[PDF][PDF] Reactivation of developmentally silenced globin genes by forced chromatin looping

W Deng, JW Rupon, I Krivega, L Breda, I Motta… - Cell, 2014 - cell.com
W Deng, JW Rupon, I Krivega, L Breda, I Motta, KS Jahn, A Reik, PD Gregory, S Rivella…
Cell, 2014cell.com
Distal enhancers commonly contact target promoters via chromatin looping. In erythroid
cells, the locus control region (LCR) contacts β-type globin genes in a developmental stage-
specific manner to stimulate transcription. Previously, we induced LCR-promoter looping by
tethering the self-association domain (SA) of Ldb1 to the β-globin promoter via artificial zinc
fingers. Here, we show that targeting the SA to a developmentally silenced embryonic globin
gene in adult murine erythroblasts triggers its transcriptional reactivation. This activity …
Summary
Distal enhancers commonly contact target promoters via chromatin looping. In erythroid cells, the locus control region (LCR) contacts β-type globin genes in a developmental stage-specific manner to stimulate transcription. Previously, we induced LCR-promoter looping by tethering the self-association domain (SA) of Ldb1 to the β-globin promoter via artificial zinc fingers. Here, we show that targeting the SA to a developmentally silenced embryonic globin gene in adult murine erythroblasts triggers its transcriptional reactivation. This activity depends on the LCR, consistent with an LCR-promoter looping mechanism. Strikingly, targeting the SA to the fetal γ-globin promoter in primary adult human erythroblasts increases γ-globin promoter-LCR contacts, stimulating transcription to approximately 85% of total β-globin synthesis, with a reciprocal reduction in adult β-globin expression. Our findings demonstrate that forced chromatin looping can override a stringent developmental gene expression program and suggest a novel approach to control the balance of globin gene transcription for therapeutic applications.
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