个人简介

Dmitri Kudryashov received his MD from the Russian Medical State University (RGMU) in Moscow and PhD from the Russian Academy of Medical Sciences and Cardiology Research Center, where he studied the function of the Myosin Light Chain Kinase (MLCK) family of proteins. Dmitri continued his research on the actin and myosin cytoskeleton as a postdoctoral fellow at UCLA - in Prof. Emil Reisler’s group. For his postdoctoral work, Dr. Kudryashov received the Paul Boyer Award for Outstanding Postdoctoral Studies in Biochemistry and Herbert Newby McCoy Award. Dr. Kudryashov has joined the Department of Biochemistry at OSU and will commence his work there in April of 2011.

研究领域

Biochemistry

1. Actin – numerous functions of one protein. Actin is one of the most abundant and functionally versatile proteins on our planet. As a major component of the cytoskeleton, actin serves as a track for myosin-based motility and thus is involved in muscle contraction, organelle transport, and closure of the contractile ring. In addition, polymerization of actin itself also serves motor purposes and thus drives exo- and endocytosis, cell division, migration, invasion, and other cellular processes of high physiological and pathological relevance. Thus invasion of cancer cells underlies metastatic dissemination of human cancers and is actively pursued as a potential therapeutic target. Currently, our interests in this area are focused on the following directions: Actin is involved in the pathogenesis of infectious diseases as an element of the innate immune system, but also as a target that can be hijacked by many bacterial and viral toxins. We are interested in deciphering the role of actin in both phenomena. Thus, we investigate properties and the role of actin binding protein L-plastin in phagocytosis and migration of immune cells. There are three plastin isoforms in humans all of which seem to bind and bundle actin filaments in Ca2+-dependent manner. Interestingly, expression of L-plastin, but not the other two isoforms is frequently elevated in tumors and associated with their increased metastatic activity. We compare properties of L-plastin with two other human plastins (T- and I-plastins) in order to understand what makes the L-isoform particularly suitable for invasion. Next, we investigate the molecular and cellular mechanisms of the ACD (actin crosslinking domain) toxin from V.cholerae and several other Gram-negative bacteria. ACD covalently cross-links actin subunits into polymerization-defective oligomers and thus hampers the ability of immune cells to engulf and eliminate bacteria. Our data suggest that ACD is highly effective even at very low doses, when only a small population of actin in the affected cells is cross-linked. We propose that the cross-linked oligomers interfere with the activity of several vital cytoskeletal proteins (e.g. nucleators of actin polymerization formins) when present at very low concentrations leading to i) impaired ability of macrophages to fight bacterial cells and to ii) increased permeability of intestinal epithelial layers. Lately, the role of actin in numerous nuclear functions has been proposed, but progress in understanding of these roles at the cellular level is hampered by the lack of tools for selective targeting nuclear but not the cytoplasmic actin. Our lab is actively involved in development of such tools by utilizing actin-specific activities of bacterial toxins (ACD, SipA, etc.) and mammalian actin modifiers. 2. Selective targeting and elimination of cancer cells with bacterial toxins Several bacterial toxins have attracted significant interest as potent antitumor agents due to their selectivity, ability to penetrate the cell membrane, high resistance against host defense systems, and demonstrated capacity to kill cells by mechanisms independent of the drug-resistant phenotypes of most tumors. Yet, the specificity of the currently recognized toxins towards tumor cells is limited due to a broad cross-specificity of the toxin receptors. We propose to deliver split variants of potent bacterial toxins via two different pathways uniquely represented only on the surface of cancer cells. The idea is that the fully functional toxin will be assembled only in the cytoplasm of a doubly targeted cancer cell. 3. Selective inactivation of bacterial toxins by human defensins. Defensins are a family of short cationic immune peptides with a broad repertoire of anti-microbial activities. Defensins disorganize bacterial cell membranes and inactivate protein bacterial toxins while showing little effect on host’s proteins. Yet, the amazing selectivity of defensins against various unrelated toxins is not well understood, nor has a coherent unifying hypothesis been proposed to explain this selectivity. In collaboration with Dr. Seveau from the Department of Microbiology at OSU we have developed a keen interest in deciphering the mechanisms of amazingly selective inactivation of bacterial toxins by human defensins. We propose that many bacterial toxins share an elusive common property that can be efficiently exploited by human defensins and we are currently in the process of identification of these elusive properties. The data acquired in the course of the project should lead to the development of rationally designed anti-toxin therapeutic agents. To accomplish our goals we employ highly interdisciplinary combination of biochemical, biophysical, and cell biology approaches, including but not limited to methods of fluorescence spectroscopy, circular dichroism, calorimetry, mass spectrometry, electron microscopy, cell imaging, and others. In addition, we collaborate with several groups for X-ray crystallography, NMR, and computational biology experiments. Because our lab is in the process of active growth and development, prospective graduate and undergraduate students are highly encouraged to join us. Your bright and open minds, innovative ideas, and skilled hands will find a welcome home in our group whether you are a graduate student in search for a project or an undergrad who is seeking to gain laboratory skills and contribute to solving important biological problems.

近期论文

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Kudryashova, E., Quintyn, R.S., Lu, W., Seveau, S., Wysocki, V., Kudryashov, D.S. (2014) Human defensins facilitate local unfolding of thermodynamically unstable regions of bacterial toxins. Immunity. 41(5), 709–721. Wang, N., Wang, M., Zhu, Y.H., Grosel, T.W., Sun, D., Kudryashov, D.S., Wu, J.Q. (2014) The Rho-GEF Gef3 interacts with the septin complex and activates the GTPase Rho4 during fission yeast cytokinesis Mol. Biol. Cell mbc.E14-07-1196; doi:10.1091/mbc.E14-07-1196 Ge P, Oztug Durer, Z., Kudryashov, D.S., Zhou H.Z., Reisler, E. (2014) CryoEM reveals different coronin binding modes for ADP- and ADP-BeFx- actin filaments. Nat. Struct. Mol. Biol. 2014 Nov 2. doi: 10.1038/nsmb.2907. Kudryashova, E., Heisler, D., Zywiec, A., Kudryashov, D.S. (2014) Structural plasticity of the effector domains of MARTX toxins suggests their unfolding for translocation across the host membrane. Mol. Microb. 92(5):1056-71. Lyon, A.N., Pineda, R.H., Kudryashova, E., Kudryashov, D.S., Beattie, C.E. (2014) Calcium binding is essential for plastin-3 function in Smn-deficient motor neurons. Hum. Mol. Genetics. 23(8):1990-2004. Kudryashov, D.S., Reisler, E. (2013) ATP and ADP actin states. Biopolymers. 99(4): 245–256 Kudryashova, E., Kalda, C., Kudryashov, D. (2012) Glutamyl phosphate is an activated intermediate in actin crosslinking by actin crosslinking domain (ACD) toxin. PLoS One. 7(9):e45721 Oztug Durer,Z.A., Kudryashov, D.S., Sawaya, M.R., Altenbach, C., Hubbell, W., Reisler, E. (2012) Structural states and dynamics of the D-loop in actin. Biophys J.103(5): 930-9 Galkin, V., Orlova, A., Kudryashov, D., Solodukhin A., Reisler, E., Schroeder, G., Egelman, E. (2011) Remodeling of Actin Filaments by ADF/Cofilin Proteins. Proc.Natl.Acad.Sci. USA. 2011 108(51):20568-72. Kudryashov, D.S., Grintsevich, E.E, Rubenstein P.A., Reisler, E.(2010) A Nucleotide State-sensing Region on Actin. J.Biol.Chem. 285(33): 25591-601. Grintsevich, E., Galkin, V., Orlova, A., Ytterberg, A., Mikati, M.M., Kudryashov, D., Loo, J.R., Egelman, E., Reisler, E. (2010) Mapping of drebrin binding site on F-actin. J.Mol.Biol. 498(4):542-554. Durer, Z., Deriviyam, K., Sept, D., Kudryashov, D., Reisler, E. (2010) F-Actin Structure Destabilization and DNase I Binding Loop Fluctuations Mutational Cross-Linking and Electron Microscopy Analysis of Loop States and Effects on F-Actin J.Mol.Biol. 395(3);544-557. Kudryashov, D.S., Durer, Z.A., Ytterberg, A.J., Sawaya, M.R., Pashkov, I., Yeates, T.0., Ogorzalek Loo, R., Loo, J., Satchell, K.J., Reisler, E. (2008) Connecting actin monomers by iso-peptide bond is a toxicity mechanism of the Vibrio cholerae MARTX toxin. Proc.Natl.Acad.Sci. USA. 105(47):18537-42. Sawaya, M.R., Kudryashov, D.S., Pashkov, I., Reisler, E., Yeates, T.O. (2008) Multiple crystal structures of actin dimers and their implications for interactions in the actin filament. actin dimers Acta Crystallographica Section D. 64:454-65. PMC2631129. Kudryashov, D.S., Cordero, C.L., Reisler, E., Satchell, KJ. (2008) Characterization of the enzymatic activity of the actin cross-linking domain from the Vibrio Cholerae MART toxin. J.Biol.Chem. 4;283(1):445-52. Cordero, C.L., Kudryashov, D.S., Reisler, E., Satchell, K.J.(2006) The Actin cross-linking domain of the Vibrio cholerae RTX toxin directly catalyzes the covalent cross-linking of actin. J.Biol.Chem. 281(43):32366-74. Kudryashov, D.S., Galkin, V.E., Orlova, A., Phan, M., Egelman, E.H., Reisler, E. (2006) Cofilin cross-bridges adjacent actin protomers and replaces part of the longitudinal F-actin interface. J.Mol.Biol. 358(3):785-97. Kudryashova, E., Kudryashov, D., Kramerova, I., Spencer, M.J. (2005) Trim32 is a ubiquitin ligase mutated in limb girdle muscular dystrophy type 2H that binds to skeletal muscle myosin and ubiquitinates actin. J.Mol.Biol. 354(2):413-24. Kudryashov, D.S., Sawaya, M.R., Adisetiyo, H., Norcross, T., Hegyi, G., Reisler, E., Yeates, T.O. (2005) The crystal structure of a cross-linked actin dimer suggests a detailed molecular interface in F-actin. Proc.Natl.Acad.Sci. USA. Sep 102(37):13105-10. Orlova, A., Shvetsov, A., Galkin, V.E., Kudryashov, D.S., Rubenstein, P.A., Egelman, E.H., Reisler, E. (2004) Actin-destabilizing factors disrupt filaments by means of a time reversal of polymerization. Proc.Natl.Acad.Sci. USA. 101(51):17664-8.