Intrinsically disordered Meningioma-1 stabilizes the BAF complex to cause AML
Simone S Riedel1, Congcong Lu2, Hongbo M Xie3
1Division of Pediatric Oncology, Children's Hospital of Philadelphia, Philadelphia, PA, USA.
Molecular Cell
|May 11, 2021
Summary
Meningioma-1 (MN1) overexpression drives acute myeloid leukemia (AML) by disrupting gene regulation. This disordered protein over-stabilizes a key complex on DNA, impairing cell development and causing cancer.
Area of Science:
- Hematology
- Molecular Biology
- Cancer Research
Background:
- Meningioma-1 (MN1) overexpression in acute myeloid leukemia (AML) correlates with poor prognosis and can induce leukemia in murine models.
- The precise mechanism by which MN1 contributes to AML pathogenesis remains incompletely understood.
Purpose of the Study:
- To elucidate the molecular mechanisms underlying MN1-induced acute myeloid leukemia.
- To identify MN1's interaction partners and their role in leukemogenesis.
Main Methods:
- Utilized translocation analysis to identify mechanisms of MN1 overexpression.
- Performed structural predictions to analyze MN1's protein structure.
- Employed co-immunoprecipitation and chromatin immunoprecipitation assays to identify MN1 interaction partners and binding sites.
- Investigated the role of the polyglutamine (polyQ) stretch in MN1 function.
Main Results:
- MN1 overexpression can be driven by enhancer hijacking via chromosomal translocations.
- MN1 possesses a disordered protein structure, with its entire coding frame lacking stable tertiary structure.
- The myeloid progenitor-specific BAF complex was identified as a key interaction partner of MN1.
- MN1, particularly via its polyQ stretch, over-stabilizes the BAF complex on enhancer chromatin.
- This aberrant BAF stabilization prevents the normal shutdown of enhancers regulating hematopoietic stem/progenitor genes, leading to blocked myeloid differentiation and AML development.
Conclusions:
- MN1 overexpression, induced by enhancer hijacking, drives AML by disrupting epigenetic regulation of hematopoietic development.
- The polyQ-rich, disordered nature of MN1 is crucial for its oncogenic function, leading to BAF complex over-stabilization and impaired myeloid differentiation.
- These findings highlight how overexpression of a disordered polyQ protein, without coding mutations, can be sufficient for malignant transformation, offering new therapeutic targets for AML.
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