title: Coactosin-like protein supports 5-lipoxygenase enzyme activity and up-regulates leukotriene A4 production.
abstract: Regulation of 5-lipoxygenase (5LO) activity is a key determinant for the biosynthesis of proinflammatory leukotrienes. Coactosin-like protein (CLP) is an F-actin-binding protein that can also bind 5LO. Here, we report that CLP can up-regulate and modulate 5LO activity [formation of 5(S)-hydroperoxy-6-trans-8,11,14-cis-eicosatetraenoic acid (5-HPETE)], 5(S)-hydroxy-6-trans-8,11,14-cis-eicosatetraenoic acid (5-HETE), and 5(S)-trans-5,6-oxido-7,9-trans-11,14-cis-eicosatetraenoic acid (LTA(4)) in vitro. Three findings are presented. First, CLP up-regulates Ca(2+)-induced 5LO activity, in the absence of phosphatidylcholine (membrane). Apparently, CLP can function as a scaffold for 5LO, similar to membranes. Second, CLP gives a considerable (3-fold) increase in the amount of LTA(4) formed by 5LO, when present together with phosphatidylcholine. Third, CLP increases the ratio of 5-HETE/5-HPETE. These effects require protein interaction by Trp residues in ligand-binding loops of the 5LO beta-sandwich; both binding and stimulatory effects of CLP were abolished for the mutant 5LO-W13/75/102A. In polymorphonuclear leukocytes stimulated with Ca(2+) ionophore, both CLP and 5LO associated with the nucleus, whereas in resting cells, CLP and 5LO were cytosolic. These findings establish CLP as a factor relevant for 5LO product formation. Functioning as a 5LO scaffold, CLP may provide a basis for the formation of 5-HETE in the cytosol of different cell types. Furthermore, in stimulated cells, CLP appears to function in a complex together with 5LO and membranes, increasing the capacity of 5LO for leukotriene biosynthesis.
authors.affiliation: Department of Medical Biochemistry and Biophysics, Division of Physiological Chemistry II, Karolinska Institutet, S-171 77 Stockholm, Sweden.
authors.forename: Marija
authors.initials: M
authors.lastname: Rakonjac
authors.forename: Lutz
authors.initials: L
authors.lastname: Fischer
authors.forename: Patrick
authors.initials: P
authors.lastname: Provost
authors.forename: Oliver
authors.initials: O
authors.lastname: Werz
authors.forename: Dieter
authors.initials: D
authors.lastname: Steinhilber
authors.forename: Bengt
authors.initials: B
authors.lastname: Samuelsson
authors.forename: Olof
authors.initials: O
authors.lastname: Rådmark
mesh_terms: D001094:Arachidonate 5-Lipoxygenase / Q000378:metabolism*; D002118:Calcium / Q000494:pharmacology; D002384:Catalysis / Q000187:drug effects; D002467:Cell Nucleus / Q000187:drug effects; D006801:Humans; D007476:Ionophores / Q000494:pharmacology; D007700:Kinetics; D007962:Leukocytes / Q000187:drug effects / Q000201:enzymology; D017572:Leukotriene A4 / Q000096:biosynthesis*; D008054:Lipid Peroxides / Q000378:metabolism; D008274:Magnesium / Q000494:pharmacology; D008840:Microfilament Proteins / Q000378:metabolism*; D050505:Mutant Proteins / Q000378:metabolism; D010544:Peroxidases / Q000378:metabolism; D011485:Protein Binding / Q000187:drug effects; D021381:Protein Transport / Q000187:drug effects; D013997:Time Factors; D014364:Tryptophan / Q000378:metabolism
chemical_list: C118115:COTL1 protein, human; D007476:Ionophores; D017572:Leukotriene A4; D008054:Lipid Peroxides; D008840:Microfilament Proteins; D050505:Mutant Proteins; D014364:Tryptophan; D010544:Peroxidases; D001094:Arachidonate 5-Lipoxygenase; D008274:Magnesium; D002118:Calcium