What is the Difference Between Lamellipodia and Filopodia?

Lamellipodia and filopodia are both actin-based protrusions found in migrating cells, but they have distinct structures and functions. Here are the main differences between them:

1. Structure: Lamellipodia are broad, flat protrusions that extend from the cell body, while filopodia are slender, finger-like protrusions that extend beyond the leading edge of lamellipodia. Filopodia are composed of a bundle of parallel linear actin filaments.
2. Protrusion Force: Lamellipodia produce greater protrusion forces than filopodia.
3. Function: Lamellipodia are primarily involved in cell movement and adhesion to the extracellular matrix via p21-activated kinases (PAKs). Filopodia, on the other hand, are considered cellular antennas that sense chemical and/or mechanical cues in the environment. They play roles in sensing, migration, neurite outgrowth, and cell-cell interaction.
4. Migration Mode: Lamellipodia are associated with a random walk mode of migration, where cells move in a less directed manner. Filopodia, in contrast, promote a ballistic, more exploitative mode of migration guided by external inputs.
5. Cell Types: Although most cells in culture express both lamellipodia and filopodia, some cells, such as keratocytes or neutrophils, express lamellipodia almost exclusively.

Comparative Table: Lamellipodia vs Filopodia

Lamellipodia and filopodia are two cellular extensions found in migratory cells that play crucial roles in cell mobility. They both contain actin filaments but have distinct structures and functions. Here is a table summarizing their differences:

Lamellipodia are cytoskeletal extensions that are highly specialized for cell migration, while filopodia are cytoplasmic extensions that probe the extracellular environment and play a role in sensing.