Type: Oral
Session: 602. Disordered Gene Expression in Hematologic Malignancy, including Disordered Epigenetic Regulation: Aberrant Nuclear Architecture and Chromatin Remodeling
Hematology Disease Topics & Pathways:
AML, Diseases, Biological Processes, epigenetics, Myeloid Malignancies, genomics, hematopoiesis, molecular interactions, pathways
Here, Combined RNA-seq, ChIP-seq, NG-Capture-C and Hi-C integrated analysis demonstrated that HOTTIP dependent stratification/formation of TADs at WNT/b-catenin loci is critical for b-catenin (CTNNB1) target gene transcription in AML cells. We further showed that HOTTIP specifically interacts with CTCF-occupied TAD boundary CTCF binding sites (CBSs) at b-catenin and its target loci (e.g. MYC and MECOM) by formation of R-loops. To test whether HOTTIP-mediated R-loops contribute to boundary maintanence and TAD stablization, we created CRISPR/dCas9-RNaseH-mediated disruption of R-loop structure In MOLM13 cells by which the Ribonuclease H (RNase H) was targeted to the HOTTIP/CTCF co-occupied CTNNB1 or MYC boundary CBSs to specifically target RNA: DNA hybridization region. Our DNA-RNA immunoprecipitation (DRIP)-qPCR data indicated that CRISPR/dCas9-RNaseH-mediated sgRNAs disrupted the R-loop structure in MYC and CTNNB1 defined TAD boundary regions. Furthermore, HOTTIP CHIRP-qPCR and CTCF CHIP-qPCR suggested that loss of R-loop structure in MYC or CTNNB1 TAD boundary CBSs decreased both CTCF and HOTTIP binding in these CBSs. Disruption of R-loops also affects the long-range interaction within CTNNB1 or MYC TADs that are important for WNT/b-catenin signaling network and AML leukemogenesis.
In conclusion, our finding demonstrated that HOTTIP forming DNA∙RNA hybridized R-loops mediate AML genome organization at specific gene loci and control leukemic transcription program. Thus, HOTTIP lncRNA mediated R-loop structure will be considered as a novel molecular mechanism in AML leukemogensis.
Disclosures: Claxton: Daiichi Sankyo Co: Research Funding; Astellas Pharma: Research Funding; Incyte Corporation: Research Funding; Cyclacel Pharmaceuticals, Inc.: Research Funding.
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