Phospholipid regulation of a cyclic AMP-specific phosphodiesterase (PDE4) from U937 cells.
The regulation of phosphodiesterase-4 (PDE4) by various phospholipids was explored using PDE4s partially purified from U937 cells. Preincubation (5 min, 4 degrees C) of the large molecular weight PDE4 denoted "Peak 2 PDE4" with mixed phosphatidic acids (PAs) produced a 2-fold increase in its Vmax without changing its Km (approximately 2 microM) for cyclic AMP. This "activation" was not limited to PAs with specific fatty acid substituents: Synthetic PAs containing saturated and/or unsaturated fatty acids 16-20 carbons long produced similar effects. Lysophosphatidic acids (LPAs) and phosphatidylserines (PSs) also induced PDE4 activation, whereas phosphatidylcholines (PCs), phosphatidylethanolamines (PEs) and diacylglycerol did not. Antibodies to a peptide region near the PDE4 catalytic site specifically inhibited PA-induced activation. The data demonstrate that anionic phospholipids can act as non-essential activators of a leukocyte PDE4, and suggest biochemical crosstalk between phospholipid-dependent and cyclic AMP-dependent signalling pathways in human leukocytes.
DiSanto
M E
ME
Inflammatory Diseases Division, Wyeth-Ayerst Research, Princeton, NJ 08543-8000, USA.
Glaser
K B
KB
Heaslip
R J
RJ
D015105:3',5'-Cyclic-AMP Phosphodiesterases; D000595:Amino Acid Sequence; D000818:Animals; D000917:Antibody Formation; D000242:Cyclic AMP / Q000378:metabolism*; D006152:Cyclic GMP / Q000494:pharmacology; D054703:Cyclic Nucleotide Phosphodiesterases, Type 4; D004789:Enzyme Activation / Q000187:drug effects; D005227:Fatty Acids / Q000032:analysis; D006801:Humans; D016403:Lymphoma, Large B-Cell, Diffuse / Q000473:pathology; D008246:Lysophospholipids / Q000494:pharmacology; D008969:Molecular Sequence Data; D009000:Monocytes / Q000187:drug effects* / Q000201:enzymology; D009363:Neoplasm Proteins / Q000378:metabolism; D010446:Peptide Fragments / Q000276:immunology; D010712:Phosphatidic Acids / Q000494:pharmacology; D010713:Phosphatidylcholines / Q000494:pharmacology; D010743:Phospholipids / Q000737:chemistry / Q000494:pharmacology*; D010727:Phosphoric Diester Hydrolases / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D011760:Pyrrolidinones / Q000494:pharmacology; D011817:Rabbits; D020889:Rolipram; D013329:Structure-Activity Relationship; D014407:Tumor Cells, Cultured / Q000187:drug effects
D005227:Fatty Acids; D008246:Lysophospholipids; D009363:Neoplasm Proteins; D010446:Peptide Fragments; D010712:Phosphatidic Acids; D010713:Phosphatidylcholines; D010743:Phospholipids; D011760:Pyrrolidinones; D000242:Cyclic AMP; D010727:Phosphoric Diester Hydrolases; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D054703:Cyclic Nucleotide Phosphodiesterases, Type 4; D006152:Cyclic GMP; D020889:Rolipram