title: Phosphatidylinositol 3- and 4-phosphate modulate actin filament reorganization in guard cells of day flower.
abstract: Phosphatidylinositol 3-kinases (PtdIns 3-kinases) that produce phosphatidylinositol (3,4,5) triphosphate (PtdIns(3,4,5)P(3)) are considered to be important regulators of actin dynamics in animal cells. In plants, neither PtdIns(3,4,5)P(3) nor the enzyme that produces this lipid has been reported. However, a PtdIns 3-kinase that produces phosphatidylinositol 3-phosphate (PtdIns3P) has been identified, suggesting that PtdIns3P, instead of PtdIns(3,4,5)P(3), regulates actin dynamics in plant cells. Phosphatidylinositol 4-kinase (PtdIns 4-kinase) is closely associated with the actin cytoskeleton in plant cells, suggesting a role for this lipid kinase and its product phosphatidylinositol 4-phosphate (PtdIns4P) in actin-related processes. Here, we investigated whether or not PtdIns3P or PtdIns4P plays a role in actin reorganization induced by a plant hormone abscisic acid (ABA) in guard cells of day flower (Commelina communis). ABA-induced changes in actin filaments were inhibited by LY294002 (LY) and wortmannin (WM), inhibitors of PtdIns3P and PtdIns4P synthesis. Expression of PtdIns3P- and PtdIns4P-binding domains also inhibited ABA-induced actin reorganization in a manner similar to LY and WM. These results suggest that PtdIns3P and PtdIns4P regulate actin dynamics in guard cells. Furthermore, we demonstrate that PtdIns3P exerts its effect on actin dynamics, at least in part, via generation of reactive oxygen species (ROS) in response to ABA.
authors: Division of Molecular and Life Sciences, POSTECH, Pohang 790-784, Korea.
authors: Yunjung
authors: Y
authors: Choi
authors: Yuree
authors: Y
authors: Lee
authors: Byeong Wook
authors: BW
authors: Jeon
authors: Christopher J
authors: CJ
authors: Staiger
authors: Youngsook
authors: Y
authors: Lee
mesh_terms: D019870:1-Phosphatidylinositol 4-Kinase / Q000037:antagonists & inhibitors; D000040:Abscisic Acid / Q000378:metabolism / Q000494:pharmacology; D000199:Actins / Q000378:metabolism*; D000730:Androstadienes / Q000494:pharmacology; D002867:Chromones / Q000494:pharmacology; D034822:Commelina / Q000166:cytology* / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant / Q000502:physiology; D009025:Morpholines / Q000494:pharmacology; D018129:Phosphatidylinositol Phosphates / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D054046:Plant Stomata / Q000166:cytology* / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D000077191:Wortmannin
chemical_list: D000199:Actins; D000730:Androstadienes; D002867:Chromones; D009025:Morpholines; D018129:Phosphatidylinositol Phosphates; D000081082:Phosphoinositide-3 Kinase Inhibitors; D017382:Reactive Oxygen Species; C055525:phosphatidylinositol 3-phosphate; C037178:phosphatidylinositol 4-phosphate; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D000040:Abscisic Acid; D019870:1-Phosphatidylinositol 4-Kinase; D000077191:Wortmannin