A Conserved Quadruplex Motif Located in a Transcription Activation Site of the Human c-kit Oncogene
| Autor: | Sarah Rankin, Shankar Balasubramanian, Stephen Neidle, Himesh Fernando, Sylvain Ladame, Ashok R. Venkitaraman, Julian L. Huppert, Anthony P. Reszka |
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| Rok vydání: | 2006 |
| Předmět: |
Transcriptional Activation
Circular dichroism Pan troglodytes Amino Acid Motifs Molecular Sequence Data G-quadruplex Biochemistry Article Receptor tyrosine kinase Mice chemistry.chemical_compound Animals Humans heterocyclic compounds Nuclear Magnetic Resonance Biomolecular Kit oncogene Gene Base Sequence biology Circular Dichroism Promoter DNA Oncogenes Small molecule Molecular biology Rats G-Quadruplexes Proto-Oncogene Proteins c-kit chemistry biology.protein Nucleic Acid Conformation Spectrophotometry Ultraviolet |
| Zdroj: | Biochemistry. 45:7854-7860 |
| ISSN: | 1520-4995 0006-2960 |
| DOI: | 10.1021/bi0601510 |
| Popis: | The c-kit gene encodes a receptor tyrosine kinase, whose engagement by its ligand triggers signals leading to cell proliferation. c-kit activity is elevated in gastrointestinal stromal tumors (GISTs), and its therapeutic inhibition by small molecules such as imatinib is clinically validated. We identified a putative quadruplex forming 21-nucleotide sequence upstream of the c-kit transcription initiation site (c-kit21), on the G-rich strand, which occupies a site required for core promoter activity. Here, we show by nuclear magnetic resonance (NMR), circular dichroism (CD), and ultraviolet (UV) spectroscopic methods that c-kit21 forms quadruplexes under physiological conditions. Mutational analysis of c-kit21 has provided insights into its structural polymorphism. In particular, one mutated form appears to form a single quadruplex species that adopts a parallel conformation. The quadruplex-forming sequence shows a high level of sequence conservation across human, mouse, rat, and chimpanzee. The small variation in sequence between the quadruplex in human/chimpanzee as compared to the rat/mouse was examined more closely by biophysical methods. Despite a variation in the sequence and length of loop 2, the quadruplexes showed both comparable CD spectra, indicative of parallel quadruplexes, and also similar thermal-stability profiles, suggesting conservation of biophysical characteristics. Collectively, the evidence suggests that this quadruplex is a serious target for a detailed functional investigation at the cell-biology level. |
| Databáze: | OpenAIRE |
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