Homeobox genes encode transcription factors impacting key developmental processes including embryogenesis, organogenesis, and cell differentiation. Reflecting their tight transcriptional control, homeobox genes are often embedded in large non-coding, cis-regulatory regions, containing tissue specific elements. In T-cell acute lymphoblastic leukemia (T-ALL) homeobox genes are frequently deregulated by chromosomal aberrations, notably translocations adding T-cell specific activatory elements. NKX3-1 is a prostate specific homeobox gene activated in T-ALL patients expressing oncogenic TAL1 or displaying immature T-cell characteristics. After investigating regulation of NKX3-1 in primary cells and cell lines, we report its ectopic expression in T-ALL cells independent of chromosomal rearrangements. Using siRNAs and expression profiling, we exploited NKX3-1 positive T-ALL cell lines as tools to investigate aberrant activatory mechanisms. Our data confirmed NKX3-1 activation by TAL1/GATA3/LMO and identified LYL1 as an alternative activator in immature T-ALL cells devoid of GATA3. Moreover, we showed that NKX3-1 is directly activated by early T-cell homeodomain factor MSX2. These activators were regulated by MLL and/or by IL7-, BMP4- and IGF2-signalling. Finally, we demonstrated homeobox gene SIX6 as a direct leukemic target of NKX3-1 in T-ALL. In conclusion, we identified three major mechanisms of NKX3-1 regulation in T-ALL cell lines which are represented by activators TAL1, LYL1 and MSX2, corresponding to particular T-ALL subtypes described in patients. These results may contribute to the understanding of leukemic transcriptional networks underlying disturbed T-cell differentiation in T-ALL.
Pubmed ID: 22848398 RIS Download
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Welcome to Michael Eisens lab in the Howard Hughes Medical Institute (HHMI) at University of California at Berkeley (UCB) and the Lawrence Berkeley National Lab (LBNL). We are part of the Department of Molecular and Cell Biology of UCB and the Genomics Division of LBNL, and the. We are located in Stanley Hall on the Berkeley campus.Our lab applies computational and experimental genomic approaches to study how genome sequences specify organismal form and function. We are particularly interested in the regulation of gene expression, and focus on how the information that specifies when and where genes are expressed is encoded in genome sequences, the role that regulated gene expression plays in animal development and the response of microbes to their environments, and how variation in and evolution of gene expression contributes to phenotypic variation and the remarkable diversity of life on Earth. This site contains a more detailed description of our research projects, an introduction to members of the lab, reprints of all of our publications, free downloadable and web-based software. Sponsor. Experimental work described here was supported by a Howard Hughes Medical Institute Investigator award to MBE and by National Institutes of Health (NIH) grant GM704403 to MBE and MDB. Computational analyses were supported in by NIH grant HG002779 to MBE. Work at Lawrence Berkeley National Laboratory was conducted under Department of Energy contract DE-AC02-05CH11231. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
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