Membranblebbing

Membranblebbing is a process in which the plasma membrane forms spherical protrusions, or blebs, as a result of local detachment of the actin cortex from the membrane and hydrostatic pressure from the cytoplasm. Blebbing is observed in many eukaryotic cells and can occur during development, cell migration, division, and response to stress, as well as during programmed cell death.

Blebs arise when the linkage between the plasma membrane and the underlying cortex weakens or is disrupted, allowing cytoplasmic pressure to push the membrane outward. This process is driven by actomyosin contraction, often regulated by the RhoA-ROCK pathway, and can involve influx of calcium and remodeling of actin. Retraction of a bleb requires reassembly of actin at the bleb rim, after which the bleb can collapse or pinch off as a microvesicle.

Blebbing is particularly prominent during apoptosis, where characteristic blebbing accompanies cellular disassembly, but it also features in dynamic cell motility (amoeboid movement) and cytokinesis, where blebs aid shape changes and separation of daughter cells.

Blebs are typically 1–5 micrometers in diameter, and cycles of expansion and retraction can occur rapidly. In some contexts, detached blebs contribute to intercellular communication via extracellular vesicles.