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HOXA9 forms triple complexes with PBX2 and MEIS1 in myeloid cells
W F Shen1, S Rozenfeld, A Kwong
1Departments of Medicine, University of California VA Medical Center, San Francisco, California, USA. largman@cgl.ucsf.edu
Molecular and Cellular Biology
|March 19, 1999
Summary
Aberrant HOX, MEIS, and PBX homeodomain protein activation drives leukemia. MEIS1 forms trimeric complexes with PBX and HOXA9, binding specific DNA targets in myeloid leukemia cells.
Area of Science:
- Molecular Biology
- Hematology
- Cancer Research
Background:
- Aberrant activation of HOX, MEIS, and PBX homeodomain proteins is linked to leukemias.
- HOXA9 and MEIS1 coexpression can induce myeloid leukemia in mice.
- HOX-9/10 proteins uniquely form cooperative DNA complexes with PBX or MEIS proteins.
Purpose of the Study:
- To investigate the in vitro and in vivo DNA binding interactions of HOXA9, MEIS1, and PBX proteins.
- To determine the role of MEIS1 in forming complexes with HOXA9 and PBX.
- To elucidate the functional consequences of these protein interactions in myeloid cells.
Main Methods:
- In vitro DNA site selection assays.
- Electrophoretic mobility shift assays (EMSA) to detect protein-DNA complexes.
- Co-immunoprecipitation to identify protein interactions in cell extracts.
- Reporter gene assays to assess transcriptional activity.
Main Results:
- MEIS1, HOXA9, and PBX form trimeric complexes that bind to a consensus PBX-HOXA9 DNA site.
- These proteins (HOXA9, PBX2, MEIS1) are coexpressed and colocalized in the nucleus of myeloid cells.
- While complexes form, cotransfection minimally affected reporter gene transcription.
Conclusions:
- MEIS1 forms trimeric complexes with PBX and HOXA9 in myeloid leukemia cells.
- These trimeric complexes bind to specific DNA targets.
- The functional impact on transcription requires further investigation.