Rac1 mediates cadherin-11 induced cellular pathogenic processes in aortic valve calcification

Area of Science:

• Cardiovascular Biology
• Molecular Medicine
• Biochemistry

Background:

• Calcific aortic valve disease (CAVD) lacks pharmacological treatments, despite Cadherin-11 (Cad11) being a therapeutic target.
• Direct Cad11 inhibition has failed clinically; targeting downstream effectors is a potential alternative.
• Downstream effectors of Cad11 in aortic valve pathogenesis remain uninvestigated.

Purpose of the Study:

• To investigate the downstream signaling pathways mediating Cadherin-11 (Cad11) induced pathogenesis in calcific aortic valve disease (CAVD).
• To identify specific Rac1-GEFs as potential therapeutic targets for CAVD.

Main Methods:

• Immunofluorescence analysis of human aortic valves to assess GTP-Rac1 and GTP-RhoA co-localization with Cad11.
• Utilized dominant-negative mutants in porcine aortic valve interstitial cells (PAVICs) to study Cad11-Rac1 interactions.
• Ex vivo assays on porcine aortic valve leaflets and PAVICs treated with osteogenic media, employing Rac1-GEF inhibitors (NSC23766, ITX3).
• Analysis of Cad11 overexpressing mouse models (Cad11 OX) to evaluate GTP-Rac1 and Trio expression.

Main Results:

• GTP-Rac1 was significantly upregulated and co-localized with Cad11 in calcified human aortic valves.
• Cad11 predominantly regulates Runx2 nuclear localization via Rac1 in PAVICs.
• Rac1-GEF inhibition reduced ex vivo calcification by 2.8-fold and prevented Cad11-induced cellular changes.
• GTP-Rac1 and Trio were significantly upregulated in Cad11 OX mice.
• Trio-specific inhibitor ITX3 prevented Cad11-induced calcification and Runx2 induction.

Conclusions:

• Cadherin-11 (Cad11) induces pathogenic cellular processes in calcific aortic valve disease (CAVD) primarily through Rac1 signaling.
• Rac1 inhibition effectively mitigates Cad11-induced aortic disease phenotypes.
• Targeting Rac1-GEFs presents a promising therapeutic strategy for CAVD.