Optogenetics

Decision processes by cells depend to a large extent on the precise spatial and temporal coordination of molecular events. Work of the last decade has focused on the identification of the key components of these networks, including their interactions and post-translational modifications. These studies were aided by technical developments in mass spectrometry and systems biology approaches. However, due to the lack of appropriate approaches, the impact of the kinetics of signalling processes on cellular decisions is still not well understood. We believe that optogenetics will enable us to design and perform the experiments required to fill this knowledge gap.

Tool development

Thus, we develop new optogenetic tools focussing on receptor signalling in T cells. We use the photoreceptor phytochrome B (PhyB) from Arabidopsis as a new ligand for an engineered TCR. We have developed TCRs that are fused to the PhyB-interacting factor PIF6. Thus, with red light PhyB binds to the PIF6-TCR and with far red light this interaction is stopped (Yousefi et al, 2020, 2019; Idstein et al, 2023). In a cooperation with us the system was also applied to integrins by the lab of Prof. Wilfried Weber (Baaske et al, 2019). We have also developed the so called opto-antigen presenting cells (opto-APCs), in which PhyB is presented on the cell surface as a membrane tethered protein (Russ et al, 2023).

T cell biology

Using our optogenetic TCR system we have shown that TCRs can distinguish ligands according to their half-life of binding (Yousefi et al, 2019). This mechanistically explains how T cells can distinguish self (low affinity and short half-life) from foreign (high affinity and long half-life) antigens. Importantly, the short binders serve as antagonists for the long binders (Yousefi et al, 2021). Currently, we are working on memory generation in the TCR signalling pathways using our optogenetic tools.

References

Idstein V, Ehret AK, Yousefi OS & Schamel WW (2023) Engineering of an Optogenetic T Cell Receptor Compatible with Fluorescence-Based Readouts. ACS Synth Biol 12: 2857–2864

Russ M, Ehret AK, Hörner M, Peschkov D, Bohnert R, Idstein V, Minguet S, Weber W, Lillemeier BF, Yousefi OS, et al (2023) Opto-APC: Engineering of cells that display phytochrome B on their surface for optogenetic studies of cell-cell interactions. Front Mol Biosci 10: 1143274

Yousefi OS, Ruggieri M, Idstein V, von Prillwitz KU, Herr LA, Chalupsky J, Köhn M, Weber W, Timmer J & Schamel WWA (2021) Cross-TCR antagonism revealed by optogenetically tuning the half-life of the TCR ligand binding. Int J Mol Sci 22

Yousefi OS, Hörner M, Wess M, Idstein V, Weber W & Schamel W (2020) Optogenetic Tuning of Ligand Binding to The Human T cell Receptor Using The opto-ligand-TCR System. Bio Protoc 10

Yousefi OS, Günther M, Hörner M, Chalupsky J, Wess M, Brandl SM, Smith RW, Fleck C, Kunkel T, Zurbriggen MD, et al (2019) Optogenetic control shows that kinetic proofreading regulates the activity of the T cell receptor. Elife 8

Baaske J, Mühlhäuser WWD, Yousefi OS, Zanner S, Radziwill G, Hörner M, Schamel WWA & Weber W (2019) Optogenetic control of integrin-matrix interaction. Commun Biol 2: 15