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HOXA9 – Acute Myeloid Leukemia. HOX Genes encode transcription factors. http://en.wikipedia.org/wiki/Image:Homeodomain-dna-1ahd.png. The role of HOX Genes. -Anteroposterior Development-. Universally specify regional development Specify the anterior-posterior axis.
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HOXA9 – Acute Myeloid Leukemia
HOX Genesencodetranscription factors http://en.wikipedia.org/wiki/Image:Homeodomain-dna-1ahd.png
The role of HOX Genes -Anteroposterior Development- • Universally specify regional development • Specify the anterior-posterior axis http://www.nybooks.com/images/tables/20060511012img1.jpg
http://evonet.sdsc.edu/evoscisociety/short/images/hox_gene.gifhttp://evonet.sdsc.edu/evoscisociety/short/images/hox_gene.gif
What happens in development when you knockout a HOX gene? **Anterior transformations** Development. Fromental-Ramain et al. 122 (2): 461
HOXA9 plays a key role inhematopoiesis Normal development of hematopoietic cells
HOXA9 plays a key role inhematopoiesis Knocking out HOXA9 disrupts T cell development http://www.bloodlines.stemcells.com/img/Metcalf_Fig3_2.gif
Acute Myeloid Leukemia (AML) Overexpress HOXA9 hematological malignancies http://content.answers.com/main/content/wp/en-commons/2/20/Illu_blood_cell_lineage.jpg
Acute Myeloid Leukemia(AML) • Replace bone marrow with primitive cells • Differentiation arrest and loss of apoptosis • Immunosuppression infection death
Mechanisms by which HOXA9 is deregulated Gene Translocation Fusion Proteins Deregulation of HOXA9 http://staff.jccc.net/PDECELL/evolution/mutations/translocation.gif
More on Translocations, Fusion Proteins HOXA9-NUP98 A Potent Oncogene, Fusion Protein • NUP98 is translocated next to HOXA9 • Translation creates HOXA9-NUP98 protein
Fusion Proteins induce proliferation and contribute to AML 1. Express NUP98-HOXA9 Transformation of myeloblasts (progenitor cells) 2. Transplant the transformed cells to bone marrow of healthy mice AML onset Evert Kroon, et al. The EMBO Journal (2001) 20, 350–361
Mechanisms by which HOXA9 contributes to cancer (Part 2) non-HOX genes can serve as cofactors Accelerated leukemogenesis How?? 1. Alter properties of HOXA9 proteins 2. Promotes overexpression of HOXA9
More on Cofactors • MEIS cofactors are synthesized with HOX proteins during embryogenesis • Meis1a – routinely coactivated with HOXA9
HOXA9 overexpression Meis1a cofactor Acute Myeloid Leukemia Evert Kroon, et al. The EMBO Journal (1998) 17, 3714–3725
Expression of Meis1a with HOXA9 accelerates Leukemogenesis in Mice Evert Kroon, et al. The EMBO Journal (2001) 20, 350–361
Cofactor Meis1a intensifies proliferative effect of fusion protein NUP98-HOXA9 Evert Kroon, et al. The EMBO Journal (2001) 20, 350–361