Integrin Activation and Signaling Mechanisms

Integrins are heterodimeric transmembrane receptors that mediate adhesion to the extracellular matrix and engage bidirectional signalling across the plasma membrane. Activation is controlled by large‐scale conformational rearrangements within the α and β subunits, shifting from a low‐affinity bent state to an extended high‐affinity state in response to intracellular cues in an ‘inside‐out’ mechanism. Ligand binding then initiates ‘outside‐in’ signalling, recruiting cytoskeletal adaptors and kinases to regulate cell shape, migration, proliferation and survival. Key adaptor proteins such as talin and kindlin bind the β‐integrin cytoplasmic tail to disrupt inhibitory interactions and stabilise the active conformation, enabling mechanical linkages to actin networks and the transmission of biomechanical forces. This dynamic interplay underpins processes as diverse as haemostasis, immune cell trafficking and tissue morphogenesis. Dysregulation of integrin activation or signalling can contribute to pathological states including thrombosis, chronic inflammation and tumour metastasis, making integrins pivotal therapeutic targets. Recent advances in structural biology, biophysical measurements and live‐cell imaging have refined our understanding of the energy landscapes and molecular checkpoints governing integrin function, offering guidance for the rational design of selective modulators.

Research from Nature Portfolio

A near‐atomic resolution cryo‐electron microscopy analysis of the full‐length platelet integrin αIIbβ3 has revealed unexpected features of its inactive and drug‐bound states. The inactive receptor adopts a bent conformation in which the transmembrane helices are separated and the ligand‐binding site remains accessible, challenging the notion that membrane proximity alone occludes ligand access. Binding of a clinically employed antagonist induces pronounced conformational shifts, clarifying how therapeutic molecules can both inhibit thrombosis and impair primary haemostasis. These structural insights refine models of activation and inform the development of safer integrin inhibitors.

Single‐molecule tension‐sensor imaging in migrating T cells has demonstrated that actin‐driven forces exerted on the cytoplasmic β‐subunit directly stabilise an active integrin conformation. This work established that localised actin polymerisation generates intramolecular tension that is essential to coordinate activation at the leading edge, linking cytoskeletal dynamics and integrin‐mediated traction in immune motility. The study highlights the central role of mechanical force in integrin regulation and suggests conserved principles across diverse cell types.

Integrin Activation and Signaling Mechanisms publication trend

The graph below shows the total number of articles in integrin activation and signaling mechanisms across all publications each year (not limited to Nature Index journals).

Technical terms

Integrin heterodimer: A receptor composed of one α and one β subunit that together mediate cell adhesion and signalling.

Inside‐out signalling: The process by which intracellular events induce conformational changes in integrins to increase their extracellular ligand affinity.

Outside‐in signalling: The cascade of intracellular pathways triggered by ligand engagement of the activated integrin.

Talin: A cytoskeletal adaptor protein that binds β‐integrin tails to destabilise inhibitory interfaces and promote activation.

Kindlin: A co‐activator that cooperates with talin at the integrin cytoplasmic domain to stabilise the high‐affinity state.

Conformational equilibrium: The distribution of integrin states (bent, extended‐closed, extended‐open) determined by free‐energy landscapes.

Mechanotransduction: The conversion of mechanical forces into biochemical signals via integrin‐cytoskeleton linkages.

References

1. Targeting integrin pathways: mechanisms and advances in therapy. Signal Transduction and Targeted Therapy (2023).
2. Cryo-EM structures of full-length integrin αIIbβ3 in native lipids. Nature Communications (2023).
3. Force-Regulated Spontaneous Conformational Changes of Integrins α5β1 and αVβ3. ACS Nano (2023).
4. Coordinated integrin activation by actin-dependent force during T-cell migration. Nature Communications (2016).