Neutrophil recruitment, mediated by β2
integrins, combats pyogenic
infections but also plays a key role in
ischemia-reperfusion injury and other inflammatory disorders.
Talin induces allosteric rearrangements in
integrins that increase affinity for
ligands (activation).
Talin also links
integrins to actin and other
proteins that enable formation of adhesions. Structural studies have identified a talin1 mutant (L325R) that perturbs activation without impairing
talin's capacity to link
integrins to actin and other
proteins. Here, we found that mice engineered to express only talin1(L325R) in myeloid cells were protected from renal
ischemia-reperfusion injury. Dissection of neutrophil function in vitro and in vivo revealed that talin1(L325R) neutrophils had markedly impaired
chemokine-induced, β2
integrin-mediated arrest, spreading, and migration. Surprisingly, talin1(L325R) neutrophils exhibited normal
selectin-induced, β2
integrin-mediated slow rolling, in sharp contrast to the defective slow rolling of neutrophils lacking talin1 or expressing a talin1 mutant (W359A) that blocks
talin interaction with
integrins. These studies reveal the importance of
talin-mediated activation of
integrins for renal
ischemia-reperfusion injury. They further show that neutrophil arrest requires
talin recruitment to and activation of
integrins. However, although neutrophil slow rolling requires
talin recruitment to
integrins,
talin-mediated
integrin activation is dispensable.