Swallowed Whole

With its target in reach, it opens wide and swallows it whole. This is phagocytosis; a process immune cells use to ingest harmful micro-organisms. Phagocytosis requires a cell to quickly reorganise its architecture to bend its membrane and change shape. This involves a complex of proteins called actomyosin, though the molecular details are unclear. Here, researchers combined live-cell lattice light-sheet microscopy (LLSM) and microparticle traction force microscopy (MP-TFM) to investigate the proteins involved and forces generated in real-time as immune cells ingest microparticles. During ingestion (pictured), the microparticles were squeezed — a process called constriction. The team revealed that constriction is driven by a protein complex called Arp2/3 which assembles protrusions of actin (grey), myosin 1e and 1f, taking on the appearance of a ring of teeth. As the macrophage closes in around the microparticle, myosin-II plays a role. This brings us closer to understanding how our body fights infection.

Written by Lux Fatimathas

Lux Fatimathas

Writer

Having pursued science through a career in research, communications and publishing, she is currently a writer and editor for a healthcare marketing agency and also juggles freelance science writing.

• Video from work by Daan Vorselen and Sarah R Barger, and colleagues
• Department of Cell and Developmental Biology, State University of New York Upstate Medical University, Syracuse, NY and Department of Biology and Howard Hughes Medical Institute, University of Washington, Seattle, WA, USA
• Video originally published with a Creative Commons Attribution 4.0 International (CC BY 4.0)
• Published in eLife, October 2021