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Defects in hemopoietic stem cell activity in Ikaros mutant mice.

Nichogiannopoulou A, Trevisan M, Neben S, Friedrich C, Georgopoulos K - J. Exp. Med. (1999)

Bottom Line: The defect in HSC activity is also illustrated by the ability of wild-type marrow to repopulate unconditioned Ikaros mutants.A progressive reduction in multipotent CFU-S(14) (colony-forming unit-spleen) progenitors and the earliest erythroid-restricted precursors (BFU-E [burst-forming unit-erythroid]) is also detected in the Ikaros mutant strains consistent with the reduction in HSCs.Nonetheless, the more mature clonogenic erythroid and myeloid precursors are less affected, indicating either the action of a compensatory mechanism to provide more progeny or a negative role of Ikaros at later stages of erythromyeloid differentiation.

View Article: PubMed Central - PubMed

Affiliation: Cutaneous Biology Research Center, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts 02129, USA.

ABSTRACT
Here we provide evidence that the Ikaros family of DNA binding factors is critical for the activity of hemopoietic stem cells (HSCs) in the mouse. Mice homozygous for an Ikaros mutation display a >30-fold reduction in long-term repopulation units, whereas mice homozygous for an Ikaros dominant negative mutation have no measurable activity. The defect in HSC activity is also illustrated by the ability of wild-type marrow to repopulate unconditioned Ikaros mutants. A progressive reduction in multipotent CFU-S(14) (colony-forming unit-spleen) progenitors and the earliest erythroid-restricted precursors (BFU-E [burst-forming unit-erythroid]) is also detected in the Ikaros mutant strains consistent with the reduction in HSCs. Nonetheless, the more mature clonogenic erythroid and myeloid precursors are less affected, indicating either the action of a compensatory mechanism to provide more progeny or a negative role of Ikaros at later stages of erythromyeloid differentiation. In Ikaros mutant mice, a decrease in expression of the tyrosine kinase receptors flk-2 and c-kit is observed in the lineage-depleted c-kit(+)Sca-1(+) population that is normally enriched for HSCs and may in part contribute to the early hemopoietic phenotypes manifested in the absence of Ikaros.

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Analysis of lin− Ikaros mutant hemopoietic cells. (A) Total BM cells from 2–4 wk-old wild-type (+/+), Ikaros  (Ik −/−), and Ikaros (Ik) DN−/− mice were lineage depleted and stained for c-kit and Sca-1 (as described in Materials and Methods). The c-kithi, c-kitlo, and c-kit+Sca-1+ populations are boxed and percentages are indicated. (B) Histograms of cell surface c-kit expression in Ikaros mutant lin− BM populations (dashed lines) and wild type (solid lines) are shown. The left and right panels contrast Ikaros  and Ikaros DN−/− cells, respectively, with wild-type cells. (C) RT-PCR analysis of sorted hemopoietic cells from wild-type and Ikaros mutant mice. BM cells were lineage depleted and sorted according to expression of c-kit and Sca-1, as indicated in A. cDNA was obtained from each sorted population and PCR amplified for the indicated genes. cDNA levels were normalized to HPRT levels.
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Figure 7: Analysis of lin− Ikaros mutant hemopoietic cells. (A) Total BM cells from 2–4 wk-old wild-type (+/+), Ikaros (Ik −/−), and Ikaros (Ik) DN−/− mice were lineage depleted and stained for c-kit and Sca-1 (as described in Materials and Methods). The c-kithi, c-kitlo, and c-kit+Sca-1+ populations are boxed and percentages are indicated. (B) Histograms of cell surface c-kit expression in Ikaros mutant lin− BM populations (dashed lines) and wild type (solid lines) are shown. The left and right panels contrast Ikaros and Ikaros DN−/− cells, respectively, with wild-type cells. (C) RT-PCR analysis of sorted hemopoietic cells from wild-type and Ikaros mutant mice. BM cells were lineage depleted and sorted according to expression of c-kit and Sca-1, as indicated in A. cDNA was obtained from each sorted population and PCR amplified for the indicated genes. cDNA levels were normalized to HPRT levels.

Mentions: Hemopoietic cells that lack expression of mature lineage markers (lin−) and that coexpress Sca-1/Ly6A and the tyrosine kinase receptor c-kit on their cell surfaces (lin−c-kit+Sca-1+) are highly enriched in HSC activity in normal mice 2728. The HSC-enriched lin− c-kit+Sca-1+ population was detected in Ikaros BM (Fig. 7 A, center). In sharp contrast, no c-kit+/Sca-1+ cells were present among the lin− BM cells of Ikaros DN−/− mice (Fig. 7 A, right). The lack of BM cells with a lin− c-kit+Sca-1+ surface phenotype in Ikaros DN−/− mice is consistent with the dramatic depletion in HSC activity in these mutant mice.


Defects in hemopoietic stem cell activity in Ikaros mutant mice.

Nichogiannopoulou A, Trevisan M, Neben S, Friedrich C, Georgopoulos K - J. Exp. Med. (1999)

Analysis of lin− Ikaros mutant hemopoietic cells. (A) Total BM cells from 2–4 wk-old wild-type (+/+), Ikaros  (Ik −/−), and Ikaros (Ik) DN−/− mice were lineage depleted and stained for c-kit and Sca-1 (as described in Materials and Methods). The c-kithi, c-kitlo, and c-kit+Sca-1+ populations are boxed and percentages are indicated. (B) Histograms of cell surface c-kit expression in Ikaros mutant lin− BM populations (dashed lines) and wild type (solid lines) are shown. The left and right panels contrast Ikaros  and Ikaros DN−/− cells, respectively, with wild-type cells. (C) RT-PCR analysis of sorted hemopoietic cells from wild-type and Ikaros mutant mice. BM cells were lineage depleted and sorted according to expression of c-kit and Sca-1, as indicated in A. cDNA was obtained from each sorted population and PCR amplified for the indicated genes. cDNA levels were normalized to HPRT levels.
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Figure 7: Analysis of lin− Ikaros mutant hemopoietic cells. (A) Total BM cells from 2–4 wk-old wild-type (+/+), Ikaros (Ik −/−), and Ikaros (Ik) DN−/− mice were lineage depleted and stained for c-kit and Sca-1 (as described in Materials and Methods). The c-kithi, c-kitlo, and c-kit+Sca-1+ populations are boxed and percentages are indicated. (B) Histograms of cell surface c-kit expression in Ikaros mutant lin− BM populations (dashed lines) and wild type (solid lines) are shown. The left and right panels contrast Ikaros and Ikaros DN−/− cells, respectively, with wild-type cells. (C) RT-PCR analysis of sorted hemopoietic cells from wild-type and Ikaros mutant mice. BM cells were lineage depleted and sorted according to expression of c-kit and Sca-1, as indicated in A. cDNA was obtained from each sorted population and PCR amplified for the indicated genes. cDNA levels were normalized to HPRT levels.
Mentions: Hemopoietic cells that lack expression of mature lineage markers (lin−) and that coexpress Sca-1/Ly6A and the tyrosine kinase receptor c-kit on their cell surfaces (lin−c-kit+Sca-1+) are highly enriched in HSC activity in normal mice 2728. The HSC-enriched lin− c-kit+Sca-1+ population was detected in Ikaros BM (Fig. 7 A, center). In sharp contrast, no c-kit+/Sca-1+ cells were present among the lin− BM cells of Ikaros DN−/− mice (Fig. 7 A, right). The lack of BM cells with a lin− c-kit+Sca-1+ surface phenotype in Ikaros DN−/− mice is consistent with the dramatic depletion in HSC activity in these mutant mice.

Bottom Line: The defect in HSC activity is also illustrated by the ability of wild-type marrow to repopulate unconditioned Ikaros mutants.A progressive reduction in multipotent CFU-S(14) (colony-forming unit-spleen) progenitors and the earliest erythroid-restricted precursors (BFU-E [burst-forming unit-erythroid]) is also detected in the Ikaros mutant strains consistent with the reduction in HSCs.Nonetheless, the more mature clonogenic erythroid and myeloid precursors are less affected, indicating either the action of a compensatory mechanism to provide more progeny or a negative role of Ikaros at later stages of erythromyeloid differentiation.

View Article: PubMed Central - PubMed

Affiliation: Cutaneous Biology Research Center, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts 02129, USA.

ABSTRACT
Here we provide evidence that the Ikaros family of DNA binding factors is critical for the activity of hemopoietic stem cells (HSCs) in the mouse. Mice homozygous for an Ikaros mutation display a >30-fold reduction in long-term repopulation units, whereas mice homozygous for an Ikaros dominant negative mutation have no measurable activity. The defect in HSC activity is also illustrated by the ability of wild-type marrow to repopulate unconditioned Ikaros mutants. A progressive reduction in multipotent CFU-S(14) (colony-forming unit-spleen) progenitors and the earliest erythroid-restricted precursors (BFU-E [burst-forming unit-erythroid]) is also detected in the Ikaros mutant strains consistent with the reduction in HSCs. Nonetheless, the more mature clonogenic erythroid and myeloid precursors are less affected, indicating either the action of a compensatory mechanism to provide more progeny or a negative role of Ikaros at later stages of erythromyeloid differentiation. In Ikaros mutant mice, a decrease in expression of the tyrosine kinase receptors flk-2 and c-kit is observed in the lineage-depleted c-kit(+)Sca-1(+) population that is normally enriched for HSCs and may in part contribute to the early hemopoietic phenotypes manifested in the absence of Ikaros.

Show MeSH
Related in: MedlinePlus