@article {47697, title = {Forced chromatin looping raises fetal hemoglobin in adult sickle cells to higher levels than pharmacologic inducers.}, journal = {Blood}, year = {2016}, month = {2016 Jul 12}, abstract = {

Overcoming the silencing of the fetal γ-globin gene has been a long standing goal in the treatment of sickle cell disease (SCD). The major transcriptional enhancer of the β-globin locus, called LCR, dynamically interacts with the developmental stage-appropriate β-type globin genes via chromatin looping, a process requiring the protein Ldb1. In adult erythroid cells the LCR can be re-directed from the adult β- to the fetal γ-globin promoter by tethering Ldb1 to the human γ-globin promoter with custom designed zinc finger proteins (ZF-Ldb1), leading to reactivation of γ-globin gene expression. To compare this approach to pharmacological reactivation of fetal hemoglobin (HbF), hematopoietic cells from SCD patients were treated with a lentivirus expressing the ZF-Ldb1 or with chemical HbF inducers. The HbF increase in cells treated with ZF-Ldb1 was more than double of that observed with decitabine and pomalidomide; butyrate had an intermediate effect while tranylcypromine and hydroxyurea showed relatively low HbF reactivation. ZF-Ldb1 showed comparatively little toxicity, and reduced sickle Hb (HbS) synthesis as well as sickling of SCD erythroid cells under hypoxic conditions. The efficacy and low cytotoxicity of lentiviral-mediated ZF-Ldb1 gene transfer compared to the drug regimens support its therapeutic potential for the treatment of SCD.

}, issn = {1528-0020}, doi = {10.1182/blood-2016-01-691089}, author = {Breda, Laura and Motta, Irene and Lourenco, Silvia and Gemmo, Chiara and Deng, Wulan and Rupon, Jeremy W and Abdulmalik, Osheiza Y and Manwani, Deepa and Blobel, Gerd A and Rivella, Stefano} } @article {45054, title = {Manipulating nuclear architecture.}, journal = {Current Opinion in Genetics \& Development}, volume = {25}, year = {2014}, month = {2014 Apr 25}, pages = {1-7}, abstract = {

The eukaryotic genome is highly organized in the nucleus. Genes can be localized to specific nuclear compartments in a manner reflecting their activity. A plethora of recent reports has described multiple levels of chromosomal folding that can be related to gene-specific expression states. Here we discuss studies designed to probe the causal impact of genome organization on gene expression. The picture that emerges is that of a reciprocal relationship in which nuclear organization is not only shaped by gene expression states but also directly influences them.

}, issn = {1879-0380}, doi = {10.1016/j.gde.2013.10.014}, author = {Deng, Wulan and Blobel, Gerd A} } @article {45412, title = {Reactivation of developmentally silenced globin genes by forced chromatin looping.}, journal = {Cell}, volume = {158}, year = {2014}, month = {2014 Aug 14}, pages = {849-60}, abstract = {

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.

}, issn = {1097-4172}, doi = {10.1016/j.cell.2014.05.050}, author = {Deng, Wulan and Rupon, Jeremy W and Krivega, Ivan and Breda, Laura and Motta, Irene and Jahn, Kristen S and Reik, Andreas and Gregory, Philip D and Rivella, Stefano and Dean, Ann and Blobel, Gerd A} }