Limits...
Bruton's tyrosine kinase regulates the activation of gene rearrangements at the lambda light chain locus in precursor B cells in the mouse.

Dingjan GM, Middendorp S, Dahlenborg K, Maas A, Grosveld F, Hendriks RW - J. Exp. Med. (2001)

Bottom Line: As the kappa/lambda ratio is dependent on (a) the level and kinetics of kappa and lambda locus activation, (b) the life span of pre-B cells, and (c) the extent of receptor editing, we analyzed the role of Btk in these processes.Also, Btk-deficient surface Ig(+) B cells that were generated in vitro in interleukin 7-driven bone marrow cultures manifested reduced lambda usage.These results implicate Btk in the regulation of the activation of the lambda locus for V(D)J recombination in pre-B cells.

View Article: PubMed Central - PubMed

Affiliation: Department of Immunology, Faculty of Medicine, Erasmus University Rotterdam, 3000 DR Rotterdam, The Netherlands.

ABSTRACT
Bruton's tyrosine kinase (Btk) is a nonreceptor tyrosine kinase involved in precursor B (pre-B) cell receptor signaling. Here we demonstrate that Btk-deficient mice have an approximately 50% reduction in the frequency of immunoglobulin (Ig) lambda light chain expression, already at the immature B cell stage in the bone marrow. Conversely, transgenic mice expressing the activated mutant Btk(E41K) showed increased lambda usage. As the kappa/lambda ratio is dependent on (a) the level and kinetics of kappa and lambda locus activation, (b) the life span of pre-B cells, and (c) the extent of receptor editing, we analyzed the role of Btk in these processes. Enforced expression of the Bcl-2 apoptosis inhibitor did not alter the Btk dependence of lambda usage. Crossing 3-83mudelta autoantibody transgenic mice into Btk-deficient mice showed that Btk is not essential for receptor editing. Also, Btk-deficient surface Ig(+) B cells that were generated in vitro in interleukin 7-driven bone marrow cultures manifested reduced lambda usage. An intrinsic defect in lambda locus recombination was further supported by the finding in Btk-deficient mice of reduced lambda usage in the fraction of pre-B cells that express light chains in their cytoplasm. These results implicate Btk in the regulation of the activation of the lambda locus for V(D)J recombination in pre-B cells.

Show MeSH

Related in: MedlinePlus

Decreased λ L chain usage in in vitro–generated Btk− B cells and in Btk− pre-B cells in vivo. (A) Fraction of B220+ cells that express κ and λ L chain on the cell surface in bone marrow cultures from Btk+ and Btk− mice (n = 10). Cells were grown in IL-7 for 5 d and subsequently recultured on S17 stroma in the absence of IL-7 for 48 h. Cells were stained with mAbs specific for B220, IgM, IgD, and either κ or λ. (B) Fraction of sIgM−sIgD−B220+ cells that express L chains in their cytoplasm in the bone marrow of Btk+ and Btk− mice (n = 8).
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2193329&req=5

Figure 5: Decreased λ L chain usage in in vitro–generated Btk− B cells and in Btk− pre-B cells in vivo. (A) Fraction of B220+ cells that express κ and λ L chain on the cell surface in bone marrow cultures from Btk+ and Btk− mice (n = 10). Cells were grown in IL-7 for 5 d and subsequently recultured on S17 stroma in the absence of IL-7 for 48 h. Cells were stained with mAbs specific for B220, IgM, IgD, and either κ or λ. (B) Fraction of sIgM−sIgD−B220+ cells that express L chains in their cytoplasm in the bone marrow of Btk+ and Btk− mice (n = 8).

Mentions: To further investigate the relation between Btk signaling and λ chain rearrangement, we performed IL-7–driven bone marrow culture experiments as described previously 741. When surface IgM− bone marrow cell suspensions from WT or Btk-deficient mice were cultured for 5 d in the presence of IL-7, the majority of cells consisted of B220+IgM− pre-B cells that expressed μ H chain in their cytoplasm. In these cultures, a considerable fraction of the WT B220+ cells (∼15%) matured to surface IgM+ B cells, while <5% of Btk-deficient B220+ cells were surface IgM+, suggesting that the progression from pre-B cell to sIg+ B cell is hampered in Btk-deficient mice. When cells were subsequently cultured without IL-7 on S17 stroma cells for 48 h, allowing the cells to exit from the cell cycle and further differentiate 36, significant fractions of the WT (∼40%) and Btk-deficient (∼30%) B220+ cells were surface IgM+. In these cultures, in vitro–generated Btk-deficient surface IgM+ B cells showed significantly reduced usage of λ L chains, compared with WT B cells (Fig. 5 A).


Bruton's tyrosine kinase regulates the activation of gene rearrangements at the lambda light chain locus in precursor B cells in the mouse.

Dingjan GM, Middendorp S, Dahlenborg K, Maas A, Grosveld F, Hendriks RW - J. Exp. Med. (2001)

Decreased λ L chain usage in in vitro–generated Btk− B cells and in Btk− pre-B cells in vivo. (A) Fraction of B220+ cells that express κ and λ L chain on the cell surface in bone marrow cultures from Btk+ and Btk− mice (n = 10). Cells were grown in IL-7 for 5 d and subsequently recultured on S17 stroma in the absence of IL-7 for 48 h. Cells were stained with mAbs specific for B220, IgM, IgD, and either κ or λ. (B) Fraction of sIgM−sIgD−B220+ cells that express L chains in their cytoplasm in the bone marrow of Btk+ and Btk− mice (n = 8).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2193329&req=5

Figure 5: Decreased λ L chain usage in in vitro–generated Btk− B cells and in Btk− pre-B cells in vivo. (A) Fraction of B220+ cells that express κ and λ L chain on the cell surface in bone marrow cultures from Btk+ and Btk− mice (n = 10). Cells were grown in IL-7 for 5 d and subsequently recultured on S17 stroma in the absence of IL-7 for 48 h. Cells were stained with mAbs specific for B220, IgM, IgD, and either κ or λ. (B) Fraction of sIgM−sIgD−B220+ cells that express L chains in their cytoplasm in the bone marrow of Btk+ and Btk− mice (n = 8).
Mentions: To further investigate the relation between Btk signaling and λ chain rearrangement, we performed IL-7–driven bone marrow culture experiments as described previously 741. When surface IgM− bone marrow cell suspensions from WT or Btk-deficient mice were cultured for 5 d in the presence of IL-7, the majority of cells consisted of B220+IgM− pre-B cells that expressed μ H chain in their cytoplasm. In these cultures, a considerable fraction of the WT B220+ cells (∼15%) matured to surface IgM+ B cells, while <5% of Btk-deficient B220+ cells were surface IgM+, suggesting that the progression from pre-B cell to sIg+ B cell is hampered in Btk-deficient mice. When cells were subsequently cultured without IL-7 on S17 stroma cells for 48 h, allowing the cells to exit from the cell cycle and further differentiate 36, significant fractions of the WT (∼40%) and Btk-deficient (∼30%) B220+ cells were surface IgM+. In these cultures, in vitro–generated Btk-deficient surface IgM+ B cells showed significantly reduced usage of λ L chains, compared with WT B cells (Fig. 5 A).

Bottom Line: As the kappa/lambda ratio is dependent on (a) the level and kinetics of kappa and lambda locus activation, (b) the life span of pre-B cells, and (c) the extent of receptor editing, we analyzed the role of Btk in these processes.Also, Btk-deficient surface Ig(+) B cells that were generated in vitro in interleukin 7-driven bone marrow cultures manifested reduced lambda usage.These results implicate Btk in the regulation of the activation of the lambda locus for V(D)J recombination in pre-B cells.

View Article: PubMed Central - PubMed

Affiliation: Department of Immunology, Faculty of Medicine, Erasmus University Rotterdam, 3000 DR Rotterdam, The Netherlands.

ABSTRACT
Bruton's tyrosine kinase (Btk) is a nonreceptor tyrosine kinase involved in precursor B (pre-B) cell receptor signaling. Here we demonstrate that Btk-deficient mice have an approximately 50% reduction in the frequency of immunoglobulin (Ig) lambda light chain expression, already at the immature B cell stage in the bone marrow. Conversely, transgenic mice expressing the activated mutant Btk(E41K) showed increased lambda usage. As the kappa/lambda ratio is dependent on (a) the level and kinetics of kappa and lambda locus activation, (b) the life span of pre-B cells, and (c) the extent of receptor editing, we analyzed the role of Btk in these processes. Enforced expression of the Bcl-2 apoptosis inhibitor did not alter the Btk dependence of lambda usage. Crossing 3-83mudelta autoantibody transgenic mice into Btk-deficient mice showed that Btk is not essential for receptor editing. Also, Btk-deficient surface Ig(+) B cells that were generated in vitro in interleukin 7-driven bone marrow cultures manifested reduced lambda usage. An intrinsic defect in lambda locus recombination was further supported by the finding in Btk-deficient mice of reduced lambda usage in the fraction of pre-B cells that express light chains in their cytoplasm. These results implicate Btk in the regulation of the activation of the lambda locus for V(D)J recombination in pre-B cells.

Show MeSH
Related in: MedlinePlus