Deciphering the regulatory code of transcription
Final Report Abstract
“Function requires structure” – this is a common statement throughout structural biology. Indeed, most proteins need to adopt a defined three-dimensional structure to carry out their function. However, recent studies have indicated that a large fraction of the genome of any organism encodes proteins that, completely or in part, do not adopt a defined three-dimensional structure but are nevertheless essential for cellular function: the so-called intrinsically or natively disordered proteins/regions. Despite of an ongoing debate it has been generally accepted recently that IDRs are highly abundant in nature and that their functional repertoire complements the function of ordered proteins. In this research project we focused on the molecular mechanisms by which transcription protein complexes are built up via intrinsically disordered transcription factor proteins, and how these proteins are acting as key regulators of cell and organismal fate. Our focus is on two key transcription factors that link the regulatory Wnt pathway with insulin/growth factor signaling and oxygen metabolism via the transcriptional co-regulator β-catenin: 1) Forkhead box O (FOXO) and 2) T Cell Factor/Lymphoid Enhancer-Binding Factor (TCF/LEF). Strikingly, it was shown that FOXO and TCF/LEF compete under conditions of oxidative stress for β-catenin binding thereby establishing a mechanism of counterbalancing. In agreement and in contrast to FOXO, Wnt signaling through β-catenin/TCF/LEF stimulates cell proliferation and cancer. The function and action of FOXO is diverse, deregulation of FOXO contributes to lifespan and agerelated diseases such as diabetes and cancer. Although a central role for FOXO in mediating trade-offs between lifespan and age-related diseases is becoming well accepted the molecular details of this have been largely unknown. Here we obtained a detailed characterization of the interactions and regulation of the key transcription factors LEF-1, and FOXO4, including their interaction with the co-factor proteins β-catenin, transportin-1, the role of PTMs in these interactions, targeting β-catenin binding by a regulatory factor and studying the key biological roles of the LEF-1 and FOXO4 transcription factors in vivo. Based on our findings we propose a general mode of transcription factor regulation by βcatenin via highly specific binding to several short motifs located within the long disordered transactivation domains. Given that many other transcription factors appear to be dependent on β-catenin (TCF & FOXP & FOXO families, OCT4, etc.), our results provide first insight into the general mechanisms of transcription factor regulation by β-catenin, including regulation by PTMs and transcription factor switching via regulatory proteins.
Publications
- Studying structure and dynamics of biomolecules using soluble paramagnetic probes, ChemPhysChem 14 (2013), 3082-3094
Hocking H.G., Zangger K., Madl T.
(See online at https://doi.org/10.1002/cphc.201300219) - Hsp90-Tau complex reveals molecular basis for specificity in chaperone action, Cell 156 (2014) 963-974
Karagöz G.E., Duarte A.M.S., Akoury E., Ippel H., Biernat J., Luengo T.M., Radli M., Didenko T., Nordhues B.A., Veprintsev D.P., Dickey C., Mandelkow E., Zweckstetter M., Boelens R., Madl T., Rüdiger S.G.D.
(See online at https://doi.org/10.1016/j.cell.2014.01.037) - Modulation of the Hsp90 chaperone cycle by a stringent client protein, Molecular Cell 53 (2014) 941-953
Lorenz O., Freiburger F., Rutz D., Krause M., Zierer B., Alvira A., Cuéllar J., Valpuesta J.M., Madl T., Sattler M., Buchner J.
(See online at https://doi.org/10.1016/j.molcel.2014.02.003) - NMR approaches for structural analysis of multidomain proteins and complexes in solution, Progress in Nuclear Magnetic Resonance Spectroscopy 80 (2014) 26-63
Göbl C., Madl T., Simon B., Sattler M.
(See online at https://doi.org/10.1016/j.pnmrs.2014.05.003) - Transient electrostatic interactions dominate the conformational equilibrium sampled by multi-domain splicing factor U2AF65: A combined NMR and SAXS study, Journal of the American Chemical Society 136 (2014) 7068-7076
Huang J.R., Warner L.R., Sanchez C., Gabel F., Madl T., Mackereth C.D., Sattler M., Blackledge M.
(See online at https://doi.org/10.1021/ja502030n) - Cancer mutations derail Wnt signaling via conformational conversion of the scaffold protein Axin, Nature Structural and Molecular Biology 23 (2016) 324-332
Anvarian Z., Nojima H., van Kappel E.C., Madl T., Spit M., Viertler M., Jordens I., Low T.Y., van Scherpenzeel R., Kuper I., Richter K., Heck A.J.R., Boelens R., Vincent J.P., Rüdiger S.G.D., Maurice M.M.
(See online at https://doi.org/10.1038/nsmb.3191) - Protein structure prediction using surface accessibility data, Angewandte Chemie 55 (2016) 11970-11974
Hartlmüller C., Göbl C., Madl T.
(See online at https://doi.org/10.1002/anie.201604788)
