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Peripheral expression of Jak3 is required to maintain T lymphocyte function.

Thomis DC, Berg LJ - J. Exp. Med. (1997)

Bottom Line: The Jak family tyrosine kinase, Jak3, is involved in signaling through cytokine receptors that utilize the common gamma chain (gammac), such as those for IL-2, IL-4, IL-7, IL-9, and IL-15.Jak3 expression in the thymus restores normal T cell development, including CD8+, gammadelta, and natural killer cells.However, the loss of Jak3 protein in peripheral T cells leads to the Jak3-/- phenotype, demonstrating that Jak3 is constitutively required to maintain T cell function.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts 02138, USA.

ABSTRACT
The Jak family tyrosine kinase, Jak3, is involved in signaling through cytokine receptors that utilize the common gamma chain (gammac), such as those for IL-2, IL-4, IL-7, IL-9, and IL-15. Recent studies of Jak3-deficient mice and humans have demonstrated that Jak3 plays a critical role in B and T lymphocyte maturation and function. The T lymphocyte defects in Jak3-deficient mice include a small thymus, a decrease in peripheral CD8+ cells, an increase in the surface expression of activation markers, and a severe reduction in proliferative and cytokine secretion responses to mitogenic stimuli. To determine whether the peripheral T lymphocyte defects result from aberrant maturation in the thymus or from the absence of Jak3 protein in peripheral T cells, we generated reconstituted mice that express normal levels of Jak3 protein in the thymus but lose Jak3 expression in peripheral T cells. Jak3 expression in the thymus restores normal T cell development, including CD8+, gammadelta, and natural killer cells. However, the loss of Jak3 protein in peripheral T cells leads to the Jak3-/- phenotype, demonstrating that Jak3 is constitutively required to maintain T cell function.

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Reconstituted expression of Jak3 in Jak3−/− mice  with Lck–Jak3 transgenes. (A)  Southern blot of EcoRI-digested  tail DNA from mouse pups indicating the genotyping of the endogenous Jak3 locus (Jak3+/−,  lanes 1, 2, 4; and Jak3−/−, lanes 3  and 5), as well as the wild-type  Jak3 transgenes (tgthy+spl, lanes 3  and 4; and tgthy, lanes 1 and 5).  The blot was probed with an  0.35-kb EcoRI–HindIII fragment of the Jak3 cDNA clone  (33). (B, C, D) Protein immunoblots of Jak3 immunoprecipitates from thymocytes and splenocytes of the indicated mice.  Lysates were from Jak3−/−  (tgthy+spl) and Jak3−/− (tgthy) mice  at 25 d of age (B) or 33 d of age  (C). In (D), lysates were from a  Jak3−/− (tgthy+spl) mouse at 120 d  of age and a Jak3−/− (tgkd) mouse  at 49 days of age. Jak3 was immunoprecipitated using an antiJak3 monoclonal antibody (33)  from lysate of 1 × 107 thymocytes or 2 × 107 splenocytes.  The membranes were probed with  anti-Jak3 rabbit antiserum (26).
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Figure 1: Reconstituted expression of Jak3 in Jak3−/− mice with Lck–Jak3 transgenes. (A) Southern blot of EcoRI-digested tail DNA from mouse pups indicating the genotyping of the endogenous Jak3 locus (Jak3+/−, lanes 1, 2, 4; and Jak3−/−, lanes 3 and 5), as well as the wild-type Jak3 transgenes (tgthy+spl, lanes 3 and 4; and tgthy, lanes 1 and 5). The blot was probed with an 0.35-kb EcoRI–HindIII fragment of the Jak3 cDNA clone (33). (B, C, D) Protein immunoblots of Jak3 immunoprecipitates from thymocytes and splenocytes of the indicated mice. Lysates were from Jak3−/− (tgthy+spl) and Jak3−/− (tgthy) mice at 25 d of age (B) or 33 d of age (C). In (D), lysates were from a Jak3−/− (tgthy+spl) mouse at 120 d of age and a Jak3−/− (tgkd) mouse at 49 days of age. Jak3 was immunoprecipitated using an antiJak3 monoclonal antibody (33) from lysate of 1 × 107 thymocytes or 2 × 107 splenocytes. The membranes were probed with anti-Jak3 rabbit antiserum (26).

Mentions: Both transgenic lines were crossed to the Jak3−/− mice, to generate mice homozygous for the Jak3 mutation and heterozygous for one of the transgenes (Fig. 1 A). Analysis of Jak3 protein levels indicated that both transgenic lines expressed substantial amounts of Jak3 in thymocytes, while only the Jak3−/− (tgthy+spl) line expressed levels of Jak3 comparable to wild type in the spleen (Fig. 1 B). In the Jak3−/− (tgthy) line, Jak3 protein is barely detectable in spleen cells of a very young mouse (25 d) and becomes undetectable in older mice (Fig. 1 B and C); in contrast, no decrease in the levels of Jak3 protein was observed in the spleens of Jak3−/− (tgthy+spl) mice up to 120 d of age (Fig. 1 D). These findings strongly suggest that Jak3 is constitutively expressed in peripheral T cells in the Jak3−/− (tgthy+spl) mice, as the majority of T cells in a 4-mo-old mouse are not recent thymic emigrants, but cells that have been out of the thymus for several months. In contrast, the loss of detectable Jak3 protein from the spleen cells of older Jak3−/− (tgthy) mice suggests that, in this transgenic line, the peripheral Jak3 protein observed in young animals is the residue of thymic Jak3 expression. However, we cannot rule out the possibility that the difference in detectable Jak3 expression between these two transgenic lines results from a difference in the dose of expression of the transgenes.


Peripheral expression of Jak3 is required to maintain T lymphocyte function.

Thomis DC, Berg LJ - J. Exp. Med. (1997)

Reconstituted expression of Jak3 in Jak3−/− mice  with Lck–Jak3 transgenes. (A)  Southern blot of EcoRI-digested  tail DNA from mouse pups indicating the genotyping of the endogenous Jak3 locus (Jak3+/−,  lanes 1, 2, 4; and Jak3−/−, lanes 3  and 5), as well as the wild-type  Jak3 transgenes (tgthy+spl, lanes 3  and 4; and tgthy, lanes 1 and 5).  The blot was probed with an  0.35-kb EcoRI–HindIII fragment of the Jak3 cDNA clone  (33). (B, C, D) Protein immunoblots of Jak3 immunoprecipitates from thymocytes and splenocytes of the indicated mice.  Lysates were from Jak3−/−  (tgthy+spl) and Jak3−/− (tgthy) mice  at 25 d of age (B) or 33 d of age  (C). In (D), lysates were from a  Jak3−/− (tgthy+spl) mouse at 120 d  of age and a Jak3−/− (tgkd) mouse  at 49 days of age. Jak3 was immunoprecipitated using an antiJak3 monoclonal antibody (33)  from lysate of 1 × 107 thymocytes or 2 × 107 splenocytes.  The membranes were probed with  anti-Jak3 rabbit antiserum (26).
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Related In: Results  -  Collection

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Figure 1: Reconstituted expression of Jak3 in Jak3−/− mice with Lck–Jak3 transgenes. (A) Southern blot of EcoRI-digested tail DNA from mouse pups indicating the genotyping of the endogenous Jak3 locus (Jak3+/−, lanes 1, 2, 4; and Jak3−/−, lanes 3 and 5), as well as the wild-type Jak3 transgenes (tgthy+spl, lanes 3 and 4; and tgthy, lanes 1 and 5). The blot was probed with an 0.35-kb EcoRI–HindIII fragment of the Jak3 cDNA clone (33). (B, C, D) Protein immunoblots of Jak3 immunoprecipitates from thymocytes and splenocytes of the indicated mice. Lysates were from Jak3−/− (tgthy+spl) and Jak3−/− (tgthy) mice at 25 d of age (B) or 33 d of age (C). In (D), lysates were from a Jak3−/− (tgthy+spl) mouse at 120 d of age and a Jak3−/− (tgkd) mouse at 49 days of age. Jak3 was immunoprecipitated using an antiJak3 monoclonal antibody (33) from lysate of 1 × 107 thymocytes or 2 × 107 splenocytes. The membranes were probed with anti-Jak3 rabbit antiserum (26).
Mentions: Both transgenic lines were crossed to the Jak3−/− mice, to generate mice homozygous for the Jak3 mutation and heterozygous for one of the transgenes (Fig. 1 A). Analysis of Jak3 protein levels indicated that both transgenic lines expressed substantial amounts of Jak3 in thymocytes, while only the Jak3−/− (tgthy+spl) line expressed levels of Jak3 comparable to wild type in the spleen (Fig. 1 B). In the Jak3−/− (tgthy) line, Jak3 protein is barely detectable in spleen cells of a very young mouse (25 d) and becomes undetectable in older mice (Fig. 1 B and C); in contrast, no decrease in the levels of Jak3 protein was observed in the spleens of Jak3−/− (tgthy+spl) mice up to 120 d of age (Fig. 1 D). These findings strongly suggest that Jak3 is constitutively expressed in peripheral T cells in the Jak3−/− (tgthy+spl) mice, as the majority of T cells in a 4-mo-old mouse are not recent thymic emigrants, but cells that have been out of the thymus for several months. In contrast, the loss of detectable Jak3 protein from the spleen cells of older Jak3−/− (tgthy) mice suggests that, in this transgenic line, the peripheral Jak3 protein observed in young animals is the residue of thymic Jak3 expression. However, we cannot rule out the possibility that the difference in detectable Jak3 expression between these two transgenic lines results from a difference in the dose of expression of the transgenes.

Bottom Line: The Jak family tyrosine kinase, Jak3, is involved in signaling through cytokine receptors that utilize the common gamma chain (gammac), such as those for IL-2, IL-4, IL-7, IL-9, and IL-15.Jak3 expression in the thymus restores normal T cell development, including CD8+, gammadelta, and natural killer cells.However, the loss of Jak3 protein in peripheral T cells leads to the Jak3-/- phenotype, demonstrating that Jak3 is constitutively required to maintain T cell function.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts 02138, USA.

ABSTRACT
The Jak family tyrosine kinase, Jak3, is involved in signaling through cytokine receptors that utilize the common gamma chain (gammac), such as those for IL-2, IL-4, IL-7, IL-9, and IL-15. Recent studies of Jak3-deficient mice and humans have demonstrated that Jak3 plays a critical role in B and T lymphocyte maturation and function. The T lymphocyte defects in Jak3-deficient mice include a small thymus, a decrease in peripheral CD8+ cells, an increase in the surface expression of activation markers, and a severe reduction in proliferative and cytokine secretion responses to mitogenic stimuli. To determine whether the peripheral T lymphocyte defects result from aberrant maturation in the thymus or from the absence of Jak3 protein in peripheral T cells, we generated reconstituted mice that express normal levels of Jak3 protein in the thymus but lose Jak3 expression in peripheral T cells. Jak3 expression in the thymus restores normal T cell development, including CD8+, gammadelta, and natural killer cells. However, the loss of Jak3 protein in peripheral T cells leads to the Jak3-/- phenotype, demonstrating that Jak3 is constitutively required to maintain T cell function.

Show MeSH
Related in: MedlinePlus