Regulation of N-myc oncogene expression is an important determinant of the
biological behavior of neuroblastoma. The N-myc promoter contains several potential
binding sites for transcription factors of the Sp1 family. Mutation of a CT-box motif
contained within a 26 base pair region required for N-myc downregulation by retinoic
acid decreased basal transcriptional activity and altered DNA-protein interactions of the
promoter, while mutations flanking this motif did neither. On gel shift this region
generated 3 specific DNA-protein complexes that were reliant on wild type sequence of
the core CT element within it. Both Spl and Sp3 bound to the wild type probe as distinct
complexes in specifically retarded bands, while neither protein was present on mutated
sequences. Lysates from Drosophila S2 cells expressing exogenous Sp1 and Sp3
proteins were able to reproduce the gel shift complexes seen with neuroblastoma nuclear
extract. Transient transfections of S2 cells showed that individually or together, Sp1 and
Sp3 were able to trans-activate a N-myc CT-box-containing luciferase reporter construct
in a dose-dependent manner. Conversely, transfection of CT-box oligonucleotide was
able to decrease endogenous N-myc expression in neuroblastoma cells. Together these
results suggest that the CT-box element serves a critical functional role, and in the basal
state allows for N-myc transactivation by Spl and Sp3.
| Identifer | oai:union.ndltd.org:UHAWAII/oai:scholarspace.manoa.hawaii.edu:10125/987 |
| Date | 05 1900 |
| Creators | Tuthill, Matthew Charles |
| Contributors | Wada, Randal K |
| Publisher | University of Hawaii at Manoa |
| Source Sets | University of Hawaii at Manoa Libraries |
| Language | en-US |
| Detected Language | English |
| Type | Thesis, Text |
| Rights | All UHM dissertations and theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission from the copyright owner., https://scholarspace.manoa.hawaii.edu/handle/10125/865 |
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