Arbeitsgruppe Liebscher

 

Prof. Dr. Dr. Ines Liebscher
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Telefon: +49 (0)341 97 22 141
Telefax: +49 (0)341 97 22 159

 

  

Arbeitsgruppe Liebscher

 

Prof. Dr. Dr. Ines Liebscher
E-Mail: Diese E-Mail-Adresse ist vor Spambots geschützt! Zur Anzeige muss JavaScript eingeschaltet sein!

Telefon: +49 (0)341 97 22 141
Telefax: +49 (0)341 97 22 159

 

  

Research Overview

G protein-coupled Receptors (GPCR) govern essential physiological functions and are causative for a variety of human diseases (Schöneberg and Liebscher, Pharmacol Rev. 2021). The majority of approved pharmaceutics target this receptor family. About one third of the GPCR family is still orphan, which means that either function or activation are unknown. Deciphering the role of orphan GPCRs is of high interest to basic research and of clinical importance as it has the potential to yield even more therapeutic approaches. With 33 members, adhesion GPCRs (aGPCRs) form the second largest group of the GPCR family and the majority of them are orphan. They share structural features with all other representatives of the GPCR family including a 7-transmembrane domain, an extracellular N-terminus as well as an intracellular C-terminus. However, there are structural features which separate them from the rest of the GPCR family. The N-terminus is characterized by its enormous size and complexity. It contains several functional domains, which are assumed to convey cell-cell- as well as cell-matrix- interactions. A hallmark structure is the GPCR autoproteolysis-inducing (GAIN) domain, which harbors the GPCR proteolysis site at which the receptor is autoproteolytically cleaved into an N- and a C-terminal fragment. The cleavage site also marks the beginning of the tethered agonist sequence, coined the Stachel sequence. Together with the sizeable C-terminus, the N-terminus contributes to the fact, that members of the aGPCR family form the largest membrane-standing proteins in vertebrates. Numerous splice variants increase the amount of potential receptor-subspecies. This makes this specific GPCR family a highly interesting, yet difficult to study, group.

The Liebscher Lab aims to unravel the function of these receptors on a molecular as well as on a physiological level. We have solved the signal transduction of several aGPCRs and have recently described a tethered agonist activation mechanism (Liebscher et al. Cell Rep. 2014), which allows now for in vitro and in vivo manipulation of this orphan receptor group through derived synthetic peptides. We could show that several aGPCRs can be activated through mechanical stimuli and/ or the interaction with the surrounding extracellular matrix components (Petersen et al. Neuron 2015). 

Modes of aGPCR activation

 

These observations led to the hypothesis that these giant receptors “sense” their environment and contribute to a context-dependent signal transduction. Based on our receptor library of > 20 mouse / human constructs we are now able to conclude common mechanisms and receptor-specific features in aGPCR pharmacology. With the European COST network CA18240: Adhesion GPCR Network: Research and Implementation set the path for Future Exploration (https://www.adhernrise.eu) we managed to assemble numerous researchers in Europe as well as worldwide to join us in the task of unraveling this enigmatic receptor group. 

 

Projects

1) Structure/function relations in aGPCR signal transduction

Adhesion GPCRs are highly complex molecules composed of a diverse set of functional domains, which are encoded by several exons. As such they are subjected to splicing, which yields multiple different receptor proteins. These receptor variants can lack N-terminal domains or even transmembrane domains (Knierim et al. Sci Rep. 2019). The functional testing of a large set of receptor mutants reveals significant influence of the N-terminal domains on basal signaling levels. The splicing events appear to have tissue preferences, thus allowing for a broader range of functional regulation (Wilde et al. Faseb 2016). Further, numerous single nucleotide polymorphisms have functional implications for aGPCRs (Fischer et al. BMC Genomics 2016). To elucidate the role of structural components on signal transduction cascades, ligand binding and activation levels of aGPCRs we are using an overexpression approach of mutant vs wildtype receptors in heterologous cell systems. Intracellular signaling pathways are studied using second messenger accumulation assays, ELISA techniques, luciferase reporters, Western Blot or FRET/BRET. We further aim to identify the points of interaction between the tethered agonist and its binding pocket using biochemical and computational approaches.

 

A

B

Structure-function relations of aGPCRs. (A) Adhesion GPCRs signal through G proteins, which can be detected at different levels of the signaling cascade. (B) Mutational studies indicate that the structural components of an aGPCR influence its basal signaling activity.

 

2) Means of aGPCR activation (Ligand identification, mechanical stimulus, small molecule compounds)

Modifying aGPCR activation levels is the basis to study their function in vitro and in vivo. Upon identification of a tethered agonist sequence within the receptor, we established derived peptides as agonists and antagonists (Liebscher et al. Cell Rep. 2014, Demberg et al.BBRC 2015, Wilde et al. Faseb 2016, Demberg et al. JBC 2017). These peptides, however, have several disadvantages e.g. low affinity, bad solubility and unspecific activation of several aGPCRs. Thus, there is a need for alternate ways to modulate aGPCR activity. Thus, we are pharmacologically characterizing small molecule compounds that have been identified in in vivo (Bradley et al. ANYAS 2019) as well as in silico drug screens. Further, we test potential ligands, which are mainly components of the extracellular matrix, for their impact on receptor signal transduction (Petersen et al. Neuron 2015). We could show that aGPCRs can be activated by different mechanical stimuli, e.g. vibration, shaking or cell swelling. We are currently seeking to characterize these forces that act on the receptor.

 

A B
C D
Means to activate aGPCRs. (A) Synthetic peptides (p16 on GPR126) derived from the Stachel sequence can be used to activate the aGPCR in a concentration-dependent manner. (B) An in vivo compound screen (performed in the labs of Kelly R. Monk at the Vollum Institute, OSHU Portland, OR, USA and Sarah C. Petersen at Kenyon College, Gambier, OH, USA) identified several compounds that rescue the myelination defect in GPR126 mutant zebrafish. Pharmacological in vitro evaluation of these compounds revealed specific agonistic effects of apomorphine on GPR126. (C) Laminin-211 inhibits activation of GPR126 under static conditions but induces activation under shaking conditions. (D) Testing setup to assess mechano-activation of aGPCRs.

 

3) G protein-dependent and independent intracellular pathways

The majority of aGPCRs have been shown to functionally couple to G proteins. However, interaction of the C-terminus with the cytoskeleton has been shown (Hilbig et al. Cell Rep. 2018). There is increasing evidence that aGPCRs can also signal through other G protein-independent pathways like Wnt or sonic hedgehog (shh). We aim to characterize these interactions and to identify other intracellular binding partners that could convey so far unknown functions of aGPCRs.

 

4) The role of aGPCRs in tissue function

As aGPCRs act as mediators or sensors of their immediate surrounding, it is of great interest to us to elucidate their role in a specific tissue environment, such as the function of CD97 in retinal pigment epithelium cells (Eichler et al.ANYAS 2019), or the role of aGPCRs in adipose tissue. We established the repertoire of a mouse and human aGPCRs in different adipose tissue depots under normal and high fat diet conditions (Suchy et al. Int J Obes 2020). We identified several aGPCRs that are decisively contributing to differentiation of 3T3-L1 cells, which is a model cell line for adipocyte function. Our current focus is to investigate the influence of mechanical force on aGPCR function in adipocytes. To mimic the physiological forces that can occur in adipose tissue through hypertrophy and hyperplasia of expanding adipocytes as well as the potential forces mediated by changing extracellular matrix compositions, we use cell swelling or cell stretch applied by a Fexcell Tension® system. We are further interested in the role of aGPCRs in fibroblasts, muscle and bone cells.

 

A

 

 

B

 C

aGPCRs play a role in adipose tissue. (A) Expression analysis of all mouse and human aGPCRs in different adipose tissue depots under lean and obese conditions. (B) Knock-down of highly expressed aGPCRs in 3T3-L1 cells impairs lipid accumulation. (C) Experimental setup to investigate the effect of stretch on adipocyte function in WT and aGPCR-deficient cells.

 

 5) The physiological role of aGPCRs in mouse and zebrafish with implications for human diseases

GPCRs are among the most important drug targets. Thus, identifying the physiological role of the orphan class of aGPCRs will help to unravel their contribution to diseases, which forms the basis of establishing them as new therapeutic targets. We investigate the consequences of receptor knock-out (KO) in mice in order to identify potential human phenotypes that might be caused by mutations in the receptor gene. Once physiological impairments have been assessed, genome wide association studies and human cohorts will be screened to identify affected human individuals. To further delineate the molecular causes of each phenotype we employ tissue-specific KO mice and zebrafish as an easy-to-target and observable animal model.

Our current projects involve:

• The role of GPR133 in cardiac dysfunction
• The role of GPR133 in metabolism
• The role of GPR133 in bone homeostasis
• The role of GPR133 in spine development
• The role of GPR114 in immune response

 

 

Team

Current members

  • Prof. Dr. Dr. Ines Liebscher
  • Postdocs/Group leaders
    • Dr. Caroline Wilde
    • Dr. Juliane Lehmann
    • Dr. Sandra Berndt
  • MD students
    • Julius Franke
    • Jakob Mitgau
  • PhD students
    • Tomáš Suchý
    • Christian Ullmann
  • Technician
    • Kay-Uwe Simon

Former members

  • Dr. Julia Buchold (geb. Schön)
  • Dr. Lilian Marie Demberg
  • Dr. Franziska Rößler
  • Dr. Liane Seiler (geb. Fischer)
  • Dr. Gabriele Stephan
  • Anja Wieprecht
  • Nina Auerbach

Publications

Publications

Peer-reviewed Publications

  1. Favara DM, Liebscher I, Jazayeri A, Nambiar M, Sheldon H, Banham AH, Harris AL. Elevated expression of the adhesion GPCR ADGRL4/ELTD1 promotes endothelial sprouting angiogenesis without activating canonical GPCR signalling. Sci Rep. 2021; 11(1):8870.
  2. Frenster JD, Stephan G, Ravn-Boess N, Bready D, Wilcox J, Kieslich B, Wilde C, Sträter N, Wiggin GR, Liebscher ISchöneberg T, Placantonakis DG. Functional impact of intramolecular cleavage and dissociation of adhesion G protein-coupled receptor GPR133 (ADGRD1) on canonical signaling. J Biol Chem. 2021; 100798. Online ahead of print.
  3. Schöneberg T, Liebscher I. Mutations in G Protein-Coupled Receptors: Mechanisms, Pathophysiology and Potential Therapeutic Approaches. Pharmacol Rev. 2021.doi: 10.1124/pharmrev.120.000011.
  4. Frenster JD, Kader M, Kamen S, Sun J, Chiriboga L, Serrano J, Bready D, Golub D, Ravn-Boess N, Stephan G, Chi AS, Kurz SC, Jain R, Park CY, Fenyo D, Liebscher I, Schöneberg T, Wiggin G, Newman R, Barnes M, Dickson JK, MacNeil DJ, Huang X, Shohdy N, Snuderl M, Zagzag D, Placantonakis DG. Expression profiling of the adhesion G protein-coupled receptor GPR133 (ADGRD1) in glioma subtypes. Neurooncol Adv. 2020. doi: 10.1093/noajnl/vdaa053. eCollection 2020 Jan-Dec.
  5. Suchý T, Zieschang C, Popkova Y, Kaczmarek I, Weiner J, Liebing AD, Çakir MV, Landgraf K, Gericke M, Pospisilik JA, Körner A, Heiker JT, Dannenberger D, Schiller J, Schöneberg T, Liebscher I, Thor D. The repertoire of Adhesion G protein-coupled receptors in adipocytes and their functional relevance. Int J Obes (Lond). 2020. doi: 10.1038/s41366-020-0570-2. [Epub ahead of print].
  6. Bradley EC, Cunningham RL, Wilde C, Morgan RK, Klug EA, Letcher SM, Schöneberg T, Monk KR, Liebscher I, Petersen SC. In vivo identification of small molecules mediating Gpr126/Adgrg6 signaling during Schwann cell development. Annals of the New York Academy of Sciences. 2019. doi: 10.1111/nyas.14233. [Epub ahead of print].
  7. Eichler W, Lohrenz A, Simon KU, Krohn S, Lange J, Bürger S, Liebscher I. The role of ADGRE5/CD97 in human retinal pigment epithelial cell growth and survival. Annals of the New York Academy of Sciences. 2019. doi: 10.1111/nyas.14210. [Epub ahead of print].
  8. Knierim AB, Röthe J, Çakir MV, Lede V, Wilde C, Liebscher I, Thor D, Schöneberg T. Genetic basis of functional variability in adhesion G protein-coupled receptors. Sci Rep. 2019. doi: 10.1038/s41598-019-46265-x.
  9. Morgan RK, Anderson GR, Araç D, Aust G, Balenga N, Boucard A, Bridges JP, Engel FB, Formstone CJ, Glitsch MD, Gray RS, Hall RA, Hsiao CC, Kim HY, Knierim AB, Kusuluri DK, Leon K, Liebscher I, Piao X, Prömel S, Scholz N, Srivastava S,Thor D, Tolias KF, Ushkaryov YA, Vallon M, Van Meir EG, Vanhollebeke B, Wolfrum U, Wright KM, Monk KR, Mogha A. The expanding functional roles and signaling mechanisms of adhesion G protein-coupled receptors. Annals of the New York Academy of Sciences. 2019; doi: 10.1111/nyas.14094. [Epub ahead of print].
  10. Hsiao CC, Chu TY, Wu CJ, van den Biggelaar M, Pabst C, Hébert J, Kuijpers TW, Scicluna BP, I KY, Chen TC, Liebscher I, Hamann J, Lin HH. The adhesion G protein-coupled receptor GPR97/ADGRG3 is expressed in human granulocytes and triggers antimicrobial effector functions. Front Immunol. 2018; 9:2830.
  11. Hilbig D, Sittig D, Hoffmann F, Rothemund S, Warmt E, Quaas M, Stürmer J, Seiler L, Liebscher I, Hoang NA, Käs JA, Banks L, Aust G. Mechano-Dependent Phosphorylation of the PDZ-Binding Motif of CD97/ADGRE5 Modulates Cellular Detachment. Cell Rep. 2018; 24(8).
  12. Demberg LM, Winkler J, Wilde C, Simon KU, Schön J, Rothemund S, Schöneberg T, Prömel S*, and Liebscher I*. Activation of adhesion G protein-coupled receptors: agonist specificity of Stachel sequence-derived peptides. JBC 2017, 292(11):4383-4394. (* shared contribution)
  13. Fischer L, Wilde C, Schöneberg T, Liebscher I. Functional relevance of naturally occurring mutations in adhesion G protein-coupled receptor ADGRD1 (GPR133). BMC Genomics. 2016, 17(1):609.
  14. Wilde C, Fischer L, Lede V, Kirchberger J, Rothemund S, Schöneberg T, Liebscher I. The constitutive activity of the adhesion GPCR GPR114/ADGRG5 is mediated by its tethered agonist. Faseb J. 2016, 30(2):666-73.
  15. Monk KR, Hamann J, Langenhan T, Nijmeijer S, Schöneberg T, Liebscher I. Adhesion GPCRs: From In Vitro Pharmacology to In Vivo Mechanisms. Mol Pharmacol. 2015, 88(3):617-23.
  16. Schöneberg T, Liebscher I, Luo R, Monk KR, Piao X. Tethered agonists: a new mechanism underlying adhesion G protein-coupled receptor activation. J Recept Signal Transduct Res. 2015, 35(3):220-3.
  17. Liebscher I, Monk KR, Schöneberg T. How to wake a giant. Oncotarget. 2015; 6(27):23038-9.
  18. Demberg LM, Rothemund S, Schöneberg T, Liebscher I. Identification of the tethered peptide agonist of the adhesion G protein-coupled receptor GPR64/ADGRG2. Biochem Biophys Res Commun 2015; 464(3):743-7.
  19. Hamann J, Aust G, Araç D, Engel FB, Formstone C, Fredriksson R, Hall RA, Harty BL, Kirchhoff C, Knapp B, Krishnan A, Liebscher I, Lin HH, Martinelli DC, Monk KR, Peeters MC, Piao X, Prömel S, Schöneberg T, Schwartz TW, Singer K, Stacey M, Ushkaryov YA, Vallon M, Wolfrum U, Wright MW, Xu L, Langenhan T, Schiöth HB. International Union of Basic and Clinical Pharmacology. XCIV. Adhesion G protein-coupled receptors. Pharmacol Rev. 2015, 67(2): 338-67.
  20. Petersen SC*, Luo R*, Liebscher I*, Giera S, Jeong SJ, Mogha A, Ghidinelli M, Feltri ML, Schöneberg T, Piao X, Monk KR. The Adhesion GPCR GPR126 Has Distinct, Domain-Dependent Functions in Schwann Cell Development Mediated by Interaction with Laminin-211, Neuron 2015; 85(4):755-69. (*shared first authorship)
  21. Liebscher I*, Schön J*, Petersen SC, Fischer L, Auerbach N, Demberg LM, Mogha A, Cöster M, Simon KU, Rothemund S, Monk KR, Schöneberg T. A Tethered Agonist within the Ectodomain Activates the Adhesion G Protein-Coupled Receptors GPR126 and GPR133. Cell Rep. 2014; 9(6):2018-26. (*shared first authorship)
  22. Liebscher I, Ackley B, Araç D, Ariestanti DM, Aust G, Bae BI, Bista BR, Bridges JP, Duman JG, Engel FB, Giera S, Goffinet AM, Hall RA, Hamann J, Hartmann N, Lin HH, Liu M, Luo R, Mogha A, Monk KR, Peeters MC, Prömel S, Ressl S, Schiöth HB, Sigoillot SM, Song H, Talbot WS, Tall GG, White JP, Wolfrum U, Xu L, Piao X. New functions and signaling mechanisms for the class of adhesion G protein-coupled receptors. Ann N Y Acad Sci. 2014; 1333:43-64.
  23. Borte S, Meeths M, Liebscher I, Krist K, Nordenskjöld M, Hammarström L, von Döbeln U, Henter JI, Bryceson YT. Combined newborn screening for familial hemophagocytic lymphohistiocytosis and severe T- and B-cell immunodeficiencies. J Allergy Clin Immunol 2014; 134(1):226-8.
  24. Mogha A, Benesh AE, Patra C, Engel FB, Schöneberg T, Liebscher I, Monk KR. Gpr126 functions in Schwann cells to control differentiation and myelination via G-protein activation. J. Neurosci. 2013; 33(46):17976-85.
  25. Liebscher I, Schöneberg T, Prömel S. Progress in demystification of adhesion G protein-coupled receptors. Biol Chem 2013; 394(8):937-50.
  26. Ritscher L, Engemaier E, Stäubert C, Liebscher I, Schmidt P, Hermsdorf T, Römpler H, Schulz A, Schöneberg T. The ligand specificity of the G-protein-coupled receptor GPR34. Biochem J 2012; 443(3):841-50.
  27. Araç D, Aust G, Calebiro D, Engel FB, Formstone C, Goffinet A, Hamann J, Kittel RJ, Liebscher I, Lin HH, Monk KR, Petrenko A, Piao X, Prömel S, Schiöth HB, Schwartz TW, Stacey M, Ushkaryov YA, Wobus M, Wolfrum U, Xu L, Langenhan T. Dissecting signaling and functions of adhesion G protein-coupled receptors. Ann N Y Acad Sci. 2012, 1276:1-25.
  28. Liebscher I, Müller U, Teupser D, Engemaier E, Ritscher L, Thor D, Sangkuhl K, Ricken A, Wurm A, Schmutzler S, Fuhrmann H, Albert FW, Reichenbach A, Thiery J, Schöneberg T, Schulz A. Altered immune response in GPR34-deficient mice. J Biol Chem. 2011; 286: 2101-10.
  29. Schöneberg T, Hermsdorf T, Engemaier E, Engel K, Liebscher I, Thor D, Zierau K, Römpler H, Schulz A. Structural and functional evolution of the P2Y(12)-like receptor group.Purinergic Signal 2007; 3(4):255-68.

Monographs, teaching and manuals

  1. Liebscher I, Schöneberg T. Tethered Agonism: A Common Activation Mechanism of Adhesion GPCRs. Handb Exp Pharmacol. 2016; 234:111-125.

 

Funding

Our research projects have been supported by the German Research Foundation (CRC1052/B06, CRC1423/B05, FOR2149/P05), the BMBF (IFB AdipositasErkrankungen Leipzig: AD2-7102 and K7-67), the Leipzig University (Formel-1 start-up fund) and the European Union (European Social Fund: Junior research group: 3752 and EFRE invest fund). Further, these projects were the basis for a successful collaborative application for an EU funded COST Action (https://www.adhernrise.eu).