Decoding ADGRE5: How Proteolytic Cleavage and Mechanical Forces Unleash Cellular Signals.

Area of Science:

• Molecular and Cellular Biology
• G protein-coupled receptor (GPCR) signaling
• Cancer biology and drug discovery

Background:

• The adhesion GPCR ADGRE5 (CD97) is frequently overexpressed in various cancers, making it a promising oncology and immuno-oncology target.
• Understanding the precise activation and signaling pathways of ADGRE5 is critical for developing effective therapeutics.

Purpose of the Study:

• To elucidate the signaling mechanisms of human ADGRE5 (hADGRE5) using advanced biosensor technologies.
• To investigate both G protein-dependent and β-arrestin-dependent signaling pathways activated by hADGRE5.
• To explore novel activation mechanisms, including protease cleavage and mechanical stimulation.

Main Methods:

• Utilized enhanced bystander bioluminescence resonance energy transfer (ebBRET)-based biosensors to monitor hADGRE5 signaling.
• Employed a synthetic TEV protease-cleavable receptor chimera for controlled tethered agonist exposure.
• Investigated signaling induced by Gingipain K (Kgp) and mechanical stimulation (MS) on hADGRE5.

Main Results:

• Controlled agonist exposure via TEV protease revealed signaling through Gα12/Gα13 and β-arrestin 1/2 recruitment.
• Gingipain K (Kgp) cleavage activated Gαz/Gα11 and mimicked TEV-induced signaling, demonstrating GPS cleavage-independent activation.
• Mechanical stimulation (MS) induced β-arrestin 2 recruitment, dependent on the GPCR proteolysis site (GPS) and CD55 interaction.

Conclusions:

• This study provides significant insights into the multifaceted signaling capabilities of hADGRE5.
• hADGRE5 exhibits plasticity, activating signaling pathways through both GPS cleavage-dependent and -independent mechanisms.
• Findings support ADGRE5 as a versatile target in cancer therapy, with potential for targeting mechanical cues.