Geminin
Geminin, DNA replication inhibitor, also known as GMNN, is a protein in humans encoded by the GMNN gene.[1]
Geminin is a nuclear protein that is present in most eukaryotics and highly conserved across species. Numerous functions have been elucidated for Geminin including roles in metazoan cell cycle, cellular proliferation, cell lineage commitment, and neural differentiation.[2]
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[edit] History
Geminin was originally identified as an inhibitor of DNA replication and substrate of the anaphase promoting complex (APC).[3] Coincidentally, Geminin was also shown to expand the neural plate in the developing Xenopus embryo.[4]
[edit] Structure
Geminin is a nuclear protein made up of about 200 amino acids, with a molecular weight of approximately 25 kDa.[3] It contains an atypical leucine-zipper coiled-coil domain. It has no known enzymatic activity nor DNA binding motifs.
[edit] Function
[edit] Cell cycle control
Geminin is absent during G1 phase and accumulates through S, G2 phase and M phases of the cell cycle. Geminin levels drop at the metaphase / anaphase transition of mitosis when it is degraded by the Anaphase Promoting Complex (APC).[3]
[edit] S phase
During S phase, geminin is a negative regulator of DNA replication. In many cancer cell lines, inhibition of geminin by RNAi results in re-replication of portions of the genome, which leads to aneuploidy. In these cell lines, geminin knockdown leads to markedly slowed growth and apoptosis within several days.[5] However, the same is not true for primary and immortalized human cell lines, where other mechanisms exists to prevent re-replication.[5] Since geminin knockdown leads to cell death in many cancer cell lines but not primary cell lines, it has been proposed as a potential therapeutic target for cancer treatment.[5]
[edit] Mitosis
During mitosis or M phase, geminin stabilizes the replication factor Cdt1 by protecting it from ubiquitination and therefore subsequence proteolysis, thereby potentially promoting DNA replication during the following cell cycle. Although inhibition of geminin by RNAi leads to destabilization of Cdt1 protein and impairment of DNA replication during the following cell cycle in many cancer cell lines, no such cell cycle defect is seen in primary and immortalized cell lines (although Cdt1 levels are still reduced in these cells).[5]
Geminin therefore is an important player in ensuring that one and only one round of replication occurs during each cell cycle.
[edit] Developmental control
Geminin promotes early neural fate commitment by hyperacetylating the chromatin.[6] This effect allows neural genes to be accessible for transcription, promoting the expression of these genes. Ultimately, Geminin allows cells uncommitted to any particular lineage to acquire neural characteristics.
Geminin has also been shown to interact with the SWI/SNF chromatin remodeling complex.[7] In neural precursor cells, high levels of Geminin prevent terminal differention. When the interaction between Geminin and SWI/SNF is eliminated, Geminin's inhibition to this process is eliminated and neural precurors are allowed to differentiate.
[edit] Model organisms
| Characteristic | Phenotype |
|---|---|
| Homozygote viability | Abnormal |
| Recessive lethal study | Abnormal |
| Fertility | Normal |
| Body weight | Normal |
| Anxiety | Normal |
| Neurological assessment | Normal |
| Grip strength | Normal |
| Hot plate | Normal |
| Dysmorphology | Normal |
| Indirect calorimetry | Normal |
| Glucose tolerance test | Normal |
| Auditory brainstem response | Normal |
| DEXA | Normal |
| Radiography | Normal |
| Body temperature | Normal |
| Eye morphology | Abnormal[8] |
| Clinical chemistry | Normal |
| Plasma immunoglobulins | Normal |
| Haematology | Normal |
| Peripheral blood lymphocytes | Normal |
| Micronucleus test | Normal |
| Heart weight | Normal |
| Skin Histopathology | Normal |
| Brain histopathology | Normal |
| Salmonella infection | Normal[9] |
| Citrobacter infection | Normal[10] |
| All tests and analysis from[11][12] |
Model organisms have been used in the study of Geminin function. A conditional knockout mouse line, called Gmnntm1a(KOMP)Wtsi[13][14] was generated as part of the International Knockout Mouse Consortium program, a high-throughput mutagenesis project to generate and distribute animal models of disease to interested scientists.[15][16][17]
Male and female animals underwent a standardized phenotypic screen to determine the effects of deletion.[11][18] Twenty six tests were carried out and three significant abnormalities were observed. A recessive lethal study found no homozygous mutant embryos during gestation, and therefore none survived until weaning. The remaining tests were carried out on heterozygous mutant adult mice and showed that females had abnormal lens morphology and cataracts. [11]
[edit] Clinical significance
Recently, geminin has been found to be overexpressed in several malignancies and cancer cell lines.[19]
[edit] References
- ^ "Entrez Gene: GMNN geminin, DNA replication inhibitor". http://www.ncbi.nlm.nih.gov/sites/entrez?Db=gene&Cmd=ShowDetailView&TermToSearch=51053.
- ^ Kroll, KL (2007). "Geminin in embryonic development: coordinating transcription and the cell cycle during differentiation.". Front Biosci. 12 (4): 1395–409. doi:10.2741/2156. PMID 17127390.
- ^ a b c McGarry TJ; Depamphilis, ML (1998). "Geminin, an inhibitor of DNA replication, is degraded during mitosis". Cell 93 (11): 1043–1053. doi:10.1016/S0092-8674(00)81209-X. PMID 9635433.
- ^ Kroll KL, Salic AN, Evans LM, Kirschner, MW (1998). "Geminin, a neuralizing molecule that demarcates the future neural plate at the onset of gastrulation". Development 125 (16): 3247–58. PMID 9671596.
- ^ a b c d Zhu W, Depamphilis ML (June 2009). "Selective killing of cancer cells by suppression of geminin activity". Cancer Res 69 (11): 4870–4877. doi:10.1158/0008-5472.CAN-08-4559. PMC 2749580. PMID 19487297. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2749580.
- ^ Yellajoshyula D, Patterson ES, Elitt MS, Kroll KL (2011). "Geminin promotes neural fate acquisition of embryonic stem cells by maintaining chromatin in an accessible and hyperacetylated state". PNAS 108 (8): 3294–9. doi:10.1073/pnas.1012053108. PMC 3044367. PMID 21300881. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3044367.
- ^ Seo S, Herr A, Lim JW, Richardson GA, Kroll KL (July 2005). "Geminin regulates neuronal differentiation by antagonizing Brg1 activity". Genes Dev 19 (14): 1723–34. doi:10.1101/gad.1319105. PMC 1176010. PMID 16024661. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1176010.
- ^ "Eye morphology data for Gmnn". Wellcome Trust Sanger Institute. http://www.sanger.ac.uk/mouseportal/phenotyping/MAEB/eye-morphology/.
- ^ "Salmonella infection data for Gmnn". Wellcome Trust Sanger Institute. http://www.sanger.ac.uk/mouseportal/phenotyping/MAEB/salmonella-challenge/.
- ^ "Citrobacter infection data for Gmnn". Wellcome Trust Sanger Institute. http://www.sanger.ac.uk/mouseportal/phenotyping/MAEB/citrobacter-challenge/.
- ^ a b c Gerdin AK (2010). "The Sanger Mouse Genetics Programme: High throughput characterisation of knockout mice". Acta Ophthalmologica 88 (S248). doi:10.1111/j.1755-3768.2010.4142.x.
- ^ Mouse Resources Portal, Wellcome Trust Sanger Institute.
- ^ "International Knockout Mouse Consortium". http://www.knockoutmouse.org/martsearch/search?query=Gmnn.
- ^ "Mouse Genome Informatics". http://www.informatics.jax.org/searchtool/Search.do?query=MGI:4363191.
- ^ Skarnes, W. C.; Rosen, B.; West, A. P.; Koutsourakis, M.; Bushell, W.; Iyer, V.; Mujica, A. O.; Thomas, M. et al. (2011). "A conditional knockout resource for the genome-wide study of mouse gene function". Nature 474 (7351): 337–342. doi:10.1038/nature10163. PMID 21677750.
- ^ Dolgin E (June 2011). "Mouse library set to be knockout". Nature 474 (7351): 262–3. doi:10.1038/474262a. PMID 21677718.
- ^ Collins FS, Rossant J, Wurst W (January 2007). "A mouse for all reasons". Cell 128 (1): 9–13. doi:10.1016/j.cell.2006.12.018. PMID 17218247.
- ^ van der Weyden L, White JK, Adams DJ, Logan DW (2011). "The mouse genetics toolkit: revealing function and mechanism.". Genome Biol 12 (6): 224. doi:10.1186/gb-2011-12-6-224. PMID 21722353. http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=21722353.
- ^ Montanari M, Boninsegna A, Faraglia B, Coco C, Giordano A, Cittadini A, Sgambato A (2005). "Increased expression of geminin stimulates the growth of mammary epithelial cells and is a frequent event in human tumors". J Cell Physiol 202 (1): 215–22. doi:10.1002/jcp.20120. PMID 15389519.
[edit] Further reading
- Maruyama K, Sugano S (1994). "Oligo-capping: a simple method to replace the cap structure of eukaryotic mRNAs with oligoribonucleotides". Gene 138 (1–2): 171–4. doi:10.1016/0378-1119(94)90802-8. PMID 8125298.
- Suzuki Y, Yoshitomo-Nakagawa K, Maruyama K, et al. (1997). "Construction and characterization of a full length-enriched and a 5'-end-enriched cDNA library". Gene 200 (1–2): 149–56. doi:10.1016/S0378-1119(97)00411-3. PMID 9373149.
- McGarry TJ, Kirschner MW (1998). "Geminin, an inhibitor of DNA replication, is degraded during mitosis". Cell 93 (6): 1043–53. doi:10.1016/S0092-8674(00)81209-X. PMID 9635433.
- Kroll KL, Salic AN, Evans LM, Kirschner MW (1998). "Geminin, a neuralizing molecule that demarcates the future neural plate at the onset of gastrulation". Development 125 (16): 3247–58. PMID 9671596.
- Wohlschlegel JA, Dwyer BT, Dhar SK, et al. (2001). "Inhibition of eukaryotic DNA replication by geminin binding to Cdt1". Science 290 (5500): 2309–12. doi:10.1126/science.290.5500.2309. PMID 11125146.
- Bermejo R, Vilaboa N, Calés C (2003). "Regulation of CDC6, geminin, and CDT1 in human cells that undergo polyploidization". Mol. Biol. Cell 13 (11): 3989–4000. doi:10.1091/mbc.E02-04-0217. PMC 133609. PMID 12429841. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=133609.
- Strausberg RL, Feingold EA, Grouse LH, et al. (2003). "Generation and initial analysis of more than 15,000 full-length human and mouse cDNA sequences". Proc. Natl. Acad. Sci. U.S.A. 99 (26): 16899–903. doi:10.1073/pnas.242603899. PMC 139241. PMID 12477932. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=139241.
- Biswas N, Sanchez V, Spector DH (2003). "Human cytomegalovirus infection leads to accumulation of geminin and inhibition of the licensing of cellular DNA replication". J. Virol. 77 (4): 2369–76. doi:10.1128/JVI.77.4.2369-2376.2003. PMC 141111. PMID 12551974. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=141111.
- Kulartz M, Kreitz S, Hiller E, et al. (2003). "Expression and phosphorylation of the replication regulator protein geminin". Biochem. Biophys. Res. Commun. 305 (2): 412–20. doi:10.1016/S0006-291X(03)00773-3. PMID 12745091.
- Mungall AJ, Palmer SA, Sims SK, et al. (2003). "The DNA sequence and analysis of human chromosome 6". Nature 425 (6960): 805–11. doi:10.1038/nature02055. PMID 14574404.
- Ota T, Suzuki Y, Nishikawa T, et al. (2004). "Complete sequencing and characterization of 21,243 full-length human cDNAs". Nat. Genet. 36 (1): 40–5. doi:10.1038/ng1285. PMID 14702039.
- Del Bene F, Tessmar-Raible K, Wittbrodt J (2004). "Direct interaction of geminin and Six3 in eye development". Nature 427 (6976): 745–9. doi:10.1038/nature02292. PMID 14973488.
- Luo L, Yang X, Takihara Y, et al. (2004). "The cell-cycle regulator geminin inhibits Hox function through direct and polycomb-mediated interactions". Nature 427 (6976): 749–53. doi:10.1038/nature02305. PMID 14973489.
- Sugimoto N, Tatsumi Y, Tsurumi T, et al. (2004). "Cdt1 phosphorylation by cyclin A-dependent kinases negatively regulates its function without affecting geminin binding". J. Biol. Chem. 279 (19): 19691–7. doi:10.1074/jbc.M313175200. PMID 14993212.
- Melixetian M, Ballabeni A, Masiero L, et al. (2004). "Loss of Geminin induces rereplication in the presence of functional p53". J. Cell Biol. 165 (4): 473–82. doi:10.1083/jcb.200403106. PMC 2172361. PMID 15159417. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2172361.
- Ramachandran N, Hainsworth E, Bhullar B, et al. (2004). "Self-assembling protein microarrays". Science 305 (5680): 86–90. doi:10.1126/science.1097639. PMID 15232106.
- Ballabeni A, Melixetian M, Zamponi R, et al. (2005). "Human geminin promotes pre-RC formation and DNA replication by stabilizing CDT1 in mitosis". EMBO J. 23 (15): 3122–32. doi:10.1038/sj.emboj.7600314. PMC 514931. PMID 15257290. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=514931.
- Saxena S, Yuan P, Dhar SK, et al. (2004). "A dimerized coiled-coil domain and an adjoining part of geminin interact with two sites on Cdt1 for replication inhibition". Mol. Cell 15 (2): 245–58. doi:10.1016/j.molcel.2004.06.045. PMID 15260975.
- Zhu W, Chen Y, Dutta A (2004). "Rereplication by depletion of geminin is seen regardless of p53 status and activates a G2/M checkpoint". Mol. Cell. Biol. 24 (16): 7140–50. doi:10.1128/MCB.24.16.7140-7150.2004. PMC 479725. PMID 15282313. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=479725.
- Kulartz M, Knippers R (2004). "The replicative regulator protein geminin on chromatin in the HeLa cell cycle". J. Biol. Chem. 279 (40): 41686–94. doi:10.1074/jbc.M405798200. PMID 15284237.
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