• Canada
• OA Publications Mandate: Yes close
• 2019 close
• 2021 close

G protein-coupled receptors (GPCRs) represent the largest family of cell surface proteins. Agonist binding to GPCRs activates G proteins regulating many cellular effectors. Classically, G protein activation occurs at the plasma membrane and is rapidly terminated by β-arrestin recruitment to the activated GPCRs, promoting G protein uncoupling from receptor, GPCR internalisation and signalling arrest. However, recent studies revealed that upon internalisation, some GPCRs continue to activate G proteins from internal compartments leading to sustained production of second messengers far from the plasma membrane. This different spatiotemporal signalling profile allows distinct cellular functions from the ones occurring at the plasma membrane that can be exploited in the near future to design new pharmacological approaches. My collaborators and I recently observed that for some GPCRs such as the vasopressin type 2 receptor, formation of a GPCR-G protein-β-arrestin complex (baptised megaplex) in internal compartments is required for non-canonical Gs protein signalling. The initial research programme I propose aims to tackle the following important questions underlying this novel signalling mode: 1. Is G protein selectivity different at intracellular compartments vs at plasma membrane? 2. Is megaplex formation restricted to Gs isoform? 3. What is the specific role of β-arrestin within the megaplex? Environmental stimulants (hormones, neurotransmitters) can be compared to keys able to bind to and activate (open) cell surface receptors (locks). When a key opens a lock, proteins detecting this opened lock (called G proteins) are activated at the cell surface leading to specific outcomes. Some proteins (ß-arrestins) are then recruited to remove G proteins from the receptor and bring it inside the cell leading to signalling arrest. Recently, we observed that active G proteins can also be found inside the cell mediating different outcomes than when located at cell surface and that ß-arrestins was promoting receptor signalling inside the cell instead of stopping it. My objective is to explore this new G protein signalling, to learn how ß-arrestins can promote internalised receptor signalling, and determine if they activate other G proteins than the ones at the cell surface. This could lead to development of new medications with less side effects.

Sample preparation is considered to be the most difficult step in analytic workflow. Current methods for extraction and separation of minute substances in liquid samples are laborious, time-consuming, often involve large amounts of toxic organic solvents, and are often difficult to automatize, implying high costs of man-power. An innovative sample preparation technique which has the potential to overcome these shortcomings will be developed in this project. Based on the first promising results in the ERC-AdG project DDD, we propose a surface nanodroplet-based sensing approach for liquid-liquid extraction and online analysis of traces of analytes in aqueous solutions, including in biomedical, health, pharmaceutical and environmental contexts. The basis of our approach, referred to as nanoextraction, will be surface nanodroplets pre-formed on a substrate within a microflow channel. The principle of the nanoextraction is that the partition coefficient of the compound in the droplets is much higher than in the sample solution. The compound in the flow will thus be extracted to the nanodroplets that are immobilized on the channel walls. The concentration of the compound in the droplets will be quantified by surface-sensitive spectroscopic techniques. Our proposed approach can potentially achieve extraction-separation-detection of analytes at extremely low concentrations in one single and simple step. The ability to achieve extraction-separation- detection of micropollutants in one single step is creating new and unique market opportunities which we want to explore. First, the technology can improve the state-of-the-art solutions in current markets, because of the easy usage and the small scale, thus saving time and costs. Second, we foresee new markets for the method, due to the higher sensitivity and point-of-care character of the solution. Our final goal in this project is to create a solid and investor-ready business plan, supported by a prototype.