PAM mediates sustained inhibition of cAMP signaling by sphingosine-1-phosphate.
PAM (Protein Associated with Myc) is an almost ubiquitously expressed protein that is one of the most potent inhibitors of adenylyl cyclase activity known so far. Here we show that PAM is localized at the endoplasmic reticulum in HeLa cells and that upon serum treatment PAM is recruited to the plasma membrane, causing an inhibition of adenylyl cyclase activity. We purified the serum factor that induced PAM translocation and identified it as sphingosine-1-phosphate (S1P). Within 15 min after incubation with S1P, PAM appeared at the plasma membrane and was detectable for up to 120 min. Sphingosine-1-phosphate induced adenylyl cyclase inhibition in two phases: an initial (1-10 min) and a late (20-240 min) phase. The initial adenylyl cyclase inhibition was Gi-mediated and PAM independent. In the late phase, adenylyl cyclase inhibition was PAM dependent and attenuated cyclic AMP (cAMP) signaling by various cAMP-elevating signals. This makes PAM the longest lasting nontranscriptional regulator of adenylyl cyclase activity known to date and presents a novel mechanism for the temporal regulation of cAMP signaling.
Pierre
Sandra C
SC
Pharmazentrum frankfurt, Klinikum der Johann Wolfgang Goethe-Universität Frankfurt, Frankfurt, Germany.
Häusler
Julia
J
Birod
Kerstin
K
Geisslinger
Gerd
G
Scholich
Klaus
K
D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D000067956:Adenylyl Cyclase Inhibitors; D000262:Adenylyl Cyclases / Q000378:metabolism; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006367:HeLa Cells; D006801:Humans; D008246:Lysophospholipids / Q000494:pharmacology*; D006899:Mixed Function Oxygenases / Q000235:genetics / Q000378:metabolism*; D037342:Pertussis Toxin / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism; D021381:Protein Transport / Q000187:drug effects; D044967:Serum; D015398:Signal Transduction / Q000187:drug effects*; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000494:pharmacology*; D010738:Type C Phospholipases / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases
D048868:Adaptor Proteins, Signal Transducing; D000067956:Adenylyl Cyclase Inhibitors; D004791:Enzyme Inhibitors; D008246:Lysophospholipids; C060506:sphingosine 1-phosphate; D000242:Cyclic AMP; D006899:Mixed Function Oxygenases; C114022:MYCBP2 protein, human; D044767:Ubiquitin-Protein Ligases; D037342:Pertussis Toxin; D011493:Protein Kinase C; D010738:Type C Phospholipases; D000262:Adenylyl Cyclases; D013110:Sphingosine