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The motheaten mutation rescues B cell signaling and development in CD45-deficient mice.

Pani G, Siminovitch KA, Paige CJ - J. Exp. Med. (1997)

Bottom Line: These PTPs differ, however, in their effects on BCR function.However, BCR-elicited increases in the tyrosine phosphorylation of several SHP-1-associated phosphoproteins, including CD19, were substantially enhanced in CD45-/SHP-1-, compared to wild-type and CD45- cells.These findings indicate a critical role for the balance of SHP-1 and CD45 activities in determining the outcome of BCR stimulation and suggest that these PTPs act in a coordinate fashion to couple antigen receptor engagement to B cell activation and maturation.

View Article: PubMed Central - PubMed

Affiliation: Department of Immunology, University of Toronto, Toronto, Ontario, M4Y 1J3, Canada.

ABSTRACT
The cytosolic SHP-1 and transmembrane CD45 protein tyrosine phosphatases (PTP) play critical roles in regulating signal transduction via the B cell antigen receptor (BCR). These PTPs differ, however, in their effects on BCR function. For example, BCR-mediated mitogenesis is essentially ablated in mice lacking CD45 (CD45(-)), but is enhanced in SHP-1-deficient motheaten (me) and viable motheaten (mev) mice. To determine whether these PTPs act independently or coordinately in modulating the physiologic outcome of BCR engagement, we assessed B cell development and signaling in CD45-deficient mev (CD45-/SHP-1-) mice. Here we report that the CD45-/SHP-1-) cells undergo appropriate induction of protein kinase activity, mitogen-activated protein kinase activation, and proliferative responses after BCR aggregation. However, BCR-elicited increases in the tyrosine phosphorylation of several SHP-1-associated phosphoproteins, including CD19, were substantially enhanced in CD45-/SHP-1-, compared to wild-type and CD45- cells. In addition, we observed that the patterns of cell surface expression of mu, delta, and CD5, which distinguish the PTP-deficient from normal mice, are largely restored to normal levels in the double mutant animals. These findings indicate a critical role for the balance of SHP-1 and CD45 activities in determining the outcome of BCR stimulation and suggest that these PTPs act in a coordinate fashion to couple antigen receptor engagement to B cell activation and maturation.

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B cell proliferative responses and autoantibody production in  PTP-deficient mice. (A) Effects of anti-Ig and LPS on proliferation  ([3H]thymidine incorporation) of CD45−/SHP-1−, CD45−, and CD45+/ SHP-1+ (wild-type) B cells (all LPS-treated groups as well as anti-μ–treated  groups (CD45+/SHP-1+) and (CD45−/SHP-1−) differed significantly  from their counterparts in the No stimulation group based on analysis by a  two-tailed t test (P <0.05 in all cases). (B) Comparisons of antitopoisomerase antibody titers in 4-wk-old CD45−/SHP-1−, CD45−, CD45+/ SHP-1+ and SHP-1− mice. (C) Immunostaining of renal tissues from  4-wk-old CD45+/SHP-1+, CD45−, CD45−/SHP-1−, and SHP-1− mice.
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Figure 2: B cell proliferative responses and autoantibody production in PTP-deficient mice. (A) Effects of anti-Ig and LPS on proliferation ([3H]thymidine incorporation) of CD45−/SHP-1−, CD45−, and CD45+/ SHP-1+ (wild-type) B cells (all LPS-treated groups as well as anti-μ–treated groups (CD45+/SHP-1+) and (CD45−/SHP-1−) differed significantly from their counterparts in the No stimulation group based on analysis by a two-tailed t test (P <0.05 in all cases). (B) Comparisons of antitopoisomerase antibody titers in 4-wk-old CD45−/SHP-1−, CD45−, CD45+/ SHP-1+ and SHP-1− mice. (C) Immunostaining of renal tissues from 4-wk-old CD45+/SHP-1+, CD45−, CD45−/SHP-1−, and SHP-1− mice.

Mentions: After fixation in formalin and paraffin embedding, 3-micron sections of renal tissues harvested from normal and mutant mice were successively incubated at room temperature with rabbit anti–mouse IgM (1.5 h) and biotinylated goat anti–rabbit (30 min) antibodies (Zymed Labs., Inc., S. San Francisco, CA), peroxidase-conjugated streptavidin (30 min), and aminoethylcarbazole in 0.2 M sodium acetate (15 min; Sigma Chemical Co.). Sections were then counterstained in hematoxylin and mounted with Crystal/Mount (Biomeda Corp., Foster City, CA). Original magnification was at 250. Positive staining is indicated by the red-brown deposition seen most prominently in the lower left panel (Fig. 2 C).


The motheaten mutation rescues B cell signaling and development in CD45-deficient mice.

Pani G, Siminovitch KA, Paige CJ - J. Exp. Med. (1997)

B cell proliferative responses and autoantibody production in  PTP-deficient mice. (A) Effects of anti-Ig and LPS on proliferation  ([3H]thymidine incorporation) of CD45−/SHP-1−, CD45−, and CD45+/ SHP-1+ (wild-type) B cells (all LPS-treated groups as well as anti-μ–treated  groups (CD45+/SHP-1+) and (CD45−/SHP-1−) differed significantly  from their counterparts in the No stimulation group based on analysis by a  two-tailed t test (P <0.05 in all cases). (B) Comparisons of antitopoisomerase antibody titers in 4-wk-old CD45−/SHP-1−, CD45−, CD45+/ SHP-1+ and SHP-1− mice. (C) Immunostaining of renal tissues from  4-wk-old CD45+/SHP-1+, CD45−, CD45−/SHP-1−, and SHP-1− mice.
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Related In: Results  -  Collection

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Figure 2: B cell proliferative responses and autoantibody production in PTP-deficient mice. (A) Effects of anti-Ig and LPS on proliferation ([3H]thymidine incorporation) of CD45−/SHP-1−, CD45−, and CD45+/ SHP-1+ (wild-type) B cells (all LPS-treated groups as well as anti-μ–treated groups (CD45+/SHP-1+) and (CD45−/SHP-1−) differed significantly from their counterparts in the No stimulation group based on analysis by a two-tailed t test (P <0.05 in all cases). (B) Comparisons of antitopoisomerase antibody titers in 4-wk-old CD45−/SHP-1−, CD45−, CD45+/ SHP-1+ and SHP-1− mice. (C) Immunostaining of renal tissues from 4-wk-old CD45+/SHP-1+, CD45−, CD45−/SHP-1−, and SHP-1− mice.
Mentions: After fixation in formalin and paraffin embedding, 3-micron sections of renal tissues harvested from normal and mutant mice were successively incubated at room temperature with rabbit anti–mouse IgM (1.5 h) and biotinylated goat anti–rabbit (30 min) antibodies (Zymed Labs., Inc., S. San Francisco, CA), peroxidase-conjugated streptavidin (30 min), and aminoethylcarbazole in 0.2 M sodium acetate (15 min; Sigma Chemical Co.). Sections were then counterstained in hematoxylin and mounted with Crystal/Mount (Biomeda Corp., Foster City, CA). Original magnification was at 250. Positive staining is indicated by the red-brown deposition seen most prominently in the lower left panel (Fig. 2 C).

Bottom Line: These PTPs differ, however, in their effects on BCR function.However, BCR-elicited increases in the tyrosine phosphorylation of several SHP-1-associated phosphoproteins, including CD19, were substantially enhanced in CD45-/SHP-1-, compared to wild-type and CD45- cells.These findings indicate a critical role for the balance of SHP-1 and CD45 activities in determining the outcome of BCR stimulation and suggest that these PTPs act in a coordinate fashion to couple antigen receptor engagement to B cell activation and maturation.

View Article: PubMed Central - PubMed

Affiliation: Department of Immunology, University of Toronto, Toronto, Ontario, M4Y 1J3, Canada.

ABSTRACT
The cytosolic SHP-1 and transmembrane CD45 protein tyrosine phosphatases (PTP) play critical roles in regulating signal transduction via the B cell antigen receptor (BCR). These PTPs differ, however, in their effects on BCR function. For example, BCR-mediated mitogenesis is essentially ablated in mice lacking CD45 (CD45(-)), but is enhanced in SHP-1-deficient motheaten (me) and viable motheaten (mev) mice. To determine whether these PTPs act independently or coordinately in modulating the physiologic outcome of BCR engagement, we assessed B cell development and signaling in CD45-deficient mev (CD45-/SHP-1-) mice. Here we report that the CD45-/SHP-1-) cells undergo appropriate induction of protein kinase activity, mitogen-activated protein kinase activation, and proliferative responses after BCR aggregation. However, BCR-elicited increases in the tyrosine phosphorylation of several SHP-1-associated phosphoproteins, including CD19, were substantially enhanced in CD45-/SHP-1-, compared to wild-type and CD45- cells. In addition, we observed that the patterns of cell surface expression of mu, delta, and CD5, which distinguish the PTP-deficient from normal mice, are largely restored to normal levels in the double mutant animals. These findings indicate a critical role for the balance of SHP-1 and CD45 activities in determining the outcome of BCR stimulation and suggest that these PTPs act in a coordinate fashion to couple antigen receptor engagement to B cell activation and maturation.

Show MeSH