Naslov
Activation of phospholipase C in Saccharomyces cerevisiae after release from pheromone-induced cell cycle block

Autori
Banfić, Hrvoje ; Višnjić, Dora

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, neobjavljeni rad, znanstveni

Skup
Gordon Research Conference “Signal Transduction within the Nucleus”

Mjesto i datum
Ventura (CA), Sjedinjene Američke Države, 27.02.2011. - 04.03.2011

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
phospholipase C; inositol phosphates; yeast; cell cycle

Sažetak
In mammalian cells, the activation of nuclear phospholipase C (PLC) has been observed during different phases of the cell cycle, but the intranuclear function and metabolism of PLC products, such as Ins (1, 4, 5)P3 is only fragmentary understood. In the budding yeast, Ins(1, 4, 5)P3 serves as a precursor for the synthesis of higher inositol phosphates that have been proved to regulate important nuclear events. As kinases responsible for the generation of inositol phosphates are evolutionary conserved from yeast to man, and several studies suggest that nuclear phospholipid metabolism is similar to signaling in yeasts, the present study was undertaken in order to test for possible changes in PLC activity and inositol metabolism in Saccharomyces cerevisiae during progression through the cell cycle. HPLC analysis of yeast cells labeled with [3H]inositol and synchronized by the addition of alpha-factor revealed an increase in Ins(1, 4, 5)P3 radioactivity with correspondent decrease in PtdIns(4, 5)P2 30 - 60 min after release from pheromone block. A parallel increase in PLC-activity in lysates was measured in an assay using [3H] - labeled PtdIns(4, 5)P2 as a substrate, and FACS analysis of Sytox-stained yeast cells indicated that an increase in PLC activity corresponded to the progression through the S phase. At the same time points, a decrease in InsP6 and inositol pyrophosphates was observed in equilibrium labeling experiments, and rapid incorporation of radiolabel into InsP6 in pulse-chase experiments, suggesting high turnover rate of InsP6 during S-phase. The presence of PLC inhibitor U73122 completely inhibited the activation of PLC and delayed the progression of wild type yeast cells through S phase similar to that observed in yeast plcΔ and ipk1Δkcs1Δ mutants. These results demonstrate the activation of PLC and the increase in InsP6 turnover rate in yeast cells early after pheromone block and release, and suggest that these events are important for the progression of S. cerevisiae through the S phase of the cell cycle.

Izvorni jezik
Engleski

Znanstvena područja
Temeljne medicinske znanosti

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