Proteomic mapping of intercellular synaptic environments via flavin-dependent photoredox catalysis
Tyler J Bechtel1, Jayde M Bertoch1, Aleksandra K Olow2
1Exploratory Science Center, Merck & Co., Inc., Cambridge, MA, 02139, USA. tamara.reyes.robles@merck.com.
Insights
This study identifies protein microenvironments in immune synapses using photocatalytic labeling. It reveals known and novel proteins involved in T cell and antigen-presenting cell communication.
Area of Science:
- Immunology
- Cell Biology
- Proteomics
Background:
- Receptor-ligand interactions are crucial for intercellular signaling, especially at the immune synapse.
- The immune synapse facilitates communication between T cells and antigen-presenting cells, regulating immune responses.
- Understanding protein organization within the immune synapse is key to deciphering immune signaling.
Purpose of the Study:
- To identify protein microenvironments within immunological synapses.
- To characterize the protein composition of intercellular regions in immune synapse-forming co-cultures.
Main Methods:
- Utilized a flavin-dependent photocatalytic labeling strategy.
- Combined photocatalysis with quantitative mass spectrometry-based proteomics.
- Employed single-domain antibody (VHH)-based photocatalyst targeting modalities (α-PD-L1 or α-PD-1).
Main Results:
- Successfully profiled protein microenvironments in immune synapse co-cultures.
- Observed enrichment of programmed death-ligand 1 (PD-L1) and programmed death-1 (PD-1) using targeted modalities.
- Identified known immune synapse proteins, surface proteins, and novel synapse-residing proteins.
Conclusions:
- Photocatalytic labeling coupled with mass spectrometry is effective for mapping immune synapse proteomes.
- This approach can uncover both established and previously unknown protein players in immune cell interactions.
- The findings provide insights into the molecular architecture governing immune synapse function.
Abstract:
Receptor-ligand interactions play essential signaling roles within intercellular contact regions. This is particularly important within the context of the immune synapse where protein communication at the surface of physically interacting T cells and antigen-presenting cells regulate downstream immune signaling responses. To identify protein microenvironments within immunological synapses, we combined a flavin-dependent photocatalytic labeling strategy with quantitative mass spectrometry-based proteomics. Using α-PD-L1 or α-PD-1 single-domain antibody (VHH)-based photocatalyst targeting modalities, we profiled protein microenvironments within the intercellular region of an immune synapse-forming co-culture system. In addition to enrichment of both PD-L1 and PD-1 with either targeting modality, we also observed enrichment of both known immune synapse residing receptor-ligand pairs and surface proteins, as well as previously unknown synapse residing proteins.
