We have focused on antimitotic peptides, often of marine origin, because these are among the most potent anti-MT agents known, they have been synthesized and analogs are available, and because they induce the MT subunits to assume unusual and characteristic ring shapes. We are studying the structural and dynamic properties of these ring polymers by analytical ultracentrifugation, cryoelectron microscopy, fluorescence correlation spectroscopy, and protease mapping. The high stability and uniformity of these rings that our studies revealed have led us to attempt crystallization of these polymers to achieve atomic resolution of their structure. We are also examining the effects on microtubule polymerization of synthetic analogs of thalidomide and combretastatin A. We have also demonstrated the role of posttranslational modifications by deacetylases, and the effects of proteasome inhibitors on microtubule stability.? We have identified a number of new modified peptides derived from the natural peptide tubulysin. Thes new peptides show a range of antimicrotubule activity in assays with purified proteins as well as in cells. In addition we have examined a new """"""""second generation"""""""" of microtubule stabilizers, focusing on the natural compound peloruside. We have also shown that an old chemotherapy agent, a nitrosourea, may affect microtubule stability indirectly by altering the activity of the protein stathmin. This results in reduced migration and invasion by malignant glioma cells.? We are seeking to identify small molecules that do not bind well with mammalian tubulin but do bind to parasite tubulin. The tubulin molecule is quite conserved evolutionarily, but differences do exist, and several molecules are known that can target, for example, yeast rather than mammalian tubulin or vice-versa. We are looking for molecules that will target Leishmania, the infectious cause of an important group of human diseases. We have identified several small molecules that show promise as selective agents, binding to Leishmania tubulin preferentially over mammalian tubulin, and preventing parasite multiplication inside human macrophage cells.

Project Start
Project End
Budget Start
Budget End
Support Year
6
Fiscal Year
2008
Total Cost
$248,016
Indirect Cost
City
State
Country
United States
Zip Code
Huzil, J Torin; Chik, John K; Slysz, Gordon W et al. (2008) A unique mode of microtubule stabilization induced by peloruside A. J Mol Biol 378:1016-30
Balasubramanian, Ranganathan; Raghavan, Bhooma; Steele, Jaeson C et al. (2008) Tubulysin analogs incorporating desmethyl and dimethyl tubuphenylalanine derivatives. Bioorg Med Chem Lett 18:2996-9
Sackett, Dan L; Ozbun, Laurent; Zudaire, Enrique et al. (2008) Intracellular proadrenomedullin-derived peptides decorate the microtubules and contribute to cytoskeleton function. Endocrinology 149:2888-98
Poruchynsky, Marianne S; Sackett, Dan L; Robey, Robert W et al. (2008) Proteasome inhibitors increase tubulin polymerization and stabilization in tissue culture cells: a possible mechanism contributing to peripheral neuropathy and cellular toxicity following proteasome inhibition. Cell Cycle 7:940-9
Raghavan, Bhooma; Balasubramanian, Ranganathan; Steele, Jaeson C et al. (2008) Cytotoxic simplified tubulysin analogues. J Med Chem 51:1530-3
Zhuang, Sen H; Hung, Y Elizabeth; Hung, Laura et al. (2007) Evidence for microtubule target engagement in tumors of patients receiving ixabepilone. Clin Cancer Res 13:7480-6
Boukari, Hacene; Sackett, Dan L; Schuck, Peter et al. (2007) Single-walled tubulin ring polymers. Biopolymers 86:424-36
Piekarz, Richard L; Sackett, Dan L; Bates, Susan E (2007) Histone deacetylase inhibitors and demethylating agents: clinical development of histone deacetylase inhibitors for cancer therapy. Cancer J 13:30-9
Kim, Yeoun Jin; Sackett, Dan L; Schapira, Matthieu et al. (2006) Identification of 12Cysbeta on tubulin as the binding site of tubulyzine. Bioorg Med Chem 14:1169-75
Trostel, Shana Y; Sackett, Dan L; Fojo, Tito (2006) Oligomerization of p53 precedes its association with dynein and nuclear accumulation. Cell Cycle 5:2253-9

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