Trop2 Forms a Stable Dimer with Significant Structural Differences within the Membrane-Distal Region as Compared to...

Area of Science:

• Structural biology
• Molecular and cell biology
• Cancer research

Background:

• Trop2 is a cell-surface glycoprotein crucial for epithelial tissue integrity and a marker in carcinoma.
• Trop2 and EpCAM share claudin-interaction capacity and are involved in ectodomain cleavage signaling.
• Trop2 exhibits unique interactions with IGF-1, neuregulin-1, and α5β1 integrin regulating cell proliferation.

Purpose of the Study:

• To elucidate structural distinctions between Trop2 and EpCAM.
• To determine the crystal structure of a Trop2 ectodomain dimer.
• To compare the Trop2 dimer structure with the analogous EpCAM structure.

Main Methods:

• X-ray crystallography was employed to determine the Trop2 ectodomain dimer structure.
• Comparative structural analysis was performed between Trop2 and EpCAM dimers.
• Analysis focused on inter-subunit contacts and membrane-distal regions.

Main Results:

• The crystal structure of the Trop2 ectodomain dimer was successfully determined.
• Trop2 dimers exhibit more extensive inter-subunit contacts than EpCAM dimers.
• Significant differences were observed in the membrane-distal regions, including Trop2's exposed N-terminal domain and a reduced cleft.

Conclusions:

• Structural disparities between Trop2 and EpCAM highlight their divergent evolutionary paths.
• Trop2's dimeric structure allows direct accessibility to its proteolytic cleavage site, unlike EpCAM.
• These structural findings provide a basis for developing structure-based therapeutic strategies targeting Trop2.