Centralspindlin

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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]

Cytokinesis The division of the cytoplasm and the plasma membrane of a cell and its partitioning into two daughter cells.

Cytokinesis is the part of the cell division process during which the cytoplasm of a single eukaryotic cell divides into two daughter cells. Cytoplasmic division begins during or after the late stages of nuclear division in mitosis and meiosis. During cytokinesis the spindle apparatus partitions and transports duplicated chromatids into the cytoplasm of the separating daughter cells. It thereby ensures that chromosome number and complement are maintained from one generation to the next and that, except in special cases, the daughter cells will be functional copies of the parent cell. After the completion of the telophase and cytokinesis, each daughter cell enters the interphase of the cell cycle.

Midbody (cell biology)

The midbody is a transient structure found in mammalian cells and is present near the end of cytokinesis just prior to the complete separation of the dividing cells. The structure was first described by Walther Flemming in 1891. The central section of a midbody was named after Flemming and is called the Flemming body.

Contents

Structure

Centralspindlin is a heteroteramer consisting of two different subunit proteins: [1]

  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
  1. 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 centraspindlin 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]

ECT2 gene of the species Homo sapiens

Protein ECT2 is a protein that in humans is encoded by the ECT2 gene.

Interactions

PRC1 protein-coding gene in the species Homo sapiens

Protein Regulator of cytokinesis 1 (PRC1) is a protein that in humans is encoded by the PRC1 gene and is involved in cytokinesis.

Related Research Articles

Mitosis nuclear division cycle for eukaryotic cells in which the two resulting nuclei are genetically identical

In cell biology, mitosis is a part of the cell cycle when replicated chromosomes are separated into two new nuclei. Cell division gives rise to genetically identical cells in which the number of chromosomes is maintained. In general, mitosis is preceded by the S stage of interphase and is often accompanied or followed by cytokinesis, which divides the cytoplasm, organelles and cell membrane into two new cells containing roughly equal shares of these cellular components. Mitosis and cytokinesis together define the mitotic (M) phase of an animal cell cycle—the division of the mother cell into two daughter cells genetically identical to each other.

Microtubule any of the long, generally straight, hollow tubes of internal diameter 12-15 nm and external diameter 24 nm found in a wide variety of eukaryotic cells; each consists (usually) of 13 protofilaments of polymeric tubulin.

Microtubules are polymers of tubulin that form part of the cytoskeleton and provide structure and shape to the cytoplasm of eukaryotic cells, some bacteria and some archaea. A microtubule can grow as long as 50 micrometres and are highly dynamic. The outer diameter of a microtubule is about 24 nm while the inner diameter is about 12 nm. They are formed by the polymerization of a dimer of two globular proteins, alpha and beta tubulin into protofilaments that can then associate laterally to form a hollow tube, the microtubule. The most common form of a microtubule consists of 13 protofilaments in the tubular arrangement.

Spindle apparatus the array of microtubules and associated molecules that forms between opposite poles of a eukaryotic cell during mitosis or meiosis and serves to move the duplicated chromosomes apart.

In cell biology, the spindle apparatus refers to the cytoskeletal structure of eukaryotic cells that forms during cell division to separate sister chromatids between daughter cells. It is referred to as the mitotic spindle during mitosis, a process that produces genetically identical daughter cells, or the meiotic spindle during meiosis, a process that produces gametes with half the number of chromosomes of the parent cell.

Cleavage furrow The cleavage furrow is a plasma membrane invagination at the cell division site. The cleavage furrow begins as a shallow groove and eventually deepens to divide the cytoplasm.

In cell biology, the cleavage furrow is the indentation of the cell's surface that begins the progression of cleavage, by which animal and some algal cells undergo cytokinesis, the final splitting of the membrane, in the process of cell division. The same proteins responsible for muscle contraction, actin and myosin, begin the process of forming the cleavage furrow, creating an actomyosin ring. Other cytoskeletal proteins and actin binding proteins are involved in the procedure.

Preprophase cell cycle phase only found in plants

Preprophase is an additional phase during mitosis in plant cells that does not occur in other eukaryotes such as animals or fungi. It precedes prophase and is characterized by two distinct events:

Aurora B kinase protein-coding gene in the species Homo sapiens

Aurora B kinase is a protein that functions in the attachment of the mitotic spindle to the centromere.

Polo-like kinases (Plks) are regulatory serine/threonin kinases of the cell cycle involved in mitotic entry, mitotic exit, spindle formation, cytokinesis, and meiosis. Only one Plk is found in the genomes of fruit flies (Polo), budding yeast (Cdc5) and fission yeast (Plo1). Vertebrates, however, have many Plk family members including Plk1, Plk2/Snk, Plk3/Prk/FnK, Plk4/Sak and Plk5. Of the vertebrate Plk family members, the mammalian Plk1 has been most extensively studied. During mitosis and cytokinesis, Plks associate with several structures including the centrosome, kinetochores, and the central spindle.

RACGAP1 protein-coding gene in the species Homo sapiens

Rac GTPase-activating protein 1 is an enzyme that in humans is encoded by the RACGAP1 gene.

Dynactin

Dynactin is a 23 subunit protein complex that acts as a co-factor for the microtubule motor cytoplasmic dynein-1. It is built around a short filament of actin related protein-1 (Arp1).

KIF23 protein-coding gene in the species Homo sapiens

Kinesin-like protein KIF23 is a protein that in humans is encoded by the KIF23 gene.

KIF4A protein-coding gene in the species Homo sapiens

Chromosome-associated kinesin KIF4A is a protein that in humans is encoded by the KIF4A gene.

Citron kinase protein-coding gene in the species Homo sapiens

Citron Rho-interacting kinase is an enzyme that in humans is encoded by the CIT gene.

ANLN protein-coding gene in the species Homo sapiens

Anillin is a conserved protein implicated in cytoskeletal dynamics during cellularization and cytokinesis. The ANLN gene in humans and the scraps gene in Drosophila encode Anillin. In 1989, anillin was first isolated in embryos of Drosophila melanogaster. It was identified as an F-actin binding protein. Six years later, the anillin gene was cloned from cDNA originating from a Drosophila ovary. Staining with anti-anillin antibody showed the anillin localizes to the nucleus during interphase and to the contractile ring during cytokinesis. These observations agree with further research that found anillin in high concentrations near the cleavage furrow coinciding with RhoA, a key regulator of contractile ring formation.

CEP55 protein-coding gene in the species Homo sapiens

Centrosomal protein of 55 kDa is a protein that in humans is encoded by the CEP55 gene.

KIFC1 protein-coding gene in the species Homo sapiens

Kinesin-like protein KIFC1 is a protein that in humans is encoded by the KIFC1 gene.

The endosomal sorting complexes required for transport (ESCRT) machinery is made up of cytosolic protein complexes, known as ESCRT-0, ESCRT-I, ESCRT-II, and ESCRT-III. Together with a number of accessory proteins, these ESCRT complexes enable a unique mode of membrane remodeling that results in membranes bending/budding away from the cytoplasm. These ESCRT components have been isolated and studied in a number of organisms including yeast and humans.

KIF15 protein-coding gene in the species Homo sapiens

Kinesin family member 15 is a protein that in humans is encoded by the KIF15 gene.

References

  1. 1 2 3 4 5 6 Glotzer, Michael. "Cytokinesis: Centralspindlin Moonlights as a Membrane Anchor", Current Biology , 18 February 2013
  2. 1 2 3 4 5 Glotzer, Michael " The 3Ms of central spindle assembly: microtubules, motors and MAPs", Nature , January 2009
  3. 1 2 Nature Publishing Group. "Research Highlights", Cell Migration Consortium, 2009. Retrieved on 01 March 2014.
  4. 1 2 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
  5. 1 2 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
  6. ↑ "Cytokinesis microtubule organisers at a glance". J Cell Sci.
  7. 1 2 Yuce et al. "An ECT2–centralspindlin complex regulates the localization and function of RhoA", Journal of Cell Biology , 15 August 2005
  8. ↑ Gene Editing Rat Resource Center "Gene-Term Annotation Report", Retrieved on 01 March 2014
  9. 1 2 Douglas et al. "Aurora B and 14-3-3 Coordinately Regulate Clustering of Centralspindlin during Cytokinesis", Current Biology , 25 May 2010
  10. ↑ Lee KY, Esmaeili B, Zealley B, Mishima M (2015). "Direct interaction between centralspindlin and PRC1 reinforces mechanical resilience of the central spindle". Nature Communications. 6: 7290. doi:10.1038/ncomms8290. PMC   4557309  Lock-green.svg. PMID   26088160.
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