LDB1-mediated enhancer looping can be established independent of mediator and cohesin.
Nucleic Acids Res
; 45(14): 8255-8268, 2017 Aug 21.
Article
em En
| MEDLINE
| ID: mdl-28520978
ABSTRACT
Mechanistic studies in erythroid cells indicate that LDB1, as part of a GATA1/TAL1/LMO2 complex, brings erythroid-expressed genes into proximity with enhancers for transcription activation. The role of co-activators in establishing this long-range interaction is poorly understood. Here we tested the contributions of the RNA Pol II pre-initiation complex (PIC), mediator and cohesin to establishment of locus control region (LCR)/ß-globin proximity. CRISPR/Cas9 editing of the ß-globin promoter to eliminate the RNA Pol II PIC by deleting the TATA-box resulted in loss of transcription, but enhancer-promoter interaction was unaffected. Additional deletion of the promoter GATA1 site eliminated LDB1 complex and mediator occupancy and resulted in loss of LCR/ß-globin proximity. To separate the roles of LDB1 and mediator in LCR looping, we expressed a looping-competent but transcription-activation deficient form of LDB1 in LDB1 knock down cells LCR/ß-globin proximity was restored without mediator core occupancy. Further, Cas9-directed tethering of mutant LDB1 to the ß-globin promoter forced LCR loop formation in the absence of mediator or cohesin occupancy. Moreover, ENCODE data and our chromatin immunoprecipitation results indicate that cohesin is almost completely absent from validated and predicted LDB1-regulated erythroid enhancer-gene pairs. Thus, lineage specific factors largely mediate enhancer-promoter looping in erythroid cells independent of mediator and cohesin.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Proteínas Cromossômicas não Histona
/
Regulação Leucêmica da Expressão Gênica
/
Elementos Facilitadores Genéticos
/
Proteínas de Ciclo Celular
/
Proteínas de Ligação a DNA
/
Proteínas com Domínio LIM
Tipo de estudo:
Prognostic_studies
Limite:
Animals
Idioma:
En
Ano de publicação:
2017
Tipo de documento:
Article