Complete discrimination of docosahexaenoate from arachidonate by 85 kDa cytosolic phospholipase A2 during the hydrolysis of diacyl- and alkenylacylglycerophosphoethanolamine

Mayumi Shikano, Yasuo Masuzawa, Kazunaga Yazawa, Kiyoshi Takayama, Ichiro Kudo, Keizo Inoue

Research output: Contribution to journalArticle

82 Citations (Scopus)

Abstract

In our previous report (Shikano, M., Masuzawa, Y. and Yazawa, K. (1993) J. Immunol. 150, 3525-3533), we described that the enrichment of docosahexaenoic acid (DHA, 22:6(n - 3) reduces both arachidonic acid (AA, 20:4(n - 6)) release and platelet-activating factor (PAF) synthesis in human eosinophilic leukemia cells, Eol-1. Since no DHA release was observed in response to Ca-ionophore stimulation, we presumed that the phospholipase A2 (PLA2) responsible for AA release and PAF synthesis can not hydrolyze the DHA moiety of phospholipids. In the present paper, we examined whether DHA-containing diacyl- and alkenylacylglycerophosphoethanolamine (DHA-diacylGPE and DHA-alkenylacyGPE) are susceptible to the action of AA-preferential 85 kDa cytosolic phospholipase A2 (cPLA2) from rabbit platelets in comparison with AA and eicosapentaenoic acid (EPA, 20:5(n - 3)) derivatives. When diacylGPE was used as a substrate, DHA release was almost negligible under the assay condition that allowed AA and EPA to be liberated at the rates of 4.3 μmol/min per mg protein and 2.5 μmol/min per mg protein, respectively. On the other hand, 14 kDa type II PLA2 hydrolyzed DHA-diacylGPE as well as AA-diacylGPE and EPA-diacylGPE. When DHA-diacylGPE and AA-diacylGPE were mixed at equimolar concentrations, DHA release by cPLA2 was not observed and AA release was reduced to 32% in the case without DHA-diacylGPE. This indicated that DHA-diacylGPE is a poor substrate but possesses the inhibitory activity for cPLA2. cPLA2 does not clearly discriminate between AA-alkenylacylGPE and AA-diacylGPE. As in the case using diacylGPE as a substrate, DHA-alkenylacylGPE was completely discriminated from AA-alkenylacylGPE by cPLA2. The roles of DHA and cPLA2 in the synthesis of lipid mediators will be discussed in relation to the new aspects of the substrate specificity of cPLA2 provided here.

Original languageEnglish
Pages (from-to)211-216
Number of pages6
JournalBiochimica et Biophysica Acta (BBA)/Lipids and Lipid Metabolism
Volume1212
Issue number2
DOIs
Publication statusPublished - 1994 May 13
Externally publishedYes

Fingerprint

Cytosolic Phospholipases A2
Docosahexaenoic Acids
Hydrolysis
Platelet Activating Factor
Substrates
Group II Phospholipases A2
Hypereosinophilic Syndrome
Eicosapentaenoic Acid
Phospholipases A2
Ionophores
Substrate Specificity
Platelets
Arachidonic Acid
Assays
Phospholipids
Proteins
Blood Platelets
Rabbits
Derivatives
Lipids

Keywords

  • (Rabbit)
  • Alkenylacylglycerophosphoethanolamine
  • Arachidonic acid
  • Docosahexaenoic acid
  • Icosapentaenoic acid
  • Phospholipase A
  • Phospholipase A type II

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Endocrinology

Cite this

Complete discrimination of docosahexaenoate from arachidonate by 85 kDa cytosolic phospholipase A2 during the hydrolysis of diacyl- and alkenylacylglycerophosphoethanolamine. / Shikano, Mayumi; Masuzawa, Yasuo; Yazawa, Kazunaga; Takayama, Kiyoshi; Kudo, Ichiro; Inoue, Keizo.

In: Biochimica et Biophysica Acta (BBA)/Lipids and Lipid Metabolism, Vol. 1212, No. 2, 13.05.1994, p. 211-216.

Research output: Contribution to journalArticle

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AU - Yazawa, Kazunaga

AU - Takayama, Kiyoshi

AU - Kudo, Ichiro

AU - Inoue, Keizo

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