Phospholipid scramblase 1 modulates a selected set of IgE receptor-mediated mast cell responses through LAT-dependent pathway.
Engagement of the IgE receptor (FcepsilonRI) on mast cells leads to the release of preformed and newly formed mediators as well as of cytokines. The signaling pathways responsible for these responses involve tyrosine phosphorylation of multiple proteins. We previously reported the phosphorylation on tyrosine of phospholipid scramblase 1 (PLSCR1) after FcepsilonRI aggregation. Here, PLSCR1 expression was knocked down in the RBL-2H3 mast cell line using short hairpin RNA. Knocking down PLSCR1 expression resulted in significantly impaired degranulation responses after FcepsilonRI aggregation and release of vascular endothelial growth factor, whereas release of MCP-1 was minimally affected. The release of neither leukotriene C4 nor prostaglandin D2 was altered by knocking down of PLSCR1. Analysis of FcepsilonRI-dependent signaling pathways revealed that whereas tyrosine phosphorylation of ERK and Akt was unaffected, tyrosine phosphorylation of LAT was significantly reduced in PLSCR1 knocked down cells. Tyrosine phosphorylation of phospholipase Cgamma1 and consequently the mobilization of calcium were also significantly reduced in these cells. In nonactivated mast cells, PLSCR1 was found in part in lipid rafts where it was further recruited after cell activation and was constitutively associated with Lyn and Syk but not with LAT or Fyn. Altogether, these data identify PLSCR1 as a novel amplifier of FcepsilonRI signaling that acts selectively on the Lyn-initiated LAT/phospholipase Cgamma1/calcium axis, resulting in potentiation of a selected set of mast cell responses.
Amir-Moazami
Omid
O
INSERM U699, and Université Paris 7, FacultédeMédecine Xavier Bichat, 16 Rue Henri Huchard, F-75018 Paris, France.
Alexia
Catherine
C
INSERM U699, and Université Paris 7, FacultédeMédecine Xavier Bichat, 16 Rue Henri Huchard, F-75018 Paris, France.
Charles
Nicolas
N
INSERM U699, and Université Paris 7, FacultédeMédecine Xavier Bichat, 16 Rue Henri Huchard, F-75018 Paris, France.
Launay
Pierre
P
INSERM U699, and Université Paris 7, FacultédeMédecine Xavier Bichat, 16 Rue Henri Huchard, F-75018 Paris, France.
Monteiro
Renato C
RC
INSERM U699, and Université Paris 7, FacultédeMédecine Xavier Bichat, 16 Rue Henri Huchard, F-75018 Paris, France.
Benhamou
Marc
M
INSERM U699, and Université Paris 7, FacultédeMédecine Xavier Bichat, 16 Rue Henri Huchard, F-75018 Paris, France. Electronic address: Marc.Benhamou@inserm.fr.
D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D006801:Humans; D008407:Mast Cells / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism*; D051966:Phospholipase C gamma / Q000378:metabolism*; D049294:Phospholipid Transfer Proteins / Q000378:metabolism / Q000502:physiology*; D010750:Phosphoproteins / Q000378:metabolism*; D015230:Prostaglandin D2 / Q000378:metabolism; D051381:Rats; D017455:Receptors, IgE / Q000737:chemistry* / Q000378:metabolism*; D015398:Signal Transduction; D019061:src-Family Kinases / Q000378:metabolism*
D048868:Adaptor Proteins, Signal Transducing; C110810:LAT protein, human; C491733:Lat protein, rat; D008565:Membrane Proteins; C493422:PLSCR1 protein, human; C532350:PLSCR1 protein, rat; D049294:Phospholipid Transfer Proteins; D010750:Phosphoproteins; D017455:Receptors, IgE; C060902:lyn protein-tyrosine kinase; D019061:src-Family Kinases; D048049:Extracellular Signal-Regulated MAP Kinases; D051966:Phospholipase C gamma; D015230:Prostaglandin D2; D002118:Calcium