CRISPR Activation Screening Identifies VGLL3-TEAD1-RUNX1/3 as a Transcriptional Complex for PD-L1 Expression.

Area of Science:

• Immunology
• Molecular Biology
• Genetics

Background:

• The PD-L1/2-PD-1 pathway is vital for immune tolerance and preventing autoimmunity.
• Tumor cells hijack PD-L1/2 expression for immune evasion.
• Factors controlling PD-L1/2 expression in various cell types are not fully understood.

Purpose of the Study:

• To identify novel regulators of PD-L1 expression.
• To elucidate the molecular mechanisms controlling PD-L1/2 upregulation.
• To understand the role of VGLL3 in immune regulation.

Main Methods:

• Genome-wide CRISPR activation screening to identify PD-L1 regulators.
• Functional assays to assess the role of VGLL3 in PD-L1/2 expression.
• Co-immunoprecipitation and secondary screening to identify VGLL3-interacting proteins.

Main Results:

• GATA2, MBD6, and VGLL3 were identified as key inducers of PD-L1.
• VGLL3 alone could induce PD-L1 in multiple cell types.
• Loss of VGLL3 diminished IFN-γ-induced PD-L1/2 expression in keratinocytes.
• VGLL3 forms a transcriptional complex with TEAD1 and RUNX1/3 to drive PD-L1/2 expression.

Conclusions:

• A novel transcriptional complex involving VGLL3, TEAD1, and RUNX1/3 controls PD-L1/2 expression.
• VGLL3 plays a dual role in regulating inflammation by upregulating both pro- and anti-inflammatory genes.
• This discovery offers new insights into immune checkpoint regulation and potential therapeutic targets.