A kindlin-3-leupaxin-paxillin signaling pathway regulates podosome stability.

ABSTRACT

Binding of kindlins to integrins is required for integrin activation, stable ligand binding, and subsequent intracellular signaling. How hematopoietic kindlin-3 contributes to the assembly and stability of the adhesion complex is not known. Here we report that kindlin-3 recruits leupaxin into podosomes and thereby regulates paxillin phosphorylation and podosome turnover. We demonstrate that the activity of the protein tyrosine phosphatase PTP-PEST, which controls paxillin phosphorylation, requires leupaxin. In contrast, despite sharing the same binding mode with leupaxin, paxillin recruitment into podosomes is kindlin-3 independent. Instead, we found paxillin together with talin and vinculin in initial adhesion patches of kindlin-3-null cells. Surprisingly, despite its presence in these early adhesion patches, podosomes can form in the absence of paxillin or any paxillin member. In conclusion, our findings show that kindlin-3 not only activates and clusters integrins into podosomes but also regulates their lifetime by recruiting leupaxin, which controls PTP-PEST activity and thereby paxillin phosphorylation and downstream signaling.