What is cytochalasin B and how does it affect cells?

Cytochalasin B (CB) is a cell-permeable mycotoxin. It inhibits cytoplasmic division by blocking the formation of contractile microfilaments, it inhibits cell movement and induces nuclear extrusion.

How does cytochalasin B interfere with cell division?

It inhibits cytoplasmic division by blocking the formation of contractile microfilaments. It inhibits cell movement and induces nuclear extrusion. Cytochalasin B shortens actin filaments by blocking monomer addition at the fast-growing end of polymers.

What does cytochalasin do to cells?

As a result of the inhibition of actin polymerization, cytochalasins can change cellular morphology, inhibit cellular processes such as cell division, and even cause cells to undergo apoptosis. Cytochalasins have the ability to permeate cell membranes, prevent cellular translocation and cause cells to enucleate.

How does cytochalasin modulate polymerization?

Cytochalasins reduce the viscosity of actin gels, by both decreasing the average filament length through a change in the steady state between net polymerizing and depolymerizing ends, and by inhibiting the reannealing of spontaneous breaks in F‐actin.

Is Phalloidin toxic?

Phalloidin belongs to a class of toxins called phallotoxins, which are found in the death cap mushroom (Amanita phalloides). It is a rigid bicyclic heptapeptide that is lethal after a few days when injected into the bloodstream….Phalloidin.

Identifiers
Melting point	281 °C (538 °F; 554 K) (hyd)

How does cytochalasin D work?

Cytochalasin D is a cell permeable fungal toxin that binds to the barbed end of actin filaments inhibiting both the association and dissociation of subunits. This compound causes the disruption of actin filaments and inhibition of actin polymerization.

Does cytochalasin inhibit cytokinesis?

Cytochalasins inhibit cellular processes that require actin polymerization and depolymerization (e.g., phagocytosis, cytokinesis, clot retraction) and also act by severing and capping actin filaments.

What does Latrunculin B do?

Latrunculin B causes concentration-dependent changes in cell shape and actin organization. It sequesters G-actin and prevents F-actin assembly. It binds monomeric actin with 1:1 stoichiometry and can be used to block actin polymerization both in vitro and in cells (Kd = 60 nM).

What is an example of drug targeting Microfilaments?

Some of these drugs have multiple effects on the cytoskeleton, for example Latrunculin both prevents actin polymerization as well as enhancing its rate of depolymerization. Typically the microtubule targeting drugs can be found in the clinic where they are used therapeutically in the treatment of some forms of cancer.

What does phalloidin do to live cells?

Phalloidin binds F-actin, preventing its depolymerization and poisoning the cell. Overall, phalloidin is found to react stoichiometrically with actin, strongly promote actin polymerization, and stabilize actin polymers. Phalloidin functions differently at various concentrations in cells.

What happens when cytochalasin B is present in the cell?

If cytochalasin B is present in the cell, the deprotonation of thiol is competed. The reactive beta-unsaturated ester group of cytochalasin B reacts with the thiol group of actin via a nucleophilic attack of the charged sulfur onto the beta-carbon atom. This forces the π-bond to get dislocated on the left site of the beta-carbon.

When was the discovery of cytochalasin B made?

Cytochalasin B was first described in 1967, when it had been isolated from moulds by Dr W.B. Turner. Smith et al. found that CB causes multinucleation in cells and significantly affects cell motility.

How does cytochalasin B shorten actin filaments?

Cytochalasin B shortens actin filaments by blocking monomer addition at the fast-growing end of polymers. Cytochalasin B inhibits glucose transport and platelet aggregation. It blocks adenosine -induced apoptotic body formation without affecting activation of endogenous ADP -ribosylation in leukemia HL-60 cells.

How does cytochalasin B affect Amoeba proteus?

Cytochalasin B is unable to transform 3T3-like tumor cells, but it did increase the frequency of cell transformation by the polyoma virus 8-40 fold. Furthermore, CB can intensify pinocytosis, which is induced by concanavalin A in amoeba proteus.