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Stefanie Karlshøj

Stefanie Karlshøj

Assistant professor

My research is focused on the pharmacological characterization of G protein coupled receptors (GPCRs). GPCRs are the most abundant drug target today, and hold great potential for future drug development. Amongst those, I focus on chemokine receptors (class A GPCRs). In my group, which belongs to the Rosenkilde Lab for Molecular Pharmacology, we study the molecular basis for interactions between receptor and chemokine or small molecule ligand. We try to understand the structural grounds for allosteric interactions in chemokine receptors; we investigate the role of newly identified conserved receptor regions; and we perform ligand screens on the hunt for a good antagonist

 

Chemokine receptors:

Chemokine receptors mediate the migration of leukocytes and play an important role in the pathology of autoinflammatory and allergic diseases, viral infections (e.g. HIV) and also cancer development and progression. The chemokine system comprises more than 50 human endogenous peptide ligands, the chemokines (chemotactic cytokines), and 20 receptors. The system is characterized by a large degree of promiscuity among the ligand:receptor pairs which might result in redundancy of the system. Yet, at the same time the system is tightly controlled in vivo, in time and space, e.g. by mechanisms of bias (ligand, receptor, tissue bias), or specific expression of certain chemokines depending on timing, location, and circumstances. Furthermore, chemokines are subject to posttranslational processing, mainly cleavage by matrixmetalloproteases, which can render their activity and receptor specificity.

 

Projects:

In my group, which is affiliated to the Rosenkilde Lab for Molecular Pharmacology, we study the molecular basis for the interaction of chemokines and small molecule drug candidates with chemokine receptors, and the structural rationale for allosteric interactions between both ligand classes (peptide and small molecule). We have e.g. found that small molecule ligands that interact with a pocket in the transmembrane receptor domain are not necessarily allosteric towards the chemokines, which are known to bind to the extracellular receptor domains. Also, we defined an allosteric interface as the contact area between chemokine and small molecule, which can be modulated towards positive or negative allosteric effects. Ongoing projects include the identification of conserved domains within the transmembrane area, and the extracellular loops, and their importance for the receptor activation mechanism and drug action. Recently, we have established a chemokine production technique, which ensures exact N-terminal sequences not starting with Methionine - this is important since the N-terminus of chemokines mediates receptor activation and modification thereof often render chemokines inactive. This method will be used to test the effect of N-terminal chemokine truncations on small molecule drug activity.

 

Key techniques:

  • in vitro pharmacology
  • cell-based signal transduction assays for G protein-dependent and -independent pathways (IP3, cAMP, Ca2+, GTP-γ-S-binding, β-arrestin recruitment)
  • radio-label techniques, enzyme-fragment complementation techniques, BRET-based techniques, ELISA
  • Homo- and heterologous competition binding, saturation binding, kinetic binding studies
  • receptor mutagenesis and binding site mappings for small molecule and peptide ligands
  • ligand screens
  • protein expression and purification

 

Collaborations

  • Thomas Frimurer, Computational modeling, Novo Nordisk Foundation, Center for Basic Metabolic Research, University of Copenhagen
  • Jon Våbenø, Computational modeling, Norway
  • Trond Ulven, chemistry, Department of Drug Design and Pharmacology, SUND, University of Copenhagen

Teaching

  • since 2018: Biochemistry for Medical Students
  • 2015-pres.: Course leader for the "Master thesis grant application writing" for Human Biology students
  • 2013-pres.: Course leader of the 2-day workshop "Molecular Pharmacology" for Human Biology students
  • 2012-pres.: Seminars on basic molecular pharmacology and chemotherapy for medical students

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