CD300b regulates the phagocytosis of apoptotic cells via phosphatidylserine recognition

Cell Death Differ. 2014 Nov;21(11):1746-57. doi: 10.1038/cdd.2014.86. Epub 2014 Jul 18.


The CD300 receptor family members are a group of molecules that modulate a variety of immune cell processes. We show that mouse CD300b (CLM7/LMIR5), expressed on myeloid cells, recognizes outer membrane-exposed phosphatidylserine (PS) and does not, as previously reported, directly recognize TIM1 or TIM4. CD300b accumulates in phagocytic cups along with F-actin at apoptotic cell contacts, thereby facilitating their engulfment. The CD300b-mediated activation signal is conveyed through CD300b association with the adaptor molecule DAP12, and requires a functional DAP12 ITAM motif. Binding of apoptotic cells promotes the activation of the PI3K-Akt kinase pathway in macrophages, while silencing of CD300b expression diminishes PI3K-Akt kinase activation and impairs efferocytosis. Collectively, our data show that CD300b recognizes PS as a ligand, and regulates the phagocytosis of apoptotic cells via the DAP12 signaling pathway.

Publication types

  • Research Support, N.I.H., Intramural

MeSH terms

  • Adaptor Proteins, Signal Transducing / metabolism*
  • Animals
  • Apoptosis / physiology*
  • Humans
  • Mice
  • Phagocytosis*
  • Phosphatidylinositol 3-Kinases / metabolism*
  • Phosphatidylserines / metabolism*
  • Receptors, Immunologic / metabolism*
  • Signal Transduction


  • Adaptor Proteins, Signal Transducing
  • LMIR5 protein, mouse
  • Phosphatidylserines
  • Receptors, Immunologic
  • Tyrobp protein, mouse
  • Phosphatidylinositol 3-Kinases