Alternative titles; symbols
HGNC Approved Gene Symbol: CCNG1
Cytogenetic location: 5q34 Genomic coordinates (GRCh38): 5:163,437,571-163,457,640 (from NCBI)
The eukaryotic cell cycle is governed by cyclin-dependent protein kinases (CDKs) whose activities are regulated by cyclins and CDK inhibitors. The 8 species of cyclins reported in mammals, cyclins A (123835) through H, share a conserved amino acid sequence of about 90 residues called the cyclin box. Endo et al. (1996) cloned and analyzed human cDNA encoding cyclin G. The amino acid sequence of cyclin G is well conserved among mammals. Human cyclin G, with 295 amino acids, has 1 extra threonine at residue 6 compared with rat and mouse cyclin G (294 amino acids).
Horne et al. (1996) and Bates et al. (1996) isolated human cyclin G1 and cyclin G2 (603203) cDNAs. Horne et al. (1996) noted that cyclin G1 lacks the protein destabilizing (PEST) sequences and 'destruction box' sequence that are present in previously identified cyclins. Northern blot analysis revealed that the levels of the 2.8-kb cyclin G1 mRNA do not change significantly following an apparent induction in early G1. These authors stated that the absence of destabilization motifs in cyclin G1 and the lack of any periodicity in its mRNA during the cell cycle suggest that the control of its activity may occur at the posttranscriptional or posttranslational level.
Bates et al. (1996) demonstrated that p53 (TP53; 191170) plays a role in induction of cyclin G1, since elevation of cyclin G1 expression following DNA damage or transfection was directly correlated with the presence of functional p53.
Using microarray, Northern blot, and RT-PCR analyses, Gramantieri et al. (2007) found that expression of microRNA-122A (miR122A, or MIRN122A; 609582) was downregulated in about 70% of hepatocellular carcinomas (HCCs) from cirrhotic livers and in all HCC-derived cell lines examined. miR122A modulated cyclin G1 expression in HCC-derived cell lines, and an inverse correlation between miR122A and cyclin G1 expression was observed in primary liver carcinomas. Using the putative miR122A target sequence from the 3-prime UTR of cyclin G1 coupled to a reporter gene, Gramantieri et al. (2007) confirmed that miR122A directly controlled expression of cyclin G1.
Endo et al. (1996) reported that the CCNG1 gene contains 6 exons. They identified a putative binding site for the p53 tumor suppressor within the first intron of CCNG1.
By fluorescence in situ hybridization, Endo et al. (1996) mapped the human cyclin G1 gene to chromosome 5q32-q34. Jensen et al. (1997) used fluorescence in situ hybridization to map the mouse cyclin G1 gene to chromosome 11B1.1, a region showing homology of synteny with human 5q31-q32.
Bates, S., Rowan, S., Vousden, K. H. Characterisation of human cyclin G1 and G2: DNA damage inducible genes. Oncogene 13: 1103-1109, 1996. [PubMed: 8806701]
Endo, Y., Fujita, T., Tamura, K., Tsuruga, H., Nojima, H. Structure and chromosomal assignment of the human cyclin G gene. Genomics 38: 92-95, 1996. [PubMed: 8954786] [Full Text: https://doi.org/10.1006/geno.1996.0598]
Gramantieri, L., Ferracin, M., Fornari, F., Veronese, A., Sabbioni, S., Liu, C.-G., Calin, G. A., Giovannini, C., Ferrazzi, E., Grazi, G. L., Croce, C. M., Bolondi, L., Negrini, M. Cyclin G1 is a target of miR-122a, a microRNA frequently down-regulated in human hepatocellular carcinoma. Cancer Res. 67: 6092-6099, 2007. [PubMed: 17616664] [Full Text: https://doi.org/10.1158/0008-5472.CAN-06-4607]
Horne, M. C., Goolsby, G. L., Donaldson, K. L., Tran, D., Neubauer, M., Wahl, A. F. Cyclin G1 and cyclin G2 comprise a new family of cyclins with contrasting tissue-specific and cell cycle-regulated expression. J. Biol. Chem. 271: 6050-6061, 1996. [PubMed: 8626390] [Full Text: https://doi.org/10.1074/jbc.271.11.6050]
Jensen, M. R., Factor, V. M., Zimonjic, D. B., Miller, M. J., Keck, C. L., Thorgeirsson, S. S. Chromosome localization and structure of the murine cyclin G1 gene promoter sequence. Genomics 45: 297-303, 1997. [PubMed: 9344652] [Full Text: https://doi.org/10.1006/geno.1997.4947]