels of serum IL-6, adipocyte hypertrophy with increased insulin resistance and increased levels of serum leptin. Some aspects of the ZIP14 knockout phenotype increase with age and some are gender-specific. Overall ZIP14 function, via zinc transport, appears to control inflammation. Two critical worldwide medical problems are diabetes and obesity. These metabolic disorders are characterized by insulin resistance and low-grade inflammation; they are shared with the Zip14 knockout phenotype in mice. The hypothesis for this renewal project is that ZIP14 dysfunction leads to low grade proinflammatory conditions produced by diminished intestinal barrier function that causes low grade chronic inflammation, insulin resistance in adipose tissue and ER stress in liver. The project will utilize whole-body and tissue-specific Zip14 knockout mouse models. There are three interconnected Specific Aims: 1. Evaluate the mechanism through which ZIP14 operates to maintain intestinal barrier function and limits endotoxemia and its responsiveness to high dietary fat and therapeutic interventions with zinc. 2. Evaluate the influence of ZIP14 and targeted zinc transport on inflammatory signaling in adipose tissue and skeletal muscle and the influence of proinflammatory mediators on Zip14 gene regulation. 3. Characterize hepatic ER stress in Zip14 knockout mice and the influence of ER stress on Zip14 gene regulation. Rigorous companion experiments will utilize Caco-2, HepG2, AML12, 3T3-L1 and other cells for mechanistic studies. The goal of the project is to clarify how zinc, through targeted transport activity, can influence metabolic disorders and illuminate new therapeutic options.
Zinc provided from the diet performs many functions that influence well-being. Health benefits include control of inflammation, resistance to infections and regulation of metabolic disorders such as diabetes and obesity. A zinc transporter that regulates body zinc pathways during inflammation is the focus of this project and is therefore relevant to the NIH?s overarching mission in seeking to enhance health, lengthen life, and reduce illness and disability.
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