Funktionelle Analyse des TTF-Komplexes und seiner Rolle bei neuronalen Entwicklungskrankheiten

• Antragsteller: Professor Dr. Utz Fischer
• Fachliche Zuordnung: Allgemeine Genetik und funktionelle Genomforschung ; Molekulare Biologie und Physiologie von Nerven- und Gliazellen ; Zellbiologie
• Förderung: Förderung von 2015 bis 2019
• Projektkennung: Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 271023333

• Erstellungsjahr: 2021

Zusammenfassung der Projektergebnisse

Topoisomerases are enzymes that act predominantly, if not exclusively, on DNA substrates in cells of all kingdoms. It was therefore a surprise when we could show that eukaryotic topoisomerase TOP3ß is a cytosolic RNA binding protein that exhibits enzymatic activity on RNA substrates in vitro. It was further revealed that TOP3ß forms together with TDRD3, a scaffolding protein, and FMRP, affected in Fragile X mental retardation syndrome (FXS) an as yet unknown trimeric complex in vivo. In this project we have elucidated the role of this unit, which we have named TOP3ß-TDRD3-FMRP (TTF)- complex in RNA metabolism by identifying its RNA targets in vivo and determining its catalytic and/or regulatory function in RNA metabolism. We showed that the TTF complex is recruited to mRNPs via the exon junction complex (EJC) in a sequence independent manner. The biochemical composition of TTF-containing mRNPs and their association with polysomes further suggests that they are engaged in the pioneer round of translation. These studies also helped to shed light on a potential RNA-based etiology of neuropsychiatric disorders. In addition, we investigated the cellular functions of the La-related protein Larp4B, as well as the helicase IGHMBP2, linked to the neuromuscular disorder DSMA1. Both proteins were shown to interact with specific sets of cellular mRNA targets and regulate their translational output.

Projektbezogene Publikationen (Auswahl)

• „Untersuchung zur Rolle des La-verwandten Proteins LARP4B im mRNA-Metabolismus“
  Maritta Küspert
  
• Accumulated common variants in the broader fragile X gene family modulate autistic phenotypes (2015). EMBO molecular medicine 7 (12), 1565-1579
  Stepniak B, Kästner A, Poggi G, Mitjans M, Begemann M, Hartmann A, Van der Auwera S, Sananbenesi F, Krueger-Burg D, Matuszko G, Brosi C, Homuth G, Völzke H, Benseler F, Bagni C, Fischer U, Dityatev A, Grabe HJ, Rujescu D, Fischer A, Ehrenreich H.
  
• LARP4B is an AU-rich sequence associated factor that promotes mRNA accumulation and translation (2015). RNA 21 (7), 1294-1305
  M Küspert, Y Murakawa, K Schäffler, JT Vanselow, E Wolf, S Juranek, A. Schlosser, M. Landthaler and U Fischer
  
• mRNA metabolism and neuronal disease (2015). FEBS Letters 589 (14), 1598-1606
  B Linder, U Fischer, NH Gehring
  
• ProteoPlex: stability optimization of macromolecular complexes by sparse-matrix screening of chemical space (2015). Nature Methods 12 (9), 859-865
  Chari A, Haselbach D, Kirves JM, Ohmer J, Paknia E, Fischer N, Ganichkin O, Möller V, Frye JJ, Petzold G, Jarvis M, Tietzel M, Grimm C, Peters JM, Schulman BA, Tittmann K, Markl J, Fischer U, Stark H.
  
• Loss of LARP4B, an early event in the tumorigenesis of brain cancer? (2016). Translational Cancer Research 5 (S6)
  S Blagden, C Schneider, U Fischer
  
• Deciphering the mRNP code: RNA-bound determinants of post-transcriptional gene regulation (2017). TIBS 42 (5), 369-382
  NH Gehring, E Wahle, U Fischer
  
• „Functional characterization of the TTF complex and its role in neurodevelopmental disorders “
  Cornelia Brosi
  
• Impaired local translation of β-actin mRNA in Ighmbp2-deficient motoneurons: implications for spinal muscular atrophy with respiratory distress (SMARD1) (2018). Neuroscience 386, 24-40
  Surrey V, Zöller C, Lork AA, Moradi M, Balk S, Dombert B, Saal-Bauernschubert L, Briese M, Appenzeller S, Fischer U, Jablonka S.
  
• Crystal Structure of a Variant PAM2 Motif of LARP4B Bound to the MLLE Domain of PABPC1 (2020). Biomolecules 10 (6), 872
  C Grimm, JP Pelz, C Schneider, K Schäffler, U Fischer
  
• The SARS-CoV-2 RNA–protein interactome in infected human cells (2020). Nature Microbiology, 1-15
  Schmidt N, Lareau CA, Keshishian H, Ganskih S, Schneider C, Hennig T, Melanson R, Werner S, Wei Y, Zimmer M, Ade J, Kirschner L, Zielinski S, Dölken L, Lander ES, Caliskan N, Fischer U, Vogel J, Carr SA, Bodem J, Munschauer M.