Rosenthal M D
Department of Biochemistry, Eastern Virginia Medical School, Norfolk 23501.
Prog Lipid Res. 1987;26(2):87-124. doi: 10.1016/0163-7827(87)90009-9.
It is now clear that a wide variety of differentiated cells in culture exhibit essentially the full spectrum of mammalian fatty acid metabolism. These cells readily incorporate free fatty acids into membrane phosphoglycerides, modify exogenous fatty acids by desaturation and elongation, and store excess fatty acyl groups, primarily as triacylglycerols. Similarly, many different types of cells synthesize cyclooxygenase and lipoxygenase derivatives of long chain polyunsaturated fatty acids. Furthermore, although the fatty acid composition of cellular phospholipids can be modified by medium supplementation, cells in culture exhibit definite fatty acyl specificities for the various steps of fatty acid activation, transesterification and release. As the extensive repertoire of fatty acid metabolism in mammalian cells has been elucidated, and as the ability to grow differentiated cells in culture has increased, new questions have arisen. There is still much to be learned about the enzymes involved in synthesizing and maintaining the unique fatty acid composition of the different cellular phospholipids and the processes which regulate the desaturation, elongation and retroconversion of polyunsaturated fatty acids. Other areas of great current interest are the mechanisms by which certain long chain polyunsaturated fatty acids are made available for conversion to oxygenated, biologically-active derivatives, the metabolic interactions between different polyunsaturated fatty acids, particularly n-3 and n-6 fatty acids, the cellular roles of the C22 polyunsaturated fatty acids, and the functions of particular molecular species of phospholipids in membrane-mediated events. Further research in these areas will contribute to unravelling the role of fatty acids and fatty acid derivatives in the physiological processes of mammalian cells.
现在已经清楚，培养中的多种分化细胞基本上展现出哺乳动物脂肪酸代谢的全谱。这些细胞很容易将游离脂肪酸掺入膜磷脂中，通过去饱和作用和延长作用来修饰外源脂肪酸，并储存过量的脂肪酰基，主要是以三酰甘油的形式储存。同样，许多不同类型的细胞会合成长链多不饱和脂肪酸的环氧化酶和脂氧化酶衍生物。此外，虽然细胞磷脂的脂肪酸组成可以通过培养基添加来改变，但培养中的细胞在脂肪酸活化、转酯作用和释放的各个步骤中表现出明确的脂肪酰基特异性。随着哺乳动物细胞中广泛的脂肪酸代谢谱被阐明，以及在培养中培养分化细胞的能力提高，新的问题出现了。关于参与合成和维持不同细胞磷脂独特脂肪酸组成的酶以及调节多不饱和脂肪酸去饱和、延长和逆向转化的过程，仍有许多需要了解的地方。当前其他备受关注的领域包括某些长链多不饱和脂肪酸转化为氧化的、具有生物活性的衍生物的机制、不同多不饱和脂肪酸之间的代谢相互作用，特别是n-3和n-6脂肪酸之间的相互作用、C22多不饱和脂肪酸的细胞作用以及特定分子种类的磷脂在膜介导事件中的功能。这些领域的进一步研究将有助于揭示脂肪酸和脂肪酸衍生物在哺乳动物细胞生理过程中的作用。
