The activities of diacylglycerol and monoacylglycerol lipases are markedly elevated in the nucleus basalis and hippocampus of Alzheimer disease brains as compared to controls. Neuron-enriched primary cultures show a marked stimulation of diacylglycerol and monoacylglycerol lipase and phospholipase A2 activities after treatment with glutamate or NMDA. The proposed work seeks to determine a mechanism for the stimulation of lipases and phospholipases A2. The stimulation may be due to (a) induction, (b) translocation, and/or (c) covalent modification (phosphorylation) of lipases and phospholipases. The amount of diacylglycerol lipase and phospholipase A2 will be quantified by Western blotting. Homogeneous preparations of diacylglycerol lipase and Ca2+- independent phospholipase A2 will be phosphorylated using various kinases. Activities and kinetic properties of phosphorylated diacylglycerol lipase and Ca2+-independent phospholipase A2 will be compared to native enzymes. The effects of inhibitors of protein kinases on the stimulation of lipases and phospholipases by glutamate and its analogs will be studied. Activity of nitric oxide synthase and effects of its inhibitors on the stimulation of lipases and phospholipases will be evaluated. Finally, levels of lipid peroxides and the phospholipid composition of neuron-enriched cultures will be determined in cultures treated with glutamate and its analogs. Results of these experiments will test our specific hypothesis that stimulation of lipases and phospholipases may produce changes in membrane permeability and fluidity, and this may be responsible for neurodegeneration.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS029441-05
Application #
2267613
Study Section
Neurological Sciences Subcommittee 1 (NLS)
Project Start
1991-04-01
Project End
1997-03-31
Budget Start
1995-04-01
Budget End
1996-03-31
Support Year
5
Fiscal Year
1995
Total Cost
Indirect Cost
Name
Ohio State University
Department
Biochemistry
Type
Schools of Medicine
DUNS #
098987217
City
Columbus
State
OH
Country
United States
Zip Code
43210
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Antony, P; Freysz, L; Horrocks, L A et al. (2001) Effect of retinoic acid on the Ca2+-independent phospholipase A2 in nuclei of LA-N-1 neuroblastoma cells. Neurochem Res 26:83-8
Antony, P; Farooqui, A A; Horrocks, L A et al. (2001) Effect of D609 on phosphatidylcholine metabolism in the nuclei of LA-N-1 neuroblastoma cells: a key role for diacylglycerol. FEBS Lett 509:115-8
Farooqui, A A; Litsky, M L; Farooqui, T et al. (1999) Inhibitors of intracellular phospholipase A2 activity: their neurochemical effects and therapeutical importance for neurological disorders. Brain Res Bull 49:139-53
Farooqui, A A; Horrocks, L A (1999) Purification of lipases and phospholipases by heparin-sepharose chromatography. Methods Mol Biol 109:133-43
Farooqui, A A; Yang, H C; Hirashima, Y et al. (1999) Determination of plasmalogen-selective phospholipase A2 activity by radiochemical and fluorometric assay procedures. Methods Mol Biol 109:39-47
Ong, W Y; Horrocks, L A; Farooqui, A A (1999) Immunocytochemical localization of cPLA2 in rat and monkey spinal cord. J Mol Neurosci 12:123-30
Farooqui, A A; Horrocks, L A (1998) Plasmalogen-selective phospholipase A2 and its involvement in Alzheimer's disease. Biochem Soc Trans 26:243-6
Sandhya, T L; Ong, W Y; Horrocks, L A et al. (1998) A light and electron microscopic study of cytoplasmic phospholipase A2 and cyclooxygenase-2 in the hippocampus after kainate lesions. Brain Res 788:223-31
Farooqui, A A; Yang, H C; Rosenberger, T A et al. (1997) Phospholipase A2 and its role in brain tissue. J Neurochem 69:889-901

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