Direct recruitment of N-myc to target gene promoters.
Mol Carcinog
; 29(2): 76-86, 2000 Oct.
Article
en En
| MEDLINE
| ID: mdl-11074604
ABSTRACT
The N-myc gene is amplified in 20-25% of human neuroblastomas, and this amplification serves as a poor prognostic factor. However, few genes have been determined to be direct targets of N-myc. Our current studies focused on identifying N-myc target genes, especially those affected in cells such as neuroblastomas that have high levels of N-myc protein. To pursue this goal, we performed differential expression screens with cell-culture systems containing high versus low levels of N-myc. The design of our experiments was such that we should identify genes both upregulated and downregulated by N-myc. Accordingly, we identified 22 genes upregulated by N-myc and one gene downregulated by N-myc. However, only five of these genes responded to increased N-myc levels in more than one system. Further analysis of the regulation of these genes required determining whether they were direct or indirect targets of N-myc. Therefore, we used a formaldehyde crosslinking and immunoprecipitation procedure to determine whether N-myc was bound to the promoters of these putative target genes in living cells. We found that low levels of N-myc were bound to the promoters of the telomerase and prothymosin genes in neuroblastoma cells having low amounts of N-myc but that the amounts of N-myc bound to these promoters greatly increased with overexpression of N-myc. However, the amount of max bound to the promoters was high before and after induction of N-myc. Therefore, our studies suggest that N-myc competes with other max partners for binding to target promoters. Our use of the chromatin immunoprecipitation assay suggests a molecular explanation for the consequences of amplification of the N-myc gene in neuroblastomas.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Activación Transcripcional
/
Proteínas Proto-Oncogénicas c-myc
/
Regiones Promotoras Genéticas
Tipo de estudio:
Prognostic_studies
Límite:
Humans
Idioma:
En
Revista:
Mol Carcinog
Asunto de la revista:
BIOLOGIA MOLECULAR
/
NEOPLASIAS
Año:
2000
Tipo del documento:
Article
País de afiliación:
Estados Unidos