Integrin alpha-5 beta-1 and other RGD-recognizing integrins (ITGA5/ITGB1 and RGD-integrins)

Integrin alpha-5 beta-1 (α5β1) and other RGD-recognizing integrins (including αvβ1, αvβ3, αvβ5, αvβ6, αvβ8, α8β1, and αIIbβ3) are a specialized subset of the integrin family that bind to the Arginine-Glycine-Aspartic acid (RGD) peptide motif found in extracellular matrix (ECM) proteins such as fibronectin, vitronectin, and fibrinogen [1, 2]. These heterodimeric transmembrane receptors function as mechanical and chemical transducers, linking the ECM to the intracellular cytoskeleton to regulate cell adhesion, migration, proliferation, and survival [4, 11]. In pathological states, these integrins are frequently upregulated; for instance, αvβ3 and α5β1 are critical for tumor angiogenesis and metastasis, while αvβ6 and αvβ8 play pivotal roles in activating latent TGF-beta, thereby driving tissue fibrosis [4, 5, 10]. Therapeutic targeting of these receptors involves monoclonal antibodies, cyclic peptides (e.g., Cilengitide), and small molecule antagonists designed to block the RGD-binding pocket [7, 15]. While αIIbβ3 antagonists are established clinical treatments for thrombosis, many RGD-targeted agents in oncology have struggled in clinical trials due to the complex redundancy of integrin signaling and the potential for paradoxical receptor activation [9, 11]. Recent drug development has shifted toward high-selectivity inhibitors for specific subtypes like αvβ6 for fibrosis or α5β1 for pulmonary arterial hypertension [6, 12].

Other names

Fibronectin receptorVitronectin receptorFibrinogen receptorVLA-5CD49e/CD29RGD-binding integrins

Competitive antagonism of the RGD (Arg-Gly-Asp) binding site on the integrin heterodimer, preventing interaction with extracellular matrix ligands and inhibiting downstream pro-survival and pro-migratory signaling pathways.