Limits...
BCL11A enhancer dissection by Cas9-mediated in situ saturating mutagenesis.

Canver MC, Smith EC, Sher F, Pinello L, Sanjana NE, Shalem O, Chen DD, Schupp PG, Vinjamur DS, Garcia SP, Luc S, Kurita R, Nakamura Y, Fujiwara Y, Maeda T, Yuan GC, Zhang F, Orkin SH, Bauer DE - Nature (2015)

Bottom Line: Despite conserved function of the composite enhancers, their architecture diverges.The crucial human sequences appear to be primate-specific.The detailed enhancer map will inform therapeutic genome editing, and the screening approach described here is generally applicable to functional interrogation of non-coding genomic elements.

View Article: PubMed Central - PubMed

Affiliation: Division of Hematology/Oncology, Boston Children's Hospital, Department of Pediatric Oncology, Dana-Farber Cancer Institute, Harvard Stem Cell Institute, Department of Pediatrics, Harvard Medical School, Boston, Massachusetts 02115, USA.

ABSTRACT
Enhancers, critical determinants of cellular identity, are commonly recognized by correlative chromatin marks and gain-of-function potential, although only loss-of-function studies can demonstrate their requirement in the native genomic context. Previously, we identified an erythroid enhancer of human BCL11A, subject to common genetic variation associated with the fetal haemoglobin level, the mouse orthologue of which is necessary for erythroid BCL11A expression. Here we develop pooled clustered regularly interspaced palindromic repeat (CRISPR)-Cas9 guide RNA libraries to perform in situ saturating mutagenesis of the human and mouse enhancers. This approach reveals critical minimal features and discrete vulnerabilities of these enhancers. Despite conserved function of the composite enhancers, their architecture diverges. The crucial human sequences appear to be primate-specific. Through editing of primary human progenitors and mouse transgenesis, we validate the BCL11A erythroid enhancer as a target for fetal haemoglobin reinduction. The detailed enhancer map will inform therapeutic genome editing, and the screening approach described here is generally applicable to functional interrogation of non-coding genomic elements.

Show MeSH
Validation of enhancer screena, HbF+ fraction in HUDEP-2 cells transduced in arrayed format with 24 sgRNAs from all 5 mapping categories with enrichment scores ranging from the highest to the lowest in the screen. b, Correlation between HbF enrichment score from pooled sgRNA screen and HbF+ fraction by arrayed validation of individual sgRNAs in HUDEP-2 cells. c, Erythroid differentiation of primary human erythroid precursors evaluated by CD71 and CD235a surface markers, enucleation frequency (CD235a+ Hoescht33342-), and morphology by May-Grünwald-Giemsa staining.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4644101&req=5

Figure 3: Validation of enhancer screena, HbF+ fraction in HUDEP-2 cells transduced in arrayed format with 24 sgRNAs from all 5 mapping categories with enrichment scores ranging from the highest to the lowest in the screen. b, Correlation between HbF enrichment score from pooled sgRNA screen and HbF+ fraction by arrayed validation of individual sgRNAs in HUDEP-2 cells. c, Erythroid differentiation of primary human erythroid precursors evaluated by CD71 and CD235a surface markers, enucleation frequency (CD235a+ Hoescht33342-), and morphology by May-Grünwald-Giemsa staining.

Mentions: To validate the findings from the HUDEP-2 cells, the top-scoring enhancer targeting sgRNA from the screen (#1621 at h+58) was tested in primary human erythroblasts by lentiviral transduction of human CD34+ HSPCs exposed to ex vivo erythroid culture conditions. Consistent with the screen results, sgRNA-1621 resulted in downregulation of BCL11A expression and corresponding upregulation of γ-globin expression and increase in HbF+ cells (Fig. 2f-h). Notably, sgRNA-1621 did not alter surface marker profile, enucleation frequency, or cellular morphology (Extended Data Fig. 3c). Together these results suggest proof-of-principle of an individual sgRNA targeting a noncoding element for therapeutic genome editing of β-hemoglobin disorders.


BCL11A enhancer dissection by Cas9-mediated in situ saturating mutagenesis.

Canver MC, Smith EC, Sher F, Pinello L, Sanjana NE, Shalem O, Chen DD, Schupp PG, Vinjamur DS, Garcia SP, Luc S, Kurita R, Nakamura Y, Fujiwara Y, Maeda T, Yuan GC, Zhang F, Orkin SH, Bauer DE - Nature (2015)

Validation of enhancer screena, HbF+ fraction in HUDEP-2 cells transduced in arrayed format with 24 sgRNAs from all 5 mapping categories with enrichment scores ranging from the highest to the lowest in the screen. b, Correlation between HbF enrichment score from pooled sgRNA screen and HbF+ fraction by arrayed validation of individual sgRNAs in HUDEP-2 cells. c, Erythroid differentiation of primary human erythroid precursors evaluated by CD71 and CD235a surface markers, enucleation frequency (CD235a+ Hoescht33342-), and morphology by May-Grünwald-Giemsa staining.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4644101&req=5

Figure 3: Validation of enhancer screena, HbF+ fraction in HUDEP-2 cells transduced in arrayed format with 24 sgRNAs from all 5 mapping categories with enrichment scores ranging from the highest to the lowest in the screen. b, Correlation between HbF enrichment score from pooled sgRNA screen and HbF+ fraction by arrayed validation of individual sgRNAs in HUDEP-2 cells. c, Erythroid differentiation of primary human erythroid precursors evaluated by CD71 and CD235a surface markers, enucleation frequency (CD235a+ Hoescht33342-), and morphology by May-Grünwald-Giemsa staining.
Mentions: To validate the findings from the HUDEP-2 cells, the top-scoring enhancer targeting sgRNA from the screen (#1621 at h+58) was tested in primary human erythroblasts by lentiviral transduction of human CD34+ HSPCs exposed to ex vivo erythroid culture conditions. Consistent with the screen results, sgRNA-1621 resulted in downregulation of BCL11A expression and corresponding upregulation of γ-globin expression and increase in HbF+ cells (Fig. 2f-h). Notably, sgRNA-1621 did not alter surface marker profile, enucleation frequency, or cellular morphology (Extended Data Fig. 3c). Together these results suggest proof-of-principle of an individual sgRNA targeting a noncoding element for therapeutic genome editing of β-hemoglobin disorders.

Bottom Line: Despite conserved function of the composite enhancers, their architecture diverges.The crucial human sequences appear to be primate-specific.The detailed enhancer map will inform therapeutic genome editing, and the screening approach described here is generally applicable to functional interrogation of non-coding genomic elements.

View Article: PubMed Central - PubMed

Affiliation: Division of Hematology/Oncology, Boston Children's Hospital, Department of Pediatric Oncology, Dana-Farber Cancer Institute, Harvard Stem Cell Institute, Department of Pediatrics, Harvard Medical School, Boston, Massachusetts 02115, USA.

ABSTRACT
Enhancers, critical determinants of cellular identity, are commonly recognized by correlative chromatin marks and gain-of-function potential, although only loss-of-function studies can demonstrate their requirement in the native genomic context. Previously, we identified an erythroid enhancer of human BCL11A, subject to common genetic variation associated with the fetal haemoglobin level, the mouse orthologue of which is necessary for erythroid BCL11A expression. Here we develop pooled clustered regularly interspaced palindromic repeat (CRISPR)-Cas9 guide RNA libraries to perform in situ saturating mutagenesis of the human and mouse enhancers. This approach reveals critical minimal features and discrete vulnerabilities of these enhancers. Despite conserved function of the composite enhancers, their architecture diverges. The crucial human sequences appear to be primate-specific. Through editing of primary human progenitors and mouse transgenesis, we validate the BCL11A erythroid enhancer as a target for fetal haemoglobin reinduction. The detailed enhancer map will inform therapeutic genome editing, and the screening approach described here is generally applicable to functional interrogation of non-coding genomic elements.

Show MeSH