Liquid-liquid phase separation of EphB4 drives pulmonary hypertension via YAP activation.

Summary

Matrix stiffening induces liquid–liquid phase separation of EphB4’s intrinsically disordered C-terminus in PASMCs, forming condensates that release YAP from cytoplasmic restraint and drive proliferation. A retro-inverso peptide targeting EphB4’s IDR, delivered via VAPG-modified nanoparticles, inhibited LLPS and attenuated pulmonary hypertension in rats, establishing EphB4 phase separation as a druggable node.

Key Findings

• EphB4 expression is upregulated in pulmonary hypertension; smooth muscle-specific EphB4 deficiency alleviates PH in rats.
• Matrix stiffening extends EphB4’s C-terminal IDR, inducing liquid–liquid phase separation and condensate formation.
• EphB4 condensates sequester YAP regulators (ANXA2, YWHA), promoting YAP nuclear translocation and PASMC proliferation.
• A retro-inverso peptide targeting EphB4’s IDR, delivered via VAPG-modified nanoparticles, inhibits LLPS and attenuates PH progression.

Clinical Implications

EphB4 phase separation represents a therapeutic target for pulmonary hypertension, suggesting development of IDR-directed inhibitors and delivery systems; translation will require human tissue validation and safety studies.

Limitations

• Preclinical models; human validation of EphB4 LLPS and safety/PK of peptide-nanoparticle therapy are lacking.
• Long-term efficacy and potential off-target effects of EphB4 IDR inhibition remain unknown.

Future Directions

Validate EphB4 LLPS and the ANXA2/YWHA–YAP axis in human PH tissues; optimize IDR-directed inhibitors and delivery; evaluate safety and efficacy in large-animal models and early-phase clinical trials.