Release of cholesterol-rich particles from the macrophage plasma membrane during movement of filopodia and lamellipodia
Abstract
Cultured mouse peritoneal macrophages release large numbers of ~30-nm cholesterol-rich particles. Here, we show that those particles represent fragments of the plasma membrane that are pulled away and left behind during the projection and retraction of filopodia and lamellipodia. Consistent with this finding, the particles are enriched in proteins found in focal adhesions, which attach macrophages to the substrate. The release of particles is abolished by blocking cell movement (either by depolymerizing actin with latrunculin A or by inhibiting myosin II with blebbistatin). Confocal microscopy and NanoSIMS imaging studies revealed that the plasma membrane–derived particles are enriched in 'accessible cholesterol' (a mobile pool of cholesterol detectable with the modified cytolysin ALO-D4) but not in sphingolipid-sequestered cholesterol (a pool detectable with ostreolysin A (OlyA)]. The discovery that macrophages release cholesterol-rich particles during cellular locomotion is likely relevant to cholesterol efflux and could contribute to extracellular cholesterol deposition in atherosclerotic plaques.
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All data generated or analysed during this study are included in the manuscript and supporting files.
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Funding
National Heart, Lung, and Blood Institute (HL090553)
- Stephen G Young
National Heart, Lung, and Blood Institute (HL087228)
- Stephen G Young
National Heart, Lung, and Blood Institute (HL125335))
- Stephen G Young
Fondation Leducq (12CVD04).)
- Stephen G Young
Ruth L Kirschstein National Research Service Award (T32HL69766))
- Xuchen Hu
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Ethics
Animal experimentation: Animal housing and experimental protocols were approved by UCLA's Animal Research Committee (ARC; 2004-125-51). The animals were housed in an AAALAC (Association for Assessment andAccreditation of Laboratory Animal Care International)-approved facility and cared for accordingto guidelines established by UCLA's Animal Research Committee.
Copyright
© 2019, Hu 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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