Project B07

Uncovering novel molecular mechanisms within Wnt signaling

Project leaders: Irmgard Sinning and Suat Özbek

Abstract

The project aims at unraveling molecular mechanisms of Wnt signaling by a combination of integrated
structural biology with cell and molecular biology. In the current funding period, the Sinning lab became a
focal point in this consortium for mechanistic studies of key interactions in Wnt signaling. We will continue to
dissect the basis of Dishevelled regulation by the interplay between Dead-box helicases and Casein kinases
with Niehrs (B01). Based on the data of the current funding period, we will characterize specific helicase/
kinase pairs to allow for structural and enzymatic analysis to understand the basis of kinase activation.
We continue the detailed analysis of Evi/Wls interaction with Wnt, including the integral membrane protein
Porcupine, and novel protein partners with Boutros (A01). Importantly, we will expand our efforts in Wnt
expression in order to overcome this bottleneck for mechanistic studies of Wnt complexes. Building on these
efforts, we will join forces with the Özbek lab to unravel a novel mechanism of Wnt inhibition by specific
proteolysis as a new project in this consortium. We will analyze the structural basis of Wnt ligand cleavage
by the recently identified Hydra astacin proteinase HAS-7 and aim to determine the crystal structure of a
HAS-7/Wnt complex. We will produce a catalytically inactive variant of HAS-7 and employ different variants
in in vitro reconstitution experiments with recombinant Hydra Wnt3 or Wnt9/10c. As astacins constitute a
highly conserved group of metalloproteases, the project promises important implications also for other model
systems, including vertebrate astacin proteinases. With these combined efforts, the Sinning lab will continue
to support this consortium by their expertise in studying protein complexes by integrated structural biology
and providing access to high-end biochemical, biophysical and structural studies.

Project-related publications

  • Ziegler, B., I. Yiallouros, B. Trageser, S. Kumar, M. Mercker, S. Kling, M. Fath, U. Warnken, M. Schnölzer, T.W. Holstein, M. Hartl, A. Marciniak-Czochra, J. Stetefeld, W. Stöcker, and S. Özbek. 2021. The Wnt-specific
    astacin proteinase controls head formation in Hydra. BMC Biol., 19(1):120. PMID: 34107975
  • McDowell, M.A., M. Heimes, F. Fiorentino, S. Mehmood, Á. Farkas, J. Coy-Vergara, D. Wu, J.R. Bolla, V.
    Schmid, R. Heinze, K. Wild, D. Flemming, S. Pfeffer, B. Schwappach, C.V. Robinson, and I. Sinning.
    2020. Structural Basis of Tail-Anchored Membrane Protein Biogenesis by the GET Insertase Complex.
    Mol Cell. 80:72-86. PMID: 32910895
  • Wild, K., M. Aleksić, K. Lapouge, K.D. Juaire, D. Flemming, S. Pfeffer, and I. Sinning. 2020. MetAP-like
    Ebp1 occupies the human ribosomal tunnel exit and recruits flexible rRNA expansion segments. Nat
    Commun. 11:776. PMID: 32034140
  • Zhang, Y., G. Valentín Gesé, C. Conz, K. Lapouge, J. Kopp, T. Wölfle, S. Rospert, and I. Sinning. 2020. The
    ribosome-associated complex RAC serves in a relay that directs nascent chains to Ssb. Nat Commun.
    11:1504. PMID: 32198371.
  • Mattes, B., Y. Dang, G. Greicius, L.T. Kaufmann, B. Prunsche, J. Rosenbauer, J. Stegmaier, R. Mikut, S.
    Ozbek, G.U. Nienhaus, A. Schug, D.M. Virshup, and S. Scholpp. 2018. Wnt/PCP controls spreading of
    Wnt/beta-catenin signals by cytonemes in vertebrates. Elife. 7. PMID: 30863851
  • Lommel, M., J. Strompen, A.L. Hellewell, G.P. Balasubramanian, E.D. Christofidou, A.R. Thomson, A.L.
    Boyle, D.N. Woolfson, K. Puglisi, M. Hartl, T.W. Holstein, J.C. Adams, and S. Ozbek. 2018. Hydra
    Mesoglea Proteome Identifies Thrombospondin as a Conserved Component Active in Head Organizer
    Restriction. Sci Rep. 8:11753. PMID: 30082916
  • Brinkmann, E.M., B. Mattes, R. Kumar, A.I. Hagemann, D. Gradl, S. Scholpp, H. Steinbeisser, L.T. Kaufmann,
    and S. Ozbek. 2016. Secreted Frizzled-related Protein 2 (sFRP2) Redirects Non-canonical Wnt
    Signaling from Fz7 to Ror2 during Vertebrate Gastrulation. J Biol Chem. 291:13730-13742. PMID:
    30082916
  • Watanabe, H., H.A. Schmidt, A. Kuhn, S.K. Hoger, Y. Kocagoz, N. Laumann-Lipp, S. Ozbek, and T.W.
    Holstein. 2014. Nodal signalling determines biradial asymmetry in Hydra. Nature. PMID: 25156256
  • Kumar, S., M. Zigman, T.R. Patel, B. Trageser, J.C. Gross, K. Rahm, M. Boutros, D. Gradl, H. Steinbeisser, T.
    Holstein, J. Stetefeld, and S. Ozbek. 2014. Molecular dissection of Wnt3a-Frizzled8 interaction reveals
    essential and modulatory determinants of Wnt signaling activity. BMC Biol. 12:44. PMID: 24885675
  • Stefer, S., S. Reitz, F. Wang, K. Wild, Y.Y. Pang, D. Schwarz, J. Bomke, C. Hein, F. Löhr, F. Bernhard, V.
    Denic, V. Dötsch, and I. Sinning. 2011. Structural basis for tail-anchored membrane protein biogenesis
    by the Get3-receptor complex. Science. 333:758-762. PMID: 21719644