Structural Basis of Paxillin Recruitment by Kindlin-2 in Regulating Cell Adhesion

Area of Science:

• Cell biology
• Structural biology
• Biochemistry

Background:

• Integrin activation initiates cell adhesion, but subsequent outside-in signaling to form focal adhesions (FAs) is poorly understood.
• Kindlin-2, an integrin activator, associates with paxillin in early FAs, suggesting a role in initial signaling events.

Purpose of the Study:

• To elucidate the structural basis of the kindlin-2/paxillin interaction in the context of focal adhesion assembly.
• To understand the mechanism by which kindlin-2 recruits paxillin to initiate outside-in integrin signaling.

Main Methods:

• X-ray crystallography to determine the structure of the kindlin-2 F0 domain bound to the paxillin LIM4 domain.
• Biochemical assays to assess the binding interface and its functional significance.
• Cell-based assays to evaluate the impact of interface disruption on focal adhesion formation and cell migration.

Main Results:

• The study reveals a distinct structural interface between the kindlin-2 F0 domain and the paxillin LIM4 domain.
• This interaction site is located near the membrane-binding region of kindlin-2 F0, facilitating targeted recruitment of paxillin.
• Disruption of the kindlin-2/paxillin interface significantly impaired paxillin localization, focal adhesion assembly, and cell migration.

Conclusions:

• The findings uncover a structural mechanism for kindlin-2-mediated recruitment of paxillin, crucial for initiating focal adhesion assembly.
• This interaction is a key event in integrin outside-in signaling, regulating dynamic cell adhesion and migration.
• The study provides a structural foundation for understanding how kindlin-2 controls cell adhesion dynamics.