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In cell biology, the spindle apparatus is 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.
Maturation-promoting factor (abbreviated MPF, also called mitosis-promoting factor or M-Phase-promoting factor) is the cyclin-Cdk complex that was discovered first in frog eggs. It stimulates the mitotic and meiotic phases of the cell cycle. MPF promotes the entrance into mitosis (the M phase) from the G2 phase by phosphorylating multiple proteins needed during mitosis. MPF is activated at the end of G2 by a phosphatase, which removes an inhibitory phosphate group added earlier.
The spindle checkpoint, also known as the metaphase-to-anaphase transition, the spindle assembly checkpoint (SAC), the metaphase checkpoint, or the mitotic checkpoint, is a cell cycle checkpoint during metaphase of mitosis or meiosis that prevents the separation of the duplicated chromosomes (anaphase) until each chromosome is properly attached to the spindle. To achieve proper segregation, the two kinetochores on the sister chromatids must be attached to opposite spindle poles. Only this pattern of attachment will ensure that each daughter cell receives one copy of the chromosome. The defining biochemical feature of this checkpoint is the stimulation of the anaphase-promoting complex by M-phase cyclin-CDK complexes, which in turn causes the proteolytic destruction of cyclins and proteins that hold the sister chromatids together.
A kinetochore is a disc-shaped protein structure associated with duplicated chromatids in eukaryotic cells where the spindle fibers attach during cell division to pull sister chromatids apart. The kinetochore assembles on the centromere and links the chromosome to microtubule polymers from the mitotic spindle during mitosis and meiosis. The term kinetochore was first used in a footnote in a 1934 Cytology book by Lester W. Sharp and commonly accepted in 1936. Sharp's footnote reads: "The convenient term kinetochore has been suggested to the author by J. A. Moore", likely referring to John Alexander Moore who had joined Columbia University as a freshman in 1932.
Aurora kinase A also known as serine/threonine-protein kinase 6 is an enzyme that in humans is encoded by the AURKA gene.
A serine/threonine protein kinase is a kinase enzyme, in particular a protein kinase, that phosphorylates the OH group of the amino-acid residues serine or threonine, which have similar side chains. At least 350 of the 500+ human protein kinases are serine/threonine kinases (STK).
Aurora kinase B is a protein that functions in the attachment of the mitotic spindle to the centromere.
Aurora kinase inhibitors are a putative drug class for treating cancer. The Aurora kinase enzymes could be potential targets for novel small-molecule enzyme inhibitors.
Polo-like kinases (Plks) are regulatory serine/threonine 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 the fly Drosophila melanogaster (Polo), budding yeast (Cdc5) and fission yeast (Plo1). Vertebrates and other animals, 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.
Serine/threonine-protein kinase PLK1, also known as polo-like kinase 1 (PLK-1) or serine/threonine-protein kinase 13 (STPK13), is an enzyme that in humans is encoded by the PLK1 gene.
Mitotic checkpoint serine/threonine-protein kinase BUB1 also known as BUB1 is an enzyme that in humans is encoded by the BUB1 gene.
Mitotic checkpoint serine/threonine-protein kinase BUB1 beta is an enzyme that in humans is encoded by the BUB1B gene. Also known as BubR1, this protein is recognized for its mitotic roles in the spindle assembly checkpoint (SAC) and kinetochore-microtubule interactions that facilitate chromosome migration and alignment. BubR1 promotes mitotic fidelity and protects against aneuploidy by ensuring proper chromosome segregation between daughter cells. BubR1 is proposed to prevent tumorigenesis.
In enzymology, a polo kinase is a kinase enzyme i.e. one that catalyzes the chemical reaction
Serine/threonine-protein kinase Nek2 is an enzyme that in humans is encoded by the NEK2 gene.
Targeting protein for Xklp2 is a protein that in humans is encoded by the TPX2 gene. It is one of the many spindle assembly factors that play a key role in inducing microtubule assembly and growth during M phase.
Aurora kinase C, also Serine/threonine-protein kinase 13 is an enzyme that in humans is encoded by the AURKC gene.
Serine/threonine-protein kinase PLK4 also known as polo-like kinase 4 is an enzyme that in humans is encoded by the PLK4 gene. The Drosophila homolog is SAK, the C elegans homolog is zyg-1, and the Xenopus homolog is Plx4.
Cdh1 is one of the substrate adaptor proteins of the anaphase-promoting complex (APC) in the budding yeast Saccharomyces cerevisiae. Functioning as an activator of the APC/C, Cdh1 regulates the activity and substrate specificity of this ubiquitin E3-ligase. The human homolog is encoded by the FZR1 gene, which is not to be confused with the CDH1 gene.
Centrosomes are the major microtubule organizing centers (MTOC) in mammalian cells. Failure of centrosome regulation can cause mistakes in chromosome segregation and is associated with aneuploidy. A centrosome is composed of two orthogonal cylindrical protein assemblies, called centrioles, which are surrounded by a protein dense amorphous cloud of pericentriolar material (PCM). The PCM is essential for nucleation and organization of microtubules. The centrosome cycle is important to ensure that daughter cells receive a centrosome after cell division. As the cell cycle progresses, the centrosome undergoes a series of morphological and functional changes. Initiation of the centrosome cycle occurs early in the cell cycle in order to have two centrosomes by the time mitosis occurs.
Multipolar spindles are spindle formations characteristic of cancer cells. Spindle formation is mostly conducted by the aster of the centrosome which it forms around itself. In a mitotic cell wherever two asters convene the formation of a spindle occurs.
References
- 1 2 Bolanos-Garcia V M. Aurora kinases. The International Journal of Biochemistry & Cell Biology 37 (2005) 1572–1577.
- ↑ Fu, Jingyan (January 2007). "Roles of Aurora Kinases in Mitosis and Tumorigenesis" (PDF). Molecular Cancer Research. 5 (1): 1. doi:10.1158/1541-7786.MCR-06-0208. PMID 17259342 . Retrieved 7 February 2022.
- ↑ Giet R, Prigent C. Aurora/Ipl1p-related kinases, a new oncogenic family of mitotic serine-threonine kinases. Journal of Cell Science 112 (1999) 3591–3601.
- ↑ Eyers PA, Erikson E, Chen LG, Eyers PA (April 2003). "A novel mechanism for activation of the protein kinase Aurora A". Current Biology. 13 (8): 691–697. doi: 10.1016/s0960-9822(03)00166-0 . PMID 12699628.
- ↑ Bayliss R, Sardon T, Vernos I, Conti E (April 2003). "Structural basis of Aurora-A activation by TPX2 at the mitotic spindle". Molecular Cell. 13 (8): 691–697. doi: 10.1016/s1097-2765(03)00392-7 . PMID 14580337.
- ↑ Tsuchiya Y, Byrne DP, Burgess SG, Bormann J, Bakovic J, Huang Y, Zhyvoloup A, Yu BY, Peak Chew S, Tran T, Bellany F, Tabor AB, Chan AE, Guruprasad L, Garifulin O, Filonenko V, Vonderach M, Ferries S, Eyers CE, Carroll J, Skehel M, Bayliss R, Eyers PA, Gout I (Sep 2019). "Covalent Aurora A regulation by the metabolic integrator coenzyme A". Redox Biology. doi: 10.1016/j.redox.2019.101318 . PMC 6812009 . PMID 31546169.
