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SON and its alternatively spliced isoforms control MLL complex-mediated H3K4me3 and transcription of leukemia-associated genes (ChIP-seq data)

ABSTRACT: Dysregulation of MLL complex-mediated histone methylation plays a pivotal role in gene expression associated with diseases, but little is known about cellular factors modulating MLL complex activity. Here, we report that SON, previously known as an RNA splicing factor, controls MLL complex-mediated transcriptional initiation. SON binds to DNA near transcription start sites, interacts with menin, and inhibits MLL complex assembly, resulting in decreased H3K4me3 and transcriptional repression. Importantly, alternatively spliced short isoforms of SON are markedly upregulated in acute myeloid leukemia. The short isoforms compete with full-length SON for chromatin occupancy, but lack the menin-binding ability, thereby antagonizing full-length SON function in transcriptional repression while not impairing full-length SON-mediated RNA splicing. Furthermore, overexpression of a short isoform of SON enhances replating potential of hematopoietic progenitors. Our findings define SON as a fine-tuner of the MLL-menin interaction and reveal short SON overexpression as a marker indicating aberrant transcriptional initiation in leukemia.

ORGANISM(S): Homo sapiens

PROVIDER: GSE76910 | GEO | 2016/03/24

SECONDARY ACCESSION(S): PRJNA308925

REPOSITORIES: GEO

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Project description:Protein aggregation is a hallmark of many neurodegenerative diseases. In order to cope with misfolding and aggregation, cells have evolved an elaborate network of molecular chaperones, composed of different families. But while chaperoning mechanisms for different families are well established, functional and regulatory diversification within chaperone families is still largely a mystery. Here we decided to explore chaperone functional diversity, through the lens of pathological aggregation. We revealed that different naturally-occurring isoforms of DNAJ chaperones showed differential effects on different types of aggregates. We performed a chaperone screen for modulators of two neurodegeneration-related aggregating proteins, the Huntington’s disease-related HTT-polyQ, and the ALS-related mutant FUS (mutFUS). The screen identified known modulators of HTT-polyQ aggregation, confirming the validity of our approach. Surprisingly, modulators of mutFUS aggregation were completely different than those of HTT-polyQ. Interestingly, different naturally-occurring isoforms of DNAJ chaperones had opposing effects on HTT-polyQ vs. mutFUS aggregation. We identified a complex of the full length (FL) DNAJB14 and DNAJB12 isoforms which substantially alleviated mutFUS aggregation, in an HSP70-dependent manner. Their naturally occurring short isoforms were unable to form the complex, nor to interact with HSP70, and lost their ability to reduce mutFUS aggregation. In contrast, the short isoform of DNAJB12 significantly alleviated HTT-polyQ aggregation, while DNAJB12-FL aggravated HTT-polyQ aggregation. Finally, we demonstrated that full-length DNAJB14 ameliorated mutFUS aggregation compared to DNAJB14-short in primary neurons. Together, our data unraveled distinct molecular properties required for aggregation protection in different neurodegenerative diseases, and revealed a new layer of complexity of the chaperone network elicited by naturally occurring J-protein isoforms, highlighting functional diversity among the DNAJ family.

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SON and its alternatively spliced isoforms control MLL complex-mediated H3K4me3 and transcription of leukemia-associated genes (ChIP-seq data)

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