Cytoskeletal alterations in Dictyostelium induced by expression of human cdc42.
The rho family of small G proteins has been shown to be involved in controlling actin filament dynamics in cells. To evaluate the functional overlap between human and Dictyostelium G proteins, we conditionally expressed constitutively active human cdc42 (V12-cdc42) in Dictyostelium cells. Upon induction, cells adopted a unique morphology: a flattened shape with wrinkles running from the cell edge toward the center. The appearance of these wrinkles is highly dynamic so that the cells cycle between the wrinkled and relatively normal morphologies. Phalloidin staining indicates that the stellate wrinkles contain dense actin structures and also that numerous filopods project vertically from the center of these cells. Consistent with the hypothesis that cdc42 induces actin polymerization in vivo, cells expressing V12-cdc42 show an increase in the amount of F-actin associated with the cytoskeleton. This is accompanied by an increase in the association of the actin-binding proteins 34-kDa bundler, ABP-120 and alpha-actinin with the cytoskeleton. In conclusion, human cdc42 has various effects on the Dictyostelium actin cytoskeleton consistent with a conserved role of small GTPases in control of the cytoskeleton.
Lee
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Department of Molecular and Cell Biology, University of Connecticut, Storrs 06260, USA.
Knecht
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DA
D008841:Actin Cytoskeleton / Q000378:metabolism* / Q000648:ultrastructure; D000199:Actins / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D000818:Animals; D002465:Cell Movement / Q000235:genetics; D048429:Cell Size / Q000235:genetics; D002478:Cells, Cultured / Q000378:metabolism / Q000648:ultrastructure; D003593:Cytoplasm / Q000378:metabolism / Q000648:ultrastructure; D004023:Dictyostelium / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D005492:Folic Acid / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000502:physiology*; D017930:Genes, Reporter / Q000502:physiology; D005822:Genetic Vectors / Q000502:physiology; D049452:Green Fluorescent Proteins; D006801:Humans; D007202:Indicators and Reagents / Q000378:metabolism; D008164:Luminescent Proteins / Q000378:metabolism; D008840:Microfilament Proteins / Q000235:genetics / Q000378:metabolism; D008855:Microscopy, Electron, Scanning; D018715:Microscopy, Video; D011401:Promoter Regions, Genetic / Q000502:physiology; D011554:Pseudopodia / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D014162:Transfection; D020764:cdc42 GTP-Binding Protein / Q000235:genetics* / Q000378:metabolism*
D000199:Actins; D007202:Indicators and Reagents; D008164:Luminescent Proteins; D008840:Microfilament Proteins; D049452:Green Fluorescent Proteins; D005492:Folic Acid; D020764:cdc42 GTP-Binding Protein