Drug transporters, such as the Breast Cancer Resistance Protein (ABCG2), are recognized as key players in the distribution of drugs in human. The localization of this efflux pump in organs responsible for drug biotransformation and excretion gives ABCG2 an important gatekeeper function in controlling drug access to metabolizing enzymes and excretory pathways. ABCG2 is also found in cancer cells, where it mediates the extrusion of drug to the cell's exterior. In doing so, it prevents entry of anticancer drugs into cells and, hence, impairs the chemotherapeutic treatment of this life-threatening disease. In this proposal, we will study fundamental aspects of the transport mechanism of human ABCG2. In particular, we will study the previously unknown ability of ABCG2 to transport ions such as protons. We are interested to learn which ions are transported (in addition to protons, for example sodium, potassium, chloride ions), how ABCG2 transports these ions, and why? What is the relationship between ion transport and drug transport? ABCG2 is thought to be active as a dimer, which we will test by mass spectrometry, and is likely to have drug binding sites that are alternately exposed to the inside surface of the membrane (where drugs bind) and outside surface of the membrane (where drugs are released). Based on the available crystal structures of multidrug binding proteins (transporters and transcriptional regulators), we hypothesize that (i) protons and other ions might displace drugs from binding sites in ABCG2 during drug release and/or (ii) their binding might support structural changes in the two ABCG2 units and their interface, that are associated with the reorientation of the drug binding sites. Fundamental knowledge about ABCG2 activity will allow the rational development of inhibitors (also termed modulators) of this efflux pump that could be used to target drugs to specific parts of the human body, and to improve chemotherapy of cancers.

Erythrocytes represent an estimated 84% of all cells in the human body. During circulation, they experience a huge variety of physical and chemical stimulations, such as pressure, shear stress, hormones or osmolarity changes. These signals are translated into cellular responses through ion channels that modulate erythrocyte function. Ion channels in erythrocytes have only recently been recognised as the utmost important players in physiology and pathophysiology. Despite this awareness, their signalling, interactions and concerted regulation, such as the generation and effects of 'pseudo action potentials', remain elusive. INNOVATION proposes a systematic, conjoined approach using molecular biology, in vitro erythropoiesis, state-of-the-art electrophysiological techniques, methods to detect erythrocyte functionality and patient samples (channelopathies and other red blood cell-related diseases) to decipher and make use of ion channel functions in terms of disease treatment concepts. We need to overcome the challenges that hinder the gain of knowledge within the field, using genetic manipulation of progenitors, cell differentiation into erythrocytes, statistically efficient electrophysiological recordings of ion channel activity that are limited by the heterogeneity of the cell population (120 days of lifespan without any protein renewal) or access to large cohorts of patients. Our multidisciplinary team includes biophysicists and cell biologists to investigate erythrocyte characteristics and bioengineers to develop diagnostic devices. INNOVATION involves academic research centres as well as diagnostic labs providing patient samples, blood bank research centres developing cultured transfusion products and SMEs that provide and develop diagnostic tools or innovative therapeutic red blood cell products. The consortium offers on-site training, secondments and a variety of courses in transferrable and complementary skills to 10 doctoral candidates.

The vision of the ETN network NeuroTrans (NEUROtransmitter TRANSporters: from single molecules to human pathologies) is to (i) enable an improved understanding of how dysfunction of neurotransmitter:sodium symporters (NSS) contributes to neuropsychiatric disease pathobiology and how psychoactive substances target NSS and (ii) to establish a robust framework for comprehending these pathologies through changes in transporter function at the molecular level. The mission of NeuroTrans is to develop a solid model that can predict changes in NSS function using fundamental principles obtained from quantitative experiments using an interdisciplinary approach. NeuroTrans will have a strong translational aspect through the development of enabling techniques in biophysics, molecular and structural biology and through industrial partner which establish novel instruments for use in live cells to quantify kinetics, dynamics and thermodynamic parameters, allowing for exploitation and commercialisation. The NeuroTrans research programme will have major generalizable scientific impact that will be of high relevance to academia, pharmaceutical industry and policy makers and is likely expand not only to other classes of transporters, but to membrane proteins in general. NeuroTrans will establish a highly interdisciplinary doctoral training program by forming an interdisciplinary and intersectorial team of world-leading European researchers. Training will include most important subdisciplines in quantitative biology, including molecular modelling, computer simulations, biophysics, biochemistry, neurobiology, molecular and structural biology. Taining will be headed by an industrial beneficiary to secure a strong industry oriented focus, ensuring that the ESRs can become part of Europe’s future generation of innovative leaders, be at the forefront of science and innovation, translate fundamental research into cutting-edge technologies, and solidify European industry leadership.