Membrane lipid metabolism at the mitotic exit

LUCIANA RODRIGUEZ SAWICKI; VERONICA VICTORIA MOSCOSO; BETINA CÓRSICO; NATALIA SCAGLIA

Congreso; Keystone Symposia: Tumor Metabolism: Mechanisms and Targets; 2017

Cell division ends with the reassemble of thenuclear envelope and the separation of the two daughter cells, process thatrequires dynamic changes in membrane phospholipids. We have previously foundthat lysophospholipid levels decrease drastically from G2/M to G1 phase, while phosphatidylcholinesynthesis increases, suggesting an enhanced membrane production concomitant witha decrease in its turnover. In addition, de novo fatty acid synthesis andincorporation into membranes increases upon cell division (Scaglia, 2014).Thus, we studied the cellular fate of phospholipids synthesized during G2/M andthe lipid requirements for cell cycle completion. We synchronized HeLa cells to study lipidsynthesis during G2/M.  Metaboliclabeling with 14C-acetate and the subsequent separation of subcellularfractions using a sucrose gradient allowed us to determine the distribution ofincorporated label into lipids during cell division. We also used the cholineanalog propargylcholine, and the coupled click-chemistry reaction, to assessthe fate of newly synthesized phosphatidylcholine in G2/M. Both approachesshowed that lipids synthesized during G2/M localized in a region compatiblewith the nucleus and endoplasmic reticulum, suggesting that newly synthesizedmembrane is used for nuclear envelope reassembly. Notably, impairment of fattyacid synthesis or Lysophospholipids reacylation induced cell cycle arrestwhereas knockdown of CTa, the rate-limiting enzyme of phosphatidylcholinesynthesis, had no effect on proliferation. These studies contribute to the knowledge ofthe metabolic requirements during the cell cycle and could have implicationsfor the treatment of hyperproliferative diseases.