文章基本信息

标题：Functional characterization of enzymes catalyzing ceramide phosphoethanolamine biosynthesis in mice
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作者：Andreas Bickert ; Christina Ginkel ; Matthijs Kol 等
期刊名称：JLR Papers In Press
印刷版ISSN：0022-2275
电子版ISSN：1539-7262
出版年度：2015
卷号：56
期号：4
页码：821-835
DOI：10.1194/jlr.M055269
语种：English
出版社：American Society for Biochemistry and Molecular Biology
摘要：Besides bulk amounts of SM, mammalian cells produce small quantities of the SM analog ceramide phosphoethanolamine (CPE). Little is known about the biological role of CPE or enzymes responsible for CPE production. Heterologous expression studies revealed that SM synthase (SMS)2 is a bifunctional enzyme producing both SM and CPE, whereas SMS-related protein (SMSr) serves as monofunctional CPE synthase. Acute disruption of SMSr catalytic activity in cultured cells causes a rise in endoplasmic reticulum (ER) ceramides, fragmentation of ER exit sites, and induction of mitochondrial apoptosis. To address the relevance of CPE biosynthesis in vivo, we analyzed the tissue-specific distribution of CPE in mice and generated mouse lines lacking SMSr and SMS2 catalytic activity. We found that CPE levels were >300-fold lower than SM in all tissues examined. Unexpectedly, combined inactivation of SMSr and SMS2 significantly reduced, but did not eliminate, tissue-specific CPE pools and had no obvious impact on mouse development or fertility. While SMSr is widely expressed and serves as the principal CPE synthase in the brain, blocking its catalytic activity did not affect ceramide levels or secretory pathway integrity in the brain or any other tissue. Our data provide a first inventory of CPE species and CPE-biosynthetic enzymes in mammals.
关键词：brain lipids ; enzyme inactivation ; genetics ; mass spectrometry ; sterile α motif domain-containing protein 8 ; sphingomyelin synthase-related protein ; sphingolipids ; sphingomyelin synthase ; transgenic mice