Phospholipase D activity is essential for actin localization and actin-based motility in Dictyostelium.
PLD (phospholipase D) activity catalyses the generation of the lipid messenger phosphatidic acid, which has been implicated in a number of cellular processes, particularly the regulation of membrane traffic. In the present study, we report that disruption of PLD signalling causes unexpectedly profound effects on the actin-based motility of Dictyostelium. Cells in which PLD activity is inhibited by butan-1-ol show a complete loss of actin-based structures, accompanied by relocalization of F-actin into small clusters, and eventually the nucleus, without a visible fall in levels of F-actin. Addition of exogenous phosphatidic acid reverses the effects of butan-1-ol, confirming that these effects are caused by inhibition of PLD. Loss of motility correlates with complete inhibition of endocytosis and a reduction in phagocytosis. Inhibition of PLD caused a major decrease in the synthesis of PtdIns(4,5)P2, which could again be reversed by exogenously applied phosphatidic acid. Thus the essential role of PLD signalling in both motility and endocytosis appears to be mediated directly via regulation of PtdIns(4)P kinase activity. This implies that localized PLD-regulated synthesis of PtdIns(4,5)P2 is essential for Dictyostelium actin function.
Zouwail
Soha
S
School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
Pettitt
Trevor R
TR
Dove
Stephen K
SK
Chibalina
Margarita V
MV
Powner
Dale J
DJ
Haynes
Lee
L
Wakelam
Michael J O
MJ
Insall
Robert H
RH
D000199:Actins / Q000378:metabolism*; D000818:Animals; D000440:Butanols / Q000494:pharmacology; D002465:Cell Movement; D004023:Dictyostelium / Q000166:cytology* / Q000201:enzymology / Q000378:metabolism*; D004705:Endocytosis / Q000187:drug effects; D020404:Glycerophospholipids / Q000378:metabolism; D010587:Phagocytosis / Q000187:drug effects; D019269:Phosphatidylinositol 4,5-Diphosphate; D018129:Phosphatidylinositol Phosphates / Q000096:biosynthesis / Q000378:metabolism; D010739:Phospholipase D / Q000037:antagonists & inhibitors / Q000378:metabolism*; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects
D000199:Actins; D000440:Butanols; D020404:Glycerophospholipids; D019269:Phosphatidylinositol 4,5-Diphosphate; D018129:Phosphatidylinositol Phosphates; C068564:phosphatidylbutanol; D017853:Phosphotransferases (Alcohol Group Acceptor); C068961:phosphatidylinositol 4,5-biphosphate kinase; D010739:Phospholipase D