Coordinate interactions of protein tyrosine kinases and protein tyrosine phosphatases in T-cell receptor-mediated signalling

Coordinate protein

interactioos

tyrosine

of protein

tyrosine

phosphatases in T-cell signalling Andrey

Washington

Shaw and Matthew

University

School

of Medicine,

kinases

and

receptor-mediated

1. Thomas St Louis, Missouri,

USA

T-cell receptor stimulation leads to a rapid increase in tyrosine phosphorylation which is regulated by both the CD45 transmembrane protein tryosine phosphatase and by intracellular protein tyrosine kinases. The Src-family members, Fyn and Lck, have been implicated in T-cell receptor signalling and may be regulated by CD45. Current

Opinion

in Cell Biology

Introduction Central to antigen recognition is the process by which the antigen is perceived and the signal transduced cuhinating in the activation of the cell. For T lymphocytes, antigen is recognized by the T-cell receptor (TCR), a complex of multiple proteins consisting of three primary components: a heterodimer of either a-p or y-6 which physically interacts with antigen; CD3, which is made up of y, 6 and E (the y6 of CD3 are distinct from the antigen recognition y-6); and a c-chain homodimer. Because none of the components of the TCR have a structure capable of signalling by themselves, additional proteins are required. The use of protein tyrosine phosphatases (PTPases) and protein tyrosine kinases (PTKases) in TCR signalling is the subject of this review. The elaborate mechanism by which a complex protein antigen is degraded by an antigen-presenting cell, and the resulting peptides, bound to major histocompatibility complex (MI-K) Class I or Class II molecules, are displayed to T cells, has been elegantly elucidated over the past few years. However, the detection of antigen is only half the story. The signals transduced by the antigen receptor across the T-cell membrane and the cascade of events that leads to activation are equally important but much less clear in molecular terms than the interaction of the TCR with MHC proteins. Nonetheless, a variety of second messengers have been described upon activation of the TCR, including an increase in intracellular Ca2+ and activation of protein kinase C. More recently, activation of phospholipase C and p21ra have been demonstrated. Evidence that phosphorylation of multiple proteins on tyrosine residues precedes activation of phospholipase C suggests that the activation of a PTKase is one of the earliest, and possibly the initial, event [lo]. In support of this concept, inhibitors of PTKase activ-

1991, 3:862-868

ity abrogate or modulate TCR-mediated signalling events [ 211. However, none of the known components of the TCR contain intrinsic tyrosine kinase activity and, therefore, a more complex program of signalling is required. Requirement phosphatase

for a protein tyrosine in TCR-mediated signalling

There has been an explosion of interest in PTPases in recent years. This is the result of the merging of two fields: the characterization of the lymphoid cellsurface glycoprotein, CD45 (reviewed in [5] >, and the isolation and characterization of an intracellular PTPase from human placenta [6]. This alignment of interests has led to the rapid identification of additional PTPases [7,8,9.,10~~,11,12]. The PTPase family, like the tyrosine kinase family, can be divided into two main groups, intracellular and transmembrane, and each group contains subfamilies and multiple members. Because of the growth-promoting activity ascribed to tyrosine kinases, it was initially thought that the PTPases would function to downregulate the activation process started by the action of PTKases. Although this may indeed be the case for some PTPases, studies on the role of PTPases in TCR signailing suggest that the interactions are more complicated and that PTPases may play a role in activating PTKases. Inhibitors of PTPase activity, such as phenylarsine oxide or vanadate, result in increased tyrosine phosphotylation of certain proteins on Thy- 1-stimulated T cells and can inhibit the return to the quiescent state of mitogen-driven blastogenesis [ 13*,14*]. Consistent with this theme, antibody crosslinking studies with the transmembrane PTPase, CD45, a major glycoprotein uniquely expressed by leukocytes, can modulate T-cell activity [15*,16,17]. More compelling data, however, have come from stud-

Abbreviations CAP-CTPase-activating

062

protein; PTKase-protein

HIV-human tyrosine

immunodeficiency kinase; PTPase-protein

@ Current

Biology

virus; IL-interleukin; tyrosine phosphatase;

Ltd ISSN 0955+674

MHC-major TCR-T-cell

histocompatibility receptor.

complex;

Protein

tyrosine

kinasqwotein

tyrosine

phosphatase

ies of T cells deficient in the expression of CD45. CD4+ T-cell clones deficient in CD45 expression are unable to proliferate in response to antigen but not to interleukin (IL)-2 [ 181. Studies with CD45-deficient leukemic lines support these findings and have also indicated that intracellular signals are disrupted [ 19”,20**]. These cells, when stimulated by an antibody to the TCR, do not show an increase in intracellular calcium, activated phospholipase C or increased tyrosine phosphorylation, indicating that the PTPase activity of CD45 is required for the activation of these other second messengers. More recently, a CD45 - CD8+ T-cell clone has been shown to have impaired ability to respond to TCR stimuli [21**]. A greatly diminished capacity to proliferate, and to produce cytokines and cytolysis-appropriate target cells was shown in response to TCR stimulation. Thus, a variety of experimental systems has indicated that the CD45 PTPase is an essential and early component of TCR signalling. Implication kinases

for intracellular

protein

tyrosine

Because of the rapid appearance of tyrosine phosphorylated proteins induced by engagement of the TCR, it is widely believed that the latter regulates the activation of a tyrosine kinase. Because the known members of the TCR complex do not possess intrinsic tyrosine kinase activity, investigators have sought to identify a tyrosine ki nase associated with the TCR. Attention has focused on the Src-family of tyrosine kinases, although it is possible that other kinases are involved. The Src-family of tyrosine kinases includes Blk, Fyn, Fgr, Hck, Lyn, Lck, Src and Yes. These proteins are exclusively cytoplasmic without access by themselves to external stimuli. Because they have been implicated in growth regulation, they may bind to transmembrane proteins which could relay external stimuli. The best example of such an interaction involves the p56lck tyrosine kinase which is expressed almost exclusively in T cells. p56’ck binds with high affinity to the cytoplasmic domain of CD4 and CD8. This has been shown to be mediated by a cysteine sequence motif present in both the cytoplasmic domain of CD4 and CD8 and the amino-terminal domain of p56’ck [22-,23-l. Crosslinking of CD4 results in autophosphorylation of p56’~k and this is correlated with variable but detectable increases in kinase activiry [24,25-l. The physiological significance of CD4 crosslinking is unclear but there is evidence to suggest that p56’Ck plays a role in CD4 or CD8-dependent antigen-specific signal transduction [ 26**,27]. T-cell hybridoma cell lines dependent on CD4 or CD8 activation, require association of p56’ck with CD4 or CD8 for T-cell activation as assessed by IL-2 secretion. In support of this, expression of mutated p56’k molecules that are constitutively active enhances the activation of T-cell hybridomas [ 28.1. These data suggest that antigen-specific responses that are dependent on CD4 or CD8 use the signalling capacity of p56”k by activating its kinase activity. There is no evidence to date, however, that the kinase activity of p56’ck is effected by engagement of the TCR in rlitlo or in t&-o.

interactions

in TCR-mediated

signalling

Shaw and Thomas

There are several reasons to doubt that p56’k is the kinase initially activated upon engagement of the TCR The rapidity with which tyrosine-phosphorylated substrates are detected suggests that the involved kinase is itself a member of the TCR complex [ 1.1. Specific stimuli such as antibodies to CD3 and Thy-l activate T cells, stimulate the appearance of phosphotyrosine-containing proteins and are not dependent on CD4 or CD8 [ 291. In addition, T-cell hybridomas, such as 2B4, that lack significant p56kk expression signal normally [30**]. This has sparked a search for kinases directly associated with the TCR. When cells are solubilized in the non-ionic detergent digitonin, another protein encoded by the src-gene family, the tyrosine kinase ~59, can be detected in anti-TCR immunoprecipitations [ 30-o1. The presence of p59.@ appears to be specific, but it is present at very low levels. A role for p59@ in TCR-mediated signal transduction is supported by experiments using transgenic mice that overexpress p5sl.“/n in thymocytes and T cells. p5!Q@ overexpression causes the mature T cells to have an increased sensitivity to stimulation [31*-l. However, other src-gene family members such as pbO~‘es,are also expressed in T cells; it will be important to test other kinases in this system to determine whether this effect is specific. The suggestion that p59@ is associated with the TCR is surprising in view of the observation that p5w has a broad range of expression and is found in a wide variety of lyrnphoid and non-lyrnphoid cells. It is possible, however, that tissue-specific splicing of p5W accounts for its participation in a highly specialized signalling complex. T cells express a unique form of p5w that uses a distinct seventh exon [ 321. Recent reports demonstrate that another src-gene family tyrosine kinase, p56!im (prirnarily expressed in B cells) also exhibits differential splicing [33]. Although differential splicing may regulate the ability of certain kinases to be used in specific signalling pathways, both forms of Fyn are able to enhance signalling in T cells. Coordinate interactions between protein tyrosine phosphatases and protein tyrosine kinases The activity of Src-related tyrosine kinases is regulated by phosphotylation. This has been characterized in most detail for the c-Src. Phosphotylation of the tyrosine at position 527 of c-Src suppresses kinase activity while phosphorylation of tyrosine at position 416 can augment kinase activity. The transforming form of c-Src, v-Src, lacks the tyrosine at position 527 and has an elevated level of kinase activity both in tlitro and in L+tjo. Because similar tyrosines are present in all of the Src-family kinases, it is thought that they are similarly regulated. Indeed, conversion of tyrosine 505 of 561ckto phenylalanine activates this kinase. Because phosphotylation of p56’k at the 505 site is found in T cells at high stoichiometty [34], a PTPase could regulate the activation of PTKase activity by dephosphotylating this site.

863

864

Cell-to-cell

contact

and extracellular

matrix

. There is evidence indicating that p56kk may be a substrate of CD45. Lymphoma and thymoma cell lines deiicient in CD45 expression contain p56lCk molecules with an increased tyrosine phosphate content at Tyr505 compared with the parent lines, suggesting that CD45 interacts with and activities ~56% However, crosslinking of CD45 with CD4 in T-cell lines causes dephosphotylation and blocks activation of p56’* kinase activity [35-l. Although there is a report suggesting that CD45 is associated with CD4 in certain T-cell lines 1361, the physiological significance of this finding is unclear. As other Src-family kinases are expressed in T cells, it will also be important to determine whether CD45 can inIluence the level of phosphorylation and/or the kinase activity of these other kinases. It is possible, therefore, that the lack of TCR signailing in CD45-deficient T-cell clones results from the inability of these cells to activate a PTKase. Whether this PTKase is p56lck is unknown. Some, but not all, transmembrane signal through the T-cell receptor

proteins pathway

Antibody binding to other surface molecules, such as CD2 and Thy-l, can activate T cells and require the expression of the TCR for signalling. Crosslinking studies have suggested a physical association with CD2, Thy-l, TCR and CD45 [37,38]. But, because of prolonged crosslinking conditions and the abundance of CD45, the significance of these studies is uncertain. It has been found, however, that CD45-deficient leukemic cells are not sensitive to stimulation with antiCD2, which further suggests that CD2-mediated signalling is coupled to the TCR [ 20-1. In contrast, signals generated by the IL-2 receptor are unaffected in CD45-deficient cells [ 18,21*-1. The lack of effect of CD45 on the IL-2 receptor pathway is of particular interest because p56 ICkhas been shown to associate with the IL-2 receptor P-chain in cotransfection studies [ 39-1, and changes in p56@ activity have been observed upon addition of exogenous IL-2 to T-cell clones [40-l. Thus, p56@ may be involved in IL-2induced proliferation. Because CD45-deficient T-cell clones are only marginally effected in their response to IL-2, CD45 may not be involved In regulation of p56 I* in the IL-2 receptor pathway [ 18,21**]. Tyrosine phosphorylation upon activation

of the TCR r-chain

One protein that is rapidly tyrosine-phosphotylated upon T-cell activation is the L-chain of the TCR. The use of chimetic proteins containing the cytoplasmic domain of the TCR c-chain has demonstrated that the c-chain alone is sufficient to activate T cells. Experiments using a chirneric protein containing the extracellular domain of CD4 and the cytoplasmic domain of the c-chain are compelling [41-l. When expressed in cytolytic CD8+ T cells, this fusion protein is able to bind and lyse target cells expressing the human immunodeliciency virus (HIV) glycoprotein gpl60. This indicates that CD4 bind-

ing to HIV gpI6O is able to activate the signalling capacity of the c-chain and that the c-chain contains all the information necessary for initiation of signal transduction. In a similar series of experiments, expression of a CD8 &chain fusion protein in Jurkat cells leads to both early and late signalling events when crosslinked with antibodies to CD8 [42-l. Additional support for the requirement of <-chain phosphotylation in early signalling comes from deletional analysis of the <-chain [43*]. Truncation of a tyrosine residue near the carboxytemlinus of r-chain results in the inability of T cells to respond to antigen. However, crosslinking of the TCR still leads to activation. This suggests that the response to antigen requires the phosphorylation of a tyrosine residue near the carboxy-terminus, but that crosslinking can somehow overcome this requirement. It is interesting to note that t-l, an alternatively spliced form of the r-chain, lacks this site. Apparently, 17 may mediate a distinct TCR-signalling pathway. The generation of other second messengers appears to follow stimulation of tyrosine phosphotylation suggesting that tyrosine phosphotylation may be required to initiate these other pathways. For example, the activation of phospholipase C appears to follow tyrosine phosphorylation [l*]. Whether the activation of other signalling pathways is dependent on tyrosine phosphotylation is not known. Nevertheless, a scheme can be envisaged in which the initial event is the activation of a PTKase with the subsequent phosphotylation of substrates such as phospholipase C-y, ras-encoded GTPaseactivating protein (GAP), inositol 1,4,5-trisphosphate kinase, MAP2 kinase and Raf, resulting in activation of other second messenger pathways such as phosphoinositol metabolism, p2lras activity, increase in cytoplasmic Ca2+ levels and the activation of a cascade of serine/ threonine kinases. It should be noted, however, that only phospholipase C-y has been shown to be regulated by tyrosine phosphorylation [44**,45-] and that the activation of ~21 rm appears to be dependent on protein kinase C [46-l and not on tyrosine phosphotylation. The activation of these other second messenger pathways is currently a topic of much interest. Conclusion Several events must take place to initiate activation through the TCR. One supposition is that recognition of antigen bound to MHC stimulates a change in the TCR This physical change could allow for the activation of a PTKase that is dependent upon the CD45 PTPase. This would require the coordinate interactions of PTKases and PTPases for TCR activation. The regulation of PTPases and PTKases and their interactions are, therefore, of much interest. The PTKases implicated so far in TCR activation are all intracellular and thus their regulation must be dependent upon the interactions of transmembrane proteins. CD45, in contrast, has a large exterior domain which, presumably, regulates PTPase activity either directly or by regulating associations with appropriate substrates or activating molecules.

Protein

tyrosine

kinase-protein

tyrosine

phosphatase

interactions

in TCR-mediated

signalling

Shaw and Thomas

Extracellular

CD45 (low molecular weight form)

Thy-l

Fyn

TCFUCD3/&

CD4/lck

CD45 (high molecular weight form)

Leukosialin

Intracellular

Fig. 1. T-cell surface glycoproteins, drawn roughly to scale (based on the calculations of Cyster et al. 147*1).

Snm

To date, no ligand for CD45 has been found. There are eight different isoforms of CD45 which differ in the size of the amino-terminal O-linked carbohydrate regions because of the variable use of three exons. Because Olinked carbohydrate regions have an extended conformation [47*], the different isoforms may vary significantly in the extent to which they extend over the cell surface. A model, drawn roughly to scale, depicting this difference *and displaying some of the other key proteins is shown in Fig. 1. The expression of CD45 isoforms is highly orchestrated during both lymphocyte differentiation and activation. It is possible that different isoforms regulate the rate of association or the interaction of CD45 with other proteins. TCR activation may therefore be regulated by sequestration of substrate. CD45 and another heavily O-linked transmembrane protein expressed by T lymphocytes, leukosialin, are abundant cell-surface molecules, together occupying approximately one-third of the cell surface (47-l. The TCR and CD4/CD8, in comparison, are relatively minor components (481. Given the extended conformations of CD45 and leukosialin, it is likely that the mucin side chains of CD45 play an important role during initial contact between the T cell and the antigen-presenting cell. These interactions may help to organize the arrangement of membrane proteins and a.fTectthe overall rate of activation. This review concentrated on the interactions of PTPases and PTKases, but there are other proteins required for

TCR activation. Recent exciting reports implicate CD28 and CD5 in T-cell activation [49,50-]. Additionally, for maximum proliferative responses, growth factors, such as IL-2, are required. This requirement for multiple associations and interactions suggests that under normal physiological conditions, antigen-induced activation is highly regulated, which may prevent inappropriate activation. Finally, it should be pointed out that CD45 is expressed by all nucleated cells of hematopoietic origin. The specific requirement of CD45 for TCR-mediated signalling begs the issue of CD45 function in other leukocytes. In this regard, members of the Src-family as well as additional members of the <-chain family have recently been described in other leukocytes. Therefore, it is possible that a signalling cascade involving CD45 and members of the Src and &chain family is a common theme in leukocyte activation. Each cell type may differ by associating different sets of family members with key proteins resulting in distinct cellular behavior and phenotypes. In support of this notion, a recent report has demonstrated a CD45 requirement for immunoglobulin activation in B lymphocytes [ 51.1. Acknowledgements Our work is supported by grants from American Heart kssociation, Council for Tdxtcco Research and USPHS grant A126363 (MLT) and CISPHS grant Al 00’997 (AS). MLT is the recipient of an Established

Investigator

Award

from

the American

Hean

Association.

865

866

Cell-to-cell

References

contact

and extracellular

matrix

and recommended

Papers of special interest, published have been highlighted ;LS: l of interest .. of outstanding interest

within

reading the annual

period

of r&t-v,

1. .

J~INE CH. FLETCHER MC, LEDHET~~R JA, SA&~ELK)N LE: Increases in Tyrosine Phosphorylation are Detectable Before Phospholipase C Acthation After T CeU Receptor Stimulation. J Imnuznol 1990, l&:1591-1599. Demonstration that tyrosine phosphorylation is one of the earliest, if not the t-arliest. change found upon T-cell receptor activation. 2.

3.

JLINE CH, FETCHER MC, LI;.I)HE~TER JA, SCHIE\XN GL, SIIXXI. JN. Paiutes AF, SAMELX)N LE: Inhibition of Tyrosine Phosphorylation Prevents T-cell Receptor-Mediated Signal Transduction. Pmc Nat1 Acad Sci (ISA 1990. 87:“22-7726. TRRIUYAN JM, Ltt % ATL~IRII D, PHIU~I’S C.& BJORNI)AHL JM: Ditferential Inhibition of T Cell Receptor Signal Transduction and Early Activation Events by a Selective Inhibitor of Protein-firosine Kinase. ./ /m??zrrnol 1990. 145:3233-3230.

4.

STANLJZI’ JB, GORtXYNSlil R. H~IANG C-K, 11X’l! J. M1Ll5 GB: Tyrosine Phosphorylation is an Obligatory Event in IL-2 Secretion. .J Inlnltrnol 1990, 145:218~2198.

5.

THO~M~ ML: The Leukocyte Common Res Imnzunol 1989, 7:339-369.

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6.

CHARBONNEALI H. TONKS NK. WAISH Leukocyte Common Antigen (CD45): Linked Protein Tyrosine Phosphatase. USA 1988. 85:8695-8701.

KA, FISCHER EFl: The a Putative ReceptorPtw Nail .4cclt/ Sci

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SAP J, D’ELISTACHIO P, GIVOL D. SCHI~XINCER J: Cloning and Expression of a Widely Expressed Receptor Tyrosine Phosphatase. Proc Nat1 Acad Sci IM 1990, 87:61 IL-61 16.

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MA~HRX’S RJ. CAH~R ED, THOILQ ML: Identification of an Additional Member of the Protein Tyrosine-Phosphatase Family: Evidence for Alternative Splicing in the Tyrosine Phosphatase Domain. Pnx Nat1 Acizd Sci l&4 1990, 87:4-1-1-1--1448.

Family.

.4,1,lrr

MATIHNVS RJ, FIDKES E. THOR ML: Protein Tyrosine Phosphatase Domains from the Rotochordate Styela Plicata. Irrr munogeneticv 1991, 33:33-i 1. The identification of over 25 PTPase domains by pol)merA.se chain reaction analysis is given. This description indicates the estent and diversib of the PTPase family. 9. .

10. ..

KRIIE(;ER NX, STR!ZLIU M. SAITO H: Structural Evolution of Human Receptor Like Protein phatases. E~tillHO J 1990, 9:3211-3252. This report characterizes five mammalian trznsmembmne shows the diversity and subfamily organization. 11.

12.

Diversity Tyrosine PTPnsrs

and Phosand

KAPLAN R. MOREL B. t!I’I’BNER K, CRCMX C. 130~~ R. IL\\?%\ M, RICCA G. JA’~E M. .%I-I~XSSINCER J: Cloning of Three Human Tyrosine Phosphatases Reveals a Multigene Family of Receptor-Linked Protein-Tyrosine Phosphatases Expressed in Brain. Proc Nzztl Auzd Sci I&4 1990. 87:7ooO-700-1. J~RIK FR. JANZI~N NM, M~
IIVANAINEN AV, IJNDQVIST C. MLISIT~JN T, ANDER\SON IX:: Phosphotyrosine Phosphatases are Involved in Reversion of T Lymphoblastic Proliferation. Eur / I777777rr77ol 19~90, 20:250%2512. The effects of a protein tyrosine phosphame inhibitor on hlastogenesis are described and it is suggested that phosphatase activity is required for a return to the quiescent state. 13. .

14. .

GARC~~-MO~S LE: Tyrosine

P, MIN~WI Y, L~IONG E. KIA~ISN~~R RD, SA~I~~L\,ON Phosphorylation in T Cells is Regulated by

Phosphatme Activity: Studies with Phenylarsine Oxide. Prf~ iV(ztl Acczd Sci 15.4 1990, 87:9255-9259. Phenylarsine oxide is used to inhibit I’TPase activity in T~ccll hyhridom;Ls. The study indicates that there is continual regulation of tyrosine phospho~lation by PTPasrs and sugg!e.sts that a PTPasr regulates a I’TKX.e. IS. .

SAhlEiSON LE. Fil:rCHt!R MC, Lt!i~HliITf:.R JA. J~INF CH: Activation of Tyrosine Phosphorylation in Human T Cells Via the CD2 Pathway. Regulation by the CD45 Tyrosine Phosphatase. ./ Il?7l77rrr7ol 1990, 145:2-t-lttL*S-r. Demohstration that CD2 crosslinking results in phosphorylation of the T-cell receptor <-chain and seveml orhrr substrates. an effect that is in common with CD3 crosslinking. This su~!esrs that the CD2 signalling pathway is linked to TCR signal transduction. Crosslinking nith CD+5 rcverst’s this efl?ct. 16.

GIIJJIANI) IEDHIXIXH Transduction the CD3/Ti 35:12?+135.

17.

~JXX~E’I-I~~R JA S(;~iii\‘li~ GL. Clclct;~ FM. Ihii~)i~i~ JE% CD45 Cross-Linking Regulates Phospholipase C Activation and Tyrosine Phosphorylation of Specific Substrates in CD3/TiStimulated T Cells. .I I777~77ro7ol 1991, 146: 1 i77-1 583.

1X.

PIXEL JT. TIIO~!,\\ ML: Evidence that the Leukoqqe-Common Antigen is Required for Antigen-Induced T Lymphocyte Proliferation. &/I 1989. 58:lOSS~IO65.

19. ..

LK. ~cll~~i\l:N GL. GROShlhlRli 1s. DAhlilf Nli. JA. CD45 Ligation in T Cells Regulates Signal Through Both the Interleukin-2 Receptor and T-Cell Receptor Complex. 7kwr A~ztigcws 1‘990.

liORWL)cl’ GA. Pitt!> J. THohbw ML. Weis A: Tyrosine phatase CM5 is Essential for Coupling T-Cell Antigen ceptor to the Phosphatidyl lnositol Pathway. Nrrlrrrc, 346:W. This study shows that second messenger pathnays involved in receptor signal tmnsduction require the CDii protein t)rosine phat;Lse.

PhosRe1990, T-cell phos-

20. ..

KOKI:-i%li~ GA. Pictl\ J, ScHi8i:r/. T. Wi:iss A: Tyrosine Phosphatasc CM5 is Required for T-Cell Antigen Receptor and CD2-Mediated Activation of a Protein Tyrosine Kinase and lnterleukin 2 Production. Prrx Mztl Auzd Sci l!C4 1991. 88:203?-20.11. This report shows that for the Jurkat cell line. CD+5 is required for tyrosine l~hosphoglation, which suggests that CD-l5 regulates a PTKase The requirement for CD-IS hut nor CD28 in CD2 signal transduction i.z also descritxxl.

21. ..

W~~A\I:H CT, PIN~XI. JT. NI:I%)N JO, TIIOM,~~ Ml.: CD8+ T-Cell Clones Deficient in the Expression of the CD45 Protein Tyrosine Phosphatase have Impaired Responses to T-Cell Receptor Stimuli. Mel Cdl Rio/ 1991. in press. This study shows that CDX + T cells require CD-15 for TCR-mediated signalling; c)lolysis. proliferation and c)Tokinc production are effected The study is important in that it anal!-les non-tmnsformed cells and also shows that the IL-2 receptor signal tmnsduction is not elfectcul h! CIX5. 22. ..

AS. CHALIWNY J. WIIIl‘NI;Y JA. HAhlhIONI) C, AhlKlilN KE. L%\‘xn IA\ I’. Swrm BM, Ro~i JL: Short Related Sequences in the Cytoplasmic Domains of CD4 and CD8 Mediate Binding to the Amino-Terminal Domain of the p56”k Tyrosine Protein Kinase. :lhl Cell Hiol 1990. lO:lH531x62. ‘This paper and [23**] describe the identitication of the binding regions of CM, CDX and p56? Both papers estnhtish the genetic hAsis of the inremction and. interestingly, iclentib a cysteine-rich motif in both proteins which possibly interacts with a metal ion. These papers also establish the idea that the unique amino-terminal domain, of Src fam ily proteins interact aith the c)qoplasmic domains of transmemhrant proteins.

23 ..

SW

sl1AW

TIIRNI:H JM. BRO~~KY MH, IRVINII BA. 11~~ SD, Pii~ihll~i-1%~ RM, I~TLhlAN DR: Interaction of the Unique N-Terminal Region of Tyrosinc Kinase p56’ck with Cytoplasmic Domains of CD4 and CD8 is Mediated by Cysteinc Motifs. Cell 1990. 60:755-765. I22**1.

Protein 23.

tyrosine

VlXlJFl-I-F A. kXXhlAN JR Signal Transduction the Activation of the Kinase p56+ Nrtlrrre

kinasqwotein

tyrosine

phosphatase

MA, HOlU& EM. S,~\llil.4ON IEL;.. IXXEN Through the CD4 Receptor Involves Internal Membrane Tyrosine-Protein 1989, 338257-259.

25. .

LIO KX, St+-roN IVvl: Crosslinking of T-Crll Surface Molecules CD4 and CD8 Stimulates Phosphorylation of the Lck Tyrosine Protein Kinase at the Autophosphorylation Site. ,Ilo/ Cell Hi01 1990. 10;5305-5313. This paper foUo\vs up the tindings of [ 2.1 1 by testing the acti\‘;ltion of p56’ck kinase activiR in scverd different T-cell lines. The magnitude of activation is Mriahlc and depends c,n the cell line tested and the sub str.Ire ttstul. In COIIIIX~ to rcsulu published in (2-11, CD.1 crosslinking results primarib in phospho~latic~n of the t)rosinc residue at position 394. 26. . .

~IAIcllliNIlAI’s N. S1I~vlu N. Lrrlx~x DR. TIXNER JM: Requirement for Association of p56kk with CD4 in Antigen-Specific Signal Transduction in 1‘ Cells. CV// 1991. 64:511-520. Using a T-cell hyhridoma that requires CD4 for effective signal lrznsduction. an eshausdvc panel of CD-I mutants were tested Only CD4 molecules able IO bind to p56’Lk showed enhancement of IL 2 sccre. tion suggesting that ;Lssociation with p56’ck plays an importanr role in T-cell activation. 27.

~AMOSSKA R, DliHtl,\bl P. &NdAN SD. VOS I II’. I~OIES JB. V~~~.~l(‘llli A. PARNI3 JR: Inability of CD8 3’ Polypeptides to Associate with p56”k Correlates with Impaired Function In Vitro and Lack of Expression In Vim NCIIUW 19X9. 342:27K-2x1.

28. .

AIUXIIAM N, MICI:II MC, PMNI% JR, VI~~E-I~I~~ A Enhancement of T-Cell Responsiveness by the Lymphocyte-Specific Tyrosine Protein Kinase ~56 ‘ck. Nulrrre 1991. 350:62-66. A T-cell hyhridoma cell line w&s transfected with both wild ‘)pe and a mutared form of p56’c”: Cells transfrctcd with rhe mutated form (which is constitutively active) have an enhanced ability to secrete II.-2 and stimulate vrosine phosphoylation. 29.

tlsl ED, SIEGI:I. JN, MINMII Y. LIIONG ET, KlAl:SNI:H RD. SAhlliL%)N IX: T Cell Activation Induces Rapid Tyrosine Phosphorylation of a Number of Cellular Substrates. ./ Rio/ oJer?l 1989. 264: 1 OH3G 10842.

SMII
30. ..

COOKE MI’. AI3IbUlMl KM, FoKI3IISH KA. PIxI~II:T~EH Rbl: Regulation of T Cell Receptor Signaling by a src Family ProteinTyrosine Kinase (pS@m). Cc/l 1991, 65:281-291. T cells from tmnsgenic mice that overexpress p5ti11 are h}ppcrstimulable zs measured by increases in intracellular Ca”+ , phosphotyrosine induction, cyokine production and proliferation. This effect is not seen in mice that overexpress p56’c.k or p59% 31. ..

32.

COOKE MP, PIXJM~UI~:R the fin Proto-Oncogene 19x9, 16674.

RM: Expression of a Novel in Hematopoietic CeUs.

Form of Nv~c~ Hiol

33.

SI’.&U~’ E, Kh11’1i S, MCE~EN 5, BOIUI’ I, 11oI.‘r/.h~~ DA, INK P, DIINN AR: Alternatively Spliced Murine lyn mRNAs Encode Distinct Proteins. A!o/ CeN Rio/ 1991. 11:339’+3406.

34.

IIIIKI~Y TR, SIF~ON RM: Analysis of the Activity and Phosphorylation of the Ick Protein in Lymphoid Cells. Ot?co~crre 1989, 4:265-272.

OS-IFHGIV\RI) Ill., TKOU~~IUIXX IS: Coclustering CD45 with CD4 or CD8 Alters the Phosphorylation and Kinase Activity of p56’Ck. J EI~ ~llrd 1990, 172:317-350. Indicates that p56@ is a possible physiological suhstmte for CD45 and shows that this kinase can he a suhstmte i,r ~~il~~.

35. ..

36.

D

DLMG!!I lJ, IQMAN M. ROJO J, YAGI J, BAHON JL, WEEDS A. JANEWAS CA JH, RO~TOMI.Y K: Molecular Associations on the

interactions

in TCR-mediated

signalling

T Cell Surface Correlate with J In~~~rrrtwl 1990. 20:22+2257.

Shaw and Thomas

Immunological

Memory.

Elrr

37.

SCIIIL\\I!S 13, %\15r,\(; Y. Al:ni\rzr P, iMi:rlea of CD2 and CD45 on Human T Lymphocytes. 345:? I-71.

SC: Association Ncrrlrre 1990,

3x.

\‘~I,\K~~\Ic 5, I%IIH~‘S CM, SI~SS~LAN JJ, ASHVXIJ. JD: Intimate Association of Thy-l and the T-Cell Antigen Receptor with the CD45 Tyrosine Phosphatase. I+XX Null Acad Sci 1l.U 1990. 87:7085-7089.

M. K.oYo T. ~OIMYA~III N, KAWAHAM A, k\‘IN SD. P~:HI~~I’~I-~I~R RM. T~~GI’CHI T: Interaction of the IL-2 Receptor with the src-Family Kinase p56@ Identification of Novel Intermolecular Association. Scietrce 1991, 252: 1523-1528. p56’cb associates wi\-ith rhe p-chain of the Il.-2 receptor when coexpressed in lihroblast cell lines. Mapping studies indicate that the proximal kin&se domain of ~56”” interacts nith the c)qoplasmic domain of rhe P-chain.

39.

I~,IAKI~,L\IA

..

IIOIL~K ID. GKI(S~ RE, LIXX PJ. Ilo~b!lc EM. WAUXIANN TA 1301.1~s JB: T-Lymphocyte lnterleukin a-Dependent Tyrosine Protein Kinase Signal Transduction Involves the activation of p45’ck. /‘t-w Nd AUJ~ Sci C%A 1991. 88:199&2000. I)mmc)nsrr.~tcs that addition of escjgenous IL-2 results in acthation of p%+k kin;cse acti\iw. This etkc~ is sptrilic: kinase act&iv of other Srcfanmilv members is nc,t effected by IL-2 treatment.

-IO. .

Roh!l;o C. S~lir) 1% Cellular Immunity to HIV Activated by CD4 Fused to T CeU or Fc Receptor Polypeptides. Cell 19~1. 64:1037-1046. Indicates that the c)Tc)pla.smic portion of the c-chain is all that is required for TCR-mediated signalling. Reconstitution of CDX+ cells with the Cnii; chain hIsion protein allows for these cells to cytolyse target cells espressing I IIV gplG0.

il. ..

IRVING IsA WEIS A: The Cytoplasmic Domain of the T CeU Receptor L-Chain is Sufficient to Couple to Receptor-Associated Signal Transduction Pathways. Cell 1991, 64:891-901. Transfection of Jurkat cells with a CDlychain fusion prt)tein results in identical SignaIling pathways to thar .seen in TCR-mediated Signaling, indicating that <.chain is sufficient for TCR-mediated signaIling.

12. ..

FRWK SJ. NIKI~NSKI BB, OKIXXF DG. MERCEI~ M, AsHwxu. JD. KIAIISNEH RD: Structural Mutations of the T CeU Receptor <-Chain and its Role in T Cell Activation. Scimce 1990, 249: I?+ 177. Mapping studies of the i&ain indicate that the carhoxyterminal phos phorylation site is required for antigen-induced TCRmediated sig nailing.

43. .

Nlstlli~li s, WNII. ML ~IERN~\~‘uE% SS. TONKS NK, RHEE SC, CAHI~I:NI’I:H G: Increase of the Catalytic Activity of Phospholipase C-yl by Tyrosine Phosphorylation. Scierzce 1990, 250:125+1256. The first JemonstrJtion that phosphorylation of phospholipase C-y on tyrosine residues can regulate its activit).

ii. ..

~Xl,SCH~lllnCP. Klbl JW, MACHEShy LM, RHEE SG, POllARD TIX Regulation of PhosphoUpase C-71 by Profdin and Tyrosine Phosphorylation. Scietrce 1991, 251:1231-1233. The actin-binding protein, prolilin, hinds to phosphatidyl inositol 4.5. hisphosphatr and inhibits hydroiysis by phospholipase C. This in. hihition c‘Jn he overcome by phosphorylation of phospholipase C.y on tyrosine residues. Previous difficulties in measuring enhancement of phospholipAse C-y activity after tyrosine phosphorylation in l?tro may have been hecause of the absence of protilin. 45. ..

46. ..

DOWWVARD J, GRAVES JD, WAKNE PH, RAY-IXR S. CANTREIL DA: Stimulation of ~21 ras Upon T-CeU Activation. Nufure 1990, 346:719-723. The first demonstration that p-lYJ rcL$ activity can he reclated by extentnal stimuli. Activation of T cells results in activation of p21rm GTPAw activity. This appears to he independent of tyrosine phosphorylation of GAP.

47. .

CYSTI% JG, SHOTON the T Lymphocyte

DM, WIIUAMS Glycoprotein

AF: The Leukosialin

Dimensions of and Ident&

867

Cell-to-cell

contact

and extracellular

matrix

cation of Linear Protein Epitopes that can be Modified by Glycosylation. mfB0 .I 1991. 10:89?+IO2. Electronmicroscopic examination of leukosialin. The study demon. strates the extended confirmation of this glycoprorein and has implications for the structure of O-linked carbohydrate regions. Calculation on the dimensions and percentage of the cell.surface area for leukosialin, CD45 and other surface molecules is illuminating. 48.

WILLLAMS AF, BARCU\Y AN: Glycoprotein Antigens of the Lymphocyte Surface and their Purification by Antibody Af%ity Chromatography. In /-lum&ok o~.~q~rirnet2t~~l fn~mzrnolofl~ edited by Weir DM, HelzenberR IA [book]. Oxford: Blaclwell Scientific 1985, ~~22.1-22.24.

49.

JUNE CH, ~IDBETIXR the CD28 Receptor 1990, 11:211-216.

50. .

VAN DE VELDE H, VON HOEGEN 1. Luo W. PARNES JR, THIEU:LIMS K: The B-Cell Surface Protein CD72/Lyb-2 is the Ligand for CD4. Nurzrre 1991, 351:662-665.

JA, in

LINSLEI PS. TH~MI~ON CB: T-Cell Activation. Imm~nol

Characterizes CDXD72 dancy in cell adherence

interactions molecules.

and indicates

breadth

and redun,

51. .

JLIS~LIE~ LB, CA?.~HEU KS. CHIEN NC, CAMIMER JC: Regulation of B Cell Antigen Receptor Signal Transduction and Phosphorylation by CD45. Scie?ice 1991. 252:18X)-1%12. Demonstrates that the inahiliv of a B-cell line (]558Lpm3) 1o mobilize Ca”+ in response to IRM crosslinking is because of a lack of CD45 expresswn.

Role of ~ocln,~ A Shaw and ML Thomas. Department versiy School of (Medicine. 660 South [ISA

of P;tthology, Washington Euclid. St Louis, Missouri

llni631 10,