Cytokinesis is mediated by an actin-based
contractile ring that is attached to the overlying cell membrane.
Cytokinesis is highly regulated in time and space. The contractile
ring assembles in the cell cortex after anaphase onset at a site
midway between the two poles of the mitotic spindle thereby ensuring
that the two sets of chromosomes are equally partitioned into the
two daughter cells. We are using the nematode C. elegans
and cultured human cells as model systems to dissect this complex
process. We are using a combination of forward and reverse genetics,
biochemistry, and live cell imaging to address the following unsolved
problems: How is the cleavage furrow positioned? How does the contractile
ring assemble and function? How does the central spindle assemble
and function? How is completion of cytokinesis achieved?
We are particularly interested in
the assembly and function of the central spindle. Central spindle
assembly begins at the metaphase to anaphase transition, when chromosomes
move polewards on shrinking kinetochore microtubules. At this time,
non-kinetochore spindle microtubules become bundled to form the
central spindle. We discovered an evolutionarily conserved protein
complex, centralspindlin, consisting of a Rho family GAP, CYK-4,
and a kinesin like protein, ZEN-4, that is directly involved in
central spindle assembly. The central spindle is essential for completion
of cytokinesis and it also regulates cleavage furrow formation.
We want to understand in mechanistic terms how this motor/RhoGAP
complex functions to coordinate central spindle assembly and how
it regulates early and late events in cytokinesis.
In C. elegans embryos, cleavage
furrow formation requires either the central spindle or astral microtubules.
These two supramolecular structures appear to regulate furrow formation
by distinct molecular mechanisms that converge at the GTPase RhoA.
We will identify the mechanisms that lead to local activation of
White, E. A., and Glotzer, M. (2012). Centralspindlin: At the heart of cytokinesis. Cytoskeleton (Hoboken) 69, 882–892. (PubMed)
Tse, Y. C., Werner, M., Longhini, K. M., Labbé, J.-C., Goldstein, B., and Glotzer, M. (2012). RhoA activation during polarization and cytokinesis of the early C. elegans embryo are differentially dependent on NOP-1 and CYK-4. Mol Biol Cell 23, 4020–4031. (PubMed)
Strickland D, Lin Y, Wagner E, Hope CM, Zayner J, Antoniou C, Sosnick TR, Weiss EL, Glotzer M. (2012) TULIPs: tunable, light-controlled interacting protein tags for cell biology. Nat Methods. 2012 Mar 4;9(4):379-84. (PubMed)
Loria A, Longhini KM, Glotzer M. (2012) The RhoGAP Domain of CYK-4 Has an Essential Role in RhoA Activation. Curr Biol. Feb 7;22(3):213-9. (PubMed)
Tse YC, Piekny A, Glotzer M Anillin promotes astral microtubule-directed cortical myosin polarization. Mol Biol Cell 2011 Sep;22(17):3165-75. (PubMed)
Afshar K, Werner ME, Tse YC, Glotzer M, Gönczy P. Regulation of cortical contractility and spindle positioning by the protein phosphatase 6 PPH-6 in one-cell stage C. elegans embryos. Development 2010 Jan;137(2):237-47. (PubMed)
Hutterer A, Glotzer M, Mishima M. Clustering of Centralspindlin Is Essential for Its Accumulation to the Central Spindle and the Midbody. Curr Biol. 2009 Dec 15;19(23):2043-9. (PubMed)
Wolfe BA, Takaki T, Petronczki M, Glotzer M. Polo-like kinase 1 directs assembly of the HsCyk-4 RhoGAP/Ect2 RhoGEF complex to initiate cleavage furrow formation. PLoS Biol. 2009 May 5;7(5):e1000110. (PubMed)
Glotzer M. The 3Ms of central spindle assembly: microtubules, motors and MAPs. Nat Rev Mol Cell Biol. 2009 Jan;10(1):9-20. (PubMed)
Glotzer M. Cytokinesis: GAP gap. Curr Biol. 2009 Feb 24;19(4):R162-5. (PubMed)