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Characterisation of human cyclin G1 and G2: DNA damage inducible genes
S Bates1, S Rowan, K H Vousden
1ABL-Basic Research Program, NCI-FCRDC, Frederick, Maryland 21702-1201, USA.
Abstract:
Several genes have been identified as targets for transcriptional activation by the p53 tumour suppressor protein. Rodent cyclin G was previously identified as a p53 responsive gene and in order to assess the role played by cyclin G as a mediator of p53 function in humans cells we have isolated full length human cyclin G1 and identified a related gene designated cyclin G2. Both human G-cyclins are induced by the DNA damaging agent actinomycin-D and although the induction of cyclin G1 is clearly p53 dependent, activation of cyclin G2 expression was observed in the absence of p53. Based on sequence similarity, the G-cyclins and the recently identified cyclin I form a distinct sub-group within the larger cyclin family, possibly reflecting some degree of functional similarity.
Insights
Researchers identified human cyclin G1 and cyclin G2, finding both are induced by DNA damage. Cyclin G1
Area of Science:
- Molecular Biology
- Cell Cycle Regulation
- Cancer Genetics
Background:
- The p53 tumor suppressor protein regulates transcriptional targets.
- Rodent cyclin G is a known p53-responsive gene.
- The role of cyclin G in human p53-mediated functions requires elucidation.
Purpose of the Study:
- To isolate and characterize human cyclin G1 and a related gene, cyclin G2.
- To investigate the role of human G-cyclins in p53-mediated cellular responses.
- To determine the p53 dependency of human cyclin G1 and G2 gene expression.
Main Methods:
- Isolation of full-length human cyclin G1 and identification of cyclin G2.
- Treatment of human cells with the DNA damaging agent actinomycin-D.
- Analysis of cyclin G1 and G2 gene expression in response to DNA damage and p53 status.
Main Results:
- Both human cyclin G1 and cyclin G2 were isolated.
- Both G-cyclins are induced by actinomycin-D, a DNA damaging agent.
- Cyclin G1 induction is p53-dependent, while cyclin G2 induction occurs independently of p53.
Conclusions:
- Human cyclin G1 and G2 represent a distinct subgroup of cyclins.
- Cyclin G1 acts as a p53-dependent gene, while cyclin G2 is induced independently of p53.
- These findings suggest differential regulation and potential distinct roles for G-cyclins in cellular processes.