The Experts below are selected from a list of 162 Experts worldwide ranked by ideXlab platform
Toby D. M. Bell - One of the best experts on this subject based on the ideXlab platform.
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Ultra-Low Colcemid Doses Induce Microtubule Dysfunction as Revealed by Super-Resolution Microscopy
bioRxiv, 2020Co-Authors: Ashley M. Rozario, Sam Duwe, Cade Elliott, Riley B. Hargreaves, Peter Dedecker, Donna R. Whelan, Toby D. M. BellAbstract:Microtubule-interacting drugs, sometimes referred to as antimitotics, are used in cancer therapy to target and disrupt micro-tubules. However, their side effects require the development of safer drug regimens that still retain clinical efficacy. Currently, many questions remain regarding microtubule-interacting drugs at clinically relevant and ultra-low doses. Here, we use super-resolution microscopies (single molecule localization and optical fluctuation based) to reveal the initial microtubule dysfunctions caused by nanomolar concentrations of Colcemid. Short exposure to 30 - 80 nM Colcemid results in aberrant microtubule curvature while microtubule fragmentation is detected upon treatment with [≥]100 nM Colcemid. Remarkably, even ultra-low doses (5 hours at
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ultra low Colcemid doses induce microtubule dysfunction as revealed by super resolution microscopy
bioRxiv, 2020Co-Authors: Ashley M. Rozario, Sam Duwe, Cade Elliott, Riley B. Hargreaves, Peter Dedecker, Donna R. Whelan, Toby D. M. BellAbstract:Microtubule-interacting drugs, sometimes referred to as antimitotics, are used in cancer therapy to target and disrupt micro-tubules. However, their side effects require the development of safer drug regimens that still retain clinical efficacy. Currently, many questions remain regarding microtubule-interacting drugs at clinically relevant and ultra-low doses. Here, we use super-resolution microscopies (single molecule localization and optical fluctuation based) to reveal the initial microtubule dysfunctions caused by nanomolar concentrations of Colcemid. Short exposure to 30 - 80 nM Colcemid results in aberrant microtubule curvature while microtubule fragmentation is detected upon treatment with [≥]100 nM Colcemid. Remarkably, even ultra-low doses (5 hours at <20 nM) led to subtle but significant microtubule architecture remodeling and suppression of microtubule dynamics. These challenges to microtubule function represent less severe precursor perturbations compared to the established antimitotic effects of microtubule-interacting drugs, and therefore offer potential for improved understanding and design of anti-cancer agents.
Bhabatarak Bhattacharyya - One of the best experts on this subject based on the ideXlab platform.
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Interaction of a Fluorescent Analog of N -Deacetyl-N -Methyl-Colchicine (Colcemid) with Liver Alcohol Dehydrogenase
FEBS Journal, 1995Co-Authors: Suparna Sengupta, Pradip K. Mahapatra, Gopal Chakrabarti, Sabita Roy, Bhabatarak BhattacharyyaAbstract:The evidence for specific binding of N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)-Colcemid (NBD-Colcemid), a fluorescent analog of Colcemid (N-deacetyl-N-methyl-colchicine), to liver alcohol dehydrogenase is presented. Alcohol dehydrogenase bound NBD-Colcemid in a time-dependent manner, enhanced the fluorescence intensity, and caused a large blue shift of the emission maximum of the free drug. The specificity of binding was determined for both the colchicine nucleus and the NBD moiety. The binding was not affected by the presence of alcohol or NAD in the reaction mixture. Preincubation of horse liver alcohol dehydrogenase with Colcemid inhibited the binding to a considerable extent. NBD-Colcemid inhibited the enzymic activity of alcohol dehydrogenase in a mixed-type noncompetitive mode with a Ki value of 32 μM, whereas Colcemid showed noncompetitive inhibition with a Ki of 100 μM. The association rate constant of NBD-Colcemid binding with liver alcohol dehydrogenase was 587 M-1 s-1 at 25 °C. The stoichiometry and dissociation constant of the binding reaction were 0.62/dimer and 12 μM, respectively. Donor quenching experiments showed that both tryptophans of alcohol dehydrogenase transferred energy to the bound NBD-Colcemid. Thus, this study reports the binding of a colchicine analog to a protein other than tubulin with high affinity. It is concluded that NBD-Colcemid binding to dehydrogenases is a general phenomenon, but the common structural element(s) that is responsible for the binding activity, and which exists among tubulin and dehydrogenases, has yet to be determined.
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N‐(7‐Nitrobenz‐2‐oxa‐1,3‐diazol‐4‐yI)Colcemid, a probe for different classes of colchincine‐binding site on tubulin
FEBS Journal, 1993Co-Authors: Suparna Sengupta, Sabita Roy, Kamal D. Puri, Avadhesha Surolia, Bhabatarak BhattacharyyaAbstract:The nature of binding of 7-nitrobenz-2-oxa-1,3-diazol-4-yl-Colcemid (NBD-Colcemid), an environment-sensitive fluorescent analogue of colchicine, to tubulin was tested. This article reports the first fluorometric study where two types of binding site of colchincine analogue on tubulin were detected. Binding of NBD-Colcemid to one of these sites equilibrates slsowly. NBD-Colcemid competes with colchicine for this site. Binding of NBD-Colcemid to this site also causes inhibition of tubulin self-assembly. In contrast, NBD-Colcemid binding to the other site is characterised by rapid equilibration and lack of competition with colchicine. Nevertheless, binding to this site is highly specific for the cholchicine nucleus, as alkyl-NBD analogues have no significant binding activity. Fast-reaction-kinetic studies gave 1.76 × 105 M–1 s–1 for the association and 0.79 s–1 for the dissociation rate constants for the binding of NBD-Colcemid to the fast site of tubulin. The association rate constants for the two phases of the slow site are 0.016 × 10–4 M–1 s–1 and 3.5 × 10–4 M–1 respectively. These two sites may be related to the two sites of colchicine reported earlier, with binding characteristics altered by the increased hydrophobic nature of NBD-Colcemid.
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n 7 nitrobenz 2 oxa 1 3 diazol 4 yi Colcemid a probe for different classes of colchincine binding site on tubulin
FEBS Journal, 1993Co-Authors: Suparna Sengupta, Sabita Roy, Kamal D. Puri, Avadhesha Surolia, Bhabatarak BhattacharyyaAbstract:The nature of binding of 7-nitrobenz-2-oxa-1,3-diazol-4-yl-Colcemid (NBD-Colcemid), an environment-sensitive fluorescent analogue of colchicine, to tubulin was tested. This article reports the first fluorometric study where two types of binding site of colchincine analogue on tubulin were detected. Binding of NBD-Colcemid to one of these sites equilibrates slsowly. NBD-Colcemid competes with colchicine for this site. Binding of NBD-Colcemid to this site also causes inhibition of tubulin self-assembly. In contrast, NBD-Colcemid binding to the other site is characterised by rapid equilibration and lack of competition with colchicine. Nevertheless, binding to this site is highly specific for the cholchicine nucleus, as alkyl-NBD analogues have no significant binding activity. Fast-reaction-kinetic studies gave 1.76 × 105 M–1 s–1 for the association and 0.79 s–1 for the dissociation rate constants for the binding of NBD-Colcemid to the fast site of tubulin. The association rate constants for the two phases of the slow site are 0.016 × 10–4 M–1 s–1 and 3.5 × 10–4 M–1 respectively. These two sites may be related to the two sites of colchicine reported earlier, with binding characteristics altered by the increased hydrophobic nature of NBD-Colcemid.
Kamal D. Puri - One of the best experts on this subject based on the ideXlab platform.
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N‐(7‐Nitrobenz‐2‐oxa‐1,3‐diazol‐4‐yI)Colcemid, a probe for different classes of colchincine‐binding site on tubulin
FEBS Journal, 1993Co-Authors: Suparna Sengupta, Sabita Roy, Kamal D. Puri, Avadhesha Surolia, Bhabatarak BhattacharyyaAbstract:The nature of binding of 7-nitrobenz-2-oxa-1,3-diazol-4-yl-Colcemid (NBD-Colcemid), an environment-sensitive fluorescent analogue of colchicine, to tubulin was tested. This article reports the first fluorometric study where two types of binding site of colchincine analogue on tubulin were detected. Binding of NBD-Colcemid to one of these sites equilibrates slsowly. NBD-Colcemid competes with colchicine for this site. Binding of NBD-Colcemid to this site also causes inhibition of tubulin self-assembly. In contrast, NBD-Colcemid binding to the other site is characterised by rapid equilibration and lack of competition with colchicine. Nevertheless, binding to this site is highly specific for the cholchicine nucleus, as alkyl-NBD analogues have no significant binding activity. Fast-reaction-kinetic studies gave 1.76 × 105 M–1 s–1 for the association and 0.79 s–1 for the dissociation rate constants for the binding of NBD-Colcemid to the fast site of tubulin. The association rate constants for the two phases of the slow site are 0.016 × 10–4 M–1 s–1 and 3.5 × 10–4 M–1 respectively. These two sites may be related to the two sites of colchicine reported earlier, with binding characteristics altered by the increased hydrophobic nature of NBD-Colcemid.
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n 7 nitrobenz 2 oxa 1 3 diazol 4 yi Colcemid a probe for different classes of colchincine binding site on tubulin
FEBS Journal, 1993Co-Authors: Suparna Sengupta, Sabita Roy, Kamal D. Puri, Avadhesha Surolia, Bhabatarak BhattacharyyaAbstract:The nature of binding of 7-nitrobenz-2-oxa-1,3-diazol-4-yl-Colcemid (NBD-Colcemid), an environment-sensitive fluorescent analogue of colchicine, to tubulin was tested. This article reports the first fluorometric study where two types of binding site of colchincine analogue on tubulin were detected. Binding of NBD-Colcemid to one of these sites equilibrates slsowly. NBD-Colcemid competes with colchicine for this site. Binding of NBD-Colcemid to this site also causes inhibition of tubulin self-assembly. In contrast, NBD-Colcemid binding to the other site is characterised by rapid equilibration and lack of competition with colchicine. Nevertheless, binding to this site is highly specific for the cholchicine nucleus, as alkyl-NBD analogues have no significant binding activity. Fast-reaction-kinetic studies gave 1.76 × 105 M–1 s–1 for the association and 0.79 s–1 for the dissociation rate constants for the binding of NBD-Colcemid to the fast site of tubulin. The association rate constants for the two phases of the slow site are 0.016 × 10–4 M–1 s–1 and 3.5 × 10–4 M–1 respectively. These two sites may be related to the two sites of colchicine reported earlier, with binding characteristics altered by the increased hydrophobic nature of NBD-Colcemid.
Avadhesha Surolia - One of the best experts on this subject based on the ideXlab platform.
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N‐(7‐Nitrobenz‐2‐oxa‐1,3‐diazol‐4‐yI)Colcemid, a probe for different classes of colchincine‐binding site on tubulin
FEBS Journal, 1993Co-Authors: Suparna Sengupta, Sabita Roy, Kamal D. Puri, Avadhesha Surolia, Bhabatarak BhattacharyyaAbstract:The nature of binding of 7-nitrobenz-2-oxa-1,3-diazol-4-yl-Colcemid (NBD-Colcemid), an environment-sensitive fluorescent analogue of colchicine, to tubulin was tested. This article reports the first fluorometric study where two types of binding site of colchincine analogue on tubulin were detected. Binding of NBD-Colcemid to one of these sites equilibrates slsowly. NBD-Colcemid competes with colchicine for this site. Binding of NBD-Colcemid to this site also causes inhibition of tubulin self-assembly. In contrast, NBD-Colcemid binding to the other site is characterised by rapid equilibration and lack of competition with colchicine. Nevertheless, binding to this site is highly specific for the cholchicine nucleus, as alkyl-NBD analogues have no significant binding activity. Fast-reaction-kinetic studies gave 1.76 × 105 M–1 s–1 for the association and 0.79 s–1 for the dissociation rate constants for the binding of NBD-Colcemid to the fast site of tubulin. The association rate constants for the two phases of the slow site are 0.016 × 10–4 M–1 s–1 and 3.5 × 10–4 M–1 respectively. These two sites may be related to the two sites of colchicine reported earlier, with binding characteristics altered by the increased hydrophobic nature of NBD-Colcemid.
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n 7 nitrobenz 2 oxa 1 3 diazol 4 yi Colcemid a probe for different classes of colchincine binding site on tubulin
FEBS Journal, 1993Co-Authors: Suparna Sengupta, Sabita Roy, Kamal D. Puri, Avadhesha Surolia, Bhabatarak BhattacharyyaAbstract:The nature of binding of 7-nitrobenz-2-oxa-1,3-diazol-4-yl-Colcemid (NBD-Colcemid), an environment-sensitive fluorescent analogue of colchicine, to tubulin was tested. This article reports the first fluorometric study where two types of binding site of colchincine analogue on tubulin were detected. Binding of NBD-Colcemid to one of these sites equilibrates slsowly. NBD-Colcemid competes with colchicine for this site. Binding of NBD-Colcemid to this site also causes inhibition of tubulin self-assembly. In contrast, NBD-Colcemid binding to the other site is characterised by rapid equilibration and lack of competition with colchicine. Nevertheless, binding to this site is highly specific for the cholchicine nucleus, as alkyl-NBD analogues have no significant binding activity. Fast-reaction-kinetic studies gave 1.76 × 105 M–1 s–1 for the association and 0.79 s–1 for the dissociation rate constants for the binding of NBD-Colcemid to the fast site of tubulin. The association rate constants for the two phases of the slow site are 0.016 × 10–4 M–1 s–1 and 3.5 × 10–4 M–1 respectively. These two sites may be related to the two sites of colchicine reported earlier, with binding characteristics altered by the increased hydrophobic nature of NBD-Colcemid.
Ashley M. Rozario - One of the best experts on this subject based on the ideXlab platform.
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Ultra-Low Colcemid Doses Induce Microtubule Dysfunction as Revealed by Super-Resolution Microscopy
bioRxiv, 2020Co-Authors: Ashley M. Rozario, Sam Duwe, Cade Elliott, Riley B. Hargreaves, Peter Dedecker, Donna R. Whelan, Toby D. M. BellAbstract:Microtubule-interacting drugs, sometimes referred to as antimitotics, are used in cancer therapy to target and disrupt micro-tubules. However, their side effects require the development of safer drug regimens that still retain clinical efficacy. Currently, many questions remain regarding microtubule-interacting drugs at clinically relevant and ultra-low doses. Here, we use super-resolution microscopies (single molecule localization and optical fluctuation based) to reveal the initial microtubule dysfunctions caused by nanomolar concentrations of Colcemid. Short exposure to 30 - 80 nM Colcemid results in aberrant microtubule curvature while microtubule fragmentation is detected upon treatment with [≥]100 nM Colcemid. Remarkably, even ultra-low doses (5 hours at
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ultra low Colcemid doses induce microtubule dysfunction as revealed by super resolution microscopy
bioRxiv, 2020Co-Authors: Ashley M. Rozario, Sam Duwe, Cade Elliott, Riley B. Hargreaves, Peter Dedecker, Donna R. Whelan, Toby D. M. BellAbstract:Microtubule-interacting drugs, sometimes referred to as antimitotics, are used in cancer therapy to target and disrupt micro-tubules. However, their side effects require the development of safer drug regimens that still retain clinical efficacy. Currently, many questions remain regarding microtubule-interacting drugs at clinically relevant and ultra-low doses. Here, we use super-resolution microscopies (single molecule localization and optical fluctuation based) to reveal the initial microtubule dysfunctions caused by nanomolar concentrations of Colcemid. Short exposure to 30 - 80 nM Colcemid results in aberrant microtubule curvature while microtubule fragmentation is detected upon treatment with [≥]100 nM Colcemid. Remarkably, even ultra-low doses (5 hours at <20 nM) led to subtle but significant microtubule architecture remodeling and suppression of microtubule dynamics. These challenges to microtubule function represent less severe precursor perturbations compared to the established antimitotic effects of microtubule-interacting drugs, and therefore offer potential for improved understanding and design of anti-cancer agents.