Project description:Genetic studies have identified common variants within the HBS1L-MYB intergenic region on chromosome 6q associated with elevated fetal hemoglobin (HbF) levels and other clinically important human erythroid traits. The mechanism by which the non-coding sequence variants affect these traits is still not clear. Here we report that several of the variants affect regulatory elements that are occupied by key erythroid transcription factors within this region. These elements interact with MYB, a critical regulator of erythroid development and HbF levels. We show that several of the variants reduce transcription factor binding, affecting long-range interactions with MYB, and MYB expression levels. We provide here a functional explanation for the genetic association of HBS1L-MYB intergenic polymorphisms with human erythroid traits and HbF levels. Our results further designate MYB as a bona fide target for therapeutic induction of HbF to ameliorate sickle cell and β-thalassemia disease severity.
Project description:Naturally occurring mutations in the γ-globin promoters can result in hereditary persistence of fetal hemoglobin (HPFH), a benign condition that ameliorates the severity of β-hemoglobinopathies through increased post-natal fetal hemoglobin (HbF) expression. Base editing to recreate the HPFH mutations is a promising approach to induce HbF. Compared with Cas9-generated indels, base-editing approaches were more potent, with the −175 A>G conversion resulting in the strongest induction of HbF by creating a new TAL1 binding motif that stimulates long-range interaction with the locus control region (LCR), a powerful upstream enhancer. Micro-Capture-C analysis showed that introducing the −175 A>G variant stimulated long-range interaction between the γ-globin promoters and the LCR in erythroid progenitor cell line. Together, these findings show that the −175 A>G variant creates a bipartite GATA–TAL1 motif, resulting in the assembly of a GATA1/TAL1/LMO2/LDB1 complex, which activates γ-globin gene transcription by enhancing its physical association with the LCR.
Project description:To explore long noncoding RNA (lncRNA) expression and the biological functions of lncRNAs in fetal hemoglobin (HbF) induction, we surveyed lncRNA and mRNA expression profiles using circulating reticulocytes isolated from individuals with hereditary persistence of fetal hemoglobin (HPFH) and β-thalassaemia minor with high HbF.
Project description:We report the application of Illumina sequencing for high-throughput profiling of miRNA in citrus root responded to long-term boron toxicity. We find miR319 is involved in citrus adapation to long-term boron toxicity via targeting a MYB gene, Ciclev10000756m.g.v1.0, which is homologus with several MYBs that modulate lateral root development in Arabidopsis.
Project description:Boontanrart et al model the cellular stress that occurs upon reduction in β-globin in human erythroid cells. Decrease in β-globin attenuates the eIF2aP-ATF4 pathway and results in upregulating fetal -globin. Down-regulation of ATF4 leads to decreased levels of the -globin repressor MYB through direct binding at the HBS1L-MYB intergenic region.
Project description:Boontanrart et al model the cellular stress that occurs upon reduction in β-globin in human erythroid cells. Decrease in β-globin attenuates the eIF2aP-ATF4 pathway and results in upregulating fetal g-globin. Down-regulation of ATF4 leads to decreased levels of the g-globin repressor MYB through direct binding at the HBS1L-MYB intergenic region.
Project description:Fetal hemoglobin (HbF) level is genetically controlled and modifies severity of adult hemoglobin (HbA) disorders. Common genetic variation affects expression of BCL11A, a critical regulator of HbF silencing. Current models suggest that BCL11A acts at a distance from the gamma-globin genes via long-distance chromosomal interactions. Here we use a functional cellular assay and protein-binding microarray to establish a requirement for a zinc-finger cluster of BCL11A for globin repression, and identify a preferred DNA recognition sequence (TGACCA). The motif is present in embryonic and fetal-expressed globin promoters, and duplicated in gamma-globin promoters, yet only the distal motif is mutated in alleles of individuals with hereditary persistence of hemoglobin. Using CUT&RUN to map protein binding sites, we detected BCL11A occupancy preferentially at the distal motif, and validated its absence in HbF-expressing, promoter-edited erythroid cells. Taken together, our findings reveal that direct gamma-globin gene promoter repression by BCL11A underlies hemoglobin switching.
Project description:The monoallelic expression of olfactory receptor (OR) genes is governed by a large number of intergenic enhancer elements that are located in intergenic regions of OR gene clusters. In mature olfactory sensory neurons (OSNs), multiple OR enhancers colocalize in an interchromosomal enhancer hub together with the active OR allele. Here we show that in OSNs OR enhancers are bound by Ldb1, but not general purpose mediators of nuclear architecture (CTCF or the cohesin complex subunit Rad21). Conditional deletion of Ldb1 in OSNs results in the dissolution of long range and interchromosomal contacts between OR Enhancers and in pervasive reductions in OR gene expression.
Project description:Here, we leveraged 297 melanoma whole-genome sequencing (WGS) samples to prioritize highly recurrent regions (HRRs). By performing a genome-scale CRISPR interference (CRISPRi) screen on HRR-associated enhancers in melanoma cells, we identified 66 significant hits which could have tumor-suppressive roles. These functional enhancers show unique mutational patterns independent of classical significantly mutated genes in melanoma. Target gene analysis for the essential enhancers revealed many known and hidden mechanisms underlying melanoma growth. Utilizing extensive functional validation experiments, we demonstrated that a super enhancer element could modulate melanoma cell proliferation by targeting MEF2A and another distal enhancer was able to sustain PTEN tumor-suppressive potential via long-range interaction.
