Actin-Binding Proteins and Cell Motility Mechanisms

Actin-binding proteins form a diverse repertoire of regulators that orchestrate the assembly, organisation and dynamics of actin filaments to drive cell movement. Bundling and crosslinking proteins such as α-actinins stabilise parallel or contractile filament arrays, while severing factors like cofilin disassemble older filaments to replenish the monomer pool. Nucleating complexes, notably Arp2/3, initiate branched networks that power lamellipodial protrusion, whereas formins generate unbranched filaments underlying filopodia. Capping and monomer-sequestering proteins fine-tune filament length and availability. These molecular activities are integrated into a cyclical motility programme comprising protrusion of the leading edge, formation and maturation of adhesions to the substrate, myosin-driven contraction to pull the cell body forward, and rear-end detachment. Mechanotransduction links extracellular cues, such as matrix stiffness or growth factors, to changes in cytoskeletal architecture, enabling cells to adapt motility strategies in processes ranging from wound healing and immune surveillance to cancer invasion and microbial pathogenesis. Understanding the biophysical principles and regulatory circuits of actin-binding proteins is essential for therapeutic targeting of aberrant migration in disease and for the engineering of cell-based delivery systems.

Research from Nature Portfolio

Recent studies have directly quantified the force-dependent lifetimes of human α-actinin dimers at the single-molecule level, revealing lifetimes in excess of 100 seconds under physiologically relevant forces. Paradoxically, this ultra-high mechanical stability derives from multiple weak interactions between spectrin‐repeat subdomains, which confer a spectrum of conformational states ranging from folded to unfolded. Such findings elucidate how weak modular contacts can coalesce into robust force-bearing assemblies, enhancing our understanding of cytoskeletal mechanotransduction and suggesting novel routes to modulate cellular stiffness and adhesion under mechanical stress.

Actin-Binding Proteins and Cell Motility Mechanisms publication trend

The graph below shows the total number of articles in actin-binding proteins and cell motility mechanisms across all publications each year (not limited to Nature Index journals).

Technical terms

α-Actinin: An antiparallel homodimeric actin crosslinker that organizes filaments into bundles or contractile arrays and associates with adhesion sites.

Arp2/3 complex: A seven-subunit nucleator that creates branched actin networks central to lamellipodial protrusion.

Filopodia: Finger-like, actin-bundled protrusions that sense the environment and guide directional movement.

Lamellipodia: Broad, sheet-like leading-edge extensions driven by dendritic actin assembly.

Focal adhesion: Multi-protein assemblies linking the actin cytoskeleton to extracellular matrix, transmitting mechanical force and signalling cues.

Stress fibre: Contractile bundles of actin and myosin that generate tension across the cell body.

Mechanotransduction: Conversion of mechanical stimuli into biochemical signals that regulate cytoskeletal dynamics and cell behaviour.

References

1. Multi-domain interaction mediated strength-building in human α-actinin dimers unveiled by direct single-molecule quantification. Nature Communications (2024).
2. From stress fiber to focal adhesion: a role of actin crosslinkers in force transmission. Frontiers in Cell and Developmental Biology (2024).
3. Role of ACTN4 in Tumorigenesis, Metastasis, and EMT. Cells (2019).
4. Induction of filopodia formation by α-Actinin-2 via RelA with a feedforward activation loop promoting overt bone marrow metastasis of gastric cancer. Journal of Translational Medicine (2023).