Stimulation of early gene induction and cell proliferation by lysophosphatidic acid in human amnion-derived WISH cells: role of phospholipase D-mediated pathway

We show that differentiation of zoospores of the late blight pathogen Phytophthora infestans into cysts, a process called encystment, was triggered by both phosphatidic acid (PA) and the G-protein activator mastoparan. Mastoparan induced the accumulation of PA, indicating that encystment by mastoparan most likely acts through PA. Likewise, mechanical agitation of zoospores, which often is used to induce synchronized encystment, resulted in increased levels of PA. The levels of diacylglycerolpyrophosphate (DGPP), the phosphorylation product of PA, increased simultaneously. Also in cysts, sporangiospores, and mycelium, mastoparan induced increases in the levels of PA and DGPP. Using an in vivo assay for phospholipase D (PLD) activity, it was shown that the mastoparan-induced increase in PA was due to a stimulation of the activity of this enzyme. Phospholipase C in combination with diacylglycerol (DAG) kinase activity also can generate PA, but activation of these enzymes by mastoparan was not detected under conditions selected to highlight 32P-PA production via DAG kinase. Primary and secondary butanol, which, like mastoparan, have been reported to activate G-proteins, also stimulated PLD activity, whereas the inactive tertiary isomer did not. Similarly, encystment was induced by n- and sec-butanol but not by tert-butanol. Together, these results show that Phytophthora infestans contains a mastoparan- and bu-tanol-inducible PLD pathway and strongly indicate that PLD is involved in zoospore encystment. The role of G-proteins in this process is discussed.

Download Full-text

Stimulation of phosphatidylcholine turnover by β-phorbol ester and diacylglycerol in the primordial human placenta: the suggested role of phospholipase D activation

Placenta ◽

10.1016/s0143-4004(97)80041-0 ◽

1997 ◽

Vol 18 (5-6) ◽

pp. 411-419 ◽

Cited By ~ 1

Author(s):

M. Tóth

Keyword(s):

Phospholipase D ◽

Phorbol Ester ◽

Human Placenta ◽

Stimulation Of

Download Full-text

1,25-Dihydroxyvitamin D3 and TPA activate phospholipase D in Caco-2 cells: role of PKC-α

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1999.276.4.g993 ◽

1999 ◽

Vol 276 (4) ◽

pp. G993-G1004 ◽

Cited By ~ 7

Author(s):

Sharad Khare ◽

Marc Bissonnette ◽

Beth Scaglione-Sewell ◽

Ramesh K. Wali ◽

Michael D. Sitrin ◽

...

Keyword(s):

Phospholipase D ◽

Dihydroxyvitamin D3 ◽

Dihydroxyvitamin D ◽

1,25 Dihydroxyvitamin D ◽

Kinase C ◽

Pkc Isoforms ◽

Gf 109203X ◽

Pkc Β ◽

Stimulation Of

1,25-Dihydroxyvitamin D3[1,25(OH)2D3] and 12- O-tetradecanoylphorbol 13-acetate (TPA) both activated phospholipase D (PLD) in Caco-2 cells. GF-109203x, an inhibitor of protein kinase C (PKC) isoforms, inhibited this activation by both of these agonists. 1,25(OH)2D3activated PKC-α, but not PKC-β1, -βII, -δ, or -ζ, whereas TPA activated PKC-α, -β1, and -δ. Chronic treatment with TPA (1 μM, 24 h) significantly reduced the expression of PKC-α, -βI, and -δ and markedly reduced the ability of 1,25(OH)2D3or TPA to acutely stimulate PLD. Removal of Ca2+ from the medium, as well as preincubation of cells with Gö-6976, an inhibitor of Ca2+-dependent PKC isoforms, significantly reduced the stimulation of PLD by 1,25(OH)2D3or TPA. Treatment with 12-deoxyphorbol-13-phenylacetate-20-acetate, which specifically activates PKC-βI and -βII, however, failed to stimulate PLD. In addition, the activation of PLD by 1,25(OH)2D3or TPA was markedly reduced or accentuated in stably transfected cells with inhibited or amplified PKC-α expression, respectively. Taken together, these observations indicate that PKC-α is intimately involved in the stimulation of PLD in Caco-2 cells by 1,25(OH)2D3or TPA.

Download Full-text