ERK activation by Ca2+ ionophores depends on Ca2+ entry in lymphocytes but not in platelets, and does not conduct membrane scrambling.
Rapid Ca2+-dependent phospholipid (PL) reorganization (scrambling) at the plasma membrane is a mechanism common to hematopoietic cells exposing procoagulant phosphatidylserine (PS). The aim of this research was to determine whether activation of the extracellular signal-regulated kinase (ERK) pathway was required for PL scrambling, based on a single report analyzing both responses induced by Ca2+ ionophores in megakaryoblastic HEL cells. Ca2+ ionophore-stimulated ERK phosphorylation was induced in platelets without external Ca2+, whereas exogenous Ca2+ entry was crucial for ERK activation in Jurkat T cells. In both cells, membrane scrambling only occurred following Ca2+ entry and was not blocked by inhibiting ERK phosphorylation. Furthermore, ERK proteins are strongly phosphorylated in transformed B lymphoblastic cell lines, which do not expose PS in their resting state. Overall, the data demonstrated that ERK activation and membrane scrambling are independent mechanisms.
INSERM U770 and Université Paris-Sud, 80 rue du Général Leclerc, 94276 Le Kremlin-Bicêtre cedex, France.
A
A
Arachiche
I
I
Badirou
J
J
Dachary-Prigent
I
I
Garcin
D
D
Geldwerth-Feniger
D
D
Kerbiriou-Nabias
D001792:Blood Platelets / Q000378:metabolism; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D005434:Flow Cytometry; D006801:Humans; D007476:Ionophores / Q000378:metabolism*; D019169:Jurkat Cells; D008214:Lymphocytes / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D010743:Phospholipids / Q000378:metabolism*; D010766:Phosphorylation; D015398:Signal Transduction / Q000502:physiology*
D007476:Ionophores; D010743:Phospholipids; D048049:Extracellular Signal-Regulated MAP Kinases; D002118:Calcium