Raft nanodomains contribute to Akt/PKB plasma membrane recruitment and activation.
Membrane rafts are thought to be sphingolipid- and cholesterol-dependent lateral assemblies involved in diverse cellular functions. Their biological roles and even their existence, however, remain controversial. Using an original fluorescence correlation spectroscopy strategy that recently enabled us to identify nanoscale membrane organizations in live cells, we report here that highly dynamic nanodomains exist in both the outer and inner leaflets of the plasma membrane. Through specific inhibition of biosynthesis, we show that sphingolipids and cholesterol are essential and act in concert for formation of nanodomains, thus corroborating their raft nature. Moreover, we find that nanodomains play a crucial role in triggering the phosphatidylinositol-3 kinase/Akt signaling pathway, by facilitating Akt recruitment and activation upon phosphatidylinositol-3,4,5-triphosphate accumulation in the plasma membrane. Thus, through direct monitoring and controlled alterations of rafts in living cells, we demonstrate that rafts are critically involved in the activation of a signaling axis that is essential for cell physiology.
Lasserre
Rémi
R
Centre d'Immunologie de Marseille-Luminy, Université de la Méditerranée, Parc scientifique de Luminy, Case 906, F-13288 Marseille Cedex 09, France.
Guo
Xiao-Jun
XJ
Conchonaud
Fabien
F
Hamon
Yannick
Y
Hawchar
Omar
O
Bernard
Anne-Marie
AM
Soudja
Saïdi M'Homa
SM
Lenne
Pierre-François
PF
Rigneault
Hervé
H
Olive
Daniel
D
Bismuth
Georges
G
Nunès
Jacques A
JA
Payrastre
Bernard
B
Marguet
Didier
D
He
Hai-Tao
HT
D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D002784:Cholesterol / Q000096:biosynthesis; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006801:Humans; D019169:Jurkat Cells; D021962:Membrane Microdomains / Q000201:enzymology / Q000378:metabolism / Q000502:physiology; D051379:Mice; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology; D013050:Spectrometry, Fluorescence; D013107:Sphingolipids / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D013601:T-Lymphocytes / Q000378:metabolism
D002784:Cholesterol; D049452:Green Fluorescent Proteins; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; D013107:Sphingolipids