Ryoma Ohi, Ph.D.

Associate Professor


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Faculty Appointments
Associate Professor of Cell and Developmental Biology
Ph.D., Cell Biology, Vanderbilt University, Nashville, TennesseeB.S., Molecular Biology , Vanderbilt University, Nashville, Tennessee
Office Address
Nashiville, TN 37232-8240
Research Description
Our group studies animal cell division. During this process, the microtubule cytoskeleton is organized into a transient structure called the mitotic spindle. This apparatus attaches replicated chromosomes via kinetochores and generates forces that power the division of chromosomes among two daughter cells. We apply a multidisciplinary approach to examine the process of mitotic spindle assembly and the interface between kinetochores and microtubules. We use quantitative light microscopy to investigate protein behavior in the mitotic spindle, biochemistry to understand the function of key mitotic regulators, and small molecules to perturb spindle function. Our long term goal is to use our findings to develop new anti-mitotic oncological therapies. Currently, our lab is studying how several families of kinesin-like proteins impact spindle assembly and function in animal cells. We are particularly interested in the roles of the kinesin-8s at spindle microtubule plus-ends, the mechanisms by which the kinesin-5 and kinesin-12 motors enforce spindle bipolarity, and the roles of kinesin-13s during cytokinesis.
Research Keywords
Microtubule organization and dynamics during cell division
Gayek AS, Ohi R. Kinetochore-microtubule stability governs the metaphase requirement for Eg5. Mol. Biol. Cell [print-electronic]. 2014 Jul 7/1/2014; 25(13): 2051-60. PMID: 24807901, PMCID: PMC4072578, PII: mbc.E14-03-0785, DOI: 10.1091/mbc.E14-03-0785, ISSN: 1939-4586.

Sturgill EG, Ohi R. Microtubule-regulating kinesins. Curr. Biol. 2013 Nov 11/4/2013; 23(21): R946-8. PMID: 24200317, PII: S0960-9822(13)00988-3, DOI: 10.1016/j.cub.2013.08.012, ISSN: 1879-0445.

Sturgill EG, Ohi R. Kinesin-12 differentially affects spindle assembly depending on its microtubule substrate. Curr. Biol [print-electronic]. 2013 Jul 7/22/2013; 23(14): 1280-90. PMID: 23791727, PMCID: PMC3725213, PII: S0960-9822(13)00638-6, DOI: 10.1016/j.cub.2013.05.043, ISSN: 1879-0445.

Chen JS, Lu LX, Ohi MD, Creamer KM, English C, Partridge JF, Ohi R, Gould KL. Cdk1 phosphorylation of the kinetochore protein Nsk1 prevents error-prone chromosome segregation. J. Cell Biol [print-electronic]. 2011 Nov 11/14/2011; 195(4): 583-93. PMID: 22065639, PMCID: PMC3257533, PII: jcb.201105074, DOI: 10.1083/jcb.201105074, ISSN: 1540-8140.

Archuleta TL, Du Y, English CA, Lory S, Lesser C, Ohi MD, Ohi R, Spiller BW. The Chlamydia effector chlamydial outer protein N (CopN) sequesters tubulin and prevents microtubule assembly. J. Biol. Chem [print-electronic]. 2011 Sep 9/30/2011; 286(39): 33992-8. PMID: 21841198, PMCID: PMC3190796, PII: M111.258426, DOI: 10.1074/jbc.M111.258426, ISSN: 1083-351X.

Stumpff J, Du Y, English CA, Maliga Z, Wagenbach M, Asbury CL, Wordeman L, Ohi R. A tethering mechanism controls the processivity and kinetochore-microtubule plus-end enrichment of the kinesin-8 Kif18A. Mol. Cell. 2011 Sep 9/2/2011; 43(5): 764-75. PMID: 21884977, PMCID: PMC3172727, PII: S1097-2765(11)00579-X, DOI: 10.1016/j.molcel.2011.07.022, ISSN: 1097-4164.

Ohi R. Kip3-ing kinetochores clustered. Cell cycle (Georgetown, Tex.). 2010 Jul 7/1/2010; 9(13) Sect. 2497.

Du Y, English CA, Ohi R. The kinesin-8 Kif18A dampens microtubule plus-end dynamics. Curr. Biol [print-electronic]. 2010 Feb 2/23/2010; 20(4): 374-80. PMID: 20153196, PII: S0960-9822(09)02212-X, DOI: 10.1016/j.cub.2009.12.049, ISSN: 1879-0445.

Needleman DJ, Groen A, Ohi R, Maresca T, Mirny L, Mitchison T. Fast microtubule dynamics in meiotic spindles measured by single molecule imaging: evidence that the spindle environment does not stabilize microtubules. Mol. Biol. Cell [print-electronic]. 2010 Jan 1/15/2010; 21(2): 323-33. PMID: 19940016, PMCID: PMC2808228, PII: E09-09-0816, DOI: 10.1091/mbc.E09-09-0816, ISSN: 1939-4586.

Maresca TJ, Groen AC, Gatlin JC, Ohi R, Mitchison TJ, Salmon ED. Spindle assembly in the absence of a RanGTP gradient requires localized CPC activity. Curr. Biol [print-electronic]. 2009 Jul 7/28/2009; 19(14): 1210-5. PMID: 19540121, PMCID: PMC2752711, PII: S0960-9822(09)01197-X, DOI: 10.1016/j.cub.2009.05.061, ISSN: 1879-0445.

Germane KL, Ohi R, Goldberg MB, Spiller BW. Structural and functional studies indicate that Shigella VirA is not a protease and does not directly destabilize microtubules. Biochemistry [print-electronic]. 2008 Sep 9/30/2008; 47(39): 10241-3. PMID: 18763811, PMCID: PMC4096815, DOI: 10.1021/bi801533k, ISSN: 1520-4995.

Efimov A, Schiefermeier N, Grigoriev I, Ohi R, Brown MC, Turner CE, Small JV, Kaverina I. Paxillin-dependent stimulation of microtubule catastrophes at focal adhesion sites. J. Cell. Sci. 2008 Jan 1/15/2008; 121(Pt 2): 196-204. PMID: 18187451, PMCID: PMC3164837, PII: 121/2/196, DOI: 10.1242/jcs.012666, ISSN: 0021-9533.

Ohi R, Burbank K, Liu Q, Mitchison TJ. Nonredundant functions of Kinesin-13s during meiotic spindle assembly. Curr. Biol [print-electronic]. 2007 Jun 6/5/2007; 17(11): 953-9. PMID: 17509883, PII: S0960-9822(07)01337-1, DOI: 10.1016/j.cub.2007.04.057, ISSN: 0960-9822.

Coughlin M, Brieher WM, Ohi R. Cell-free extract systems and the cytoskeleton: preparation of biochemical experiments for transmission electron microscopy. Methods Mol. Biol. 2007; 369: 199-212. PMID: 17656752, PII: 1-59745-294-7:199, DOI: 10.1007/978-1-59745-294-6_10, ISSN: 1064-3745.

Mitchison TJ, Maddox P, Groen A, Cameron L, Perlman Z, Ohi R, Desai A, Salmon ED, Kapoor TM. Bipolarization and poleward flux correlate during Xenopus extract spindle assembly. Mol. Biol. Cell [print-electronic]. 2004 Dec; 15(12): 5603-15. PMID: 15385629, PMCID: PMC532038, PII: E04-05-0440, DOI: 10.1091/mbc.E04-05-0440, ISSN: 1059-1524.

Groen AC, Cameron LA, Coughlin M, Miyamoto DT, Mitchison TJ, Ohi R. XRHAMM functions in ran-dependent microtubule nucleation and pole formation during anastral spindle assembly. Curr. Biol. 2004 Oct 10/26/2004; 14(20): 1801-11. PMID: 15498487, PII: S0960982204007924, DOI: 10.1016/j.cub.2004.10.002, ISSN: 0960-9822.

Sampath SC, Ohi R, Leismann O, Salic A, Pozniakovski A, Funabiki H. The chromosomal passenger complex is required for chromatin-induced microtubule stabilization and spindle assembly. Cell. 2004 Jul 7/23/2004; 118(2): 187-202. PMID: 15260989, PII: S0092867404006178, DOI: 10.1016/j.cell.2004.06.026, ISSN: 0092-8674.

Ohi R, Sapra T, Howard J, Mitchison TJ. Differentiation of cytoplasmic and meiotic spindle assembly MCAK functions by Aurora B-dependent phosphorylation. Mol. Biol. Cell [print-electronic]. 2004 Jun; 15(6): 2895-906. PMID: 15064354, PMCID: PMC420112, PII: E04-02-0082, DOI: 10.1091/mbc.E04-02-0082, ISSN: 1059-1524.

Ohi R, Coughlin ML, Lane WS, Mitchison TJ. An inner centromere protein that stimulates the microtubule depolymerizing activity of a KinI kinesin. Dev. Cell. 2003 Aug; 5(2): 309-21. PMID: 12919681, PII: S1534580703002296, ISSN: 1534-5807.

Burns CG, Ohi R, Mehta S, O'Toole ET, Winey M, Clark TA, Sugnet CW, Ares M, Gould KL. Removal of a single alpha-tubulin gene intron suppresses cell cycle arrest phenotypes of splicing factor mutations in Saccharomyces cerevisiae. Mol. Cell. Biol. 2002 Feb; 22(3): 801-15. PMID: 11784857, PMCID: PMC133559, ISSN: 0270-7306.

Burns CG, Ohi R, Krainer AR, Gould KL. Evidence that Myb-related CDC5 proteins are required for pre-mRNA splicing. Proc. Natl. Acad. Sci. U.S.A. 1999 Nov 11/23/1999; 96(24): 13789-94. PMID: 10570151, PMCID: PMC24143, ISSN: 0027-8424.

McDonald WH, Ohi R, Smelkova N, Frendewey D, Gould KL. Myb-related fission yeast cdc5p is a component of a 40S snRNP-containing complex and is essential for pre-mRNA splicing. Mol. Cell. Biol. 1999 Aug; 19(8): 5352-62. PMID: 10409726, PMCID: PMC84378, ISSN: 0270-7306.

Feoktistova A, McCollum D, Ohi R, Gould KL. Identification and characterization of Schizosaccharomyces pombe asp1(+), a gene that interacts with mutations in the Arp2/3 complex and actin. Genetics. 1999 Jul; 152(3): 895-908. PMID: 10388810, PMCID: PMC1460656, ISSN: 0016-6731.

Ohi R, Gould KL. Regulating the onset of mitosis. Curr. Opin. Cell Biol. 1999 Apr; 11(2): 267-73. PMID: 10209160, PII: S0955-0674(99)80036-2, ISSN: 0955-0674.

Ohi R, Feoktistova A, McCann S, Valentine V, Look AT, Lipsick JS, Gould KL. Myb-related Schizosaccharomyces pombe cdc5p is structurally and functionally conserved in eukaryotes. Mol. Cell. Biol. 1998 Jul; 18(7): 4097-108. PMID: 9632794, PMCID: PMC108994, ISSN: 0270-7306.

Ohi R, Feoktistova A, Gould KL. Construction of vectors and a genomic library for use with his3-deficient strains of Schizosaccharomyces pombe. Gene. 1996 Oct 10/3/1996; 174(2): 315-8. PMID: 8890754, PII: 0378111996000856, ISSN: 0378-1119.

Ohi R, McCollum D, Hirani B, Den Haese GJ, Zhang X, Burke JD, Turner K, Gould KL. The Schizosaccharomyces pombe cdc5+ gene encodes an essential protein with homology to c-Myb. EMBO J. 1994 Jan 1/15/1994; 13(2): 471-83. PMID: 8313892, PMCID: PMC394831, ISSN: 0261-4189.