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| Status |
Public on Nov 23, 2016 |
| Title |
MLL-AF4 binds directly to a BCL-2 specific enhancer and impacts H3K27 acetylation |
| Organism |
Homo sapiens |
| Experiment type |
Expression profiling by high throughput sequencing
Other
Genome binding/occupancy profiling by high throughput sequencing
|
| Summary |
Survival rates for children diagnosed with acute lymphoblastic leukemia (ALL) have drastically improved, but those carrying mutations in the Mixed Lineage Leukemia (MLL) gene continue to have a very poor prognosis. The most common MLL mutation in ALL is the t(4;11)(q21;q23) chromosome translocation that fuses MLL in frame with the AF4 gene producing MLL-AF4 and AF4-MLL fusion proteins. Previously, we showed that MLL-AF4 binds to the BCL-2 gene and directly activates it through DOT1L recruitment and increased H3K79me2/3 levels. We went on to show that MLL leukemias are particularly sensitive to treatment with the BCL-2 inhibitor venetoclax which synergizes with both standard chemotherapeutic agents as well as DOT1L inhibitors. Altered expression of other BCL-2 family members is a major cause of resistance to ventoclax, so here we perform a detalied analysis of MLL-AF4 regulation of the entire BCL-2 family. By measuring nascent RNA production, we find that of all the BCL-2 family genes, MLL-AF4 directly controls the transcription of both BCL-2 and MCL-1, but only BCL-2 shows a significant loss of steady state RNA levels. Interestingly however, both MCL-1 and BCL-XL protein levels are dependent on MLL-AF4 activity through an unknown and likely indirect mechanism. Finally, we analyze MLL-AF4 regulation of the BCL-2 gene in greater detail and using Capture C we identify a major BCL-2 specific enhancer consisting of two clusters of H3K27Ac. Loss of MLL-AF4 activity results in a reduction of H2K27Ac levels at the major BCL-2 enhancer, revealing a novel regulatory dependence on MLL-AF4 function at BCL-2.
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| Overall design |
Examination of MLL-AF4-mediated regulation at BCL2-family genes using nascent RNA-seq to observe gene expression changes following siRNA-mediated knockdown and treatment with the DOT1L inhibitor EPZ-5676. We also investigated changes in histone mark occupancy at the BCL2 promoter and enhancer following siRNA-mediated knockdown of MLL-AF4
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| Contributor(s) |
Milne TA, Kerry J |
| Citation(s) |
27856324 |
| Submission date |
Aug 24, 2016 |
| Last update date |
May 15, 2019 |
| Contact name |
Thomas Milne |
| E-mail(s) |
thomas.milne@imm.ox.ac.uk
|
| Organization name |
Weatherall Institute of Molecular Medicine
|
| Department |
Molecular Haematology Unit
|
| Street address |
John Radcliffe Hospital
|
| City |
Oxford |
| ZIP/Postal code |
OX3 9DS |
| Country |
United Kingdom |
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| Platforms (2) |
| GPL16791 |
Illumina HiSeq 2500 (Homo sapiens) |
| GPL18573 |
Illumina NextSeq 500 (Homo sapiens) |
|
| Samples (21)
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| Relations |
| BioProject |
PRJNA339938 |
| SRA |
SRP082679 |
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