Arthur G, Page L
Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Manitoba, Winnipeg, Canada.
Biochem J. 1991 Jan 1;273(Pt 1)(Pt 1):121-5. doi: 10.1042/bj2730121.
Studies with mammalian cell lines have led to suggestions that mammalian tissues may derive all of their phosphatidylethanolamine (PE) from the decarboxylation of phosphatidylserine (PS), and also that the physiological significance of the CDP-ethanolamine pathway was the synthesis of ethanolamine plasmalogen. We have therefore investigated the biosynthesis of PE and ethanolamine plasmalogen via the CDP-ethanolamine and decarboxylation pathways in vivo in three rat tissues (heart, kidney and liver), which differ in ethanolamine plasmalogen content. In all three tissues [14C]ethanolamine was incorporated into both PE and ethanolamine plasmalogen, whereas [3H]serine was incorporated into only PS and PE fractions. When [14C]ethanolamine was introduced into the animals, the specific radioactivity of ethanolamine plasmalogen in the kidney was always greater than that of the PE fraction; in the heart the specific radioactivity of the ethanolamine plasmalogen fraction was similar to that of the PE fraction, whereas in the liver the specific radioactivity of the PE fraction was always greater than that of the ethanolamine plasmalogen fraction. The results obtained in this study indicate that: (1) the CDP-ethanolamine pathway is utilized for the synthesis of both PE and ethanolamine plasmalogen in all three tissues; (2) the decarboxylation pathway is utilized solely for the synthesis of PE; (3) serine plasmalogens are not formed by base-exchange reactions; (4) the relative utilization of the CDP-ethanolamine pathway for the synthesis of PE and ethanolamine plasmalogen varies among tissues. Our studies also revealed that the hypolipidaemic drug MDL 29350 is a potent inhibitor of PE N-methyltransferase activity in vitro and in vivo.
对哺乳动物细胞系的研究表明，哺乳动物组织中的所有磷脂酰乙醇胺（PE）可能都来源于磷脂酰丝氨酸（PS）的脱羧作用，并且还表明，CDP - 乙醇胺途径的生理意义在于合成乙醇胺缩醛磷脂。因此，我们研究了在体内通过CDP - 乙醇胺途径和脱羧途径在三种乙醇胺缩醛磷脂含量不同的大鼠组织（心脏、肾脏和肝脏）中PE和乙醇胺缩醛磷脂的生物合成。在所有这三种组织中，[14C]乙醇胺都被掺入到PE和乙醇胺缩醛磷脂中，而[3H]丝氨酸仅被掺入到PS和PE组分中。当将[14C]乙醇胺引入动物体内时，肾脏中乙醇胺缩醛磷脂的比放射性总是高于PE组分；在心脏中，乙醇胺缩醛磷脂组分的比放射性与PE组分相似，而在肝脏中，PE组分的比放射性总是高于乙醇胺缩醛磷脂组分。本研究获得的结果表明：（1）CDP - 乙醇胺途径用于所有三种组织中PE和乙醇胺缩醛磷脂的合成；（2）脱羧途径仅用于PE的合成；（3）丝氨酸缩醛磷脂不是通过碱基交换反应形成的；（4）CDP - 乙醇胺途径用于合成PE和乙醇胺缩醛磷脂的相对利用率在不同组织中有所不同。我们的研究还表明，降血脂药物MDL 29350在体外和体内都是PE N - 甲基转移酶活性的有效抑制剂。
