The 5-lipoxygenase (5LO) produces leukotriene B4 and 15-epilipoxin-A4 (15-epi-LXA4). Phosphorylation at Ser523 by protein kinase A (PKA) prevents 5LO shift to the perinuclear membrane. Atorvastatin and pioglitazone up-regulate 15-epi-LXA4 production in the heart. We assessed whether phosphorylation of 5LO by PKA determines whether 5LO interacts with the membranous cytosolic phospholipase A2 (cPLA2) to produce leukotriene B4 or with cyclooxygenase-2 (COX2) to produce 15-epi-LXA4. Rats received either pioglitazone, atorvastatin, pioglitazone plus atorvastatin, vehicle, or LPS. Rat myocardial cells were incubated with pioglitazone plus atorvastatin, pioglitazone plus atorvastatin plus H-89 (PKA inhibitor), H-89, or vehicle for 8 h. Pioglitazone and atorvastatin did not affect total 5LO expression. However, both increased 5LO levels in the cytosolic fraction. H-89 caused a shift of 5LO to the membranous fraction in atorvastatin- and pioglitazone-treated rats. Pioglitazone and atorvastatin increased phospho-5LO levels. H-89 attenuated this increase. Both pioglitazone and atorvastatin increased COX2 levels in the cytosolic fraction and the membranous fraction. H-89 prevented this increase. Pioglitazone and atorvastatin increased cPLA2 expression in the membranous fraction. This effect was not attenuated by H-89. Pioglitazone plus atorvastatin increased 15-epi-LXA4 levels. H-89 attenuated the effect of pioglitazone plus atorvastatin. Pioglitazone plus atorvastatin plus H-89 increased leukotriene B4 levels. Coimmunoprecipitation showed that without H-89, atorvastatin and pioglitazone induced an interaction between 5LO and COX2 in the cytosolic fraction, whereas when H-89 was added, 5LO interacted with cPLA2 on the membranous fraction. The 5LO phosphorylation determines whether 15-epi-LXA4 (anti-inflammatory) or leukotriene B4 (inflammatory mediator) is produced.
ASJC Scopus subject areas
- Immunology and Allergy