Intramolecular Regulatory Switch in ZAP-70: Analogy with Receptor Tyrosine Kinases

ABSTRACT ZAP-70, a Syk family cytoplasmic protein tyrosine kinase (PTK), is required to couple the activated T-cell antigen receptor (TCR) to downstream signaling pathways. It contains two tandem SH2 domains that bind to phosphorylated TCR subunits and a C-terminal catalytic domain. The region connecting the SH2 domains with the kinase domain, termed interdomain B, has previously been shown to have striking regulatory effects on ZAP-70 function, presumed to be due to the recruitment of key substrates. Paradoxically, deletion of interdomain B preserves ZAP-70 function. Recent structural studies of several receptor tyrosine kinases (RTKs) revealed that their juxtamembrane regions negatively regulate their catalytic activities. In EphB2 and several other RTKs, this autoinhibition depends upon interaction between the kinase domain and tyrosine residues within the juxtamembrane region. Autoinhibition is released when these tyrosines become phosphorylated following receptor stimulation. Sequence homology suggested analogous regulation for ZAP-70. Based on mutagenesis analysis of ZAP-70 interdomain B, we find that this region downregulates ZAP-70 catalytic activity in a similar manner as the juxtamembrane region of EphB2. Similar regulation was also noted for the related Syk kinase. These findings suggest that a general autoinhibitory mechanism employed by RTKs is also used by some cytoplasmic tyrosine kinases.

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Multiple SH2-mediated interactions in v-src-transformed cells.

Molecular and Cellular Biology ◽

10.1128/mcb.12.3.1366 ◽

1992 ◽

Vol 12 (3) ◽

pp. 1366-1374 ◽

Cited By ~ 32

Author(s):

C A Koch ◽

M F Moran ◽

D Anderson ◽

X Q Liu ◽

G Mbamalu ◽

...

Keyword(s):

Protein Interactions ◽

Tyrosine Kinases ◽

Protein Tyrosine Kinase ◽

Kinase Domain ◽

Sh2 Domain ◽

Protein Tyrosine ◽

Sh2 Domains ◽

Phosphorylated Proteins

The Src homology 2 (SH2) domain is a noncatalytic region which is conserved among a number of signaling and transforming proteins, including cytoplasmic protein-tyrosine kinases and Ras GTPase-activating protein (GAP). Genetic and biochemical data indicate that the SH2 domain of the p60v-src (v-Src) protein-tyrosine kinase is required for full v-src transforming activity and may direct the association of v-Src with specific tyrosine-phosphorylated proteins. To test the ability of the v-Src SH2 domain to mediate protein-protein interactions, v-Src polypeptides were expressed as fusion proteins in Escherichia coli. The bacterial v-Src SH2 domain bound a series of tyrosine-phosphorylated proteins in a lysate of v-src-transformed Rat-2 cells, including prominent species of 130 and 62 kDa (p130 and p62). The p130 and p62 tyrosine-phosphorylated proteins that complexed v-Src SH2 in vitro also associated with v-Src in v-src-transformed Rat-2 cells; this in vivo binding was dependent on the v-Src SH2 domain. In addition to binding soluble p62 and p130, the SH2 domains of v-Src, GAP, and v-Crk directly recognized these phosphotyrosine-containing proteins which had been previously denatured and immobilized on a filter. In addition, the SH2 domains of GAP and v-Crk bound to the GAP-associated protein p190 immobilized on a nitrocellulose membrane. These results show that SH2 domains bind directly to tyrosine-phosphorylated proteins and that the Src SH2 domain can bind phosphorylated targets of the v-Src kinase domain.(ABSTRACT TRUNCATED AT 250 WORDS)

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Multiple SH2-mediated interactions in v-src-transformed cells

Molecular and Cellular Biology ◽

10.1128/mcb.12.3.1366-1374.1992 ◽

1992 ◽

Vol 12 (3) ◽

pp. 1366-1374

Author(s):

C A Koch ◽

M F Moran ◽

D Anderson ◽

X Q Liu ◽

G Mbamalu ◽

...

Keyword(s):

Protein Interactions ◽

Tyrosine Kinases ◽

Protein Tyrosine Kinase ◽

Kinase Domain ◽

Sh2 Domain ◽

Protein Tyrosine ◽

Sh2 Domains ◽

Phosphorylated Proteins

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Functional dissection of p56lck, a protein tyrosine kinase which mediates interleukin-2-induced activation of the c-fos gene

Molecular and Cellular Biology ◽

10.1128/mcb.14.9.5812-5819.1994 ◽

1994 ◽

Vol 14 (9) ◽

pp. 5812-5819

Author(s):

H Shibuya ◽

K Kohu ◽

K Yamada ◽

E L Barsoumian ◽

R M Perlmutter ◽

...

Keyword(s):

Tyrosine Kinase ◽

Tyrosine Kinases ◽

Protein Tyrosine Kinase ◽

Gene Activation ◽

Interleukin 2 ◽

Kinase Domain ◽

Tyrosine Kinase Domain ◽

Amino Acid Residues ◽

Protein Tyrosine ◽

Responsive Element

Members of the newly identified receptor family for cytokines characteristically lack the intrinsic protein tyrosine kinase domain that is a hallmark of other growth factor receptors. Instead, accumulating evidence suggests that these receptors utilize nonreceptor-type protein tyrosine kinases for downstream signal transduction by cytokines. We have shown previously that the interleukin-2 receptor beta-chain interacts both physically and functionally with a Src family member, p56lck, and that p56lck activation leads to induction of the c-fos gene. However, the mechanism linking p56lck activation with c-fos induction remains unelucidated. In the present study, we systematically examined the extent of c-fos promoter activation by expression of a series of p56lck mutants, using a transient cotransfection assay. The results define a set of the essential amino acid residues that regulate p56lck induction of the c-fos promoter. We also provide evidence that the serum-responsive element and sis-inducible element are both targets through which p56lck controls c-fos gene activation.

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Stable association of pp60src and pp59fyn with the focal adhesion-associated protein tyrosine kinase, pp125FAK

Molecular and Cellular Biology ◽

10.1128/mcb.14.1.147-155.1994 ◽

1994 ◽

Vol 14 (1) ◽

pp. 147-155

Author(s):

B S Cobb ◽

M D Schaller ◽

T H Leu ◽

J T Parsons

Keyword(s):

Focal Adhesion ◽

Tyrosine Kinases ◽

Protein Tyrosine Kinase ◽

Src Family Kinases ◽

Protein Tyrosine Kinases ◽

Protein Tyrosine ◽

Sh2 Domains ◽

Embryo Cells ◽

Stable Association

Changes in cellular growth and dramatic alterations in cell morphology and adhesion are common features of cells transformed by oncogenic protein tyrosine kinases, such as pp60src and other members of the Src family. In this report, we present evidence for the stable association of two Src family kinases (pp60src and pp59fyn) with tyrosine-phosphorylated forms of a focal adhesion-associated protein tyrosine kinase, pp125FAK. In Src-transformed chicken embryo cells, most of the pp125FAK was stably complexed with activated pp60src (e.g., pp60(527F). The stable association of pp125FAK with pp60(527F) in vivo required the structural integrity of the Src SH2 domain. The association of pp60(527F) and pp125FAK could be reconstituted in vitro by incubation of normal cell extracts with glutathione S-transferase fusion proteins containing SH2 or SH3/SH2 domains of pp60src. Furthermore, the association of isolated SH2 or SH3/SH2 domains with in vitro 32P-labeled pp125FAK protected the major site of pp125FAK autophosphorylation from digestion with a tyrosine phosphatase, indicating that the autophosphorylation site of pp125FAK participates in binding with Src. Immunoprecipitation of Src family kinases from extracts of normal chicken embryo cells revealed stable complexes of pp59fyn and tyrosine-phosphorylated pp125FAK. These data provide evidence for a direct interaction between two cytoplasmic nonreceptor protein tyrosine kinases and suggest that Src may contribute to changes in pp125FAK regulation in transformed cells. Furthermore, pp125FAK may directly participate in the targeting of pp59fyn or possibly other Src family kinases to focal adhesions in normal cells.

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Receptor Tyrosine Kinases in Kidney Development

Journal of Signal Transduction ◽

10.1155/2011/869281 ◽

2011 ◽

Vol 2011 ◽

pp. 1-10 ◽

Cited By ~ 14

Author(s):

Renfang Song ◽

Samir S. El-Dahr ◽

Ihor V. Yosypiv

Keyword(s):

Tyrosine Kinases ◽

Molecular Mechanisms ◽

Kidney Development ◽

Receptor Tyrosine Kinases ◽

Adaptor Proteins ◽

Downstream Signaling ◽

Arterial Blood ◽

Intracellular Signal ◽

Human Birth

The kidney plays a fundamental role in the regulation of arterial blood pressure and fluid/electrolyte homeostasis. As congenital anomalies of the kidney and urinary tract (CAKUT) constitute one of the most common human birth defects, improved understanding of the cellular and molecular mechanisms that lead to CAKUT is critical. Accumulating evidence indicates that aberrant signaling via receptor tyrosine kinases (RTKs) is causally linked to CAKUT. Upon activation by their ligands, RTKs dimerize, undergo autophosphorylation on specific tyrosine residues, and interact with adaptor proteins to activate intracellular signal transduction pathways that regulate diverse cell behaviours such as cell proliferation, survival, and movement. Here, we review the current understanding of role of RTKs and their downstream signaling pathways in the pathogenesis of CAKUT.

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Vav Family Proteins Couple to Diverse Cell Surface Receptors

Molecular and Cellular Biology ◽

10.1128/mcb.20.17.6364-6373.2000 ◽

2000 ◽

Vol 20 (17) ◽

pp. 6364-6373 ◽

Cited By ~ 106

Author(s):

Sheri L. Moores ◽

Laura M. Selfors ◽

Jessica Fredericks ◽

Timo Breit ◽

Keiko Fujikawa ◽

...

Keyword(s):

Growth Factor ◽

Cell Surface ◽

Tyrosine Phosphorylation ◽

Tyrosine Kinases ◽

Protein Tyrosine Kinase ◽

Receptor Activation ◽

Cell Surface Receptors ◽

Nucleotide Exchange ◽

Surface Receptors ◽

Downstream Signaling

ABSTRACT Vav proteins are guanine nucleotide exchange factors for Rho family GTPases which activate pathways leading to actin cytoskeletal rearrangements and transcriptional alterations. Vav proteins contain several protein binding domains which can link cell surface receptors to downstream signaling proteins. Vav1 is expressed exclusively in hematopoietic cells and tyrosine phosphorylated in response to activation of multiple cell surface receptors. However, it is not known whether the recently identified isoforms Vav2 and Vav3, which are broadly expressed, can couple with similar classes of receptors, nor is it known whether all Vav isoforms possess identical functional activities. We expressed Vav1, Vav2, and Vav3 at equivalent levels to directly compare the responses of the Vav proteins to receptor activation. Although each Vav isoform was tyrosine phosphorylated upon activation of representative receptor tyrosine kinases, integrin, and lymphocyte antigen receptors, we found unique aspects of Vav protein coupling in each receptor pathway. Each Vav protein coprecipitated with activated epidermal growth factor and platelet-derived growth factor (PDGF) receptors, and multiple phosphorylated tyrosine residues on the PDGF receptor were able to mediate Vav2 tyrosine phosphorylation. Integrin-induced tyrosine phosphorylation of Vav proteins was not detected in nonhematopoietic cells unless the protein tyrosine kinase Syk was also expressed, suggesting that integrin activation of Vav proteins may be restricted to cell types that express particular tyrosine kinases. In addition, we found that Vav1, but not Vav2 or Vav3, can efficiently cooperate with T-cell receptor signaling to enhance NFAT-dependent transcription, while Vav1 and Vav3, but not Vav2, can enhance NFκB-dependent transcription. Thus, although each Vav isoform can respond to similar cell surface receptors, there are isoform-specific differences in their activation of downstream signaling pathways.

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Expanding the Disorder-Function Paradigm in the C-Terminal Tails of Erbbs

Biomolecules ◽

10.3390/biom11111690 ◽

2021 ◽

Vol 11 (11) ◽

pp. 1690

Author(s):

Louise Pinet ◽

Nadine Assrir ◽

Carine van Heijenoort

Keyword(s):

Tyrosine Kinases ◽

Kinase Domain ◽

Cellular Motility ◽

Dynamic Features ◽

Sh2 Domains ◽

Intrinsically Disordered ◽

Src Homology ◽

Regulation Functions ◽

And Function

ErbBs are receptor tyrosine kinases involved not only in development, but also in a wide variety of diseases, particularly cancer. Their extracellular, transmembrane, juxtamembrane, and kinase folded domains were described extensively over the past 20 years, structurally and functionally. However, their whole C-terminal tails (CTs) following the kinase domain were only described at atomic resolution in the last 4 years. They were shown to be intrinsically disordered. The CTs are known to be tyrosine-phosphorylated when the activated homo- or hetero-dimers of ErbBs are formed. Their phosphorylation triggers interaction with phosphotyrosine binding (PTB) or Src Homology 2 (SH2) domains and activates several signaling pathways controling cellular motility, proliferation, adhesion, and apoptosis. Beyond this passive role of phosphorylated domain and site display for partners, recent structural and function studies unveiled active roles in regulation of phosphorylation and interaction: the CT regulates activity of the kinase domain; different phosphorylation states have different compaction levels, potentially modulating the succession of phosphorylation events; and prolines have an important role in structure, dynamics, and possibly regulatory interactions. Here, we review both the canonical role of the disordered CT domains of ErbBs as phosphotyrosine display domains and the recent findings that expand the known range of their regulation functions linked to specific structural and dynamic features.

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Receptor Tyrosine Kinases and Their Signaling Pathways as Therapeutic Targets of Curcumin in Cancer

Frontiers in Pharmacology ◽

10.3389/fphar.2021.772510 ◽

2021 ◽

Vol 12 ◽

Author(s):

Sareshma Sudhesh Dev ◽

Syafiq Asnawi Zainal Abidin ◽

Reyhaneh Farghadani ◽

Iekhsan Othman ◽

Rakesh Naidu

Keyword(s):

Signaling Pathways ◽

Cancer Progression ◽

Tyrosine Kinases ◽

Receptor Tyrosine Kinases ◽

Surface Proteins ◽

Downstream Signaling ◽

Anti Cancer ◽

Rtk Inhibitors

Receptor tyrosine kinases (RTKs) are transmembrane cell-surface proteins that act as signal transducers. They regulate essential cellular processes like proliferation, apoptosis, differentiation and metabolism. RTK alteration occurs in a broad spectrum of cancers, emphasising its crucial role in cancer progression and as a suitable therapeutic target. The use of small molecule RTK inhibitors however, has been crippled by the emergence of resistance, highlighting the need for a pleiotropic anti-cancer agent that can replace or be used in combination with existing pharmacological agents to enhance treatment efficacy. Curcumin is an attractive therapeutic agent mainly due to its potent anti-cancer effects, extensive range of targets and minimal toxicity. Out of the numerous documented targets of curcumin, RTKs appear to be one of the main nodes of curcumin-mediated inhibition. Many studies have found that curcumin influences RTK activation and their downstream signaling pathways resulting in increased apoptosis, decreased proliferation and decreased migration in cancer both in vitro and in vivo. This review focused on how curcumin exhibits anti-cancer effects through inhibition of RTKs and downstream signaling pathways like the MAPK, PI3K/Akt, JAK/STAT, and NF-κB pathways. Combination studies of curcumin and RTK inhibitors were also analysed with emphasis on their common molecular targets.

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Characterization of elk, a brain-specific receptor tyrosine kinase

Molecular and Cellular Biology ◽

10.1128/mcb.11.5.2496-2502.1991 ◽

1991 ◽

Vol 11 (5) ◽

pp. 2496-2502

Author(s):

V Lhoták ◽

P Greer ◽

K Letwin ◽

T Pawson

Keyword(s):

Tyrosine Kinase ◽

Receptor Tyrosine Kinase ◽

Tyrosine Kinases ◽

Protein Tyrosine Kinase ◽

Catalytic Domain ◽

Signal Sequence ◽

Tyrosine Kinase Domain ◽

Rat Tissues ◽

Protein Tyrosine

The elk gene encodes a novel receptorlike protein-tyrosine kinase, which belongs to the eph subfamily. We have previously identified a partial cDNA encompassing the elk catalytic domain (K. Letwin, S.-P. Yee, and T. Pawson, Oncogene 3:621-678, 1988). Using this cDNA as a probe, we have isolated cDNAs spanning the entire rat elk coding sequence. The predicted Elk protein contains all the hallmarks of a receptor tyrosine kinase, including an N-terminal signal sequence, a cysteine-rich extracellular domain, a membrane-spanning segment, a cytoplasmic tyrosine kinase domain, and a C-terminal tail. In both amino acid sequence and overall structure, Elk is most similar to the Eph and Eck protein-tyrosine kinases, suggesting that the eph, elk, and eck genes encode members of a new subfamily of receptorlike tyrosine kinases. Among rat tissues, elk expression appears restricted to brain and testes, with the brain having higher levels of both elk RNA and protein. Elk protein immunoprecipitated from a rat brain lysate becomes phosphorylated on tyrosine in an in vitro kinase reaction, consistent with the prediction that the mammalian elk gene encodes a tyrosine kinase capable of autophosphorylation. The characteristics of the Elk tyrosine kinase suggest that it may be involved in cell-cell interactions in the nervous system.

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SRC Kinase in Glioblastoma: News from an Old Acquaintance

Cancers ◽

10.3390/cancers12061558 ◽

2020 ◽

Vol 12 (6) ◽

pp. 1558 ◽

Cited By ~ 1

Author(s):

Claudia Cirotti ◽

Claudia Contadini ◽

Daniela Barilà

Keyword(s):

Receptor Tyrosine Kinase ◽

Tyrosine Kinases ◽

Receptor Tyrosine Kinases ◽

Metabolic Reprogramming ◽

Constitutive Activity ◽

Therapeutic Approaches ◽

Resistance To Therapy ◽

Downstream Signaling ◽

Wide Range ◽

Therapy Effectiveness

Glioblastoma multiforme (GBM) is one of the most recalcitrant brain tumors characterized by a tumor microenvironment (TME) that strongly supports GBM growth, aggressiveness, invasiveness, and resistance to therapy. Importantly, a common feature of GBM is the aberrant activation of receptor tyrosine kinases (RTKs) and of their downstream signaling cascade, including the non-receptor tyrosine kinase SRC. SRC is a central downstream intermediate of many RTKs, which triggers the phosphorylation of many substrates, therefore, promoting the regulation of a wide range of different pathways involved in cell survival, adhesion, proliferation, motility, and angiogenesis. In addition to the aforementioned pathways, SRC constitutive activity promotes and sustains inflammation and metabolic reprogramming concurring with TME development, therefore, actively sustaining tumor growth. Here, we aim to provide an updated picture of the molecular pathways that link SRC to these events in GBM. In addition, SRC targeting strategies are discussed in order to highlight strengths and weaknesses of SRC inhibitors in GBM management, focusing our attention on their potentialities in combination with conventional therapeutic approaches (i.e., temozolomide) to ameliorate therapy effectiveness.

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