Phosphatidic acid mobilized by phospholipase D is involved in the phorbol 12-myristate 13-acetate-induced G2 delay of A431 cells

Abstract

This study was aimed at gaining an understanding of metabolic events responsible for the inhibition of cells in G2 phase, a known physiological restriction site in the cell cycle of multicellular organisms. In an earlier study, phosphatidic acid was proposed as an inhibitory mediator in the epidermal growth factor (EGF)-induced inhibition of A431 cells in G2 phase via the phospholipase C pathway [Kaszkin, Richards and Kinzel (1992) Cancer Res. 52, 5627-5634]. We show here that the phorbol ester phorbol 12-myristate 13-acetate (PMA) induces a reversible inhibition of the G2/M transition in A431 cells under conditions of phospholipase D-catalysed phosphatidic acid formation. Such PMA-induced inhibition in G2 phase is largely attenuated in the presence of 1-propanol (but not of 2-propanol). In this case the amount of phosphatidic acid is reduced to almost control levels, and instead phosphatidylpropanol is formed. In the case of EGF-induced activation of a phospholipase D the amount of phosphatidic acid is only slightly decreased in the presence of a primary alcohol. Under these conditions the EGF-induced G2 delay was not affected. The correlation between the formation of phosphatidic acid and the G2 delay induced by PMA, as well as by an exogenous bacterial phospholipase D (from Streptomyces chromofuscus), could be supported by using synchronized cells in order to increase the population of cells in G2 phase. This study indicates that the formation of substantial amounts of phosphatidic acid immediately before entry into mitosis seems to be important for establishing a delay in the cell cycle at the G2/M border by exogenous ligands.

Signal transduction through epidermal growth factor receptor is altered in HeLa monolayer cells during mitosis

“…It was proposed earlier that EGF-induced inhibitory mediators derived from cellular phospholipids contribute to the mechanism of cell cycle inhibition in G2-phase [12,13], whereas cells in mitosis were either not producing them or were insensitive to them.…”

Phospholipase D activity is required for dimorphic transition in Candida albicans

“…The presence of alcohols in the culture medium has been shown to attenuate PLD-dependent responses in mammalian cells due to the formation of phosphatidylalcohol at the expense of phosphatidic acid (Kaszkin et al, 1996). Therefore, we assessed the effect of alcohols on (Fig.…”

“…The addition of exogenous PLD to culture medium has been used to artificially enhance the generation of phosphatidic acid, thus amplifying the effect of endogenous PLD activity (Kaszkin et al, 1996). Commercially purified peanut PLD was added to cultures growing in YPD at 30 and 39 "C. After 2 h, the percentage of germ tubes present in each culture was determined by direct microscopic enumeration (Fig.…”

Phosphatidylinositol-4-phosphate 5-kinase activity is stimulated during temperature-induced morphogenesis in Candida albicans

“…As in mammalian systems, PI4P5K in S. cerevisiae has been reported to be stimulated by PA (Homma et al, 1998). PA is a putative second messenger that has been implicated in the regulation of lipid metabolism (Liscovitch et al, 1999), cell proliferation (Kaszkin et al, 1996), differentiation (Amsterdam et al, 1994), secretion (Siddhanta & Shields, 1998) and actin polymerization (Ha & Exton, 1993). PA can be produced by the hydrolysis of the major membrane phospholipid, phosphatidylcholine, by signal-activated PLD1.…”