Advancing Genetically Encoded K+ Sensors for in vivo Imaging: A Multi-Stage Optimization Approach - A Follow-up application between Austria and Germany

• Applicants: Privatdozent Dr. Oliver Griesbeck; Professor Dr. Nikolaus Plesnila
• Subject Area: Molecular Biology and Physiology of Neurons and Glial Cells
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 551429233

Given the central role of potassium ions (K+) in biology, visualizing and understanding the intricate dynamics of local and global K+ alterations is pivotal for unraveling cellular function and dysfunctions, particularly in excitable cells such as neurons. Our team has been at the forefront of developing genetically encoded K+ biosensors, the GEPIIs (Genetically Encoded Potassium Ion Indicators), alongside similar Förster resonance energy transfer (FRET)-based KIRINs and single fluorescent protein (FP)-based K+ probes, the GINKOs, and KRaIONs developed by other research groups later. Despite progress, all these existing K+ biosensors still face clear limitations in sensitivity, dynamic range, pH stability, and suitability for extracellular targeting, hampering their broad application, particularly for in vivo imaging of local and global K+ alterations in physiological and pathological models such as Alzheimer's disease, epilepsy, and stroke. This grant proposal represents a continuation of our previous work and marks a collaborative effort between international research teams to optimize K+ biosensors, particularly for in vivo applications for neuroscience research. Through this collaboration, we aim to efficiently and significantly enhance the next generation of K+ biosensors through advanced methodologies, including computational refinements, structural optimizations, and directed evolution-based redesign. By optimizing genetically encoded fluorescent K+ biosensors, we strive to precisely visualize local and global K+ alterations in living cells and organisms, advancing our understanding of K+-dependent processes in neuroscience and their implications in various neurological disorders. This comprehensive approach will foster international scientific cooperation in biosensor development and multi-photon live-cell neuroimaging.

• DFG Programme: Research Grants
• International Connection: Austria
• Cooperation Partner: Professor Roland Malli