Signalling role for ARF and phospholipase D in mast cell exocytosis stimulated by crosslinking of the high affinity FcepsilonR1 receptor.
Phospholipase D (PLD) catalyses the hydrolysis of phosphatidylcholine to generate the lipid second messenger, phosphatidate (PA). Two mammalian phospholipase Ds (PLD1 and PLD2) have been cloned and both are present in RBL-2H3 mast cells. PLD1 is localised to secretory granules whilst PLD2 is localised to the plasma membrane, and the activity of both enzymes is increased upon antigen stimulation. Primary alcohols specifically interfere with the production of PLD-derived PA and are found to be potent inhibitors of antigen-stimulated exocytosis. One major intracellular regulator for PLD activity and exocytosis is ARF proteins, as depletion by permeabilisation leads to loss of both antigen-mediated PLD activation and exocytosis. Both responses can be restored in depleted cells by re-addition of ARF1 or ARF6. ARF proteins and PLD-derived PA synergistically regulate the activity of a Type I PIP 5-kinasealpha. It is suggested that ARF, by activating PLD and PIP 5-kinase activities regulate PA and PI(4,5)P(2) levels, and both are critical components of the exocytosis machinery in mast cells.
Cockcroft
Shamshad
S
Department of Physiology, Rockefeller Building, 21 University Street, University College London, WC1E 6JJ, London, UK. s.cockcroft@ucl.ac.uk
Way
Gemma
G
O'Luanaigh
Niamh
N
Pardo
Raul
R
Sarri
Elisabeth
E
Fensome
Amanda
A
D020823:ADP-Ribosylation Factor 1 / Q000502:physiology; D000089982:ADP-Ribosylation Factor 6; D020727:ADP-Ribosylation Factors / Q000502:physiology*; D000818:Animals; D005089:Exocytosis; D008407:Mast Cells / Q000166:cytology / Q000201:enzymology / Q000276:immunology*; D010712:Phosphatidic Acids / Q000502:physiology; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000378:metabolism; D010739:Phospholipase D / Q000502:physiology*; D051381:Rats; D017455:Receptors, IgE / Q000378:metabolism*; D015398:Signal Transduction
D000089982:ADP-Ribosylation Factor 6; D010712:Phosphatidic Acids; D019269:Phosphatidylinositol 4,5-Diphosphate; D017455:Receptors, IgE; C105606:phospholipase D2; D010739:Phospholipase D; C106801:phospholipase D1; D020823:ADP-Ribosylation Factor 1; D020727:ADP-Ribosylation Factors; C000715349:Arf6 protein, rat