Limits...
The developmentally regulated expression of Twisted gastrulation reveals a role for bone morphogenetic proteins in the control of T cell development.

Graf D, Nethisinghe S, Palmer DB, Fisher AG, Merkenschlager M - J. Exp. Med. (2002)

Bottom Line: The evolutionarily conserved, secreted protein Twisted gastrulation (Tsg) modulates morphogenetic effects of decapentaplegic (dpp) and its orthologs, the bone morphogenetic proteins 2 and 4 (BMP2/4), in early Drosophila and vertebrate embryos.We have uncovered a role for Tsg at a much later stage of mammalian development, during T cell differentiation in the thymus.BMP4 is expressed by thymic stroma and inhibits the proliferation of CD4(-)CD8(-) double-negative (DN) thymocytes and their differentiation to the CD4(+)CD8(+) double-positive (DP) stage in vitro.

View Article: PubMed Central - PubMed

Affiliation: Lymphocyte Development Group, Medical Research Council Clinical Sciences Centre, Imperial College of Medicine, London W12 0NN, United Kingdom.

ABSTRACT
The evolutionarily conserved, secreted protein Twisted gastrulation (Tsg) modulates morphogenetic effects of decapentaplegic (dpp) and its orthologs, the bone morphogenetic proteins 2 and 4 (BMP2/4), in early Drosophila and vertebrate embryos. We have uncovered a role for Tsg at a much later stage of mammalian development, during T cell differentiation in the thymus. BMP4 is expressed by thymic stroma and inhibits the proliferation of CD4(-)CD8(-) double-negative (DN) thymocytes and their differentiation to the CD4(+)CD8(+) double-positive (DP) stage in vitro. Tsg is expressed by thymocytes and up-regulated after T cell receptor signaling at two developmental checkpoints, the transition from the DN to the DP and from the DP to the CD4(+) or CD8(+) single-positive stage. Tsg can synergize with the BMP inhibitor chordin to block the BMP4-mediated inhibition of thymocyte proliferation and differentiation. These data suggest that the developmentally regulated expression of Tsg may allow thymocytes to temporarily withdraw from inhibitory BMP signals.

Show MeSH
TGFβ but not BMP4 induce Smad-2 phosphorylation in thymocytes. Thymocytes from E17 (or postnatal, not shown) wild-type (C57BL/6) mice were cultured with TGFβ1 (1 ng/ml) or the indicated concentrations of BMP4 for 45 min and cell lysates assayed for pSmad-2 by Western blot.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2193926&req=5

fig4: TGFβ but not BMP4 induce Smad-2 phosphorylation in thymocytes. Thymocytes from E17 (or postnatal, not shown) wild-type (C57BL/6) mice were cultured with TGFβ1 (1 ng/ml) or the indicated concentrations of BMP4 for 45 min and cell lysates assayed for pSmad-2 by Western blot.

Mentions: Like BMP4, TGFβ blocks thymocyte cell cycle activity and developmental progression (10, 40). To address the question whether thymocytes can distinguish BMP4 from TGFβ signals we analyzed the phosphorylation status of Smad-2, a downstream mediator of TGFβ signals (21) in thymocytes cultured with TGFβ1 at 1 ng/ml or a range of BMP4 concentrations from 0.1 to 1,000 ng/ml. Phosphorylated Smad-2 was readily detected in response to TGFβ but not to BMP4 by Western blotting with pSmad-2–specific antibodies (Fig. 4) . Hence, BMP4 signaling does not appear to utilize the canonical TGFβ signaling pathway in thymocytes. An analysis of Smad-1 phosphorylation in response to exogenous BMP4 remained inconclusive as pSmad-1 appeared to be present in freshly isolated thymocytes (not shown, and see Discussion).


The developmentally regulated expression of Twisted gastrulation reveals a role for bone morphogenetic proteins in the control of T cell development.

Graf D, Nethisinghe S, Palmer DB, Fisher AG, Merkenschlager M - J. Exp. Med. (2002)

TGFβ but not BMP4 induce Smad-2 phosphorylation in thymocytes. Thymocytes from E17 (or postnatal, not shown) wild-type (C57BL/6) mice were cultured with TGFβ1 (1 ng/ml) or the indicated concentrations of BMP4 for 45 min and cell lysates assayed for pSmad-2 by Western blot.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2193926&req=5

fig4: TGFβ but not BMP4 induce Smad-2 phosphorylation in thymocytes. Thymocytes from E17 (or postnatal, not shown) wild-type (C57BL/6) mice were cultured with TGFβ1 (1 ng/ml) or the indicated concentrations of BMP4 for 45 min and cell lysates assayed for pSmad-2 by Western blot.
Mentions: Like BMP4, TGFβ blocks thymocyte cell cycle activity and developmental progression (10, 40). To address the question whether thymocytes can distinguish BMP4 from TGFβ signals we analyzed the phosphorylation status of Smad-2, a downstream mediator of TGFβ signals (21) in thymocytes cultured with TGFβ1 at 1 ng/ml or a range of BMP4 concentrations from 0.1 to 1,000 ng/ml. Phosphorylated Smad-2 was readily detected in response to TGFβ but not to BMP4 by Western blotting with pSmad-2–specific antibodies (Fig. 4) . Hence, BMP4 signaling does not appear to utilize the canonical TGFβ signaling pathway in thymocytes. An analysis of Smad-1 phosphorylation in response to exogenous BMP4 remained inconclusive as pSmad-1 appeared to be present in freshly isolated thymocytes (not shown, and see Discussion).

Bottom Line: The evolutionarily conserved, secreted protein Twisted gastrulation (Tsg) modulates morphogenetic effects of decapentaplegic (dpp) and its orthologs, the bone morphogenetic proteins 2 and 4 (BMP2/4), in early Drosophila and vertebrate embryos.We have uncovered a role for Tsg at a much later stage of mammalian development, during T cell differentiation in the thymus.BMP4 is expressed by thymic stroma and inhibits the proliferation of CD4(-)CD8(-) double-negative (DN) thymocytes and their differentiation to the CD4(+)CD8(+) double-positive (DP) stage in vitro.

View Article: PubMed Central - PubMed

Affiliation: Lymphocyte Development Group, Medical Research Council Clinical Sciences Centre, Imperial College of Medicine, London W12 0NN, United Kingdom.

ABSTRACT
The evolutionarily conserved, secreted protein Twisted gastrulation (Tsg) modulates morphogenetic effects of decapentaplegic (dpp) and its orthologs, the bone morphogenetic proteins 2 and 4 (BMP2/4), in early Drosophila and vertebrate embryos. We have uncovered a role for Tsg at a much later stage of mammalian development, during T cell differentiation in the thymus. BMP4 is expressed by thymic stroma and inhibits the proliferation of CD4(-)CD8(-) double-negative (DN) thymocytes and their differentiation to the CD4(+)CD8(+) double-positive (DP) stage in vitro. Tsg is expressed by thymocytes and up-regulated after T cell receptor signaling at two developmental checkpoints, the transition from the DN to the DP and from the DP to the CD4(+) or CD8(+) single-positive stage. Tsg can synergize with the BMP inhibitor chordin to block the BMP4-mediated inhibition of thymocyte proliferation and differentiation. These data suggest that the developmentally regulated expression of Tsg may allow thymocytes to temporarily withdraw from inhibitory BMP signals.

Show MeSH