ITGA4

Integrin alpha-4 (ITGA4), also known as CD49d, is a transmembrane glycoprotein that pairs with β1 (ITGB1) or β7 (ITGB7) subunits to form heterodimeric receptors α4β1 (VLA-4) and α4β7. These integrins mediate cell-cell and cell-extracellular matrix interactions by binding ligands such as vascular cell adhesion molecule-1 (VCAM-1) and mucosal addressin cell adhesion molecule-1 (MAdCAM-1). Functionally, ITGA4 facilitates leukocyte adhesion, migration, and immune cell trafficking through mechanosensitive signaling pathways, including focal adhesion kinase (FAK) and phosphoinositide 3-kinase (PI3K)/Akt cascades. It plays critical roles in inflammatory responses, lymphoid tissue development, and hematopoietic stem cell retention in bone marrow niches.
Dysregulated ITGA4 activity is implicated in autoimmune diseases (e.g., multiple sclerosis, inflammatory bowel disease) and cancers by promoting pathological leukocyte infiltration or metastatic spread. Therapeutic targeting of α4 integrins has advanced significantly, with natalizumab (anti-α4 integrin monoclonal antibody) approved for relapsing-remitting multiple sclerosis and Crohn's disease, despite PML risk. Vedolizumab, a gut-selective α4β7 inhibitor, shows efficacy in ulcerative colitis. Emerging strategies include small-molecule antagonists and dual α4/β1 inhibitors undergoing preclinical evaluation for enhanced specificity and safety profiles.