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Beta-catenin is dispensable for hematopoiesis and lymphopoiesis.

Cobas M, Wilson A, Ernst B, Mancini SJ, MacDonald HR, Kemler R, Radtke F - J. Exp. Med. (2004)

Bottom Line: Beta-catenin-mediated Wnt signaling has been suggested to be critically involved in hematopoietic stem cell maintenance and development of T and B cells in the immune system.Unexpectedly, here we report that inducible Cre-loxP-mediated inactivation of the beta-catenin gene in bone marrow progenitors does not impair their ability to self-renew and reconstitute all hematopoietic lineages (myeloid, erythroid, and lymphoid), even in competitive mixed chimeras.In contrast to earlier reports, these data exclude an essential role for beta-catenin during hematopoiesis and lymphopoiesis.

View Article: PubMed Central - PubMed

Affiliation: Ludwig Institute for Cancer Research, Lausanne Branch, University of Lausanne, Epalinges, Switzerland.

ABSTRACT
Beta-catenin-mediated Wnt signaling has been suggested to be critically involved in hematopoietic stem cell maintenance and development of T and B cells in the immune system. Unexpectedly, here we report that inducible Cre-loxP-mediated inactivation of the beta-catenin gene in bone marrow progenitors does not impair their ability to self-renew and reconstitute all hematopoietic lineages (myeloid, erythroid, and lymphoid), even in competitive mixed chimeras. In addition, both thymocyte survival and antigen-induced proliferation of peripheral T cells is beta-catenin independent. In contrast to earlier reports, these data exclude an essential role for beta-catenin during hematopoiesis and lymphopoiesis.

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β-catenin–deficient BM reconstitutes all major hematopoietic lineages. BM chimeras were analyzed 4–7 mo after reconstitution. (a) Absolute donor cell numbers for total BM and different subsets: early erythroblasts (Early Eryth., Ter119+), granulocytes (Gran., Gr1+), B cells (B220+), megakaryocytes (Mega., CD41+), and macrophages (Mac, Gr1− CD11b+) of either β-cateninlox/lox (open bars) or β-catenin−/− (shaded bars) mice. The bars represent mean ± SD values (n = 5). (b) Absolute donor cell numbers for total thymocytes and thymocyte subsets: CD4− CD8− (DN), CD4+ CD8+ (DP), CD4+ CD8− TCRβ+ (CD4), and CD8+ CD4− TCRβ+ (CD8). The bars represent mean ± SD values for β-cateninlox/lox (open bars) or β-catenin−/− (filled bars) mice, where n = 5 for both β-cateninlox/lox and β-catenin−/− mice. (c) Absolute donor cell numbers for total splenocytes, B cells (B220+), and T cells (CD3+). n = 5 for control and β-catenin−/− mice. (d) Southern blot analysis of Eco-RI–digested genomic DNA from donor thymocytes of control (β-cateninlox/lox) or β-catenin−/− BM chimeric mice (refer to Fig.1 a for details). (e) Immunoblot analysis of β-catenin protein expression in total donor thymocytes from control or β-catenin−/− BM chimeras. The blots were probed with an antiserum specific to the COOH terminus of the β-catenin protein. To verify that equal amounts of protein were loaded, the membrane was reprobed with a monoclonal antibody against α-tubulin (bottom).
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fig2: β-catenin–deficient BM reconstitutes all major hematopoietic lineages. BM chimeras were analyzed 4–7 mo after reconstitution. (a) Absolute donor cell numbers for total BM and different subsets: early erythroblasts (Early Eryth., Ter119+), granulocytes (Gran., Gr1+), B cells (B220+), megakaryocytes (Mega., CD41+), and macrophages (Mac, Gr1− CD11b+) of either β-cateninlox/lox (open bars) or β-catenin−/− (shaded bars) mice. The bars represent mean ± SD values (n = 5). (b) Absolute donor cell numbers for total thymocytes and thymocyte subsets: CD4− CD8− (DN), CD4+ CD8+ (DP), CD4+ CD8− TCRβ+ (CD4), and CD8+ CD4− TCRβ+ (CD8). The bars represent mean ± SD values for β-cateninlox/lox (open bars) or β-catenin−/− (filled bars) mice, where n = 5 for both β-cateninlox/lox and β-catenin−/− mice. (c) Absolute donor cell numbers for total splenocytes, B cells (B220+), and T cells (CD3+). n = 5 for control and β-catenin−/− mice. (d) Southern blot analysis of Eco-RI–digested genomic DNA from donor thymocytes of control (β-cateninlox/lox) or β-catenin−/− BM chimeric mice (refer to Fig.1 a for details). (e) Immunoblot analysis of β-catenin protein expression in total donor thymocytes from control or β-catenin−/− BM chimeras. The blots were probed with an antiserum specific to the COOH terminus of the β-catenin protein. To verify that equal amounts of protein were loaded, the membrane was reprobed with a monoclonal antibody against α-tubulin (bottom).

Mentions: The early mortality of the β-catenin−/− mice precluded longitudinal analysis of the hematopoietic compartment. However, they survived long enough to obtain close to 100% deletion efficiency in BM precursor cells. Therefore, CD45.1+ WT lethally irradiated mice were injected with CD45.2+ control or β-catenin−/− BM to determine whether β-catenin–deficient BM precursors can reconstitute all major blood lineages. Interestingly, BM chimeras reconstituted with β-catenin–deficient BM survived without showing any signs of hematopoietic failure. Control or β-catenin–deficient BM chimeras were analyzed 4 and 6 mo after transplantation. Surprisingly, all major blood lineages in the BM such as granulocytes, macrophages, megakaryocytes, early erythroblasts, or B cells were generated from β-catenin–deficient BM at comparable levels to control BM (Fig. 2 a). Similarly all major thymus subsets (Fig. 2 b) as well as mature T and B cells in the spleen (Fig. 2 c) were generated normally from β-catenin−/− BM progenitors.


Beta-catenin is dispensable for hematopoiesis and lymphopoiesis.

Cobas M, Wilson A, Ernst B, Mancini SJ, MacDonald HR, Kemler R, Radtke F - J. Exp. Med. (2004)

β-catenin–deficient BM reconstitutes all major hematopoietic lineages. BM chimeras were analyzed 4–7 mo after reconstitution. (a) Absolute donor cell numbers for total BM and different subsets: early erythroblasts (Early Eryth., Ter119+), granulocytes (Gran., Gr1+), B cells (B220+), megakaryocytes (Mega., CD41+), and macrophages (Mac, Gr1− CD11b+) of either β-cateninlox/lox (open bars) or β-catenin−/− (shaded bars) mice. The bars represent mean ± SD values (n = 5). (b) Absolute donor cell numbers for total thymocytes and thymocyte subsets: CD4− CD8− (DN), CD4+ CD8+ (DP), CD4+ CD8− TCRβ+ (CD4), and CD8+ CD4− TCRβ+ (CD8). The bars represent mean ± SD values for β-cateninlox/lox (open bars) or β-catenin−/− (filled bars) mice, where n = 5 for both β-cateninlox/lox and β-catenin−/− mice. (c) Absolute donor cell numbers for total splenocytes, B cells (B220+), and T cells (CD3+). n = 5 for control and β-catenin−/− mice. (d) Southern blot analysis of Eco-RI–digested genomic DNA from donor thymocytes of control (β-cateninlox/lox) or β-catenin−/− BM chimeric mice (refer to Fig.1 a for details). (e) Immunoblot analysis of β-catenin protein expression in total donor thymocytes from control or β-catenin−/− BM chimeras. The blots were probed with an antiserum specific to the COOH terminus of the β-catenin protein. To verify that equal amounts of protein were loaded, the membrane was reprobed with a monoclonal antibody against α-tubulin (bottom).
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fig2: β-catenin–deficient BM reconstitutes all major hematopoietic lineages. BM chimeras were analyzed 4–7 mo after reconstitution. (a) Absolute donor cell numbers for total BM and different subsets: early erythroblasts (Early Eryth., Ter119+), granulocytes (Gran., Gr1+), B cells (B220+), megakaryocytes (Mega., CD41+), and macrophages (Mac, Gr1− CD11b+) of either β-cateninlox/lox (open bars) or β-catenin−/− (shaded bars) mice. The bars represent mean ± SD values (n = 5). (b) Absolute donor cell numbers for total thymocytes and thymocyte subsets: CD4− CD8− (DN), CD4+ CD8+ (DP), CD4+ CD8− TCRβ+ (CD4), and CD8+ CD4− TCRβ+ (CD8). The bars represent mean ± SD values for β-cateninlox/lox (open bars) or β-catenin−/− (filled bars) mice, where n = 5 for both β-cateninlox/lox and β-catenin−/− mice. (c) Absolute donor cell numbers for total splenocytes, B cells (B220+), and T cells (CD3+). n = 5 for control and β-catenin−/− mice. (d) Southern blot analysis of Eco-RI–digested genomic DNA from donor thymocytes of control (β-cateninlox/lox) or β-catenin−/− BM chimeric mice (refer to Fig.1 a for details). (e) Immunoblot analysis of β-catenin protein expression in total donor thymocytes from control or β-catenin−/− BM chimeras. The blots were probed with an antiserum specific to the COOH terminus of the β-catenin protein. To verify that equal amounts of protein were loaded, the membrane was reprobed with a monoclonal antibody against α-tubulin (bottom).
Mentions: The early mortality of the β-catenin−/− mice precluded longitudinal analysis of the hematopoietic compartment. However, they survived long enough to obtain close to 100% deletion efficiency in BM precursor cells. Therefore, CD45.1+ WT lethally irradiated mice were injected with CD45.2+ control or β-catenin−/− BM to determine whether β-catenin–deficient BM precursors can reconstitute all major blood lineages. Interestingly, BM chimeras reconstituted with β-catenin–deficient BM survived without showing any signs of hematopoietic failure. Control or β-catenin–deficient BM chimeras were analyzed 4 and 6 mo after transplantation. Surprisingly, all major blood lineages in the BM such as granulocytes, macrophages, megakaryocytes, early erythroblasts, or B cells were generated from β-catenin–deficient BM at comparable levels to control BM (Fig. 2 a). Similarly all major thymus subsets (Fig. 2 b) as well as mature T and B cells in the spleen (Fig. 2 c) were generated normally from β-catenin−/− BM progenitors.

Bottom Line: Beta-catenin-mediated Wnt signaling has been suggested to be critically involved in hematopoietic stem cell maintenance and development of T and B cells in the immune system.Unexpectedly, here we report that inducible Cre-loxP-mediated inactivation of the beta-catenin gene in bone marrow progenitors does not impair their ability to self-renew and reconstitute all hematopoietic lineages (myeloid, erythroid, and lymphoid), even in competitive mixed chimeras.In contrast to earlier reports, these data exclude an essential role for beta-catenin during hematopoiesis and lymphopoiesis.

View Article: PubMed Central - PubMed

Affiliation: Ludwig Institute for Cancer Research, Lausanne Branch, University of Lausanne, Epalinges, Switzerland.

ABSTRACT
Beta-catenin-mediated Wnt signaling has been suggested to be critically involved in hematopoietic stem cell maintenance and development of T and B cells in the immune system. Unexpectedly, here we report that inducible Cre-loxP-mediated inactivation of the beta-catenin gene in bone marrow progenitors does not impair their ability to self-renew and reconstitute all hematopoietic lineages (myeloid, erythroid, and lymphoid), even in competitive mixed chimeras. In addition, both thymocyte survival and antigen-induced proliferation of peripheral T cells is beta-catenin independent. In contrast to earlier reports, these data exclude an essential role for beta-catenin during hematopoiesis and lymphopoiesis.

Show MeSH
Related in: MedlinePlus