A specific alpha5beta1-integrin conformation promotes directional integrin translocation and fibronectin matrix formation.
Integrin adhesion receptors are structurally dynamic proteins that adopt a number of functionally relevant conformations. We have produced a conformation-dependent anti-alpha5 monoclonal antibody (SNAKA51) that converts alpha5beta1 integrin into a ligand-competent form and promotes fibronectin binding. In adherent fibroblasts, SNAKA51 preferentially bound to integrins in fibrillar adhesions. Clustering of integrins expressing this activation epitope induced directional translocation of alpha5beta1, mimicking fibrillar adhesion formation. Priming of alpha5beta1 integrin by SNAKA51 increased the accumulation of detergent-resistant fibronectin in the extracellular matrix, thus identifying an integrin conformation that promotes matrix assembly. The SNAKA51 epitope was mapped to the calf-1/calf-2 domains. We propose that the action of the antibody causes the legs of the integrin to change conformation and thereby primes the integrin to bind ligand. These findings identify SNAKA51 as the first anti-integrin antibody to selectively recognize a subset of adhesion contacts, and they identify an integrin conformation associated with integrin translocation and fibronectin matrix formation.
Clark
Katherine
K
Craniofacial Developmental Biology and Regeneration Branch, NIDCR, NIH, Bethesda, MA 20892, USA.
Pankov
Roumen
R
Travis
Mark A
MA
Askari
Janet A
JA
Mould
A Paul
AP
Craig
Susan E
SE
Newham
Peter
P
Yamada
Kenneth M
KM
Humphries
Martin J
MJ
D000911:Antibodies, Monoclonal / Q000494:pharmacology / Q000502:physiology; D001692:Biological Transport; D002448:Cell Adhesion / Q000187:drug effects; D005109:Extracellular Matrix / Q000187:drug effects / Q000502:physiology*; D005353:Fibronectins / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D039081:Integrin alpha5beta1 / Q000096:biosynthesis / Q000187:drug effects / Q000502:physiology*; D020014:K562 Cells; D008024:Ligands; D018716:Molecular Mimicry; D011487:Protein Conformation; D021381:Protein Transport / Q000502:physiology; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000187:drug effects / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology
D000911:Antibodies, Monoclonal; D005353:Fibronectins; D039081:Integrin alpha5beta1; D008024:Ligands; D011993:Recombinant Fusion Proteins