Structure-activity relationships in polymorphic G-quadruplex forming segment of c-MYC promoter
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| Year of publication | 2017 |
| Type | Conference abstract |
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| Citation | |
| Description | One of the driving forces of malignant transformation is activation of a protooncogene that is converted into oncogene by a mutation, which changes the protein function or expression. Misregulation of the proto-oncogene c-Myc has been identified in many human cancers. Therefore, the detailed knowledge of c-Myc regulation is necessary to develop appropriate therapies. Expression of c-Myc is co-regulated by a G-quadruplex that can be formed from a G-rich motif Pu27 within the c-Myc promoter. Pu27 consists of five G-tracts separated by one A or T nucleotide. Formation of a Gquadruplex requires only four G-tracts. Hence, the Pu27 segment give rise to several distinct G-quadruplex conformations. It is not known, which particular G-quadruplex conformation bears the biological role. To address this point, we have prepared a set of Pu27 oligonucleotides with naturally occurring nucleotide substitutions in different G-tracts that limit the number of possible G-quadruplex conformations. Using single particle FRET, we have identified populations of the G-quadruplex topologies that the Pu27 variants form in vitro. By performing pull-downs from nuclear lysates, we have revealed proteins that bind to the particular Gquadruplexes. To test the function, Pu27 element in the human c-Myc promoter has been mutated and the activity examined in a luciferase reporter assay. Preliminary data from our experiments indicate that there are several structural topologies of Gquadruplex formed from Pu27 sequence, which are functionally equivalent |
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