Mitotic checkpoint serine/threonine-protein kinase BUB1 beta is an enzyme that in humans is encoded by the BUB1B gene.[5] 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.
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This gene encodes a kinase involved in spindle checkpoint function and chromosome segregation.[6] The protein has been localized to the kinetochore and plays a role in the inhibition of the anaphase-promoting complex/cyclosome (APC/C), delaying the onset of anaphase and ensuring proper chromosome segregation. Impaired spindle checkpoint function has been found in many forms of cancer.[7]
Increased expression of BubR1 in mice extends a healthy lifespan.[8]
BubR1 has been implicated in a variety of biological processes and pathologies, including cancer, aging, mosaic variegated aneuploidy (MVA), and heart disease. BubR1 protein levels are shown to decline with age.[8][9][10] Furthermore, loss of BubR1 in young organisms is associated with rapid aging and premature onset of age-related diseases and phenotypes such as cardiac dysfunction, poor wound healing, cataracts, kyphosis, fat loss and muscle wasting (cachexia), and cancer.[9] This has been demonstrated in mice.
Chemoradiotherapy (CRT), the combination of chemotherapy and radiotherapy applied with curative intent, is used to treat a variety of cancers. CRT acts by inducing damage in the DNA of the cancer cells. Bladder cancer tumor samples were taken from patients before treatment and from the same patients after CRT treatment when the tumors had reoccurred.[11] An increased level of BUB1B expression was found in the CRT-recurrent cells. This increased expression was considered to facilitate an inaccurate DNA repair process termed alternative non-homologous end joining (A-NHEJ) that inaccurately repairs DNA damages such as those caused by the CRT. This inaccurate repair could cause additional mutations in the tumor including mutations to CRT resistance.[11]
BUB1B has been shown to interact with:
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Cayrol C, Cougoule C, Wright M (November 2002). "The beta2-adaptin clathrin adaptor interacts with the mitotic checkpoint kinase BubR1". Biochemical and Biophysical Research Communications. 298 (5): 720–730. doi:10.1016/S0006-291X(02)02522-6. PMID 12419313.
Futamura M, Arakawa H, Matsuda K, Katagiri T, Saji S, Miki Y, Nakamura Y (March 2000). "Potential role of BRCA2 in a mitotic checkpoint after phosphorylation by hBUBR1". Cancer Research. 60 (6): 1531–1535. PMID 10749118.
Wu H, Lan Z, Li W, Wu S, Weinstein J, Sakamoto KM, Dai W (September 2000). "p55CDC/hCDC20 is associated with BUBR1 and may be a downstream target of the spindle checkpoint kinase". Oncogene. 19 (40): 4557–4562. doi:10.1038/sj.onc.1203803. PMID 11030144. S2CID 23544995.
Suematsu T, Li Y, Kojima H, Nakajima K, Oshimura M, Inoue T (October 2014). "Deacetylation of the mitotic checkpoint protein BubR1 at lysine 250 by SIRT2 and subsequent effects on BubR1 degradation during the prometaphase/anaphase transition". Biochemical and Biophysical Research Communications. 453 (3): 588–594. doi:10.1016/j.bbrc.2014.09.128. PMID 25285631.
Izumi H, Matsumoto Y, Ikeuchi T, Saya H, Kajii T, Matsuura S (August 2009). "BubR1 localizes to centrosomes and suppresses centrosome amplification via regulating Plk1 activity in interphase cells". Oncogene. 28 (31): 2806–2820. doi:10.1038/onc.2009.141. PMID 19503101. S2CID 23514072.
- Posas F, Saito H (March 1998). "Activation of the yeast SSK2 MAP kinase kinase kinase by the SSK1 two-component response regulator". The EMBO Journal. 17 (5): 1385–1394. doi:10.1093/emboj/17.5.1385. PMC 1170486. PMID 9482735.
- Cahill DP, Lengauer C, Yu J, Riggins GJ, Willson JK, Markowitz SD, et al. (March 1998). "Mutations of mitotic checkpoint genes in human cancers". Nature. 392 (6673): 300–303. Bibcode:1998Natur.392..300C. doi:10.1038/32688. PMID 9521327. S2CID 4416376.
- Donadelli R, Benatti L, Remuzzi A, Morigi M, Gullans SR, Benigni A, et al. (May 1998). "Identification of a novel gene--SSK1--in human endothelial cells exposed to shear stress". Biochemical and Biophysical Research Communications. 246 (3): 881–887. doi:10.1006/bbrc.1998.8713. PMID 9618306.
- Chan GK, Schaar BT, Yen TJ (October 1998). "Characterization of the kinetochore binding domain of CENP-E reveals interactions with the kinetochore proteins CENP-F and hBUBR1". The Journal of Cell Biology. 143 (1): 49–63. doi:10.1083/jcb.143.1.49. PMC 2132809. PMID 9763420.
- Jablonski SA, Chan GK, Cooke CA, Earnshaw WC, Yen TJ (December 1998). "The hBUB1 and hBUBR1 kinases sequentially assemble onto kinetochores during prophase with hBUBR1 concentrating at the kinetochore plates in mitosis". Chromosoma. 107 (6–7): 386–396. doi:10.1007/s004120050322. PMID 9914370. S2CID 13928165.
- Cahill DP, da Costa LT, Carson-Walter EB, Kinzler KW, Vogelstein B, Lengauer C (June 1999). "Characterization of MAD2B and other mitotic spindle checkpoint genes". Genomics. 58 (2): 181–187. doi:10.1006/geno.1999.5831. PMID 10366450.
- Chan GK, Jablonski SA, Sudakin V, Hittle JC, Yen TJ (September 1999). "Human BUBR1 is a mitotic checkpoint kinase that monitors CENP-E functions at kinetochores and binds the cyclosome/APC". The Journal of Cell Biology. 146 (5): 941–954. doi:10.1083/jcb.146.5.941. PMC 2169490. PMID 10477750.
- Li W, Lan Z, Wu H, Wu S, Meadows J, Chen J, et al. (November 1999). "BUBR1 phosphorylation is regulated during mitotic checkpoint activation". Cell Growth & Differentiation. 10 (11): 769–775. PMID 10593653.
- Saffery R, Irvine DV, Griffiths B, Kalitsis P, Choo KH (October 2000). "Components of the human spindle checkpoint control mechanism localize specifically to the active centromere on dicentric chromosomes". Human Genetics. 107 (4): 376–384. doi:10.1007/s004390000386. PMID 11129339. S2CID 38578162.
- Simpson JC, Wellenreuther R, Poustka A, Pepperkok R, Wiemann S (September 2000). "Systematic subcellular localization of novel proteins identified by large-scale cDNA sequencing". EMBO Reports. 1 (3): 287–292. doi:10.1093/embo-reports/kvd058. PMC 1083732. PMID 11256614.
- Kaplan KB, Burds AA, Swedlow JR, Bekir SS, Sorger PK, Näthke IS (April 2001). "A role for the Adenomatous Polyposis Coli protein in chromosome segregation". Nature Cell Biology. 3 (4): 429–432. doi:10.1038/35070123. PMID 11283619. S2CID 12645435.
- Tang Z, Bharadwaj R, Li B, Yu H (August 2001). "Mad2-Independent inhibition of APCCdc20 by the mitotic checkpoint protein BubR1". Developmental Cell. 1 (2): 227–237. doi:10.1016/S1534-5807(01)00019-3. PMID 11702782.
- Shichiri M, Yoshinaga K, Hisatomi H, Sugihara K, Hirata Y (January 2002). "Genetic and epigenetic inactivation of mitotic checkpoint genes hBUB1 and hBUBR1 and their relationship to survival". Cancer Research. 62 (1): 13–17. PMID 11782350.
- Taylor SS, Hussein D, Wang Y, Elderkin S, Morrow CJ (December 2001). "Kinetochore localisation and phosphorylation of the mitotic checkpoint components Bub1 and BubR1 are differentially regulated by spindle events in human cells". Journal of Cell Science. 114 (Pt 24): 4385–4395. doi:10.1242/jcs.114.24.4385. PMID 11792804.