Of cytochalasin

Cytochalasins B and D are used as tools to study F-actin. Cytochalasins bind to the barbed end of F-actin and block the addition as well as dissociation of G-actin at that end. When applied to cultured cells micromolar concentrations of cytochalasins remove stress fibres and other F-actin structures. 

The cy tochalasins A, B, C, D, E, and H are found in various species of mould. Mainly cytochalasin B and D are used as experimental tools. Cytochalasin D is 10 times more potent, acting at concentrations between 2 and 35 nM in cell-free systems. Cy tochalasins bind to the barbed end of F-actin and block the addition as well as dissociation of G-actin at that end. At micromolar concentrations, cytochalasin D can bind to G-actin and actin dimers and thus block additional polymerization. When applied to cultured cells, micromolar concentrations of cytochalasins remove stress fibres and other F-actin structures. 

Figure 7. Neutrophil degranulation (A) and lndo-1-detected cytosolic Ca responses (B) in the presence of cytochalasin B. Cells were labeled with lndo-1, degranulation was measured as...

Neutrophils represent an ideal system for studying osmotic effects on exocytosis. Stimulation of cytochalasin-B-treated neutrophils with the chemotactic peptide Jlf-formylmethionyl-leucyl-phenyl-alanine (FMLP) results in a rapid compound exocytosis up to 80% of lysosomal enzymes are released within 30 s (9-14). Secretion appears to be triggered by a rise in the level of cytosolic free calcium (15-18) promoted in part by entry of extracellular calcium through receptor-gated channels and in part by release of calcium that is sequestered or bound at some intracellular site (19-21). In this presentation, we augment our previously published data (22,23), which demonstrates that lysosomal enzyme release from neutrophils is inhibited under hyperosmotic conditions and that the rise in cytosolic calcium preceding secretion is inhibited as well. 

Ohno, Y.I., Hirai, K.I., BCanoh, T., Uchino, H. andOgawa, K. (1982). Subcellular localization of H2O2 production in human neutrophils stimulated with particles and an eflfect of cytochalasin-B on the cells. Blood 60, 253-260. 

In contrast to cases 1 and 2, where the influence of opening tight junctions on Pe was assessed in a hypothetical context, this present case has been demonstrated in MDCK cell transmonolayer kinetic studies employing extracellular permeants, such as mannitol and sucrose, in the presence and absence of cytochalasin D (see Figs. 11 and 12). Here,... 

Madara JL, D Barenberg, S Carlsson. (1986). Effects of cytochalasin D on occluding junctions of intestinal absorptive cells Further evidence that the cytoskeleton may influence paracellular permeability and junctional charge selectivity. J Cell Biol 102 2125-2136. 

Prasain, J. K. Ueki, M. Stefanowicz, P. Osada, H. Rapid screening and identification of cytochalasins by electrospray tandem mass spectrometry. J. Mass Spectrom. 2002,37, 283-291. 

In addition to their chemotactic activity, C5-derived peptides can also induce degranulation in human neutrophils. This process, readily detected in cytochalasin-B-treated neutrophils, occurs rapidly (within 1 min) upon the addition of peptides. The half-maximum responses in cytochalasin-treated human neutrophils are observed at 1-5 nM C5a and 100-800 nM C5a des Arg. In the absence of cytochalasin B, degranulation can still be detected (albeit at lower rates), especially if the neutrophils are adherent prior to the... 

C5a and C5a des Arg stimulate aerobic glycolysis, hexose monophosphate shunt activity, glucose uptake and the respiratory burst of human neutrophils. All of these processes are stimulated in neutrophil suspensions incubated in the absence of cytochalasin B, but the responses are considerably enhanced if this inhibitor of microtubule assembly is present. Stimulated rates of oxidative metabolism are maximal within 2 min of addition of peptides, with half-maximal responses obtained at 30-60 nM C5a and 1-3 pM C5a des Arg. 

Bengtsson, T., Dahlgren, C., Stendahl, 0., Andersson, T. (1991). Actin assembly and regulation of neutrophil function Effects of cytochalasin B and tetracaine on chemo-tactic peptide-induced 02" production and degranulation. J. Leuk. Biol. 49,236-44. 

These approaches have been used to show conclusively that the initial, low formation of DAG that occurs during activation with soluble agonists comes from PLC activity, and that the later, more sustained generation of DAG comes from PLD activity. Such experiments have also shown that primary alcohols can inhibit the activity of the NADPH oxidase under some conditions. When neutrophils are pretreated with cytochalasin B, primary alcohols are potent inhibitors of 02" secretion, and the kinetics of phosphatidic acid formation are rapid, peaking within about 20 s and coinciding with oxidase activation. However, in the absence of cytochalasin B, primary alcohols have little effect on the initiation of O2" secretion, but decrease the duration of oxidase activity they also inhibit the later phase of luminol chemiluminescence, which is largely intracellular, and the kinetics of phosphatidic acid formation closely parallel the kinetics of this intracellular oxidase activity (Fig. 6.20). Thus, in cytochalasin-treated cells, PLD is activated rapidly, and this activation is required for 02" secretion in the absence of cytochalasin, PLD is activated more slowly and its function is not for the activation of the oxidase, but rather for sustained (and intracellular) activity. 

Forscher P and Smith SJ [1988] Actions of cytochalasins on the organization of actin filaments and microtubules in a neuronal growth cone. J Cell Biol 107 1505-1516... 

Sampath P and Pollard TD [1991] Effects of cytochalasin, phalloidin and pH on the elongation of actin. Biochemistry 30 1973-1980... 

Shurety W, Bright NA, Luzio JP. The effects of cytochalasin D and phorbol myristate acetate on the apical endocytosis of ricin in polarized Caco-2 cells. J Cell Sci 1996 109 2927-2935. 

For the purpose of this review, it has been necessary to circumscribe the type of tetramic acid metabolites to be considered. Thus, the large group of cytochalasins, chaetoglobosins and penchalasins, e.g. 3, will not be included here as they have been covered in detail elsewhere [5-7]. For these metabolites, a tetramic acid species has been postulated as the putative precursor 4 that undergoes a Diels-Alder reaction [8-10],... 

Brown, S.S., and J.A. Spudich. 1981. Mechanism of action of cytochalasin Evidence that it binds to actin filament ends. J Cell Biol 88 487. 

Salu KJ, Huang Y Bosmans JM, et al. Addition of cytochalasin D to a biocompatible oil stent coating inhibits intimal hyperplasia in a porcine coronary model. Coron Artery Dis 2003 ... 

Cox, R. H., Cutler, H. G., Hurd, R. E., and Cole, R. J. 1983. Proton and carbon-13 nuclear magnetic resonance studies on the conformation of cytochalasin H derivatives and plant growth regulating effects of cytochalasins. J. Agric. Food Chem. 31, 405-408... 

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