GRB2 and phospholipase C-gamma 1 associate with a 36- to 38-kilodalton phosphotyrosine protein after T-cell receptor stimulation

1994 ◽  
Vol 14 (7) ◽  
pp. 4435-4442
Author(s):  
M Sieh ◽  
A Batzer ◽  
J Schlessinger ◽  
A Weiss

GRB2, a 25-kDa protein comprising a single SH2 domain flanked by two SH3 domains, has been implicated in linking receptor protein tyrosine kinases (PTKs) to the Ras pathway by interacting with the guanine nucleotide exchange protein SOS. Previous studies have demonstrated that GRB2 directly interacts with Shc, a proto-oncogene product that is tyrosine phosphorylated upon receptor and nonreceptor PTK activation. In this report, we detected low levels of tyrosine phosphorylation of Shc and induced association with GRB2 upon T-cell receptor (TCR) stimulation. Instead, a prominent 36- to 38-kDa tyrosine phosphoprotein (pp36-38) associated with the SH2 domain of GRB2 and formed a stable complex with GRB2/SOS upon TCR stimulation. Cellular fractionation studies showed that whereas both GRB2 and SOS partitioned to the soluble and particulate fractions, pp36-38 was present exclusively in the particulate fraction. This phosphoprotein had the same apparent mobility in sodium dodecyl sulfate-polyacrylamide gel electrophoresis as the phosphoprotein that associates with phospholipase C-gamma 1 (PLC-gamma 1). Furthermore, following partial immunodepletion of GRB2 and of the associated pp36-38, there was a significant reduction in the amount of the 36-kDa phosphoprotein associated with PLC-gamma 1, suggesting that a trimeric PLC-gamma 1/pp36-38/GRB2 complex could form. In support of this notion, we have also been able to detect low levels of PLC-gamma 1 in GRB2 immunoprecipitates. We suggest that pp36-38 may be a bridging protein, coupling different signalling molecules to cytoplasmic PTKs regulated by the TCR.

1994 ◽  
Vol 14 (7) ◽  
pp. 4435-4442 ◽  
Author(s):  
M Sieh ◽  
A Batzer ◽  
J Schlessinger ◽  
A Weiss

GRB2, a 25-kDa protein comprising a single SH2 domain flanked by two SH3 domains, has been implicated in linking receptor protein tyrosine kinases (PTKs) to the Ras pathway by interacting with the guanine nucleotide exchange protein SOS. Previous studies have demonstrated that GRB2 directly interacts with Shc, a proto-oncogene product that is tyrosine phosphorylated upon receptor and nonreceptor PTK activation. In this report, we detected low levels of tyrosine phosphorylation of Shc and induced association with GRB2 upon T-cell receptor (TCR) stimulation. Instead, a prominent 36- to 38-kDa tyrosine phosphoprotein (pp36-38) associated with the SH2 domain of GRB2 and formed a stable complex with GRB2/SOS upon TCR stimulation. Cellular fractionation studies showed that whereas both GRB2 and SOS partitioned to the soluble and particulate fractions, pp36-38 was present exclusively in the particulate fraction. This phosphoprotein had the same apparent mobility in sodium dodecyl sulfate-polyacrylamide gel electrophoresis as the phosphoprotein that associates with phospholipase C-gamma 1 (PLC-gamma 1). Furthermore, following partial immunodepletion of GRB2 and of the associated pp36-38, there was a significant reduction in the amount of the 36-kDa phosphoprotein associated with PLC-gamma 1, suggesting that a trimeric PLC-gamma 1/pp36-38/GRB2 complex could form. In support of this notion, we have also been able to detect low levels of PLC-gamma 1 in GRB2 immunoprecipitates. We suggest that pp36-38 may be a bridging protein, coupling different signalling molecules to cytoplasmic PTKs regulated by the TCR.


1993 ◽  
Vol 178 (6) ◽  
pp. 2107-2113 ◽  
Author(s):  
A J da Silva ◽  
O Janssen ◽  
C E Rudd

Intracellular signaling from the T cell receptor (TCR)zeta/CD3 complex is likely to be mediated by associated protein tyrosine kinases such as p59fyn(T), ZAP-70, and the CD4:p56lck and CD8:p56lck coreceptors. The nature of the signaling cascade initiated by these kinases, their specificities, and downstream targets remain to be elucidated. The TCR-zeta/CD3:p59fyn(T) complex has previously been noted to coprecipitate a 120/130-kD doublet (p120/130). This intracellular protein of unknown identity associates directly with p59fyn(T) within the receptor complex. In this study, we have shown that this interaction with p120/130 is specifically mediated by the SH2 domain (not the fyn-SH3 domain) of p59fyn(T). Further, based on the results of in vitro kinase assays, p120/130 appears to be preferentially associated with p59fyn(T) in T cells, and not with p56lck. Antibody reprecipitation studies identified p120/130 as a previously described 130-kD substrate of pp60v-src whose function and structure is unknown. TCR-zeta/CD3 induced activation of T cells augmented the tyrosine phosphorylation of p120/130 in vivo as detected by antibody and GST:fyn-SH2 fusion proteins. p120/130 represents the first identified p59fyn(T):SH2 binding substrate in T cells, and as such is likely to play a key role in the early events of T cell activation.


1992 ◽  
Vol 12 (6) ◽  
pp. 2720-2729
Author(s):  
L Caron ◽  
N Abraham ◽  
T Pawson ◽  
A Veillette

To understand the mechanism(s) by which p56lck participates in T-cell receptor (TCR) signalling, we have examined the effects of mutations in known regulatory domains of p56lck on the ability of F505 p56lck to enhance the responsiveness of an antigen-specific murine T-cell hybridoma. A mutation of the amino-terminal site of myristylation (glycine 2), which prevents stable association of p56lck with the plasma membrane, completely abolished the ability of F505 p56lck to enhance TCR-induced tyrosine protein phosphorylation. Alteration of the major site of in vitro autophosphorylation, tyrosine 394, to phenylalanine diminished the enhancement of TCR-induced tyrosine protein phosphorylation by F505 p56lck. Such a finding is consistent with the previous demonstration that this site is required for full activation of p56lck by mutation of tyrosine 505. Strikingly, deletion of the noncatalytic Src homology domain 2, but not of the Src homology domain 3, markedly reduced the improvement of TCR-induced tyrosine protein phosphorylation by F505 Lck. Additional studies revealed that all the mutations tested, including deletion of the Src homology 3 region, abrogated the enhancement of antigen-triggered interleukin-2 production by F505 p56lck, thus implying more stringent requirements for augmentation of antigen responsiveness by F505 Lck. Finally, it was also observed that expression of F505 p56lck greatly increased TCR-induced tyrosine phosphorylation of phospholipase C-gamma 1, raising the possibility that phospholipase C-gamma 1 may be a substrate for p56lck in T lymphocytes. Our results indicate that p56lck regulates T-cell antigen receptor signalling through a complex process requiring multiple distinct structural domains of the protein.


Cell ◽  
1989 ◽  
Vol 58 (5) ◽  
pp. 911-921 ◽  
Author(s):  
Michael L.B. Becker ◽  
Richard Near ◽  
Meredith Mudgett-Hunter ◽  
Michael N. Margolies ◽  
Ralph T. Kubo ◽  
...  

Blood ◽  
2010 ◽  
Vol 116 (25) ◽  
pp. 5560-5570 ◽  
Author(s):  
Karla R. Wiehagen ◽  
Evann Corbo ◽  
Michelle Schmidt ◽  
Haina Shin ◽  
E. John Wherry ◽  
...  

Abstract The requirements for tonic T-cell receptor (TCR) signaling in CD8+ memory T-cell generation and homeostasis are poorly defined. The SRC homology 2 (SH2)-domain–containing leukocyte protein of 76 kDa (SLP-76) is critical for proximal TCR-generated signaling. We used temporally mediated deletion of SLP-76 to interrupt tonic and activating TCR signals after clearance of the lymphocytic choriomeningitis virus (LCMV). SLP-76–dependent signals are required during the contraction phase of the immune response for the normal generation of CD8 memory precursor cells. Conversely, LCMV-specific memory CD8 T cells generated in the presence of SLP-76 and then acutely deprived of TCR-mediated signals persist in vivo in normal numbers for more than 40 weeks. Tonic TCR signals are not required for the transition of the memory pool toward a central memory phenotype, but the absence of SLP-76 during memory homeostasis substantially alters the kinetics. Our data are consistent with a model in which tonic TCR signals are required at multiple stages of differentiation, but are dispensable for memory CD8 T-cell persistence.


1999 ◽  
Vol 145 (2) ◽  
pp. 377-389 ◽  
Author(s):  
Woutervan't Hof ◽  
Marilyn D. Resh

The first 10 residues within the Src homology domain (SH)–4 domain of the Src family kinase Fyn are required for binding to the immune receptor tyrosine-based activation motif (ITAM) of T cell receptor (TCR) subunits. Recently, mutation of glycine 2, cysteine 3, and lysines 7 and 9 was shown to block binding of Fyn to TCR ζ chain ITAMs, prompting the designation of these residues as an ITAM recognition motif (Gauen, L.K.T., M.E. Linder, and A.S. Shaw. 1996. J. Cell Biol. 133:1007–1015). Here we show that these residues do not mediate direct interactions with TCR ITAMs, but rather are required for efficient myristoylation and palmitoylation of Fyn. Specifically, coexpression of a K7,9A-Fyn mutant with N-myristoyltransferase restored myristoylation, membrane binding, and association with the cytoplasmic tail of TCR ζ fused to CD8. Conversely, treatment of cells with 2-hydroxymyristate, a myristoylation inhibitor, blocked association of wild-type Fyn with ζ. The Fyn NH2 terminus was necessary but not sufficient for interaction with ζ and both Fyn kinase and SH2 domains were required, directing phosphorylation of ζ ITAM tyrosines and binding to ζ ITAM phosphotyrosines. Fyn/ζ interaction was sensitive to octylglucoside and filipin, agents that disrupt membrane rafts. Moreover, a plasma membrane bound, farnesylated Fyn construct, G2A,C3S-FynKRas, was not enriched in the detergent insoluble fraction and did not associate with ζ. We conclude that the Fyn SH4 domain provides the signals for fatty acylation and specific plasma membrane localization, stabilizing the interactions between the Fyn SH2 domain and phosphotyrosines in TCR ζ chain ITAMs.


1995 ◽  
Vol 15 (11) ◽  
pp. 5937-5944 ◽  
Author(s):  
J F Cloutier ◽  
L M Chow ◽  
A Veillette

Previous studies from our laboratory have shown that the cytosolic tyrosine protein kinase p50csk is involved in the negative regulation of T-cell activation (L.M. L. Chow, M. Fournel, D. Davidson, and A. Veillette, Nature [London] 365:156-160, 1993). This function most probably reflects the ability of Csk to phosphorylate the inhibitory carboxy-terminal tyrosine of p56lck and p59fynT, two Src-related enzymes abundantly expressed in T lymphocytes. Herein, we have attempted to better understand the mechanisms by which Csk participates in the inhibitory phase of T-cell receptor signalling. Our results demonstrated that the Src homology 3 (SH3) and SH2 domains of p50csk are crucial for its negative impact on T-cell receptor-mediated signals. As these two sequences were not essential for phosphorylation of the carboxy-terminal tyrosine of a Src-like product in yeast cells, we postulated that they mediate protein-protein interactions allowing the recruitment of p50csk in the vicinity of activated Lck and/or FynT in T cells. In complementary studies, it was observed that linkage of a constitutive membrane targeting signal to the amino terminus of Csk rescued the deleterious impact of a point mutation in the SH2 domain of p50csk. This observation suggested that the SH2 sequence is in part necessary to translocate p50csk from the cytoplasm to the plasma membrane, where Src-related enzymes are located. Nevertheless, constitutive membrane localization was unable to correct the effect of complete deletion of the SH3 or SH2 sequence, implying that these domains provide additional functions necessary for the biological activity of p50csk.


2001 ◽  
Vol 21 (13) ◽  
pp. 4208-4218 ◽  
Author(s):  
Deborah Yablonski ◽  
Theresa Kadlecek ◽  
Arthur Weiss

ABSTRACT SLP-76 is an adapter protein required for T-cell receptor (TCR) signaling. In particular, TCR-induced tyrosine phosphorylation and activation of phospholipase C-γ1 (PLC-γ1), and the resultant TCR-inducible gene expression, depend on SLP-76. Nonetheless, the mechanisms by which SLP-76 mediates PLC-γ1 activation are not well understood. We now demonstrate that SLP-76 directly interacts with the Src homology 3 (SH3) domain of PLC-γ1. Structure-function analysis of SLP-76 revealed that each of the previously defined protein-protein interaction domains can be individually deleted without completely disrupting SLP-76 function. Additional deletion mutations revealed a new, 67-amino-acid functional domain within the proline-rich region of SLP-76, which we have termed the P-1 domain. The P-1 domain mediates a constitutive interaction of SLP-76 with the SH3 domain of PLC-γ1 and is required for TCR-mediated activation of Erk, PLC-γ1, and NFAT (nuclear factor of activated T cells). The adjacent Gads-binding domain of SLP-76, also within the proline-rich region, mediates inducible recruitment of SLP-76 to a PLC-γ1-containing complex via the recruitment of both PLC-γ1 and Gads to another cell-type-specific adapter, LAT. Thus, TCR-induced activation of PLC-γ1 entails the binding of PLC-γ1 to both LAT and SLP-76, a finding that may underlie the requirement for both LAT and SLP-76 to mediate the optimal activation of PLC-γ1.


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