title: Formation of cofilin-actin rods following cucurbitacin-B-induced actin aggregation depends on Slingshot homolog 1-mediated cofilin hyperactivation.
abstract: Accumulating evidence indicates that cucurbitacin B (CuB), as well as other cucurbitacins, damages the actin cytoskeleton in a variety of cell types. However, the underlying mechanism of such an effect is not well understood. In this study, we showed that CuB rapidly induced actin aggregation followed by actin rod formation in melanoma cells. Cofilin, a critical regulator of actin dynamics, was dramatically dephosphorylated (i.e., activated) upon CuB treatment. Notably, the activated cofilin subsequently formed rod-like aggregates, which were highly colocalized with actin rods, indicating the formation of cofilin-actin rods. Cofilin knockdown significantly suppressed rod formation but did not prevent actin aggregation. Furthermore, knockdown of the cofilin phosphatase Slingshot homolog 1 (SSH1), but not chronophin (CIN), alleviated CuB-induced cofilin hyperactivation and cofilin-actin rod formation. The activity of Rho kinase and LIM kinase, two upstream regulators of cofilin activation, was downregulated after cofilin hyperactivation. Pretreatment with a thiol-containing reactive oxygen species (ROS) scavenger N-acetyl cysteine, but not other ROS inhibitors without thiol groups, suppressed CuB-induced actin aggregation, cofilin hyperactivation and cofilin-actin rod formation, suggesting that thiol oxidation might be involved in these processes. Taken together, our results demonstrated that CuB-induced formation of cofilin-actin rods was mediated by SSH1-dependent but CIN-independent cofilin hyperactivation.
authors.affiliation: Department of Immunobiology, Jinan University, Guangzhou, China.
authors.forename: Yan-Ting
authors.initials: YT
authors.lastname: Zhang
authors.forename: Dong-Yun
authors.initials: DY
authors.lastname: Ouyang
authors.forename: Li-Hui
authors.initials: LH
authors.lastname: Xu
authors.forename: Qing-Bing
authors.initials: QB
authors.lastname: Zha
authors.forename: Xian-Hui
authors.initials: XH
authors.lastname: He
mesh_terms: D000199:Actins / Q000378:metabolism*; D000818:Animals; D002453:Cell Cycle / Q000187:drug effects; D002460:Cell Line; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D051338:Cofilin 1 / Q000378:metabolism*; D054728:Cucurbitacins / Q000494:pharmacology*; D006801:Humans; D051379:Mice; D008856:Microscopy, Fluorescence; D010749:Phosphoprotein Phosphatases / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D000199:Actins; D051338:Cofilin 1; D017382:Reactive Oxygen Species; D054728:Cucurbitacins; D010749:Phosphoprotein Phosphatases; C484329:SSH1 protein, human
keywords: ACTIN AGGREGATION; COFILIN; COFILIN-ACTIN RODS; CUCURBITACIN B; MELANOMA; SLINGSHOT HOMOLOG 1