Dissecting Hox Gene Function In Normal Hematopoiesis LossOfFunction Studies

A major strategy to assess the role of homeobox genes in hematopoiesis has been to utilize knockout mice to examine the impact of gene deletion on blood cell development. The Hoxa9 knockout yielded the best-characterized hema-topoeitic phenotype for a Hox cluster gene to date. These mice were viable and fertile and had only mild skeletal defects, but showed defects in T and B cells and granulocytes. As noted above, Hoxa9 is expressed in CD34+Lin- human he-matopoietic cells as well as in more...

Mechanism Of Eklf Transcriptional Activation

Although all the initial studies focused on the EKLF zinc fingers and how they interact with their DNA target site, the rest of the molecule remained to be analyzed. This nonfinger region of the molecule functions as a classical transac-tivation module, as its fusion to a heterologous DNA-binding motif (GAL4) results in strong activation of a target reporter that contains the GAL DNA-binding motif, yet itself does not bind DNA (Bieker and Southwood, 1995). As this region of EKLF is not...

Blunted Activation of Rxrrar Response Elements in the SCFDependent EML Cells

We performed similar studies on the stem cell factor (SCF) - dependent pluripotent EML cells derived by transducing the dominant negative RARa403 construct into normal mouse hema-topoietic cells and then culturing these cells in SCF (Tsai et al., 1994). Unlike the GM-CSF-dependent MPRO cells, which are strictly committed to granulocyte differentiation, the SCF-dependent EML cells are multipotent, exhibiting erythroid, lymphoid, and myeloid potential. The addition of IL-3 to EML cultures will...

Introduction

The core-binding factors (CBFs), which are also known as the polyomavirus enhancer binding protein 2 (PEBP2), constitute a small family of transcription factors that participate in multiple developmental processes in flies and mammals. CBFs are heterodimers consisting of a DNA-binding subunit (CBFa) and a non-DNA-bind-ing CBF subunit (Fig. 6.1) (Kamachi et al., 1990 Ogawa et al., 1993a, 1993b, Wang et al., 1993). CBFa subunits by themselves can bind DNA in vitro, but their affinity for DNA is...

Hematopoietic Lineagespecific Activation Of Ra Receptors

Establishment of Growth Factor-Dependent Mouse Hematopoietic Cell Lines Utilizing Dominant Negative RA Receptor Constructs Experiments introducing a dominant negative retinoic acid receptor into normal mouse bone marrow have indicated an important role for RA receptors in regulating normal myeloid differentiation. Truncating the 59 amino acids at the COOH-terminal end of RARa results in an altered RA receptor (designated RARa403) that inhibits the function of normal RA receptors (Damm et al.,...

Cttgaggaactgaaaacagaacct

In vitro indicates the sequence is an optimized binding site based on a PCR based site-selection experiment. 6Enh indicates enhancer elements. If not stated, binding sites are in a promoter element. In vitro indicates the sequence is an optimized binding site based on a PCR based site-selection experiment. 6Enh indicates enhancer elements. If not stated, binding sites are in a promoter element. lix-turn-helix motif. Direct contact with the GGAA core contained within the major groove of DNA is...

Info

CFU-S were counted per spleen at day 8 (D8) or day 12 (D12) following transplantation of the indicated number of cells into irradiated recipient mice following previously detailed procedures (Purton et al., 1999). CFU-S from day 0 are from 500 freshly sorted uncultured hematopoietic precursors (lin c-kit+ Sca-1+ cells). CFU-S after day 7 and 14 are from all cells that grew in liquid suspension from 500 or 1000 of these sorted hematopoietic precursors respectively. 6N A not available due to...

B

Continuous deletion steady-slate analysis inducible deletion short-term effects Figure 14.4. Conditional inactivation of Pax5 by Cre-mediated deletion. A Schematic diagram of the floxed Pax5 allele. The different targeted Pax5 alleles are shown together with a schematic representation of the Pax5 locus (Busslinger et al., 1996). The Pax5 knock-out allele was previously described (Urbanek et al., 1994). B Cre transgenic lines used for inactivation of the floxed Pax5 allele at late stages of...

Hoxaio

Hoxa10 Domain

A second direct transcriptional target of VDR is HOXAIO. Northern blot analysis of RNA derived from U937 cells demonstrated a vitamin D3-mediated induction of this gene that was resistant to the presence of cycloheximide (Liu et al., 1996 Rots et al., 1998). As in the case of p21, ectopic overexpression of the gene was sufficient to induce the differentiation of a significant percentage of U937 cells, implicating the involvement of HOXAIO in the 1,25(OH)2D3-induced differentiation of these...

Members Of Cebp Family Transportation Factors In Myeloid Cells

Since the discovery of the first C EBP protein (now known as C EBPa), five other C EBP proteins have been identified. All of these proteins contain bZIP domains at the C-terminal region. There are various names used for these factors, which are mentioned in this review. However, to simplify the description, C EBPa, - , -s, -y, and - are used in this review as Figure 8.1. Domain structure of C EBP proteins. C EBPa activation domains are marked with slashed boxes. C EBP negative regulatory...

Upstream Regulators of Hox Gene Expression

Retinoids and Retinoic Acid Receptors. The observation 10 years ago that low doses of retinoic TABLE 9.1. Hox Genes and Leukemia Lymphoma Human diseases PBX1 TCL3 Hoxa9 Hoxd13 Mouse diseases Hoxb8 Hoxb3 Hoxa9 Hoxa10 t(1 19)E2a-PBX1 t(10 14) TCR -TCL3 t(7 11) NUP98-HOXA9 t(2 11)NUP98-HOXD13 Proviral activation Retroviral overexpression Retroviral overexpression Retroviral overexpression acid (RA) induce the ordered, sequential expression of Hox genes in embryonic carcinoma cells suggested that...

The Role Of Nfe2 In Megakaryocyte Differentiation And Platelet Biogenesis

Although p45 NF-E2 is expressed in selected nonerythroid blood cell lineages, it was expected to manifest its most important functional requirements within developing red blood cells. However, the most remarkable aspect of mice with targeted disruption of p45 NF-E2 is profound thrombocytopenia (Shivdasani et al., 1995). Whereas automated platelet counts are approximately 10 of normal values, few if any platelets are detected on peripheral blood smears, and the mice display a florid hemorrhagic...

The Role Of Ikaros And Aiolos In Lymphocyte Homeostasis

Development of T-Cell Malignancies in Ikaros DN - Mice Studies with mice heterozygous for the dominant negative Ikaros mutation DN - implicate Ikaros as a tumor suppressor gene for the T-cell lineage Winandy et al., 1995 . Initially, Ikaros DN - mice have grossly normal eryth-roid, myeloid, and lymphoid populations, as determined by flow cytometry. However, ''phe-notypically normal'' Ikaros DN - thymocytes and splenocytes display augmented proliferative responses when triggered via the T-cell...