Related Experiment Video
Updated: Nov 20, 2025
Cell Surface Receptor Identification Using Genome-Scale CRISPR/Cas9 Genetic Screens
Published on: June 6, 2020
Genome-wide CRISPR screens reveal a specific ligand for the glycan-binding immune checkpoint receptor Siglec-7
Simon Wisnovsky1, Leonhard Möckl1,2, Stacy A Malaker1
1Department of Chemistry & Stanford ChEM-H, Stanford University, Stanford, CA 94305.
Abstract:
Glyco-immune checkpoint receptors, molecules that inhibit immune cell activity following binding to glycosylated cell-surface antigens, are emerging as attractive targets for cancer immunotherapy. Defining biologically relevant ligands that bind and activate such receptors, however, has historically been a significant challenge. Here, we present a CRISPRi genomic screening strategy that allowed unbiased identification of the key genes required for cell-surface presentation of glycan ligands on leukemia cells that bind the glyco-immune checkpoint receptors Siglec-7 and Siglec-9. This approach revealed a selective interaction between Siglec-7 and the mucin-type glycoprotein CD43. Further work identified a specific N-terminal glycopeptide region of CD43 containing clusters of disialylated O-glycan tetrasaccharides that form specific Siglec-7 binding motifs. Knockout or blockade of CD43 in leukemia cells relieves Siglec-7-mediated inhibition of immune killing activity. This work identifies a potential target for immune checkpoint blockade therapy and represents a generalizable approach to dissection of glycan-receptor interactions in living cells.
Insights
Researchers identified CD43 as a key ligand for the glyco-immune checkpoint receptor Siglec-7 in leukemia. Blocking CD43 can enhance anti-leukemia immune responses, offering a new target for cancer immunotherapy.
Area of Science:
- Immunology
- Glycobiology
- Cancer Research
Background:
- Glyco-immune checkpoint receptors regulate immune cell activity by binding to cell-surface glycans.
- Identifying specific ligands for these receptors is crucial for developing cancer immunotherapies.
- Siglec-7 and Siglec-9 are key glyco-immune checkpoint receptors implicated in immune regulation.
Purpose of the Study:
- To unbiasedly identify genes involved in presenting glycan ligands for Siglec-7 and Siglec-9 on leukemia cells.
- To define the specific molecular interactions between Siglec-7 and its ligands.
- To explore CD43 as a potential therapeutic target in leukemia immunotherapy.
Main Methods:
- CRISPRi genomic screening to identify genes essential for glycan ligand presentation.
- Biochemical and cellular assays to characterize Siglec-7 and CD43 interactions.
- Genetic manipulation (knockout/blockade) of CD43 in leukemia cells.
Main Results:
- The study identified CD43 as a specific ligand for the Siglec-7 receptor.
- A distinct N-terminal glycopeptide region of CD43, rich in disialylated O-glycan tetrasaccharides, forms Siglec-7 binding motifs.
- Disrupting CD43 function in leukemia cells abrogated Siglec-7-mediated immune inhibition.
Conclusions:
- CD43 is a critical Siglec-7 ligand on leukemia cells, mediating immune suppression.
- Targeting the CD43-Siglec-7 interaction presents a promising strategy for immune checkpoint blockade therapy.
- The developed CRISPRi screening approach is a generalizable method for studying glycan-receptor interactions.
