EXTRACELLULAR ATP (eATP)-SIGNALLING IN PLANTS: ROLE OF PHOSPSOLIPASES, Ca2+ AND NO

SUELDO, D.; FORESI, N. P.; CASALONGUE, C.; LAMATTINA, L.; LAXALT, A.M.

Cordoba

Congreso; SAIB; 2008

ATP is a vital molecule used by living organisms as a universal source of energy. In animals, extracellular ATP (eATP) is a well-documented regulatory signal involved in numerous physiological processes. eATP releases Ca2+ from internal stores via the phospholipase C (PLC) derived inositol-3-phosphate (IP3). In plants, eATP induces increases in citoplasmic Ca2+ concentration from both the extracellular and intracellular stores, however it is not known whether PLC-derived IP3 is involved in this process. PLC has role in signaling generating the two second-messengers, IP3 and diacylglycerol (DAG). In plants DAG is converted to phosphatidic acid (PA) via DAG kinase (DGK). Another source of PA is phospholipase D (PLD). We have previously shown that eATP induces an increase in nitric oxide (NO) production downstream of PA. The aim of the present work is to elucidate the enzymatic sources of PA production during eATP treatments and to analyze their role in cytosolic Ca2+ increases and NO production. Time course experiments showed that PA is generated within minutes. Preliminary results show that both PLD and PLC/DGK pathway are involved not only in generating PA but also required for NO production. Our results suggest that extracellular Ca2+ is involved in the response of eATP, upstream of NO production. Current studies are in progress in order to elucidate the role of Ca, PA and NO in eATP-signalling physiological responses.