Lamellipodit

Lamellipodit is a cellular protrusion observed at the leading edge of motile cells. It consists of a dense network of branched filamentous actin, which provides the structural framework for the thin, sheet-like extension that pushes the plasma membrane outward. The lamellipod’s architecture is maintained by the Arp2/3 complex, which initiates branch formation, and by various actin‑regulating proteins such as cofilin, profilin, and WASp family members. As the actin network polymerizes, treadmilling occurs: new monomers add at the barbed ends while older monomers are removed from pointed ends, sustaining forward movement.

Lamellipodit formation is regulated by signaling cascades downstream of Rho GTPases, including Rac1, which activates the WAVE complex to initiate Arp2/3 recruitment. Factors such as growth factors, chemokines, and extracellular matrix components can influence lamellipod dynamics, making them essential for processes like chemotaxis, wound healing, and embryonic development. In addition to motility, lamellipodia are implicated in endocytosis, cell–cell adhesion, and mechanosensing, as they sense and respond to mechanical forces from the cellular environment.

The study of lamellipodit offers insight into cytoskeletal remodeling and cell motility disorders. Imaging techniques such as fluorescence microscopy and electron microscopy are routinely employed to visualize their structure. Understanding lamellipod formation and regulation provides a foundation for therapeutic strategies targeting abnormal cell migration, including metastasis and tissue regeneration.