Periodic Reporting for period 4 - CellCellEM (Communications at the Synapse - a Near Atomic Resolution View into Cell-Cell Communication in the CNS)
Okres sprawozdawczy: 2025-05-01 do 2025-10-31
The CellCellEM project aims at understanding cellular communication in the brain at the molecular level through structural studies of receptors in the central nervous system (CNS). The project focuses on G protein coupled receptors (GPCRs), a class of receptors that are highly abundant in the CNS, aiming to uncover their mechanism of action through comprehensive analysis of their structure and function. The project also encompasses a broader exploration of cellular communication in the brain, focusing on investigating protein-protein interactions at the cellular interface. The overarching objective involves the characterization of both the structural and functional aspects, including signaling, of proteins residing within the CNS, as well as their intracellular and extracellular interactome. The principal method employed for this investigation is single particle cryo-electron microscopy (cryo-EM), a technique enabling the capture of detailed snapshots of macromolecules at distinct conformational states and at high resolutions. This project addresses a long-standing question regarding the operational mechanisms of CNS receptors, and its outcomes are anticipated to contribute to future endeavors aimed at targeting these proteins, which are also implicated in CNS disorders.
Achievements in the project included the determination of high-resolution structures of adhesion GPCRs (aGPCRs) captured in active and inactive states (Barros-Álvarez et. al. Nature 2022). The intracellular signaling pathways of these receptors were also delineated through this work, and a structure of receptor bound to its intracellular partners was published in collaboration with two groups at Stanford and at the University of Michigan. Collectively, these findings unveiled the distinctive signaling mechanism employed by this particular class of receptors within the brain, and paved the way for structure based drug design. Beyond adhesion GPCRs, our lab worked over the years on several GPCR species residing in the brain, these include the bitter taste receptor (TAS2R14), the dopamine receptors and the prostaglandin receptor (TPR). In these projects the group has solved numerus structures of active and inactive complexes, and characterized their cellular signaling capabilities. The TAS2R14 was published (Peri et. al. Nature Communications 2024), and the TPR work has recently been accepted for publication and is currently in press (Krawinski at al. 2025). The dopamine receptor results are now under submission for peer review.
The main goal of CellCellEM is to delineate cellular communication through understanding signaling at the structural and at the molecular levels. The project was designed to primarily characterize the structure and function of individual signaling proteins residing at the cellular membrane, but also to understand the way they communicate with their partners within the cell, outside the cell, and inside the cellular membrane. Specifically, the project focused on GPCRs, that are highly abundant in the CNS and are known to maintain multifaced interactions with proteins and small molecules within the cell, the cellular membrane and in neighboring cells. However, the initial scope of the project expanded way beyond and also covered the exploration of the evolutionary evolvement of signaling. This, yet ongoing work in our group lead to the discovery of a novel family of proteins, the bestrhodopsins, that are light activated ion channels composed of rhodopsins (GPCR ancestors) fused to bestrophin ion channels. A paper describing the bestrhodopsin discovery was published by our group (Rozenberg et al. Nature Struct. Mol. Biol. 2022). The study on bestrhodopsins is currently ongoing in the lab and as rhodopsins are considered to be ancestors of GPCRs, these studies may potentially provide hints regarding the evolution of signaling mechanisms and aid in understanding the inner workings of the more complex signaling pathways in our brain. Altogether these studies are an evolvement of the suggested ERC project and were conducted in parallel to our work on the explicit aims presented in the original proposal.