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Action of tolytoxin on cell morphology, cytoskeletal organization, and actin polymerization
G M Patterson1, C D Smith, L H Kimura
1Department of Chemistry, University of Hawaii, Manoa 96822.
Abstract:
Tolytoxin, a cytostatic, antifungal macrolide produced by blue-green algae of the genus Scytonema, is a potent, reversible inhibitor of cytokinesis in cultured mammalian cells. Treatment of KB cells with 2-16 nM tolytoxin results in profound morphological changes, beginning with the formation of zeiotic processes and culminating in nuclear protrusion. In L1210 cells, cytokinesis is inhibited by as little as 2 nM tolytoxin, while karyokinesis proceeds normally, resulting in polynucleation. Tolytoxin specifically disrupts microfilament organization in A10 cells, while having no apparent effect on microtubules or intermediate filaments. Tolytoxin inhibited actin polymerization in vitro and also caused the depolymerization or fragmentation of F-actin in vitro. Tolytoxin exhibits effects that closely resemble those of cytochalasin B but is effective at concentrations 1/50-1/1,000 that of cytochalasin B.
Insights
Tolytoxin, a macrolide from Scytonema algae, potently inhibits cell division (cytokinesis) in mammalian cells. This potent toxin disrupts microfilaments and actin polymerization, offering a powerful research tool.
Area of Science:
- Marine natural products
- Cell biology
- Biochemistry
Background:
- Blue-green algae produce diverse bioactive compounds.
- Cytokinesis is essential for cell division.
- Tolytoxin is a known cytostatic and antifungal agent.
Purpose of the Study:
- To investigate the mechanism of action of tolytoxin.
- To characterize tolytoxin's effects on mammalian cell division.
- To compare tolytoxin's potency with cytochalasin B.
Main Methods:
- Treatment of cultured mammalian cells (KB, L1210, A10) with tolytoxin.
- Morphological analysis of treated cells.
- Investigation of tolytoxin's effects on cytoskeletal components (microfilaments, microtubules).
- In vitro actin polymerization and depolymerization assays.
Main Results:
- Tolytoxin (2-16 nM) induced significant morphological changes, including zeiosis and nuclear protrusion.
- Cytokinesis was inhibited at 2 nM tolytoxin in L1210 cells, leading to polynucleation.
- Tolytoxin disrupted microfilament organization in A10 cells.
- Tolytoxin inhibited actin polymerization and caused F-actin depolymerization in vitro.
- Tolytoxin was 50-1000 times more potent than cytochalasin B.
Conclusions:
- Tolytoxin is a potent inhibitor of mammalian cell cytokinesis.
- The mechanism involves disruption of microfilaments and actin dynamics.
- Tolytoxin represents a highly potent chemical probe for studying cytokinesis.