Theme 2: Metabolism, Transport and Motion/ Metabolic Disorders
The study of disease at the molecular level - but in the context of the macromolecular world of cellular organelles, the intact cell, or organs and tissues in the entire organism - is central to the RIMLS. Within this theme studies in two areas are bundled: (a) Energy and redox metabolism and (b) Membrane transport and cellular dynamics. There are links between these topics at multiple levels: Metabolites such as ATP and NAD(P)(H) produced in key pathways like glycolysis and mitochondrial respiratory complexes are consumed as fuel or needed as co-factors for ion-transport ATPases or drug-transporters. Water and calcium and magnesium ion homeostasis is important for cellular energy metabolism. Likewise, a strong link to metabolism and calcium regulation exists for activity of the actomyosin machinery involved in organelle dynamics and cell movements.
Intrinsic genetic problems or extrinsic factors causing cellular energy deprivation, abnormal ion homeostasis, oxygen deprivation, metabolite and water transport failure, or toxic accumulation of metabolic intermediates, are very frequently involved in transition to disease. The range of diseases, in which processes studied under the heading this theme are centrally involved, is very broad and includes cancer, neuropathy and myopathy, renal tubulopathy and retinopathy, degenerative disorders like Alzheimer's and Parkinson, ischemic/anoxic organ failure due to cerebro-vascular obstruction, and exercise intolerance and fatigue. In addition, for conditions such as obesity and type II diabetes, as well as aspects of ageing, it is well established that there is often a direct connection to energy and redox metabolism or membrane transport.
Specifically, renal disease, cardiomyopathy, brain and muscle disorders can be caused by (genetic) defects in the production or assembly of mitochondrial OXPHOS complexes, ATPases or water channels. Failure in cancer treatment is often due to abnormal regulation of activity of ABC-drug transporters or abnormal actin-based cell dynamics in metastasis.
RIMLS research connected to the theme "Metabolism, Transport and Motion/ Metabolic Disorders" involves:
Energy and Redox Metabolism
This subtheme aims to improve our understanding of the principles of (biochemical) adaptation to energy and redox stress, in order to better define 'healthy responses within the normal physiological range' and the 'pathophysiological thresholds' for diseases whereby mitochondrial function or energy transfer pathways are compromised. As such we strive to make a substantial contribution to the well-being and treatment of mitochondrial disease patients and other conditions in which energy metabolism is compromised.
Research is focused on (a) 'imaging' of ATP/ADP/AMP and NAD(P)H concentration and fate with existing and novel biosensor reporters; (b) 'imaging' of metabolite fate with MRS and MRI; (c) the use of new strategies to follow mitochondrial shape and activity as well as cellular metabolic state and viability. The integration of "4-D" imaging and simultaneous recording of the behaviour of small molecules and macromolecular assemblies and cellular organelles is an important challenge. Another major topic is the design and use of cell and animal models for disease. Finally, the increasing availability of high quality genomics data, like exome sequencing and RNAseq, and newly developed techniques for the prediction of protein function and pathways is exploited for the identification of new disease genes and the understanding and prediction of their metabolic phenotype. The latter requires the integrated analysis and modelling of the metabolic fluxes in healthy and diseased cells. Such a systems biology approach depends on the standardization of measurements and the direct collaborations between the experimental and theoretical groups.
Membrane Transport and Cell Dynamics
Transport proteins currently studied are sodium (or hydrogen) and potassium ATPases, aquaporin water channels, transient receptor potential channels, organic anion and cation transporters, ATP-binding cassette (ABC) transporters and sodium cotransporters. These transporters are involved in a whole range of diseases in organs such as brain, muscles, kidney, intestine, liver and bone. Now, most transport systems have been characterised at the molecular and cellular level, and the 3D molecular structure of a few transporters has recently been unravelled. We are beginning to understand how molecular events at the transporter level account for the physiological responses in cells, organs and the whole body. A new challenge will be to analyse the integrated network of signalling pathways underlying (hormonal) regulation of transport events at various stages ranging from gene regulation, routing of newly synthesised proteins towards the plasma membrane and control of activity. Finally, the cell-matrix interactions and dynamic cell patterning during immune cell interactions and tumour invasion are studied using, among others, in vivo-imaging of tumour and immune cell migration by multiphoton microscopy. In addition, we will develop and implement new tools to tackle the outlined scientific goals including life-time imaging, large scale screening assays at the mRNA and protein level, application of small interference RNA libraries, conditional knockout models, bioinformatics and functional analysis at the molecular level. The ultimate aim is to provide a molecular basis to understand, diagnose and ultimately cure inherited and acquired diseases of transport proteins, such as channelopathies. To reach this aim, research integrates fundamental and clinical studies conducted at the genetic (gene defects, polymorphisms), molecular (transport and associated proteins), cellular (established model systems, isolated and transfected cells) and organism (conditional) knockout models) level.