Biology:Centralspindlin
Centralspindlin is a motor complex implicated in cell division. It contributes to virtually every step in cytokinesis,[1] It is highly conserved in animal cells as a component of the spindle midzone and midbody.[2] Centralspindlin is required for the assembly of the mitotic spindle[3] as well as for microtubule bundling and anchoring of midbody microtubules to the plasma membrane.[1][2] This complex is also implicated in tethering the spindle apparatus to the plasma membrane during cytokinesis[4] This interaction permits cleavage furrow ingression. In addition, centralspindlin's interaction with the ESCRT III allows for abscission to occur.[1]
Structure
Centralspindlin is a heterotetramer consisting of two different subunit proteins:[1]
- A KIF23 dimer (Kinesin 6 motor protein, also known as MKLP1 in mammals and ZEN-4 in C. elegans)
- Consists of a motor domain linked to a parallel coiled coil and a globular region by a linker
- A RACGAP1 dimer (Also known as MgcRacGAP in mammals or CYK-4 in C. elegans)
- Contains a coiled-coil and an important RhoGAP domain
Both KIF23 and RacGAP1 dimerize via their parallel coiled coil domain.[2][5] Centralspindlin oligomerizes in order to link the mitotic spindle with the plasma membrane[1] The sequences mediating interactions between KIF23 and RacGAP1 are highly variable between species. However, a high affinity interaction between these subunits is essential for the proper functioning of the Centralspindlin complex.[5]
Subunits
KIF23 interacts with microtubules at sites of overlap,[2] linking the centralspindlin complex to the mitotic spindle. RacGAP1 recruits ECT2 to the central spindle.[3] ECT2 is a Guanine nucleotide-exchange factor for RhoA. Cytokinesis is initiated when RhoA is activated by ECT2.[6] RacGAP1 is also involved in tethering the central spindle to the plasma membrane. Without this interaction, cytokinesis cannot occur.[4]
Interactions
- A glance at the busy complex [7]
- Interacts with RhoA and Rac during furrow ingression[4][8]
- Recruits cytokinetic effector proteins such as ECT2[6][9]
- Binds microtubule plus-end overlaps characteristic of the central spindle through its KIF23 subunit[2]
- Recruits the ESCRT III complex in late cytokinesis[1]
- Promotes cortical accumulation of F-actin and myosin through its RACGAP1 subunit[8]
- Stabilized through interactions with Aurora B kinase[10]
- Negatively regulated by 14-3-3[10]
- RacGAP1 binds to PRC1 microtubule crosslinker, an interaction that is crucial for maintaining the stability of the spindle midzone.[11]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Glotzer, Michael. "Cytokinesis: Centralspindlin Moonlights as a Membrane Anchor", Current Biology, 18 February 2013
- ↑ 2.0 2.1 2.2 2.3 2.4 Glotzer, Michael " The 3Ms of central spindle assembly: microtubules, motors and MAPs", Nature, January 2009
- ↑ 3.0 3.1 Nature Publishing Group. "Research Highlights", Cell Migration Consortium, 2009. Retrieved on 01 March 2014.
- ↑ 4.0 4.1 4.2 Lekomtsev et al. "Centralspindlin links the mitotic spindle to the plasma membrane during cytokinesis", Nature, 13 December 2012
- ↑ 5.0 5.1 Pavicic-Kaltenbrunner et al. "Cooperative assembly of CYK-4/MgcRacGAP and ZEN-4/MKLP1 to form the centralspindlin complex", Molecular Biology of the Cell, 17 October 2007
- ↑ 6.0 6.1 Tatsumoto et al "Human Ect2 Is an Exchange Factor for Rho Gtpases, Phosphorylated in G2/M Phases, and Involved in Cytokinesis", Journal of Cell Biology, 29 November 1999
- ↑ "Cytokinesis microtubule organisers at a glance". http://jcs.biologists.org/content/125/15/3495.
- ↑ 8.0 8.1 Yuce et al. "An ECT2–centralspindlin complex regulates the localization and function of RhoA", Journal of Cell Biology, 15 August 2005
- ↑ Gene Editing Rat Resource Center "Gene-Term Annotation Report", Retrieved on 01 March 2014
- ↑ 10.0 10.1 Douglas et al. "Aurora B and 14-3-3 Coordinately Regulate Clustering of Centralspindlin during Cytokinesis", Current Biology, 25 May 2010
- ↑ "Direct interaction between centralspindlin and PRC1 reinforces mechanical resilience of the central spindle". Nature Communications 6: 7290. 2015. doi:10.1038/ncomms8290. PMID 26088160. Bibcode: 2015NatCo...6.7290L.
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