Phosphatidylcholine biosíntesis and cell growth

ELENA, C; DE MENDOZA, D AND BANCHIO C

Mar del Plata

Congreso; Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2007

SAIB

Phosphatidylcholine (PC) is the major phospholipid in mammalian cells. The CTP:phosphocholine cytidyltransferase (CTa) catalyze the limiting step that governs the Kennedy pathway. The understanding of the mechanisms that regulate its expression during the cell cycle will contribute to interpretate the basis of cell growth. We use  CHO cells (MT58), a temperature-sensitive mutant defective in CTa, as a model. After MT58 cells are shifted to the restrictive temperature, we found that CTa is inactivated leading to cell die. The question we wish to address is why PC deficiency is essential for cell growth? To answer this question we measured changes in cell´s morphology, viability and DNA synthesis. The most important change we found was the cessation of DNA synthesis. Therefore, we investigated whether exogenous added phospholipids were able to reestablish DNA replication and if the nuclear localization of CTa is essential to induce growth. Since the described results indicate that cell cycle progression is sensitive to PC content, we used transcriptional approaches to study the regulatory mechanism involved in CTa expression during the cell cycle. The results indicate that this process is regulated by EF2. Since a similar mechanism regulates the expression of genes involved in DNA synthesis, we propose that both PC and DNA replication are coordinately regulated during cell growth.