METALGATES - Transporters as mediators of metal toxicity

The human body interacts with the environment in many ways. The body, the organs, the tissues, and the cells adapt to perturbations occurring in their surroundings. Cells are surrounded by cellular membranes that maintain the cells genetic identity and its special metabolic milieu. Take-up and release of chemical matter from the environment occurs through the action of transporters that pierce cellular membranes. Membranes are therefore the interface between cellular metabolism and the environment. The cellular metabolism and hence many biochemical processes in the cell are influenced by metals. For many reactions metals are essential but are at the same time potentially very dangerous, with metal poisoning being a serious health issue. Many people still die from metal poisoning and metals are responsible for most non-genetic mental disabilities, contribute to several cancers and developmental problems. Metals can alter enzymatic functions of proteins, compromise the cellular redox balance and thus damage proteins, lipids and DNA which can result in a mutagenic effect on the genome. For many metals we currently do not know how they are taken up into the cell or released again. Hence, the knowledge to understand and potentially mitigate metal poisoning is still limited. It is therefore important to study how metals enter and exit cells. Through the study of metal transporters, we will characterize the selectivity and specificity for metal uptake and release. We will investigate if and how metal transporters contribute to the metal homeostasis of the cell. We will study two types of membrane transporters, the largest family of transporters, solute carrier proteins (SLCs), encompassing 446 different transporters for small molecules and the 40 P-Type ATPases, hence ATP-driven pumps, in combination with 14 different metals (Pb, Cu, Al, Cd, Se, Ni, Cr, Mn, As, Hg, Mo, Co, Ag, V). Through genetic loss-of-function screens using CRISPR/Cas9 technology we will establish which of these 486 transporters is responsible for which metal uptake. The hits from the screen will be validated biochemically to determine activity, selectivity and specificity of the different transporters for the individual metals. We hope to be able to assign transporter(s) for each metal. As high doses of the metals will kill cells, we will explore how interfering with transporter activity may confer resistance to metal poisoning at the cellular level. Knowing which transporters play a role in toxifying (and detoxifying) cells could lead to ideas as to how to develop future strategies to protect cells from metal poisoning pharmacologically. Overall, we plan to better understand metal uptake and potentially mitigate poisoning.