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. 2015 Jun 5;2(4):e964625. doi: 10.4161/23723548.2014.964625

Figure 1.

Figure 1.

Simplified model for phosphatidylserine receptor-mediated efferocytosis. Apoptotic cells display various ‘eat me’ signals like phosphatidylserine (PS) on the outer leaflet of the plasma membrane that are recognized directly or indirectly (via bridging molecules such as Gas6) by different phagocytic PS receptors, including BAI1, TAMs, Stabilin1/2, TIM1/4, and CD300 family members, such as human CD300A or mouse Cd300lb and Cd300lf. The CD300 receptor family consists of both activating and inhibitory receptors. Inhibitory receptors, like CD300A, harbor immune-receptor tyrosine-based inhibitory motifs (ITIMs) within their intracellular tail to regulate signaling events. Cd300lf functions as an activating receptor via the PI3K pathway or as an inhibitory receptor, depending on cell type. The activating receptor Cd300lb requires binding to an adaptor protein, such as DAP12, to gain signaling capacity and regulates efferocytosis via the DAP12-Syk-PI3K-AKT pathway. BAI1, brain-specific angiogenesis inhibitor 1; DAP12, DNAX activation protein of 12 kDa; Gas6, growth arrest-specific 6; TAM, Tyro3, Axl, and MerTK receptor tyrosine kinase; TIM1/4, T-cell immunoglobulin and mucin domain containing 1 and 4.