Coenzyme-A Poly Unsaturated Fatty Acids (PUFA'S) and Neurodegeneration

by Nickolaos D. Skouras, PhD.

The deacylation-reacylatlon cycle is an important mechanism responsible for the introduction of polyunsaturated fatty acids into neural membrane glycerophbspholipids. It involves four enzymes, namely acyl-CoA synthetase, acyl-CoA hydrolase acyl-COA: lysophospholipid acyltransferase, and phospholipase A2. All of these enzymes have been purified and characterized from brain tissue. Under normal conditions, the stimulation of neural membrane receptors by neurotransmitters and growth factors results in the release of arachidonic acid from neural membrane glycerophospholipids. The released arachidonic acid acts as a second messenger itself. It can be further metabolized to eicosanoids, a group of second messengers involved In a variety of neurochernical functions. A lysophospholipid, the second product of reactions catalyzed by phospholipase A2, is rapidly acylated with acyl-CoA, resulting in the maintenance of the normal and essential neural membrane glycerophospholipid composition However, under pathological situations (ischemia), the overstimulation of phospholipase A2 results in a rapid generation and accumulation of free fatty acids including arachidonic acid, eicosanoids, and lipid peroxides. This results in neural inflammation, oxidative stress, and neurodegeneration. In neural membranes, the deacylation-reacylation cycle maintains a balance between free and esterified fatty acids, resulting in low levels of arachidonic acid and lysophospholipids. This is necessary for not only normal membrane integrity and function, but also for the optimal activity of the membrane-bound enzymes, receptors, and ion channels involved in normal signal-transduction processes.

Reference:

Farooqul, A. A., L. A. Horrocks, et al. (2000). "Deacylation and reacylation of neural membrane glycerophospholipids. J Mol Neurosci 14(3): 123-35.