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Updated: Apr 26, 2026

Quantification of Efferocytosis by Single-cell Fluorescence Microscopy
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CD300b regulates the phagocytosis of apoptotic cells via phosphatidylserine recognition

Y Murakami1, L Tian1, O H Voss1

  • 1Receptor Cell Biology Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, USA.

Cell Death and Differentiation
|July 19, 2014
PubMed

Insights

Mouse CD300b recognizes phosphatidylserine (PS) on apoptotic cells, facilitating their engulfment by myeloid cells. This process involves the DAP12 signaling pathway, enhancing immune cell function.

Area of Science:

  • Immunology
  • Cell Biology
  • Molecular Biology

Background:

  • The CD300 receptor family plays a crucial role in modulating immune cell functions.
  • Previous studies suggested CD300b recognizes TIM1 and TIM4, but this requires further investigation.

Purpose of the Study:

  • To elucidate the ligand recognition and signaling pathway of mouse CD300b (CLM7/LMIR5) in immune cells.
  • To investigate the role of CD300b in the phagocytosis of apoptotic cells.

Main Methods:

  • Expression analysis of mouse CD300b on myeloid cells.
  • Investigation of CD300b interaction with phosphatidylserine (PS), TIM1, and TIM4.
  • Analysis of CD300b localization during phagocytosis using F-actin staining.
  • Assessment of CD300b signaling via association with the DAP12 adaptor molecule and its ITAM motif.
  • Evaluation of the PI3K-Akt kinase pathway activation in macrophages.
  • Functional assays involving CD300b silencing to assess efferocytosis.

Main Results:

  • Mouse CD300b recognizes outer membrane-exposed phosphatidylserine (PS) on apoptotic cells, not TIM1 or TIM4.
  • CD300b localizes to phagocytic cups with F-actin, promoting apoptotic cell engulfment.
  • CD300b signaling is mediated through DAP12, requiring a functional DAP12 ITAM motif.
  • Apoptotic cell binding activates the PI3K-Akt pathway in macrophages via CD300b.
  • Silencing CD300b impairs PI3K-Akt activation and efferocytosis.

Conclusions:

  • CD300b recognizes phosphatidylserine (PS) as its primary ligand.
  • CD300b regulates apoptotic cell phagocytosis through the DAP12 signaling pathway.
  • This interaction is critical for efficient efferocytosis and immune cell activation.

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