SUMO Signaling Group
About
Head: Prof. Stefan Müller
Ubiquitin and Ubiquitin-like protein modification systems control a wide variety of cellular key processes. Our laboratory is studying mechanistic and functional aspects of the Ubiquitin-like SUMO system in mammalian cells. SUMO (Small Ubiquitin-like Modifier) functions as a post-translational modifier that is covalently attached to lysine residues of target proteins. Human cells express three SUMO forms, which are conjugated in a pathway that requires the E1 activating enzyme Aos1/Uba2, the E2 conjugating enzyme Ubc9 and in many cases involves E3 SUMO ligases.
SUMO modification is a dynamic, reversible process, in which the demodification of a given SUMO-conjugate is catalyzed by SUMO-specific proteases of the SENP family.
SUMO conjugation/deconjugation typically modulates protein-protein interactions thereby controlling cellular key pathways, including gene expression programs, ribosome biogenesis, mitotic progression or genomic integrity.
Signaling by SUMO generally relies on the recognition of a modified protein by a binding partner that contains a specialized SUMO binding module termed SUMO interaction motif (SIM).
However, a detailed understanding of SUMO function in most pathways is still incomplete because the relevant targets of modification and the corresponding SUMO-dependent binding partners have not been identified. In our work we therefore want to pinpoint the critical targets of SUMO in selected cellular pathways and aim to understand the dynamics of SUMO/SIM interactions.
Members
Lab Members
Prof. Stefan Müller
Stefan Müller studied pharmacy at Ludwig-Maximilians-University Munich and obtained his diploma and approbation in 1991. He subsequently worked as a PhD student and research assistant in the Institute of Physiological Chemistry under the supervision of Hans Joachim Seitz at Hamburg University, where he graduated in 1995. With a Marie-Curie post-doctoral fellowship from the EU he joined the laboratory of Anne Dejean at Pasteur Institute, Paris. Here he discovered the post-translational modification of PML by the ubiquitin-like SUMO modifier. He continued investigating the SUMO system and in 2001 became independent group leader at the Max Planck Institute of Biochemistry, Munich-Martinsried, in the Department of Stefan Jentsch. In 2010 he was appointed professor of biochemistry at Goethe University Frankfurt and since 2016 is the acting managing director of the Gustav-Embden-Center for Biological Chemistry. Link to Vice-Director page.
Anne Gärtner
Anne studied pharmacy at Albert-Ludwigs University in Freiburg. During her practical year at Boehringer-Ingelheim in Vienna, she worked on an ubiquitin E3 ligase as a possible new target for the treatment of cancer. In 2012 she started her PhD in the lab of Stefan Müller at the IBC II in Frankfurt, where she is now working on the redox regulation of the ubiquitin related SUMO system in macrophages.
Jan Keiten-Schmitz
Jan Keiten-Schmitz was born in Freiburg, Germany. He studied Biology in Darmstadt and Heidelberg and obtained his diploma degree in 2013. In his diploma thesis he studied the TOM complex of Leishmania tarentolae.
In September 2013 he started his PhD in the lab of Stefan Müller at the IBCII. Jan is studying the SUMO-targeted E3 ubiquitin-protein ligases (STUbLs) RNF4 and RNF111.
Hannah Mende
Hannah Mende studied Molecular Biology (B. Sc.) and Biomedicine (M. Sc.) at the JGU in Mainz and obtained her degree in 2017. In her Master´s thesis she studied RNAs associated to extracellular vesicles and the involvement of RNA binding proteins in RNA sorting mechanisms. In July 2017 she joined Stefan Müller´s group at the IBCII in Frankfurt to study the involvement of SUMOylation in autophagy within the SFB 1177.
Paul Hotz
Paul grew up in Essen and graduated from school in Wiesbaden with general qualification for university entrance (Abitur). He studied medicine at Goethe-Universität Frankfurt am Main and obtained the 1.Staatsexamen in summer 2017. Since September 2017 he started his MD Thesis in the SUMO signalling Group of Stefan Müller at Institute of Biochemestry II. He is now focussing on the role of SUMO system during cardiac ischemia/reperfusion injury and the identification of novel SUMO targets via mass spectrometry.
Kathrin Kunz
Kathrin grew up in Saarland where she completed her education in schools with the general qualification for university entrance (Abitur). She then moved to Kaiserslautern to study Food Chemistry and finally obtained her diploma degree (food chemist) in March 2014.
For her diploma thesis she worked in the group of Melanie Esselen where she investigated the influence on redox-sensitive genes from extracts of traditional Chinese foodstuff and other model substances.
Subsequently Kathrin started her PhD in the group of Stefan Müller at the Institute of Biochemistry II in Frankfurt. Since July 2014 she is focusing on redox regulation of the SUMO system.
Dr. Luca Mendler
Luca Mendler was born in Baja, Hungary. She studied medicine at the University of Szeged, Hungary and obtained her diploma in 1997. During her PhD she analyzed the molecular regulation of skeletal muscle regeneration at the University of Szeged as well as the Catholic University of Leuven, Belgium. After completing her PhD thesis in 2000, she kept on working on the molecular mechanisms regulating skeletal and cardiac muscle growth in the Institute of Biochemistry, Szeged (2000-2004). As an assistant professor she was teaching biochemistry for Hungarian, English and German medical students for several years as well (2004-2014). In 2008-2009 she received a scholarship of the Max Planck Society for deciphering the cell-autonomous role of the growth regulator myostatin in the heart in the Max-Planck-Insitute for Heart- and Lung Research, Bad Nauheim, Germany. In 2014 she joined to the Institute of Biochemistry II at the Goethe University, Frankfurt and has been involved in various teaching activities for medical students. She also started to work in the group of Stefan Müller analyzing the role of SUMO modification in the heart, more specifically, the possible function&redox regulation of SUMOylation during cardiac ischemia/reperfusion injury.
Tanja Piller
Tanja Piller studied Biotechnology at THM Gießen and obtained her master degree in June 2016. In her master thesis she worked on system-wide interactome analysis to characterize regulators of SUMO signaling pathways. In November 2016 she started her PhD in Stefan Müller’s group at IBCII in Frankfurt, where she is now focussing on the SUMO system in the control of nucleolar dynamics and ribosome biogenesis.
Projects
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Project I: Mechanistic and functional aspects of SUMO-SIM interactions
Mechanistic and functional aspects of SUMO-SIM interactions
Signaling by SUMO relies on the recognition of the post-translational mark by specialized interaction modules termed SUMO interaction motifs (SIMs). SUMO-mediated protein/protein interactions are frequently mediated by the non-covalent binding of SUMO conjugates to SIMs in a binding partner.
A common key determinant of SIMs is a core of hydrophobic amino acids. In a subset of SIM-containing proteins, including members of the PIAS (Protein inhibitor of activated STAT) family, this hydrophobic core is flanked by serine residues and a stretch of acidic residues. By using PIAS1 as a SUMO-binding model protein we could previously show that these serine residues are phosphorylated by the kinase CK2 and could demonstrate that this dictates binding of free SUMO and SUMO conjugates to PIAS1 (Stehmeier and Muller, 2009).
CK2-regulated phosphoSIM modules were also dissected in the tumor suppressor PML and the exosome component PMSCL1, indicating that these modules serve as general platforms that integrate CK2- and SUMO-regulated signaling networks. The characterization of SIMs in PIAS and PML revealed a new regulatory layer for SUMO recognition by SIM modules. One aspect of our current project is to functionally characterize the phosphoSIM modules of PIAS family members.
Moreover, we aim to elucidate other mechanisms that regulate the dynamics of SUMO/SIM interactions and want to understand how this affects specific cellular pathways, in particular PIAS-mediated transcriptional processes.
Stehmeier, P. & Muller, S. (2009). Phospho-regulated SUMO interaction modules connect the SUMO system to CK2 signaling. Mol. Cell 33, 400-409. -
Project II: The SUMO system in mammalian ribosome biogenesis
The SUMO system in mammalian ribosome biogenesis
Ribosome biogenesis is a tightly controlled pathway that requires an intricate spatial and temporal interplay of protein networks. Most structural rRNA components are generated in the nucleolus and assembled into pre-ribosomal particles, which are transferred for further maturation to the nucleoplasm and cytoplasm. In mammalian cells, however, it is largely unclear what drives these processes.
Our previous and current work revealed a critical role for the SUMO-specific protease SENP3 in the control of nucleolar dynamics and ribosome biogenesis. In particular, we could show that SENP3 is critically involved in the maturation of the 28S rRNA and the nucleolar export of the 60S pre-ribosomal subunit (Haindl et al., 2008, Finkbeiner et al., 2011). We now identified and characterized a novel SENP3-associated complex comprised of PELP1, TEX10 and WDR18 and demonstrate that this complex is involved in maturation and nucleolar release of the large ribosomal subunit. We identified PELP1 and as a SENP3-sensitive targets of SUMO2 and provide evidence that the SUMO system determines the nucleolar partitioning of the PELP1-TEX10-WDR18 complex.
This work thus defines the PELP1-TEX10-WDR18 complex as a novel regulator of ribosome biogenesis and suggests that its SUMO-regulated distribution provides a mechanism to coordinate the rate of ribosome formation. We propose a model where the balanced SUMO conjugation/deconjugation controls the dynamic association of this complex with 60S pre-ribosomal particles. We now aim to get mechanistic insights how sumoylation/desumoylation processes mediate the dynamics of pre-60S pre-ribosomal particles. Moreover, we want to understand how the SUMO system coordinates the rate of ribosome formation with the physiological state of the cell.
Haindl, M., Harasim, T., Eick, D. & Muller, S. (2008). The nucleolar SUMO-specific protease SENP3 reverses SUMO modification of nucleophosmin and is required for rRNA processing. EMBO Rep. 9, 273-279.
Finkbeiner, E., Haindl, M. & Muller S. (2011) The SUMO system controls nucleolar partitioning of a novel mammalian ribosome biogenesis complex. EMBO J., 30, 1067 – 1078.
Contact
Head: Prof. Stefan Müller
Institute of Biochemistry II
University Hospital Frankfurt
Goethe University
Theodor-Stern-Kai 7 / Building 75
60590 Frankfurt am Main
Germany
Tel (office): +49 (0) 69 6301 83647