Evidence for a unique profile of phosphatidylcholine synthesis in late mitotic cells.

Open Access
Publisher Website
Google Scholar
Abstract
Evidence is presented that the structural rearrangements in late mitosis are accompanied by an alteration in membrane lipid synthesis. This evidence was derived from analyzing phospholipid classes after rapid-labeling, as well as from determining the intracellular site of incorporation of choline by HeLa [human cervical carcinoma] S3 cells as they progressed from metaphase into early interphase (G1). Compared with postmitotic cell data, the recent mitotic cell data indicate a specific 2- to 3-fold increase in the net synthesis of phosphatidylcholine (PC) species, which appeared to contain the more saturated fatty acids. Since this was observed with glycerol, choline and orthophosphate labelings, and not with methyl labeling, it appears that the CDP-choline plus diacylglycerol pathway rather than the phosphatidylethanolamine to PC pathway was augmented. EM autoradiography of anaphase, telophase and early G1 cells demonstrated that the reformed nuclear envelope was the incorporation site of a significant proportion of the newly synthesized PC. This incorporation occurred by early telophase prior to chromosome decondensation. The potential significance of PC metabolism with regard to membrane rearrangements, such as nuclear envelope reformation, is discussed.