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Non-T cell activation linker (NTAL): a transmembrane adaptor protein involved in immunoreceptor signaling.

Brdicka T, Imrich M, Angelisová P, Brdicková N, Horváth O, Spicka J, Hilgert I, Lusková P, Dráber P, Novák P, Engels N, Wienands J, Simeoni L, Osterreicher J, Aguado E, Malissen M, Schraven B, Horejsí V - J. Exp. Med. (2002)

Bottom Line: NTAL becomes rapidly tyrosine-phosphorylated upon cross-linking of the B cell receptor (BCR) or of high-affinity Fcgamma- and Fc epsilon -receptors of myeloid cells and then associates with the cytoplasmic signaling molecules Grb2, Sos1, Gab1, and c-Cbl.NTAL expressed in the LAT-deficient T cell line J.CaM2.5 becomes tyrosine phosphorylated and rescues activation of Erk1/2 and minimal transient elevation of cytoplasmic calcium level upon TCR/CD3 cross-linking.Thus, NTAL appears to be a structural and possibly also functional homologue of LAT in non-T cells.

View Article: PubMed Central - PubMed

Affiliation: Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Vídenská 1083, 142 20 Prague 4, Czech Republic.

ABSTRACT
A key molecule necessary for activation of T lymphocytes through their antigen-specific T cell receptor (TCR) is the transmembrane adaptor protein LAT (linker for activation of T cells). Upon TCR engagement, LAT becomes rapidly tyrosine phosphorylated and then serves as a scaffold organizing a multicomponent complex that is indispensable for induction of further downstream steps of the signaling cascade. Here we describe the identification and preliminary characterization of a novel transmembrane adaptor protein that is structurally and evolutionarily related to LAT and is expressed in B lymphocytes, natural killer (NK) cells, monocytes, and mast cells but not in resting T lymphocytes. This novel transmembrane adaptor protein, termed NTAL (non-T cell activation linker) is the product of a previously identified WBSCR5 gene of so far unknown function. NTAL becomes rapidly tyrosine-phosphorylated upon cross-linking of the B cell receptor (BCR) or of high-affinity Fcgamma- and Fc epsilon -receptors of myeloid cells and then associates with the cytoplasmic signaling molecules Grb2, Sos1, Gab1, and c-Cbl. NTAL expressed in the LAT-deficient T cell line J.CaM2.5 becomes tyrosine phosphorylated and rescues activation of Erk1/2 and minimal transient elevation of cytoplasmic calcium level upon TCR/CD3 cross-linking. Thus, NTAL appears to be a structural and possibly also functional homologue of LAT in non-T cells.

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Induction of NTAL tyrosine phosphorylation and association with cytoplasmic signaling proteins. (A) THP-1 cells or purified human monocytes were stimulated via their FcγRI receptors, Ramos cells or murine B lymphocytes via BCR, and mouse BMMC via FcɛRI receptors. NTAL was immunoprecipitated from unstimulated (−) or stimulated (+) cells and analyzed by SDS-PAGE and Western blotting using anti-phosphotyrosine antibody to visualize tyrosine-phosphorylated NTAL (top panel). The bottom panel represents immunostaining of NTAL in the same samples and in the same position of the blot (around 30 kD). (B) The same NTAL immunoprecipitates as shown in part A were analyzed by Western blotting using antibodies to the indicated associated molecules. (C) Blots of NTAL immunoprecipitates from unstimulated (−) or anti-BCR-stimulated (+) Ramos cells were immunostained by antibodies to NTAL or ubiquitin (Ubq.). Only the relevant parts of the blots are shown in parts A and B, corresponding to the size of the relevant proteins.
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fig6: Induction of NTAL tyrosine phosphorylation and association with cytoplasmic signaling proteins. (A) THP-1 cells or purified human monocytes were stimulated via their FcγRI receptors, Ramos cells or murine B lymphocytes via BCR, and mouse BMMC via FcɛRI receptors. NTAL was immunoprecipitated from unstimulated (−) or stimulated (+) cells and analyzed by SDS-PAGE and Western blotting using anti-phosphotyrosine antibody to visualize tyrosine-phosphorylated NTAL (top panel). The bottom panel represents immunostaining of NTAL in the same samples and in the same position of the blot (around 30 kD). (B) The same NTAL immunoprecipitates as shown in part A were analyzed by Western blotting using antibodies to the indicated associated molecules. (C) Blots of NTAL immunoprecipitates from unstimulated (−) or anti-BCR-stimulated (+) Ramos cells were immunostained by antibodies to NTAL or ubiquitin (Ubq.). Only the relevant parts of the blots are shown in parts A and B, corresponding to the size of the relevant proteins.

Mentions: The overall similarity of NTAL to LAT and the results of in vitro kinase assay indicated that NTAL might be inducibly tyrosine-phosphorylated after triggering of immunoreceptors. Indeed, NTAL became tyrosine-phosphorylated and associated with additional phosphoproteins following cross-linking of the high-affinity IgG-receptor (FcγRI/CD64) on human THP-1 myeloid cells and blood monocytes, the high-affinity IgE-receptor (FcɛRI) on mouse BMMCs, and the BCR on human Ramos and mouse splenic B cells (Fig. 6 A).


Non-T cell activation linker (NTAL): a transmembrane adaptor protein involved in immunoreceptor signaling.

Brdicka T, Imrich M, Angelisová P, Brdicková N, Horváth O, Spicka J, Hilgert I, Lusková P, Dráber P, Novák P, Engels N, Wienands J, Simeoni L, Osterreicher J, Aguado E, Malissen M, Schraven B, Horejsí V - J. Exp. Med. (2002)

Induction of NTAL tyrosine phosphorylation and association with cytoplasmic signaling proteins. (A) THP-1 cells or purified human monocytes were stimulated via their FcγRI receptors, Ramos cells or murine B lymphocytes via BCR, and mouse BMMC via FcɛRI receptors. NTAL was immunoprecipitated from unstimulated (−) or stimulated (+) cells and analyzed by SDS-PAGE and Western blotting using anti-phosphotyrosine antibody to visualize tyrosine-phosphorylated NTAL (top panel). The bottom panel represents immunostaining of NTAL in the same samples and in the same position of the blot (around 30 kD). (B) The same NTAL immunoprecipitates as shown in part A were analyzed by Western blotting using antibodies to the indicated associated molecules. (C) Blots of NTAL immunoprecipitates from unstimulated (−) or anti-BCR-stimulated (+) Ramos cells were immunostained by antibodies to NTAL or ubiquitin (Ubq.). Only the relevant parts of the blots are shown in parts A and B, corresponding to the size of the relevant proteins.
© Copyright Policy
Related In: Results  -  Collection

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fig6: Induction of NTAL tyrosine phosphorylation and association with cytoplasmic signaling proteins. (A) THP-1 cells or purified human monocytes were stimulated via their FcγRI receptors, Ramos cells or murine B lymphocytes via BCR, and mouse BMMC via FcɛRI receptors. NTAL was immunoprecipitated from unstimulated (−) or stimulated (+) cells and analyzed by SDS-PAGE and Western blotting using anti-phosphotyrosine antibody to visualize tyrosine-phosphorylated NTAL (top panel). The bottom panel represents immunostaining of NTAL in the same samples and in the same position of the blot (around 30 kD). (B) The same NTAL immunoprecipitates as shown in part A were analyzed by Western blotting using antibodies to the indicated associated molecules. (C) Blots of NTAL immunoprecipitates from unstimulated (−) or anti-BCR-stimulated (+) Ramos cells were immunostained by antibodies to NTAL or ubiquitin (Ubq.). Only the relevant parts of the blots are shown in parts A and B, corresponding to the size of the relevant proteins.
Mentions: The overall similarity of NTAL to LAT and the results of in vitro kinase assay indicated that NTAL might be inducibly tyrosine-phosphorylated after triggering of immunoreceptors. Indeed, NTAL became tyrosine-phosphorylated and associated with additional phosphoproteins following cross-linking of the high-affinity IgG-receptor (FcγRI/CD64) on human THP-1 myeloid cells and blood monocytes, the high-affinity IgE-receptor (FcɛRI) on mouse BMMCs, and the BCR on human Ramos and mouse splenic B cells (Fig. 6 A).

Bottom Line: NTAL becomes rapidly tyrosine-phosphorylated upon cross-linking of the B cell receptor (BCR) or of high-affinity Fcgamma- and Fc epsilon -receptors of myeloid cells and then associates with the cytoplasmic signaling molecules Grb2, Sos1, Gab1, and c-Cbl.NTAL expressed in the LAT-deficient T cell line J.CaM2.5 becomes tyrosine phosphorylated and rescues activation of Erk1/2 and minimal transient elevation of cytoplasmic calcium level upon TCR/CD3 cross-linking.Thus, NTAL appears to be a structural and possibly also functional homologue of LAT in non-T cells.

View Article: PubMed Central - PubMed

Affiliation: Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Vídenská 1083, 142 20 Prague 4, Czech Republic.

ABSTRACT
A key molecule necessary for activation of T lymphocytes through their antigen-specific T cell receptor (TCR) is the transmembrane adaptor protein LAT (linker for activation of T cells). Upon TCR engagement, LAT becomes rapidly tyrosine phosphorylated and then serves as a scaffold organizing a multicomponent complex that is indispensable for induction of further downstream steps of the signaling cascade. Here we describe the identification and preliminary characterization of a novel transmembrane adaptor protein that is structurally and evolutionarily related to LAT and is expressed in B lymphocytes, natural killer (NK) cells, monocytes, and mast cells but not in resting T lymphocytes. This novel transmembrane adaptor protein, termed NTAL (non-T cell activation linker) is the product of a previously identified WBSCR5 gene of so far unknown function. NTAL becomes rapidly tyrosine-phosphorylated upon cross-linking of the B cell receptor (BCR) or of high-affinity Fcgamma- and Fc epsilon -receptors of myeloid cells and then associates with the cytoplasmic signaling molecules Grb2, Sos1, Gab1, and c-Cbl. NTAL expressed in the LAT-deficient T cell line J.CaM2.5 becomes tyrosine phosphorylated and rescues activation of Erk1/2 and minimal transient elevation of cytoplasmic calcium level upon TCR/CD3 cross-linking. Thus, NTAL appears to be a structural and possibly also functional homologue of LAT in non-T cells.

Show MeSH