The Eicosanoid Research Division @ IBGM

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Current Support

Regulation of Cyclooxygenase-2 Expression and Activity in Alzheimer's Disease

Agency - Fundación La Caixa
Reference - BM05-248-0
Period - Sep 2005 - Sep 2008
Amount - € 151,000
Personnel - J. Balsinde, M. A. Balboa, O. Montero, M. Duque, R. Pérez, V. Ruipérez

Summary - Prostaglandins and other lipid mediators regulate key aspects of neural membrane biology in the central nervous system. However overproduction of these substances may cause cellular injury. Prostaglandins derive from the enzymatic oxygenation of arachidonic acid, a fatty acid that is released from its phospholipid storage sites by phospholipase A2. Disregulated phospholipase A2 activity has been correlated with several forms of acute and chronic brain injury, including cerebral trauma, cerebral ischaemia, epilepsy, schizoprenia, and in particular, Alzheimer’s Disease. The expression of both phospholipase A2 and cyclooxygenase-2 activities is strongly up-regulated during Alzheimer’s Disease, indicating the importance of inflammatory gene pathways as a response to brain injury. Previous studies from the applicants have established that phospholipase A2 not only provides the substrate for cyclooxygenase-2 to act upon (i.e. free arachidonic acid), but also controls cyclooxygenase-2 gene induction through generation of a metabolite of unknown structure. Backed up by our experience in this area of research, we propose: (1) to establish the identity of the compound that is responsible for cyclooxygenase-2 gene induction; (2) to study the molecular regulation of the enzymes involved in its synthesis; (3) to study the expression of putative cellular targets for the aforementioned compound by microarray technology; and (4) to study the molecular regulation of these targets during an inflammatory injury. These studies will be conducted on microglial cells and astrocytes and will eventually allow us to establish trends to look for molecular targets against which to develop new drugs with anti-inflammatory potential that can be used in the treatment of chronic inflammatory diseases of the brain such as Alzheimer’s Disease.

Publications Derived from This Grant

Ruipérez, V., Casas, J., Balboa, M. A. & Balsinde, J. (2007) Group V phospholipase A2-derived lysophosphatidylcholine mediates cyclooxygenase-2 induction in lipopolysaccharide-stimulated macrophages. J. Immunol. 179: 631-638.

Pindado, J., Balsinde, J. & Balboa, M. A. (2007) TLR3-dependent induction of nitric oxide synthase in RAW 264.7 macrophage-like cells via a cytosolic phospholipase A2/cyclooxygenase-2 pathway. J. Immunol. 179: 4821-4828.

The Role of Phospholipid-remodeling Phospholipase A2s During Apoptosis
and Oxidative Stress

Agency - Spanish Ministry of Education and Science
Reference - SAF2004-04676
Period - Dec 2004 - Dec 2007
Amount - € 156,900
Personnel - M. A. Balboa, S. L. Burillo, J. Pindado

Summary - Oxidative damage is a pathophysiological condition that accompanies a variety of inflammatory states. Phagocytic cells produce substances with high oxidant capacity during inactivation and phagocytosis of invading pathogens. However, an uncontrolled production of these oxidants may lead to damage and hence, may constitute a very serious problem for the host. Oxidative damage usually occurs in parallel with the mobilization of free fatty acids such as arachidonic acid (AA) from membrane phospholipids. It is likely that these two processes are causally related, although the mechanisms involved are not understood. The current research proposal focuses on the elucidation of the molecular mechanisms through which phospholipase A2 activity is augmented during oxidative stress and the apoptotic processes that ordinarily ensue. These aspects are of paramount importance, for oxidants can negatively impact on phagocytic function and thus compromise the resolution of inflammation. The principal investigator of this proposal has been working for several years now on the role of calcium-independent phospholipase A2 (iPLA2) during membrane perturbation induced by hydrogen peroxide. Her studies have shown that this phospholipase is responsible for the mobilization of free fatty acids during oxidative stress. Based on these previous findings, we propose to study: (i) the molecular nature of the oxidized phospholipid species that are produced during cellular exposure to hydrogen peroxide, and their potential effects on iPLA2; (ii) the molecular mechanisms associated to hydrogen peroxide-induced apoptosis; (iii) changes in iPLA2 activity and/or physical state that may account for its enhanced capacity to destroy membrane phospholipid; (iv) the role of iPLA2-derived products, free fatty acids and lysophospholipids, during oxidant-induced apoptosis; and (v) the role of iPLA2 on the phagocytosis of apoptotic cells by phagocytes. These studies may provide new clues to understand the molecular processes involved in oxidative damage and thus may help uncover new molecular targets with possible therapeutic potential.

Publications Derived from This Grant

Balsinde, J., and Balboa, M. A. (2005) Review - Cellular regulation and proposed biological functions of group VIA calcium-independent phospholipase A2 in activated cells. Cell. Signal. 17: 1052-1062.

Casas, J., Gijón, M. A., Vigo, A. G., Crespo, M. S., Balsinde, J. & Balboa, M. A. (2006) Phosphatidylinositol 4,5-bisphosphate anchors cytosolic group IVA phospholipase A2 to perinuclear membranes and decreases its calcium requirement for translocation in live cells. Mol. Biol. Cell 17: 155-162.

Pérez, R., Balboa, M. A. & Balsinde, J. (2006) Involvement of group VIA calcium-independent phospholipase A2 in macrophage engulfment of hydrogen peroxide-treated U937 cells. J. Immunol. 176: 2555-2561.

Pérez, R., Matabosch, X., Llebaria, A., Balboa, M. A. & Balsinde, J. (2006) Blockade of arachidonic acid incorporation into phospholipids induces apoptosis in U937 promonocytic cells. J. Lipid Res. 47: 484-491.

Casas, J., Gijón, M. A., Vigo, A. G., Crespo, M. S., Balsinde, J. & Balboa, M. A. (2006) Overexpression of cytosolic group IVA phospholipase A2 protects cells from calcium-dependent death. J. Biol. Chem. 281: 6106-6116.

Balboa, M. A. & Balsinde, J. (2006) Review - Oxidative stress and arachidonic acid mobilization. BBA Mol. Cell Biol. Lipids 1761: 385-391.

Balsinde, J., Pérez, R. & Balboa, M. A. (2006) Review - Calcium-independent phosholipase A2 and apoptosis. BBA Mol. Cell Biol. Lipids 1761: 1344-1350.

Ruipérez, V., Casas, J., Balboa, M. A. & Balsinde, J. (2007) Group V phospholipase A2-derived lysophosphatidylcholine mediates cyclooxygenase-2 induction in lipopolysaccharide-stimulated macrophages. J. Immunol. 179: 631-638.

Regulation of Cyclooxygenase-2 Expression by Phospholipase A2-derived Lipid Products

Agency - Spanish Ministry of Education and Science
Reference - BFU2004-01886-BMC
Period - Dec 2004 - Dec 2007
Amount - € 173,650
Personnel - J. Balsinde, R. Pérez, Y. Sáez

Summary - Inflammation is a body response to external aggression, and is orchestrated to control damage, clean up debris and start reparation processes. The eicosanoids are derivatives of arachidonic acid that play important roles in inflammation by mediating the tumor, pain, redness and heat that are strikingly associated to the illness. Inflammation is a hallmark of numerous pathologies, ranging from septic shock to rheumatoid arthritis or Alzheimer’s Disease. Thus, it is important to find new molecular targets to produce anti-inflammatory drugs with improved selectivity and, as much as possible, devoid of side-effects. The principal investigator of this project has been working for several years now on the inflammatory response of macrophages to bacterial endotoxin (lipopolysaccharide). His studies have pointed to the Group V secreted phospholipase A2 as an enzyme responsible for generating free arachidonic acid to be used for the biosynthesis of prostaglandins. In addition, Group V phospholipase A2 regulates the expression of the cyclooxygenase-2 (COX-2) gene itself. This regulation appears to take place through the production of an unidentified metabolite downstream of phospholipase A2 activation. In the present grant project we plan to study: 1) the molecular nature of the metabolite responsible for COX-2 gene expression; 2) the cellular regulation of the enzymes involved in the synthesis of this metabolite; 3) changes in gene expression utilizing microarray techniques; and 4) identify the cellular targets of this metabolite. Collectively, the studies proposed in this grant will help establish important molecular principles to search for new anti-inflammatory drugs with improved selectivity.

Publications Derived from This Grant

Balsinde, J., and Balboa, M. A. (2005) Review - Cellular regulation and proposed biological functions of group VIA calcium-independent phospholipase A2 in activated cells. Cell. Signal. 17: 1052-1062.

Shirai, Y., Balsinde, J. & Dennis, E. A. (2005) Localization and functional interrelationships among cytosolic group IV, secreted group V, and Ca2+-independent group VI phospholipase A2s in P388D1 macrophages using GFP/RFP constructs. BBA Mol. Cell Biol. Lipids 1735: 119-129.

Balboa, M. A. & Balsinde, J. (2006) Review - Oxidative stress and arachidonic acid mobilization. BBA Mol. Cell Biol. Lipids 1761: 385-391.

Balsinde, J., Pérez, R. & Balboa, M. A. (2006) Review - Calcium-independent phosholipase A2 and apoptosis. BBA Mol. Cell Biol. Lipids 1761: 1344-1350.

Past Support

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