Developmental and metabolic effects of disruption of the mouse CTP:phosphoethanolamine cytidylyltransferase gene (Pcyt2).
The CDP-ethanolamine pathway is responsible for the de novo biosynthesis of ethanolamine phospholipids, where CDP-ethanolamine is coupled with diacylglycerols to form phosphatidylethanolamine. We have disrupted the mouse gene encoding CTP:phosphoethanolamine cytidylyltransferase, Pcyt2, the main regulatory enzyme in this pathway. Intercrossings of Pcyt2(+/-) animals resulted in small litter sizes and unexpected Mendelian frequencies, with no null mice genotyped. The Pcyt2(-/-) embryos die after implantation, prior to embryonic day 8.5. Examination of mRNA expression, protein content, and enzyme activity in Pcyt2(+/-) animals revealed the anticipated 50% decrease due to the gene dosage effect but rather a 20 to 35% decrease. [(14)C]ethanolamine radiolabeling of hepatocytes, liver, heart, and brain corroborated Pcyt2 gene expression and activity data and showed a decreased rate of phosphatidylethanolamine biosynthesis in heterozygotes. Total phospholipid content was maintained in Pcyt2(+/-) tissues; however, this was not due to compensatory increases in the decarboxylation of phosphatidylserine. These results establish the necessity of Pcyt2 for murine development and demonstrate that a single Pcyt2 allele in heterozygotes can maintain phospholipid homeostasis.
Fullerton
Morgan D
MD
Department of Human Health and Nutirtionla Sciences, University of Guelph, Guelph, Ontario, Canada N1G 2W1.
Hakimuddin
Fatima
F
Bakovic
Marica
M
D000818:Animals; D003570:Cytidine Triphosphate / Q000378:metabolism*; D004622:Embryo, Mammalian / Q000196:embryology / Q000201:enzymology; D005227:Fatty Acids / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D015971:Gene Expression Regulation, Enzymologic; D005838:Genotype; D006579:Heterozygote; D008099:Liver / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D008928:Mitochondria / Q000378:metabolism; D010743:Phospholipids / Q000378:metabolism; D012316:RNA Nucleotidyltransferases / Q000172:deficiency / Q000235:genetics* / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics
D005227:Fatty Acids; D010743:Phospholipids; D012333:RNA, Messenger; D003570:Cytidine Triphosphate; D012316:RNA Nucleotidyltransferases; C020126:Ethanolamine-phosphate cytidylyltransferase