Phagocytic 'teeth' and myosin-II 'jaw' power target constriction during phagocytosis
Abstract
Phagocytosis requires rapid actin reorganization and spatially controlled force generation to ingest targets ranging from pathogens to apoptotic cells. How actomyosin activity directs membrane extensions to engulf such diverse targets remains unclear. Here, we combine lattice light-sheet microscopy (LLSM) with microparticle traction force microscopy (MP-TFM) to quantify actin dynamics and subcellular forces during macrophage phagocytosis. We show that spatially localized forces leading to target constriction are prominent during phagocytosis of antibody-opsonized targets. This constriction is largely driven by Arp2/3-mediated assembly of discrete actin protrusions containing myosin 1e and 1f ('teeth') that appear to be interconnected in a ring-like organization. Contractile myosin-II activity contributes to late-stage phagocytic force generation and progression, supporting a specific role in phagocytic cup closure. Observations of partial target eating attempts and sudden target release via a popping mechanism suggest that constriction may be critical for resolving complex in vivo target encounters. Overall, our findings present a phagocytic cup-shaping mechanism that is distinct from cytoskeletal remodeling in 2D cell motility and may contribute to mechanosensing and phagocytic plasticity.
Data availability
All quantitative data generated or analysed during this study are included in the manuscript and supporting files. Source Data files contain all numerical data to generate the figures. All confocal image data is available on FigShare repositories (DOI: 10.6084/m9.figshare.16666864 and DOI: 10.6084/m9.figshare.16677373).
Article and author information
Author details
Funding
American Heart Association (Predoctoral fellowship 18PRE34070066)
- Sarah R Barger
National Institute of Diabetes and Digestive and Kidney Diseases (R01DK083345)
- Mira Krendel
Associazione Italiana per la Ricerca sul Cancro (Investigator Grant 20716)
- Nils C Gauthier
Howard Hughes Medical Institute
- Julie A Theriot
Cancer Research Institute (CRI Irvington fellowship)
- Daan Vorselen
National Institute of General Medical Sciences (R01GM138652)
- Mira Krendel
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Ethics
Animal experimentation: This study was performed in compliance with the recommendations in the Guide for the Care and Use of Laboratory Animals of the National Institutes of Health. All procedures utilizing mice were performed according to the animal protocol (IACUC# 364) approved by the IACUC of SUNY Upstate Medical University and in compliance with all applicable ethical regulations.
Copyright
© 2021, Vorselen et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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