The alpha5beta1 integrin mediates elimination of amyloid-beta peptide and protects against apoptosis.

The amyloid-beta peptide (Abeta) can mediate cell attachment by binding to beta1 integrins through an arg-his-asp sequence. We show here that the alpha5beta1 integrin, a fibronectin receptor, is an efficient binder of Abeta, and mediates cell attachment to nonfibrillar Abeta. Cells engineered to express alpha5beta1 internalized and degraded more added Abeta1-40 than did alpha5beta1-negative control cells. Deposition of an insoluble Abeta1-40 matrix around the alpha5beta1-expressing cells was reduced, and the cells showed less apoptosis than the control cells. Thus, the alpha5beta1 integrin may protect against Abeta deposition and toxicity, which is a course of Alzheimer's disease lesions.