The natural product cucurbitacin E inhibits depolymerization of actin filaments.
Although small molecule actin modulators have been widely used as research tools, only one cell-permeable small molecule inhibitor of actin depolymerization (jasplakinolide) is commercially available. We report that the natural product cucurbitacin E inhibits actin depolymerization and show that its mechanism of action is different from jasplakinolide. In assays using pure fluorescently labeled actin, cucurbitacin E specifically affects depolymerization without affecting polymerization. It inhibits actin depolymerization at substoichiometric concentrations up to 1:6 cucurbitacin E:actin. Cucurbitacin E specifically binds to filamentous actin (F-actin) forming a covalent bond at residue Cys257, but not to monomeric actin (G-actin). On the basis of its compatibility with phalloidin staining, we show that cucurbitacin E occupies a different binding site on actin filaments. Using loss of fluorescence after localized photoactivation, we found that cucurbitacin E inhibits actin depolymerization in live cells. Cucurbitacin E is a widely available plant-derived natural product, making it a useful tool to study actin dynamics in cells and actin-based processes such as cytokinesis.
Dana-Farber Cancer Institute and Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA.
Pia M
PM
Sörensen
Roxana E
RE
Iacob
Marco
M
Fritzsche
John R
JR
Engen
William M
WM
Brieher
Guillaume
G
Charras
Ulrike S
US
Eggert
D008841:Actin Cytoskeleton / Q000378:metabolism* / Q000648:ultrastructure; D000199:Actins / Q000378:metabolism* / Q000648:ultrastructure; D000818:Animals; D001688:Biological Products / Q000737:chemistry / Q000494:pharmacology*; D019662:Cucurbitaceae / Q000737:chemistry*; D047630:Depsipeptides / Q000737:chemistry / Q000494:pharmacology; D006367:HeLa Cells; D006801:Humans; D058105:Polymerization / Q000187:drug effects; D011817:Rabbits; D014315:Triterpenes / Q000737:chemistry / Q000494:pharmacology*
D000199:Actins; D001688:Biological Products; D047630:Depsipeptides; D014315:Triterpenes; C057531:jasplakinolide; C102326:cucurbitacin E