Grant: Project Grant

About 200 enzymes involved in metabolism are not found in a single location in the cell. That is, some molecules of each of these enzymes occur in the cytoplasm, and some occur in the nucleus (the cell part containing the genes). It has long been known that metabolic enzymes can occur in the nucleus. We know little, however, about what they are doing in the nucleus. For example, there has never been a comprehensive study to determine which enzymes are actually active in this part of the cell. This is a striking shortfall in the field of cell physiology given the evidence that metabolites control the expression of genes in the nucleus, including genes of high relevance to cancer. We will mount the first study to address this knowledge gap. These experiments will be performed using cells of heart, lung, pancreatic and ovarian origin. We will employ state-of-the-art methods for detecting metabolites in nuclei that have been obtained from cells in a way that perfectly preserves their content of metabolites. Nuclei will be incubated under conditions that permit metabolic reactions to occur. By determining what metabolites are made and consumed, we will be able to infer which enzymes are active in the nucleus. We will also study one specific enzyme called IDH1. IDH1 is mutated in some brain cancers and in this form produces high levels of a metabolite that can drive tumorigenesis. Because some cells in patient tumors have mutated IDH1 in the nucleus, and the metabolite it produces interferes with gene expression in the nucleus, we suspect that cancer formation is more aggressive when mutated IDH1 is in the nucleus. We will test this hypothesis with a view to possible future development of a test for cancer aggressiveness based on how much mutated IDH1 is in tumor cell nuclei. Collectively these studies will uniquely contribute to a better understanding of how metabolic enzymes are controlled in normal and cancerous cells.