PMID- 17242159
OWN - NLM
STAT- MEDLINE
DCOM- 20070517
LR  - 20211203
IS  - 1530-6860 (Electronic)
IS  - 0892-6638 (Linking)
VI  - 21
IP  - 4
DP  - 2007 Apr
TI  - Phospholipase D2-derived phosphatidic acid binds to and activates ribosomal p70 
      S6 kinase independently of mTOR.
PG  - 1075-87
AB  - The product of phospholipase D (PLD) enzymatic action in cell membranes, 
      phosphatidic acid (PA), regulates kinases implicated in NADPH oxidase activation, 
      as well as the mammalian target of rapamycin (mTOR) kinase. However, other 
      protein targets for this lipid second messenger must exist in order to explain 
      other key PA-mediated cellular functions. In this study, PA was found to 
      specifically and saturably bind to and activate recombinant and 
      immunoprecipitated endogenous ribosomal S6 kinase (S6K) with a stoichiometry of 
      94:1 lipid/protein. Polyphosphoinositides PI4-P and PI4,5P2 and cardiolipin could 
      also bind to and activate S6K, albeit with different kinetics. Conversely, PA 
      with at least one acyl side chain saturated (10:0) was ineffective in binding or 
      activating the enzyme. Transfection of COS-7 cells with a wild-type 
      myc-(pcDNA)-PLD2 construct resulted in high PLD activity, concomitantly with an 
      increase in ribosomal p70S6K enzyme activity and phosphorylation in T389 and 
      T421/S424 as well as phosphorylation of p70S6K's natural substrate S6 protein in 
      S235/S236. Overexpression of a lipase inactive mutant (K758R), however, failed to 
      induce an increase in both PLD and S6K activity or phosphorylation, indicating 
      that the enzymatic activity of PLD2 (i.e., synthesis of PA) must be present to 
      affect S6K. Neither inhibiting mTOR kinase activity with rapamycin nor silencing 
      mTOR gene expression altered the augmentative effect of PLD2 exerted on p70S6K 
      activity. This finding indicates that PA binds to and activates p70S6K, even in 
      the absence of mTOR. Lastly, COS-7 transfection with PLD2 changed the pattern of 
      subcellular expression, and a colocalization of S6K and PLD2 was observed by 
      immunofluorescence microscopy. These results show for the first time a direct 
      (mTOR-independent) participation of PLD in the p70S6K pathway and implicate PA as 
      a nexus that brings together cell phospholipases and kinases.
FAU - Lehman, Nicholas
AU  - Lehman N
AD  - Cell Biology and Physiology, Wright State University, School of Medicine, 3640 
      Colonel Glenn Hwy., Dayton, Ohio 45435, USA.
FAU - Ledford, Bill
AU  - Ledford B
FAU - Di Fulvio, Mauricio
AU  - Di Fulvio M
FAU - Frondorf, Kathleen
AU  - Frondorf K
FAU - McPhail, Linda C
AU  - McPhail LC
FAU - Gomez-Cambronero, Julian
AU  - Gomez-Cambronero J
LA  - eng
GR  - R01 AI022564/AI/NIAID NIH HHS/United States
GR  - AI22564/AI/NIAID NIH HHS/United States
GR  - HL056653/HL/NHLBI NIH HHS/United States
PT  - Journal Article
PT  - Research Support, N.I.H., Extramural
DEP - 20070122
PL  - United States
TA  - FASEB J
JT  - FASEB journal : official publication of the Federation of American Societies for 
      Experimental Biology
JID - 8804484
RN  - 0 (Lipids)
RN  - 0 (Phosphatidic Acids)
RN  - EC 2.7.- (Protein Kinases)
RN  - EC 2.7.1.1 (MTOR protein, human)
RN  - EC 2.7.11.1 (Ribosomal Protein S6 Kinases, 70-kDa)
RN  - EC 2.7.11.1 (TOR Serine-Threonine Kinases)
RN  - EC 3.1.4.- (phospholipase D2)
RN  - EC 3.1.4.4 (Phospholipase D)
SB  - IM
MH  - Animals
MH  - COS Cells
MH  - Chlorocebus aethiops
MH  - Enzyme Activation
MH  - *Gene Expression Regulation, Enzymologic
MH  - Humans
MH  - Kinetics
MH  - Lipids/chemistry
MH  - Phosphatidic Acids/*metabolism
MH  - Phospholipase D/*metabolism
MH  - Phosphorylation
MH  - Protein Binding
MH  - Protein Kinases/*metabolism
MH  - Ribosomal Protein S6 Kinases, 70-kDa/*metabolism
MH  - Signal Transduction
MH  - TOR Serine-Threonine Kinases
EDAT- 2007/01/24 09:00
MHDA- 2007/05/18 09:00
CRDT- 2007/01/24 09:00
PHST- 2007/01/24 09:00 [pubmed]
PHST- 2007/05/18 09:00 [medline]
PHST- 2007/01/24 09:00 [entrez]
AID - fj.06-6652com [pii]
AID - 10.1096/fj.06-6652com [doi]
PST - ppublish
SO  - FASEB J. 2007 Apr;21(4):1075-87. doi: 10.1096/fj.06-6652com. Epub 2007 Jan 22.