Acid sphingomyelinase activity triggers microparticle release from glial cells.
We have earlier shown that microglia, the immune cells of the CNS, release microparticles from cell plasma membrane after ATP stimulation. These vesicles contain and release IL-1beta, a crucial cytokine in CNS inflammatory events. In this study, we show that microparticles are also released by astrocytes and we get insights into the mechanism of their shedding. We show that, on activation of the ATP receptor P2X7, microparticle shedding is associated with rapid activation of acid sphingomyelinase, which moves to plasma membrane outer leaflet. ATP-induced shedding and IL-1beta release are markedly reduced by the inhibition of acid sphingomyelinase, and completely blocked in glial cultures from acid sphingomyelinase knockout mice. We also show that p38 MAPK cascade is relevant for the whole process, as specific kinase inhibitors strongly reduce acid sphingomyelinase activation, microparticle shedding and IL-1beta release. Our results represent the first demonstration that activation of acid sphingomyelinase is necessary and sufficient for microparticle release from glial cells and define key molecular effectors of microparticle formation and IL-1beta release, thus, opening new strategies for the treatment of neuroinflammatory diseases.
Bianco
Fabio
F
CNR Institute of Neuroscience and Department of Medical Pharmacology, University of Milano, Milano, Italy.
Perrotta
Cristiana
C
Novellino
Luisa
L
Francolini
Maura
M
Riganti
Loredana
L
Menna
Elisabetta
E
Saglietti
Laura
L
Schuchman
Edward H
EH
Furlan
Roberto
R
Clementi
Emilio
E
Matteoli
Michela
M
Verderio
Claudia
C
D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000378:metabolism; D018759:Adrenergic Uptake Inhibitors / Q000378:metabolism; D000345:Affinity Labels / Q000378:metabolism; D000818:Animals; D001921:Brain / Q000166:cytology / Q000378:metabolism / Q000473:pathology; D055252:Cell-Derived Microparticles / Q000201:enzymology* / Q000648:ultrastructure; D002478:Cells, Cultured; D004789:Enzyme Activation; D007099:Imipramine / Q000378:metabolism; D053583:Interleukin-1beta / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D008954:Models, Biological; D009457:Neuroglia / Q000166:cytology / Q000378:metabolism*; D010316:Particle Size; D018048:Receptors, Purinergic P2 / Q000378:metabolism; D058486:Receptors, Purinergic P2X7; D015398:Signal Transduction / Q000502:physiology; D013108:Sphingomyelin Phosphodiesterase / Q000235:genetics / Q000378:metabolism*; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism; D019061:src-Family Kinases / Q000378:metabolism
D018759:Adrenergic Uptake Inhibitors; D000345:Affinity Labels; D053583:Interleukin-1beta; C546469:P2rx7 protein, mouse; D018048:Receptors, Purinergic P2; D058486:Receptors, Purinergic P2X7; C033901:3'-O-(4-benzoyl)benzoyladenosine 5'-triphosphate; D000255:Adenosine Triphosphate; D019061:src-Family Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D013108:Sphingomyelin Phosphodiesterase; D007099:Imipramine