RNA-binding proteins in neurodegenerative diseases: Transport processes and pathomechnisms

• Applicant: Professorin Dr. Dorothee Dormann
• Subject Area: Experimental Models for the Understanding of Nervous System Diseases ; Molecular Biology and Physiology of Neurons and Glial Cells
• Term: from 2013 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 246137224

Final Report Abstract

This research project was concerned with the role of RNA-binding proteins in the pathogenesis of neurodegenerative diseases, such as ALS (amyotrophic lateral sclerosis) and FTD (frontotemporal dementia). ALS and FTD are currently incurable, and affected patients usually die within a few years of disease onset. Brains of ALS and FTD patients feature characteristic protein aggregates in the cytosol of neurons and glia cells, whose main components are the RNA-binding proteins TDP-43 and FUS. In our project, we aimed to unravel molecular mechanisms that cause TDP-43 and FUS to mislocalize and aggregate, as such an understanding will be important for developing therapeutic strategies to counteract or reverse RNA-binding protein dysfunction and neurodegeneration. Our previous work had shown that proper nuclear import of FUS and TDP-43 is crucial for neuronal health and that specific nuclear import receptors function in nuclear import and chaperoning of the aggregation-prone RNA-binding proteins, thus preventing their phase separation and aggregation in the cytoplasm. Here we could demonstrate that FUS is chaperoned by a network of nuclear import receptors and that diverse import receptors can also directly bind arginine-rich repeat proteins that arise in genetic forms of ALS/FTD and shield them from pathological interactions with various cellular components. Moreover, we examined how post-translational modifications cooperate to regulate nuclear import and aggregation of RNA-binding proteins. Our previous work had shown that post-translational methylation of arginines suppresses phase separation and aggregation of FUS. Here we now demonstrate that arginines can be post-translationally converted to citrulline by the enzyme PAD4, thus reducing nuclear import and phase separation / aggregation of FUS. Moreover, we found that arginines in RG regions of FUS are crucial for FUS’ ability to bind and process specific cellular RNAs. Last, we studied disease-associated phosphorylation sites on TDP-43 and found that this post-translational modification antagonizes TDP-43’ phase separation and aggregation, suggesting that it may be a cellular response mechanism to keep TDP-43 in a soluble, functional state. Taken together, we discovered novel cellular quality control mechanisms that antagonize pathological mislocalization and aggregation of disease-linked RNA-binding proteins, thus providing new insights into the molecular basis of neurodegenerative disorders.

Publications

• FG-nucleoporins caught in the act of liquid–liquid phase separation. Journal of Cell Biology, 219(1).
  Dormann, Dorothee
  
• A Quantitative Assay to Measure Stress Granule Association of Proteins and Peptides in Semi-permeabilized Human Cells. BIO-PROTOCOL, 10(24).
  Hutten, Saskia & Dormann, Dorothee
  
• Molecular mechanisms of neurodegeneration. Seminars in Cell & Developmental Biology, 99(2020, 3), 131-132.
  Dormann, Dorothee
  
• Nuclear Import Receptors Directly Bind to Arginine-Rich Dipeptide Repeat Proteins and Suppress Their Pathological Interactions. Cell Reports, 33(12), 108538.
  Hutten, Saskia; Usluer, Sinem; Bourgeois, Benjamin; Simonetti, Francesca; Odeh, Hana M.; Fare, Charlotte M.; Czuppa, Mareike; Hruska-Plochan, Marian; Hofweber, Mario; Polymenidou, Magdalini; Shorter, James; Edbauer, Dieter; Madl, Tobias & Dormann, Dorothee
  
• Gestörter Kerntransport und Phasentrennung von RNA-Bindeproteinen. BIOspektrum, 27(4), 365-367.
  Hutten, Saskia & Dormann, Dorothee
  
• Phosphorylation Regulates CIRBP Arginine Methylation, Transportin-1 Binding and Liquid-Liquid Phase Separation. Frontiers in Molecular Biosciences, 8(2021, 10, 19).
  Lenard, Aneta J.; Hutten, Saskia; Zhou, Qishun; Usluer, Sinem; Zhang, Fangrong; Bourgeois, Benjamin M. R.; Dormann, Dorothee & Madl, Tobias
  
• The chains of stress recovery. Science, 372(6549), 1393-1395.
  Dormann, Dorothee
  
• The phase separation-dependent FUS interactome reveals nuclear and cytoplasmic function of liquid–liquid phase separation. Nucleic Acids Research, 49(13), 7713-7731.
  Reber, Stefan; Jutzi, Daniel; Lindsay, Helen; Devoy, Anny; Mechtersheimer, Jonas; Levone, Brunno Rocha; Domanski, Michal; Bentmann, Eva; Dormann, Dorothee; Mühlemann, Oliver; Barabino, Silvia M L & Ruepp, Marc-David
  
• The RNA-binding protein FUS is chaperoned and imported into the nucleus by a network of import receptors. Journal of Biological Chemistry, 296(2021, 1), 100659.
  Baade, Imke; Hutten, Saskia; Sternburg, Erin L.; Pörschke, Marius; Hofweber, Mario; Dormann, Dorothee & Kehlenbach, Ralph H.
  
• Disease‐linked TDP‐43 hyperphosphorylation suppresses TDP‐43 condensation and aggregation. The EMBO Journal, 41(8).
  Gruijs da Silva, Lara A; Simonetti, Francesca; Hutten, Saskia; Riemenschneider, Henrick; Sternburg, Erin L; Pietrek, Lisa M; Gebel, Jakob; Dötsch, Volker; Edbauer, Dieter; Hummer, Gerhard; Stelzl, Lukas S & Dormann, Dorothee
  
• Editorial: The Role of Protein Post-Translational Modifications in Protein-RNA Interactions and RNP Assemblies. Frontiers in Molecular Biosciences, 8(2022, 1, 4).
  Giambruno, Roberto; Grzybowska, Ewa A.; Fawzi, Nicolas L. & Dormann, Dorothee
  
• Hormone-Inducible Transport Reporter Assay to Study Nuclear Import Defects in Neurodegenerative Diseases. Methods in Molecular Biology (2022), 81-90. Springer US.
  Hutten, Saskia & Dormann, Dorothee
  
• Post-translational modifications on RNA-binding proteins: accelerators, brakes, or passengers in neurodegeneration?. Trends in Biochemical Sciences, 47(1), 6-22.
  Sternburg, Erin L.; Gruijs da Silva, Lara A. & Dormann, Dorothee
  
• TDP-43 condensates and lipid droplets regulate the reactivity of microglia and regeneration after traumatic brain injury. Nature Neuroscience, 25(12), 1608-1625.
  Zambusi, Alessandro; Novoselc, Klara Tereza; Hutten, Saskia; Kalpazidou, Sofia; Koupourtidou, Christina; Schieweck, Rico; Aschenbroich, Sven; Silva, Lara; Yazgili, Ayse Seda; van Bebber, Frauke; Schmid, Bettina; Möller, Gabriel; Tritscher, Clara; Stigloher, Christian; Delbridge, Claire; Sirko, Swetlana; Günes, Zeynep Irem; Liebscher, Sabine; Schlegel, Jürgen; ...& Ninkovic, Jovica
  
• Creating overview and summary figures. Trends in Biochemical Sciences, 48(2), 97-99.
  Critcher, Meg; Gruijs da Silva, Lara A.; Dormann, Dorothee; Campbell, Zachary T.; Le, Thi Khanh; Rocchi, Palma & Sorgenfrei, Michèle
  
• Targeting the glycine-rich domain of TDP-43 with antibodies prevents its aggregation in vitro and reduces neurofilament levels in vivo. Acta Neuropathologica Communications, 11(1).
  Riemenschneider, Henrick; Simonetti, Francesca; Sheth, Udit; Katona, Eszter; Roth, Stefan; Hutten, Saskia; Farny, Daniel; Michaelsen, Meike; Nuscher, Brigitte; Schmidt, Michael K.; Flatley, Andrew; Schepers, Aloys; Gruijs da Silva, Lara A.; Zhou, Qihui; Klopstock, Thomas; Liesz, Arthur; Arzberger, Thomas; Herms, Jochen; Feederle, Regina; ... & Edbauer, Dieter