Identification of E74-like factor 1 (ELF1) as a transcriptional regulator of the Hox cofactor MEIS1
Received 1 June 2010; received in revised form 1 June 2010; accepted 4 June 2010. published online 24 June 2010.
Objective
Myeloid ectropic viral integration site 1 (MEIS1) is a Hox cofactor known for its role in development and is strongly linked to normal and leukemic hematopoiesis. Although previous studies have focused on identifying protein partners of MEIS1 and its transcriptionally regulated targets, little is known about the upstream transcriptional regulators of this tightly regulated gene. Understanding the regulation of MEIS1 is important to understanding normal hematopoiesis and leukemogenesis.
Materials and Methods
Here we describe our studies focusing on the evolutionary conserved putative MEIS1 promoter region. Phylogenetic sequence analysis and reporter assays in MEIS1-expressing (K562) and nonexpressing (HL60) leukemic cell line models were used to identify key regulatory regions and potential transcription factor binding sites within the candidate promoter region followed by functional and expression studies of one identified regulator in both cell lines and primary human cord blood and leukemia samples.
Results
Chromatin status of MEIS1 promoter region is associated with MEIS1 expression. Truncation and mutation studies coupled with reporter assays revealed that a conserved ETS family member binding site located 289 bp upstream of the annotated human MEIS1 transcription start site is required for promoter activity. Of the three ETS family members tested, only ELF1 was enriched on the MEIS1 promoter as assessed by both electrophoretic mobility shift assay and chromatin immunoprecipitation experiments in K562. This finding was confirmed in MEIS1-expressing primary human samples. Moreover, small interfering RNA−mediated knockdown of ELF1 in K562 cells was associated with a decreased MEIS1 expression.
Conclusions
We conclude that the ETS transcription factor ELF1 is an important positive regulator of MEIS1 expression.
aTerry Fox Laboratory, British Columbia Cancer Agency, Vancouver, British Columbia, Canada
bInstitute of Experimental Cancer Research, Clinical Comprehensive Centre, Ulm University, Ulm, Germany
cDepartment of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada
dDepartment of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
Offprint requests to: R. Keith Humphries, M.D., Ph.D., Terry Fox Laboratory, BC Cancer Agency, 675 West 10th Avenue, Vancouver, BC V5Z1L3, Canada
ABSTRACT