Structural analysis of membrane-inserted FGF2 oligomers using cryo-electron microscopy and molecular dynamics simulations
Prof. Dr. Walter Nickel
Heidelberg University Biochemistry Center
Start of PhD project: As soon as possible
Source of Funding:
Deutsche Forschungsgemeinschaft (SFB/TRR 83; PhD student position: E13/65%)
Fibroblast Growth Factor 2 (FGF2) is a strong mitogen promoting angiogenesis in health and disease. Under pathological conditions, FGF2 is functioning as a major activator of tumour-induced angiogenesis. FGF2 also acts as a survival factor of tumour cells mediated by an autocrine signalling loop suppressing apoptosis. Despite its defined extracellular functions, FGF2 lacks a signal peptide and was shown to get exported from cells by an unconventional, ER/Golgi-independent pathway of protein secretion. Understanding the molecular mechanism by which FGF2 is secreted from tumour cells may pave the way to develop a new class of anti-angiogenic inhibitors with a high potential to be useful in cancer therapy.
The molecular mechanism of unconventional secretion of FGF2 is based upon direct protein translocation across the plasma membrane. This process is initiated by the recruitment of FGF2 at the inner leaflet of the plasma membrane mediated by the phosphoinositide PI(4,5)P2. This interaction causes FGF2 to oligomerize followed by membrane insertion of oligomeric translocation intermediates. In a final step, cell surface heparan sulfate proteoglycans disassemble membrane-inserted FGF2 oligomers at the outer leaflet resulting in FGF2 translocation to the cell surface.
The goal of this project will be to elucidate the structure-function relationship of membrane-inserted FGF2 oligomers, the translocation intermediates of this unusual pathway of protein secretion from mammalian cells.
Dimou E, Cosentino K, Platonova, E, Ros U, Sadeghi M, Kashyap P, Katsinelos T, Wegehingel S, Noé F, García-Saéz AJ, Ewers H, Nickel W (2018) Single event visualization of unconventional secretion of FGF2. J Cell Biol, in press
Dimou E and Nickel W (2018) Unconventional mechanisms of eukaryotic protein secretion. Curr Biol 28:R406-R41
Katsilenos, T, Zeitler M, Dimou E, Karakatsani A, Müller HM, Nachman E, Steringer JP, Ruiz de Almodovar C, Nickel W, Jahn TR (2018) Unconventional secretion mediates the trans-cellular spreading of tau. Cell Rep 23:2039-2055
Steringer JP, Lange S, Čujová S, Šachl R, Poojari C, Lolicato F, Beutel O, Müller HM, Unger S, Coskun Ü, Honigmann A, Vattulainen I, Hof M, Freund C, Nickel W (2017) Key steps in unconventional secretion of fibroblast growth factor 2 reconstituted with purified components. eLife, e28985.
Brough D, Pellegrin P, and Nickel W (2017) An emerging case for membrane pore formation as a common mechanism for the unconventional secretion of FGF2 and IL-1beta. J. Cell Sci 130: 3197-3202
Methods that will be used:
Cryo-electron microscopy; electron tomography, molecular dynamics simulations; biochemical reconstitution experiments
Dr. Petr Chlanda
BioQuant, Heidelberg University
Prof. Dr. Ilpo Vattulainen
Profile of candidate’s qualification:
We are looking for enthusiastic students with a master degree in the life sciences with a solid theoretical background in biophysics and biochemistry as well as a genuine interest in structural biology.