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The Coffin‐Lowry syndrome‐associated protein RSK2 is implicated in calcium‐regulated exocytosis through the regulation of PLD1
Author(s) -
Vitale Nicolas,
ZeniouMeyer Maria,
Béglé Aurélie,
Bader MarieFrance
Publication year - 2009
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.23.1_supplement.868.1
Subject(s) - exocytosis , phospholipase d , microbiology and biotechnology , phosphatidic acid , biology , phosphorylation , secretion , signal transduction , biochemistry , membrane , phospholipid
Exocytosis of neurotransmitters and hormones occurs through the fusion of secretory vesicles with the plasma membrane. This highly regulated process involves key proteins such as SNAREs, and also specific lipids at the site of membrane fusion. Phospholipase D (PLD) has recently emerged as a promoter of membrane fusion in various exocytotic events potentially by providing fusogenic cone‐shaped phosphatidic acid. We show here that PLD1 is regulated by ribosomal S6 kinase 2 (RSK2)‐dependent phosphorylation. RSK2 is activated by a high K+induced rise in cytosolic calcium. Expression of inactive RSK2 mutants or selective knock down of endogenous RSK2 dramatically affects the different kinetic components of the exocytotic response in chromaffin cells. RSK2 physically interacts with and stimulates PLD activity through the phosphorylation of Thr147 in the PLD1 amino‐terminal PX‐domain. Expression of PLD1 phosphomimetic mutants fully restores secretion in cells depleted of RSK2, suggesting that RSK2 is a critical upstream signaling element in the activation of PLD1 to produce the lipids required for exocytosis. We propose that PLD‐related defects in neuronal and endocrine activities could contribute to the effect observed after the loss of function mutations in Rsk2 that leads to Coffin‐Lowry syndrome (CLS), an X‐linked form of growth and mental retardation.