Subnuclear targeting of Runx1 is required for synergistic activation of the myeloid specific M-CSF receptor promoter by PU.1.
Many types of acute myelogenous leukemia involve chromosomal translocations that target the C-terminus of Runx1/AML1 transcription factor, a master regulator of hematopoiesis. The C-terminus of Runx1/AML1 that includes the nuclear matrix targeting signal (NMTS) is essential for embryonic development, hematopoiesis, and target gene regulation. During the onset and normal progression of hematopoiesis, several lineage-specific factors such as C/EBPalpha and PU.1 interact with Runx1 to regulate transcription combinatorially. Here we addressed the functional interplay between subnuclear targeting of Runx1 and gene activation during hematopoiesis. Point mutations were generated in the NMTS of the human Runx1 protein and tested for their effect on transcriptional cooperativity with C/EBPalpha and PU.1 at myeloid-specific promoters. We characterized five mutants that do not alter nuclear import, DNA binding or C/EBPalpha-dependent synergistic activation of the target gene promoters. However a critical tyrosine in the NMTS is required for subnuclear targeting and activation of the granulocyte-macrophage colony stimulating factor (GM-CSF) promoter. Furthermore, this point mutation is defective for transcriptional synergism with PU.1 on the macrophage colony stimulating factor (MCSF) receptor c-FMS promoter. Our results indicate that the NMTS region of Runx1 is required for functional interactions with PU.1. Taken together, our findings establish that subnuclear targeting of Runx1 is a critical component of myeloid-specific transcriptional control.
Li
Xiangen
X
Department of Cell Biology and Cancer Center, University of Massachusetts Medical School, Worcester, Massachusetts 01655, USA.
Vradii
Diana
D
Gutierrez
Soraya
S
Lian
Jane B
JB
van Wijnen
Andre J
AJ
Stein
Janet L
JL
Stein
Gary S
GS
Javed
Amjad
A
D000595:Amino Acid Sequence; D000818:Animals; D022763:CCAAT-Enhancer-Binding Protein-alpha / Q000378:metabolism; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism*; D002478:Cells, Cultured; D050676:Core Binding Factor Alpha 2 Subunit / Q000737:chemistry / Q000378:metabolism*; D024202:Electrophoretic Mobility Shift Assay; D005786:Gene Expression Regulation; D006367:HeLa Cells; D006801:Humans; D007951:Leukemia, Myeloid / Q000235:genetics*; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics*; D021381:Protein Transport; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D016186:Receptor, Macrophage Colony-Stimulating Factor / Q000235:genetics*; D015534:Trans-Activators / Q000378:metabolism*; D015533:Transcriptional Activation; D000099232:Proto-Oncogene Protein Spi-1
D022763:CCAAT-Enhancer-Binding Protein-alpha; D050676:Core Binding Factor Alpha 2 Subunit; D011518:Proto-Oncogene Proteins; D016186:Receptor, Macrophage Colony-Stimulating Factor; D015534:Trans-Activators; D000099232:Proto-Oncogene Protein Spi-1; C493728:RUNX1 protein, human