Brady Evans, Brigham Young University
Life Sciences
Nutrient-sensing kinases, such as AMPK and mTOR, play a key role in regulating cellular metabolism. They recognize nutrient levels within the cell and distribute nutrients accordingly. The failure to coordinate metabolic processes can lead to diseases such as diabetes, obesity and cancer. PAS kinase is another member of the nutrient-sensing kinase group that regulates glucose distribution in the cell. Despite its clear importance, little is known about the mechanisms regarding PAS kinase activation and its function. Studies have shown that mice without the PAS kinase gene are resistant to weight gain and maintain insulin sensitivity when placed on a high fat diet. Weight gain and insulin resistance are associated with increased rates of diabetes, cancer and other metabolic diseases. AMPK is currently the key target for the treatment of diabetes and has been found to be a cancer target as well. The yeast homologue, Snf1, is necessary for activation of yeast PAS kinase. Further studies have shown that PAS kinase is activated under the same respiratory conditions as Snf1. The aims of this project is to determine if Snf1 directly phosphorylates PAS kinase and to determine the effects of this phosphorylation. We have found that PAS kinase is activated quickly when cells are placed under Snf1-activating conditions. In addition, Snf1 is necessary and sufficient for this activation. Snf1 also copurifies with PAS kinase suggesting this activation is direct. PAS kinase purified from wild type verses Snf1-deficient cells shows phosphorylation on two key residues, S1020 and S1035. In addition, Snf1 directly phosphorylates PAS kinase in vitro. Together these findings suggest that Snf1 directly phosphorylates PAS kinase in order to regulate cellular glucose homeostasis