title: The molecular basis of leukocyte adhesion involving phosphatidic acid and phospholipase D.
abstract: Defining how leukocytes adhere to solid surfaces, such as capillary beds, and the subsequent migration through the extracellular matrix, is a central biological issue. We show here that phospholipase D (PLD) and its enzymatic reaction product, phosphatidic acid (PA), regulate cell adhesion of immune cells (macrophages and neutrophils) to collagen and have defined the underlying molecular mechanism in a spatio-temporal manner that coincides with PLD activity timing. A rapid (t½ = 4 min) and transient activation of the PLD1 isoform occurs upon adhesion, and a slower (t½ = 7.5 min) but prolonged (>30 min) activation occurs for PLD2. Importantly, PA directly binds to actin-related protein 3 (Arp3) at EC50 = 22 nm, whereas control phosphatidylcholine did not bind. PA-activated Arp3 hastens actin nucleation with a kinetics of t½ = 3 min at 300 nm (compared with controls of no PA, t½ = 5 min). Thus, PLD and PA are intrinsic components of cell adhesion, which reinforce each other in a positive feedback loop and react from cues from their respective solid substrates. In nascent adhesion, PLD1 is key, whereas a sustained adhesion in mature or established focal points is dependent upon PLD2, PA, and Arp3. A prolonged adhesion could effectively counteract the reversible intrinsic nature of this cellular process and constitute a key player in chronic inflammation.
authors.affiliation: From the Department of Biochemistry and Molecular Biology, Wright State University School of Medicine, Dayton, Ohio 45435.
authors.forename: Francis
authors.initials: F
authors.lastname: Speranza
authors.affiliation: From the Department of Biochemistry and Molecular Biology, Wright State University School of Medicine, Dayton, Ohio 45435.
authors.forename: Madhu
authors.initials: M
authors.lastname: Mahankali
authors.affiliation: From the Department of Biochemistry and Molecular Biology, Wright State University School of Medicine, Dayton, Ohio 45435.
authors.forename: Karen M
authors.initials: KM
authors.lastname: Henkels
authors.affiliation: From the Department of Biochemistry and Molecular Biology, Wright State University School of Medicine, Dayton, Ohio 45435 julian.cambronero@wright.edu.
authors.forename: Julian
authors.initials: J
authors.lastname: Gomez-Cambronero
mesh_terms: D000199:Actins / Q000737:chemistry; D000818:Animals; D002448:Cell Adhesion; D002460:Cell Line; D049452:Green Fluorescent Proteins / Q000737:chemistry; D007249:Inflammation; D008055:Lipids / Q000737:chemistry; D008264:Macrophages / Q000166:cytology* / Q000378:metabolism; D051379:Mice; D009504:Neutrophils / Q000166:cytology* / Q000378:metabolism; D010712:Phosphatidic Acids / Q000737:chemistry*; D010713:Phosphatidylcholines / Q000737:chemistry; D010739:Phospholipase D / Q000378:metabolism*; D011485:Protein Binding; D015398:Signal Transduction; D014162:Transfection
chemical_list: D000199:Actins; D008055:Lipids; D010712:Phosphatidic Acids; D010713:Phosphatidylcholines; D049452:Green Fluorescent Proteins; C105606:phospholipase D2; D010739:Phospholipase D; C106801:phospholipase D1
keywords: Actin; Cell Adhesion; Cell Signaling; Inflammation; Lipid; Lipid-Protein Interaction; Phosphatidic Acid; Phospholipase D