| Cytometry A. 2013 Sep;83(9):830-8. |
| Inhibition of cytoplasmic streaming by cytochalasin D is superior to paraformaldehyde fixation for measuring FRET between fluorescent protein-tagged Golgi components.[Pubmed: 23520174] |
Protein-protein interaction at the organelle level can be analyzed by using tagged proteins and assessing Förster resonance energy transfer (FRET) between fluorescent donor and acceptor proteins. Such studies are able to uncover partners in the regulation of proteins and enzymes. However, any organelle movement is an issue for live FRET microscopy, as the observed organelle must not change position during measurement. One of the mobile organelles in plants is the Golgi apparatus following cytoplasmic streaming. It is involved in the decoration of proteins and processing of complex glycan structures for the cell wall. Understanding of these processes is still limited, but evidence is emerging that protein-protein interaction plays a key role in the function of this organelle. In the past, mobile organelles were usually immobilized with paraformaldehyde (PFA) for FRET-based interaction studies.
METHODS AND RESULTS:
Here, we show that the actin inhibitor Cytochalasin D (CytD) is superior to PFA for immobilization of Golgi stacks in plant cells. Two glycosyltransferases known to interact were tagged with cyan fluorescent protein (CFP) and yellow fluorescent protein (YFP), respectively, coexpressed in Nicotiana benthamiana leaves and analyzed using confocal microscopy and spectral imaging. Fixation with PFA leads to reduced emission intensity when compared to CytD treatment. Furthermore, the calculated FRET efficiency was significantly higher with CytD than with PFA.
CONCLUSIONS:
The documented improvements are beneficial for all methods measuring FRET, where immobilization of the investigated molecules is necessary. It can be expected that FRET measurement in organelles of animal cells will also benefit from the use of inhibitors acting on the cytoskeleton. |
| Asian Pac J Trop Med. 2012 Mar;5(3):169-74. |
| Cytochalasin D, a tropical fungal metabolite, inhibits CT26 tumor growth and angiogenesis.[Pubmed: 22305779] |
To investigate whether Cytochalasin D can induce antitumor activities in a tumor model.
METHODS AND RESULTS:
Murine CT26 colorectal carcinoma cells were cultured in vitro and Cytochalasin D was used as a cytotoxic agent to detect its capabilities of inhibiting CT26 cell proliferation and inducing cell apoptosis by MTT and a TUNEL-based apoptosis assay. Cytochalasin D inhibited CT26 tumor cell proliferation in time and dose dependent manner and induced significant CT26 cell apoptosis, which almost reached the level induced by the positive control nuclease. The optimum effective dose of Cytochalasin D for in vivo therapy was about 50 mg/kg. Cytochalasin D in vivo treatment significantly inhibited tumor growth and prolonged the survival times in CT26 tumor-bearing mice. The results of immunohistochemistry analysis and alginate encapsulation assay indicated that the Cytochalasin D could effectively inhibited tumor angiogenesis.
CONCLUSIONS:
Cytochalasin D inhibits CT26 tumor growth potentially through inhibition of cell proliferation, induction of cell apoptosis and suppression of tumor angiogenesis. |
| Infect Immun. 1991 Mar;59(3):758-63. |
| Effects of cytochalasin D and methylamine on intracellular growth of Legionella pneumophila in amoebae and human monocyte-like cells.[Pubmed: 1997428 ] |
A cloned and axenically cultured strain of Hartmannella vermiformis was used as a model to study intracellular multiplication of Legionella pneumophila in amoebae.
METHODS AND RESULTS:
The growth of L. pneumophilia in both H. vermiformis and a human monocyte-like cell line (U937) was investigated with cytoskeletal and metabolic inhibitors. L. pneumophila replicated only intracellularly in these cellular models, and electron microscopy showed ultrastructural similarities in the initial phase of multiplication. Treatment of amoebae with an inhibitor of microfilament-dependent phagocytosis (Cytochalasin D, 0.5 or 1.0 micrograms/ml) did not inhibit intracellular growth of L. pneumophila; however, intracellular multiplication was inhibited by treatment of U937 monocytes with the same concentrations of Cytochalasin D. Methylamine (10 to 100 mM), an inhibitor of adsorptive pinocytosis, inhibited the replication of L. pneumophila in amoebae in a dose-dependent manner. All doses of methylamine tested (10 to 50 mM) inhibited growth of L. pneumophila in U937 monocytes. Cytochalasin D and methylamine had no effect on the multiplication of L. pneumophila in culture medium or on the viability of amoebae or U937 monocytes.
CONCLUSIONS:
Intracellular replication of L. pneumophila in H. vermiformis may be accomplished by a Cytochalasin D-independent mechanism, such as adsorptive pinocytosis. In contrast, both Cytochalasin D- and methylamine-sensitive mechanisms may be essential for the intracellular multiplication of L. pneumophila in U937 monocytes. |
| J Androl. 1989 Jul-Aug;10(4):275-82. |
| Cytochalasin D inhibits penetration of hamster eggs by guinea pig and human spermatozoa.[Pubmed: 2777719] |
METHODS AND RESULTS:
Fertilization experiments using zona-free hamster eggs and spermatozoa from both guinea pig and human were conducted in the presence of Cytochalasin D to evaluate the possible role of actin filaments in fertilization processes. When the actin filament inhibitor, Cytochalasin D, was added to fertilization media at concentrations of 10 to 30 microM, penetration of eggs was significantly inhibited. Preincubation of the eggs with Cytochalasin D and washing prior to addition of spermatozoa had no effect on penetration as quantitated by the number of swollen heads in the egg cytoplasm. However, spermatozoa preincubated with Cytochalasin D and subsequently washed prior to egg addition showed reduced penetration of the same magnitude as when spermatozoa and eggs were coincubated with Cytochalasin D. Both the percentage of zona-free eggs showing decondensed sperm heads and the penetration indices (total decondensed spermatozoa/total eggs) were significantly affected when spermatozoa were exposed to Cytochalasin D. The DMSO vehicle used to dissolve Cytochalasin D had little effect on the number of decondensed heads. When the concentration of Cytochalasin D was increased (DMSO remaining constant) in human sperm experiments, percent penetration decreased and progressively fewer decondensed spermatozoa were recorded, indicating dose-responsiveness to Cytochalasin D. Motility parameters of human spermatozoa were not altered at any of the concentrations of Cytochalasin D tested. Neither guinea pig sperm motility nor acrosome reaction was altered significantly by Cytochalasin D or the DMSO vehicle.
CONCLUSIONS:
These experiments suggest that Cytochalasin D may be an inhibitor of some fertilization processes such as sperm penetration or sperm head decondensation. |
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