Roman Sarott

All Publications

• Platform Reagents Enable Synthesis of Ligand-Directed Covalent Probes: Study of Cannabinoid Receptor 2 in Live Cells. Journal of the American Chemical Society Kosar, M., Sykes, D. A., Viray, A. E., Vitale, R. M., Sarott, R. C., Ganzoni, R. L., Onion, D., Tobias, J. M., Leippe, P., Ullmer, C., Zirwes, E. A., Guba, W., Grether, U., Frank, J. A., Veprintsev, D. B., Carreira, E. M. 2023; 145 (28): 15094-15108

  Abstract

  Pharmacological modulation of cannabinoid receptor type 2 (CB2R) holds promise for the treatment of neuroinflammatory disorders, such as Alzheimer's disease. Despite the importance of CB2R, its expression and downstream signaling are insufficiently understood in disease- and tissue-specific contexts. Herein, we report the first ligand-directed covalent (LDC) labeling of CB2R enabled by a novel synthetic strategy and application of platform reagents. The LDC modification allows visualization and study of CB2R while maintaining its ability to bind other ligands at the orthosteric site. We employed in silico docking and molecular dynamics simulations to guide probe design and assess the feasibility of LDC labeling of CB2R. We demonstrate selective, covalent labeling of a peripheral lysine residue of CB2R by exploiting fluorogenic O-nitrobenzoxadiazole (O-NBD)-functionalized probes in a TR-FRET assay. The rapid proof-of-concept validation with O-NBD probes inspired incorporation of advanced electrophiles suitable for experiments in live cells. To this end, novel synthetic strategies toward N-sulfonyl pyridone (N-SP) and N-acyl-N-alkyl sulfonamide (NASA) LDC probes were developed, which allowed covalent delivery of fluorophores suitable for cellular studies. The LDC probes were characterized by a radioligand binding assay and TR-FRET experiments. Additionally, the probes were applied to specifically visualize CB2R in conventional and imaging flow cytometry as well as in confocal fluorescence microscopy using overexpressing and endogenously expressing microglial live cells.

  View details for DOI 10.1021/jacs.2c13629

  View details for PubMedID 37401816

• Cannabinoid CB2 Receptors Modulate Microglia Function and Amyloid Dynamics in a Mouse Model of Alzheimer's Disease FRONTIERS IN PHARMACOLOGY Ruiz de Martin Esteban, S., Benito-Cuesta, I., Terradillos, I., Martinez-Relimpio, A. M., Arnanz, M., Ruiz-Perez, G., Korn, C., Raposo, C., Sarott, R. C., Westphal, M. V., Elezgarai, I., Carreira, E. M., Hillard, C. J., Grether, U., Grandes, P., Grande, M., Romero, J. 2022; 13: 841766

  Abstract

  The distribution and roles of the cannabinoid CB2 receptor in the CNS are still a matter of debate. Recent data suggest that, in addition to its presence in microglial cells, the CB2 receptor may be also expressed at low levels, yet biologically relevant, in other cell types such as neurons. It is accepted that the expression of CB2 receptors in the CNS is low under physiological conditions and is significantly elevated in chronic neuroinflammatory states associated with neurodegenerative diseases such as Alzheimer's disease. By using a novel mouse model (CB2 EGFP/f/f), we studied the distribution of cannabinoid CB2 receptors in the 5xFAD mouse model of Alzheimer's disease (by generating 5xFAD/CB2 EGFP/f/f mice) and explored the roles of CB2 receptors in microglial function. We used a novel selective and brain penetrant CB2 receptor agonist (RO6866945) as well as mice lacking the CB2 receptor (5xFAD/CB2 -/-) for these studies. We found that CB2 receptors are expressed in dystrophic neurite-associated microglia and that their modulation modifies the number and activity of microglial cells as well as the metabolism of the insoluble form of the amyloid peptide. These results support microglial CB2 receptors as potential targets for the development of amyloid-modulating therapies.

  View details for DOI 10.3389/fphar.2022.841766

  View details for Web of Science ID 000801762700001

  View details for PubMedID 35645832

  View details for PubMedCentralID PMC9136843

• Detection of cannabinoid receptor type 2 in native cells and zebrafish with a highly potent, cell-permeable fluorescent probe CHEMICAL SCIENCE Gazzi, T., Brennecke, B., Atz, K., Korn, C., Sykes, D., Forn-Cuni, G., Pfaff, P., Sarott, R. C., Westphal, M., Mostinski, Y., Mach, L., Wasinska-Kalwa, M., Weise, M., Hoare, B. L., Miljus, T., Mexi, M., Roth, N., Koers, E. J., Guba, W., Alker, A., Rufer, A. C., Kusznir, E. A., Huber, S., Raposo, C., Zirwes, E. A., Osterwald, A., Pavlovic, A., Moes, S., Beck, J., Nettekoven, M., Benito-Cuesta, I., Grande, T., Drawnel, F., Widmer, G., Holzer, D., van der Wel, T., Mandhair, H., Honer, M., Fingerle, J., Scheffel, J., Broichhagen, J., Gawrisch, K., Romero, J., Hillard, C. J., Varga, Z. V., van der Stelt, M., Pacher, P., Gertsch, J., Ullmer, C., McCormick, P. J., Oddi, S., Spaink, H. P., Maccarrone, M., Veprintsev, D. B., Carreira, E. M., Grether, U., Nazare, M. 2022; 13 (19): 5539-5545

  View details for DOI 10.1039/d1sc06659e

  View details for Web of Science ID 000784920900001

• Light-mediated discovery of surfaceome nanoscale organization and intercellular receptor interaction networks NATURE COMMUNICATIONS Muller, M., Grabnitz, F., Barandun, N., Shen, Y., Wendt, F., Steiner, S. N., Severin, Y., Vetterli, S. U., Mondal, M., Prudent, J. R., Hofmann, R., van Oostrum, M., Sarott, R. C., Nesvizhskii, A. I., Carreira, E. M., Bode, J. W., Snijder, B., Robinson, J. A., Loessner, M. J., Oxenius, A., Wollscheid, B. 2021; 12 (1): 7036

  Abstract

  The molecular nanoscale organization of the surfaceome is a fundamental regulator of cellular signaling in health and disease. Technologies for mapping the spatial relationships of cell surface receptors and their extracellular signaling synapses would unlock theranostic opportunities to target protein communities and the possibility to engineer extracellular signaling. Here, we develop an optoproteomic technology termed LUX-MS that enables the targeted elucidation of acute protein interactions on and in between living cells using light-controlled singlet oxygen generators (SOG). By using SOG-coupled antibodies, small molecule drugs, biologics and intact viral particles, we demonstrate the ability of LUX-MS to decode ligand receptor interactions across organisms and to discover surfaceome receptor nanoscale organization with direct implications for drug action. Furthermore, by coupling SOG to antigens we achieved light-controlled molecular mapping of intercellular signaling within functional immune synapses between antigen-presenting cells and CD8+ T cells providing insights into T cell activation with spatiotemporal specificity. LUX-MS based decoding of surfaceome signaling architectures thereby provides a molecular framework for the rational development of theranostic strategies.

  View details for DOI 10.1038/s41467-021-27280-x

  View details for Web of Science ID 000727618000002

  View details for PubMedID 34857745

• Optical Control of Cannabinoid Receptor 2-Mediated Ca2+ Release Enabled by Synthesis of Photoswitchable Probes JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Sarott, R. C., Viray, A. G., Pfaff, P., Sadybekov, A., Rajic, G., Katritch, V., Carreira, E. M., Frank, J. A. 2021; 143 (2): 736-743

  Abstract

  Cannabinoid receptor 2 (CB2) is a promising target for the treatment of neuroinflammation and other diseases. However, a lack of understanding of its complex signaling in cells and tissues complicates the therapeutic exploitation of CB2 as a drug target. We show for the first time that benchmark CB2 agonist HU308 increases cytosolic Ca2+ levels in AtT-20(CB2) cells via CB2 and phospholipase C. The synthesis of photoswitchable derivatives of HU308 from the common building block 3-OTf-HU308 enables optical control over this pathway with spatiotemporal precision, as demonstrated in a real-time Ca2+ fluorescence assay. Our findings reveal a novel messenger pathway by which HU308 and its derivatives affect cellular excitability, and they demonstrate the utility of chemical photoswitches to control and monitor CB2 signaling in real-time.

  View details for DOI 10.1021/jacs.0c08926

  View details for Web of Science ID 000612557200028

  View details for PubMedID 33399457

• Development of High-Specificity Fluorescent Probes to Enable Cannabinoid Type 2 Receptor Studies in Living Cells JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Sarott, R. C., Westphal, M., Pfaff, P., Korn, C., Sykes, D. A., Gazzi, T., Brennecke, B., Atz, K., Weise, M., Mostinski, Y., Hompluem, P., Koers, E., Miljus, T., Roth, N. J., Asmelash, H., Vong, M. C., Piovesan, J., Guba, W., Rufer, A. C., Kusznir, E. A., Huber, S., Raposo, C., Zirwes, E. A., Osterwald, A., Pavlovic, A., Moes, S., Beck, J., Benito-Cuesta, I., Grande, T., de Martin Esteban, S., Yeliseev, A., Drawnel, F., Widmer, G., Holzer, D., van der Wel, T., Mandhair, H., Yuan, C., Drobyski, W. R., Saroz, Y., Grimsey, N., Honer, M., Fingerle, J., Gawrisch, K., Romero, J., Hillard, C. J., Varga, Z. V., van der Stelt, M., Pacher, P., Gertsch, J., McCormick, P. J., Ullmer, C., Oddi, S., Maccarrone, M., Veprintsev, D. B., Nazare, M., Grether, U., Carreira, E. M. 2020; 142 (40): 16953-16964

  Abstract

  Pharmacological modulation of cannabinoid type 2 receptor (CB2R) holds promise for the treatment of numerous conditions, including inflammatory diseases, autoimmune disorders, pain, and cancer. Despite the significance of this receptor, researchers lack reliable tools to address questions concerning the expression and complex mechanism of CB2R signaling, especially in cell-type and tissue-dependent contexts. Herein, we report for the first time a versatile ligand platform for the modular design of a collection of highly specific CB2R fluorescent probes, used successfully across applications, species, and cell types. These include flow cytometry of endogenously expressing cells, real-time confocal microscopy of mouse splenocytes and human macrophages, as well as FRET-based kinetic and equilibrium binding assays. High CB2R specificity was demonstrated by competition experiments in living cells expressing CB2R at native levels. The probes were effectively applied to FACS analysis of microglial cells derived from a mouse model relevant to Alzheimer's disease.

  View details for DOI 10.1021/jacs.0c05587

  View details for Web of Science ID 000579087600010

  View details for PubMedID 32902974

• Highly Selective, Amine-Derived Cannabinoid Receptor 2 Probes CHEMISTRY-A EUROPEAN JOURNAL Westphal, M., Sarott, R. C., Zirwes, E. A., Osterwald, A., Guba, W., Ullmer, C., Grether, U., Carreira, E. M. 2020; 26 (6): 1380-1387

  Abstract

  The endocannabinoid (eCB) system is implied in various human diseases ranging from central nervous system to autoimmune disorders. Cannabinoid receptor 2 (CB2 R) is an integral component of the eCB system. Yet, the downstream effects elicited by this G protein-coupled receptor upon binding of endogenous or synthetic ligands are insufficiently understood-likely due to the limited arsenal of reliable biological and chemical tools. Herein, we report the design and synthesis of CB2 R-selective cannabinoids along with their in vitro pharmacological characterization (binding and functional studies). They combine structural features of HU-308 and AM841 to give chimeric ligands that emerge as potent CB2 R agonists with high selectivity over the closely related cannabinoid receptor 1 (CB1 R). The synthesis work includes convenient preparation of substituted resorcinols often found in cannabinoids. The utility of the synthetic cannabinoids in this study is showcased by preparation of the most selective high-affinity fluorescent probe for CB2 R to date.

  View details for DOI 10.1002/chem.201904584

  View details for Web of Science ID 000508279100001

  View details for PubMedID 31961047

• Synthesis of Photoswitchable Delta(9)-Tetrahydrocannabinol Derivatives Enables Optical Control of Cannabinoid Receptor 1 Signaling JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Westphal, M. V., Schafroth, M. A., Sarott, R. C., Imhof, M. A., Bold, C. P., Leippe, P., Dhopeshwarkar, A., Grandner, J. M., Katritch, V., Mackie, K., Trauner, D., Carreira, E. M., Frank, J. A. 2017; 139 (50): 18206-18212

  Abstract

  The cannabinoid receptor 1 (CB1) is an inhibitory G protein-coupled receptor abundantly expressed in the central nervous system. It has rich pharmacology and largely accounts for the recreational use of cannabis. We describe efficient asymmetric syntheses of four photoswitchable Δ9-tetrahydrocannabinol derivatives (azo-THCs) from a central building block 3-Br-THC. Using electrophysiology and a FRET-based cAMP assay, two compounds are identified as potent CB1 agonists that change their effect upon illumination. As such, azo-THCs enable CB1-mediated optical control of inwardly rectifying potassium channels, as well as adenylyl cyclase.

  View details for DOI 10.1021/jacs.7b06456

  View details for Web of Science ID 000418783600019

  View details for PubMedID 29161035

• Synthesis, characterization and initial evaluation of 5-nitro-1-(trifluoromethyl)-3H-1 lambda(3),2-benziodaoxol-3-one BEILSTEIN JOURNAL OF ORGANIC CHEMISTRY Santschi, N., Sarott, R. C., Otth, E., Kissner, R., Togni, A. 2014; 10: 1-6

  Abstract

  The synthesis of 5-nitro-1-(trifluoromethyl)-3H-1λ(3),2-benziodaoxol-3-one (3), a hypervalent-iodine-based electrophilic trifluoromethylating reagent, is described. Whereas considerations based on cyclic voltammetry and X-ray structural properties would predict an inferior reactivity when compared to the non-nitrated derivative 2, (19)F NMR kinetic studies showed that this new derivative is almost one order of magnitude more reactive. Furthermore, differential scanning calorimetry measurements indicated that, in addition, it is also safer to handle.

  View details for DOI 10.3762/bjoc.10.1

  View details for Web of Science ID 000329819500001

  View details for PubMedID 24454557

  View details for PubMedCentralID PMC3896278