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Tethering and tickling: a new role for the phosphatidylserine receptor.

Somersan S, Bhardwaj N - J. Cell Biol. (2001)

Bottom Line: Several receptors are implicated in apoptotic cell (AC) uptake by phagocytic cells; however, their relative dominance in mammalian systems remains to be established.New studies shed light on the role of the phosphatidyl serine (PS) receptor (PSR).Ligation of PSR by PS on AC surfaces is considered essential for signaling uptake of ACs that are tethered to phagocytes via other receptors.

View Article: PubMed Central - PubMed

Affiliation: The Laboratory of Molecular Neuro-Oncology, The Rockefeller University, New York, NY 10021, USA.

ABSTRACT
Several receptors are implicated in apoptotic cell (AC) uptake by phagocytic cells; however, their relative dominance in mammalian systems remains to be established. New studies shed light on the role of the phosphatidyl serine (PS) receptor (PSR). Ligation of PSR by PS on AC surfaces is considered essential for signaling uptake of ACs that are tethered to phagocytes via other receptors.

Show MeSH
Phagocyte apoptotic cell interactions. Several receptors are implicated in the uptake of ACs by phagocytes. These receptors interact with their ligands on the AC either directly or via bridging proteins. The dominance, cooperation, and redundancy amongst these receptors are discussed in the text. BC, bovine conglutinin; LA, lactadherin; TSP, thrombospondin. MBL, SPA, BC, and C1q are defense collagens, which bridge AC to phagocytes via calretculin and CD91. LA and TSP are putative bridging molecules for the αvβ3 and αvβ5 integrins, respectively. The latter are thought to cooperate with CD36 in AC uptake. Gas6, a product of growth arrest–specific gene 6, appears to bridge PS with receptor tyrosine kinases such as Mer.
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fig1: Phagocyte apoptotic cell interactions. Several receptors are implicated in the uptake of ACs by phagocytes. These receptors interact with their ligands on the AC either directly or via bridging proteins. The dominance, cooperation, and redundancy amongst these receptors are discussed in the text. BC, bovine conglutinin; LA, lactadherin; TSP, thrombospondin. MBL, SPA, BC, and C1q are defense collagens, which bridge AC to phagocytes via calretculin and CD91. LA and TSP are putative bridging molecules for the αvβ3 and αvβ5 integrins, respectively. The latter are thought to cooperate with CD36 in AC uptake. Gas6, a product of growth arrest–specific gene 6, appears to bridge PS with receptor tyrosine kinases such as Mer.

Mentions: Apoptosis or programmed cell death occurs during embryogenesis, normal cell turnover, and as a consequence of immune mediated, infectious, or inflammatory effects. Clearance of intact apoptotic cells (ACs)* by phagocytes protects surrounding tissues from intracellular factors and reduces the likelihood of tissue damage caused by inappropriate autoimmune responses. ACs exhibit numerous changes including the surface exposure of phosphatidylserine (PS) and alteration of membrane carbohydrates. Multiple ligands and receptors have been implicated in the recognition and uptake of ACs (Fig. 1), but attempts to assign function to discrete receptors has proven difficult. In this issue, Hoffmann et al. (2001) assess the relative role of various receptors through AC surrogates that ligate individual receptors. These surrogates consist of biotinylated human erythrocytes coated with avidin (Eba), which are bound to a biotinylated protein ligand or antireceptor antibody, creating Ebab-X. Binding to and internalization of Ebab-X by macrophages and other cells is evaluated in the absence of serum (to prevent interference of serum proteins) and is distinguishable by microscopy.


Tethering and tickling: a new role for the phosphatidylserine receptor.

Somersan S, Bhardwaj N - J. Cell Biol. (2001)

Phagocyte apoptotic cell interactions. Several receptors are implicated in the uptake of ACs by phagocytes. These receptors interact with their ligands on the AC either directly or via bridging proteins. The dominance, cooperation, and redundancy amongst these receptors are discussed in the text. BC, bovine conglutinin; LA, lactadherin; TSP, thrombospondin. MBL, SPA, BC, and C1q are defense collagens, which bridge AC to phagocytes via calretculin and CD91. LA and TSP are putative bridging molecules for the αvβ3 and αvβ5 integrins, respectively. The latter are thought to cooperate with CD36 in AC uptake. Gas6, a product of growth arrest–specific gene 6, appears to bridge PS with receptor tyrosine kinases such as Mer.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2198851&req=5

fig1: Phagocyte apoptotic cell interactions. Several receptors are implicated in the uptake of ACs by phagocytes. These receptors interact with their ligands on the AC either directly or via bridging proteins. The dominance, cooperation, and redundancy amongst these receptors are discussed in the text. BC, bovine conglutinin; LA, lactadherin; TSP, thrombospondin. MBL, SPA, BC, and C1q are defense collagens, which bridge AC to phagocytes via calretculin and CD91. LA and TSP are putative bridging molecules for the αvβ3 and αvβ5 integrins, respectively. The latter are thought to cooperate with CD36 in AC uptake. Gas6, a product of growth arrest–specific gene 6, appears to bridge PS with receptor tyrosine kinases such as Mer.
Mentions: Apoptosis or programmed cell death occurs during embryogenesis, normal cell turnover, and as a consequence of immune mediated, infectious, or inflammatory effects. Clearance of intact apoptotic cells (ACs)* by phagocytes protects surrounding tissues from intracellular factors and reduces the likelihood of tissue damage caused by inappropriate autoimmune responses. ACs exhibit numerous changes including the surface exposure of phosphatidylserine (PS) and alteration of membrane carbohydrates. Multiple ligands and receptors have been implicated in the recognition and uptake of ACs (Fig. 1), but attempts to assign function to discrete receptors has proven difficult. In this issue, Hoffmann et al. (2001) assess the relative role of various receptors through AC surrogates that ligate individual receptors. These surrogates consist of biotinylated human erythrocytes coated with avidin (Eba), which are bound to a biotinylated protein ligand or antireceptor antibody, creating Ebab-X. Binding to and internalization of Ebab-X by macrophages and other cells is evaluated in the absence of serum (to prevent interference of serum proteins) and is distinguishable by microscopy.

Bottom Line: Several receptors are implicated in apoptotic cell (AC) uptake by phagocytic cells; however, their relative dominance in mammalian systems remains to be established.New studies shed light on the role of the phosphatidyl serine (PS) receptor (PSR).Ligation of PSR by PS on AC surfaces is considered essential for signaling uptake of ACs that are tethered to phagocytes via other receptors.

View Article: PubMed Central - PubMed

Affiliation: The Laboratory of Molecular Neuro-Oncology, The Rockefeller University, New York, NY 10021, USA.

ABSTRACT
Several receptors are implicated in apoptotic cell (AC) uptake by phagocytic cells; however, their relative dominance in mammalian systems remains to be established. New studies shed light on the role of the phosphatidyl serine (PS) receptor (PSR). Ligation of PSR by PS on AC surfaces is considered essential for signaling uptake of ACs that are tethered to phagocytes via other receptors.

Show MeSH