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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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Kinases phosphorylating NTAL. (A) Inhibition of NTAL tyrosine phosphorylation in THP-1 cells stimulated via FcγRI by the indicated PTK inhibitors. NTAL immunoprecipitates prepared from the treated and control cells were analyzed by Western blotting to detect P-Tyr or NTAL, respectively. (B) Phosphorylation of NTAL coexpressed in 293T cells with various Src- and Syk-family kinases. Total cell lysates were analyzed by SDS-PAGE and Western blotting to detect the indicated molecules.
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fig7: Kinases phosphorylating NTAL. (A) Inhibition of NTAL tyrosine phosphorylation in THP-1 cells stimulated via FcγRI by the indicated PTK inhibitors. NTAL immunoprecipitates prepared from the treated and control cells were analyzed by Western blotting to detect P-Tyr or NTAL, respectively. (B) Phosphorylation of NTAL coexpressed in 293T cells with various Src- and Syk-family kinases. Total cell lysates were analyzed by SDS-PAGE and Western blotting to detect the indicated molecules.

Mentions: To determine which protein tyrosine kinases (PTKs) are able to phosphorylate NTAL, we treated THP-1 cells with the Src-family PTK inhibitor PP2 or the Syk-family PTK inhibitor piceatannol and then stimulated them via FcγRI cross-linking. As shown in Fig. 7 A, both inhibitors suppressed tyrosine phosphorylation of NTAL. Coexpression of NTAL with Src-family kinases Lck, Lyn, Hck, or Yes and/or Syk or ZAP-70 in 293T-cells indicated that NTAL was, similarly as LAT, most strongly phosphorylated in the presence of simultaneously expressed Lck and ZAP-70 or Lck and Syk (Fig. 7 B). Furthermore, no tyrosine phosphorylation of NTAL was observed in Lyn−/− mouse BMMCs stimulated via FcɛRI (compare Fig. 6 A for the wild-type BMMCs) indicating that Lyn is directly or indirectly responsible for NTAL inducible phosphorylation in these cells (unpublished data).


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)

Kinases phosphorylating NTAL. (A) Inhibition of NTAL tyrosine phosphorylation in THP-1 cells stimulated via FcγRI by the indicated PTK inhibitors. NTAL immunoprecipitates prepared from the treated and control cells were analyzed by Western blotting to detect P-Tyr or NTAL, respectively. (B) Phosphorylation of NTAL coexpressed in 293T cells with various Src- and Syk-family kinases. Total cell lysates were analyzed by SDS-PAGE and Western blotting to detect the indicated molecules.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2196071&req=5

fig7: Kinases phosphorylating NTAL. (A) Inhibition of NTAL tyrosine phosphorylation in THP-1 cells stimulated via FcγRI by the indicated PTK inhibitors. NTAL immunoprecipitates prepared from the treated and control cells were analyzed by Western blotting to detect P-Tyr or NTAL, respectively. (B) Phosphorylation of NTAL coexpressed in 293T cells with various Src- and Syk-family kinases. Total cell lysates were analyzed by SDS-PAGE and Western blotting to detect the indicated molecules.
Mentions: To determine which protein tyrosine kinases (PTKs) are able to phosphorylate NTAL, we treated THP-1 cells with the Src-family PTK inhibitor PP2 or the Syk-family PTK inhibitor piceatannol and then stimulated them via FcγRI cross-linking. As shown in Fig. 7 A, both inhibitors suppressed tyrosine phosphorylation of NTAL. Coexpression of NTAL with Src-family kinases Lck, Lyn, Hck, or Yes and/or Syk or ZAP-70 in 293T-cells indicated that NTAL was, similarly as LAT, most strongly phosphorylated in the presence of simultaneously expressed Lck and ZAP-70 or Lck and Syk (Fig. 7 B). Furthermore, no tyrosine phosphorylation of NTAL was observed in Lyn−/− mouse BMMCs stimulated via FcɛRI (compare Fig. 6 A for the wild-type BMMCs) indicating that Lyn is directly or indirectly responsible for NTAL inducible phosphorylation in these cells (unpublished data).

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