scholarly journals Dimer Interface in Natural Variant NK1 Is Dispensable for HGF-Dependent Met Receptor Activation

2021 ◽  
Vol 22 (17) ◽  
pp. 9240
Author(s):  
Yumiko Tahira ◽  
Katsuya Sakai ◽  
Hiroki Sato ◽  
Ryu Imamura ◽  
Kunio Matsumoto
Keyword(s):  
Tyrosine Phosphorylation ◽  
Receptor Activation ◽  
Structural Basis ◽  
Wild Type ◽  
Met Receptor ◽  
Dimer Formation ◽  
Structural Mechanism ◽  
Biological Responses ◽  
Natural Variant ◽  
Hepatocyte Growth

NK1, a splicing variant of hepatocyte growth factor (HGF), binds to and activates Met receptor by forming an NK1 dimer and 2:2 complex with Met. Although the structural mechanism underlying Met activation by HGF remains incompletely resolved, it has been proposed that the NK1 dimer structure participates in this activation. We investigated the NK1 dimer interface’s role in Met activation by HGF. Because N127, V140, and K144 are closely involved in the head-to-tail NK1 dimer formation, mutant NK1 proteins with replacement of these residues by alanine were prepared. In Met tyrosine phosphorylation assays, N127-NK1, V140-NK1, and K144-NK1 showed 8.3%, 23.8%, and 52.2% activity, respectively, compared with wild-type NK1. Although wild-type NK1 promoted cell migration and scattering, N127-NK1, V140-NK1, and K144-NK1 hardly or marginally promoted them, indicating loss of activity of these mutant NK1 proteins to activate Met. In contrast, mutant HGFs (N127-HGF, V140-HGF, and K144-HGF) with the same amino acid replacements as in NK1 induced Met tyrosine phosphorylation and biological responses at levels comparable to those of wild-type HGF. These results indicate that the structural basis responsible for NK1-dependent Met dimer formation and activation differs from, or is at least distinguishable from, the structural basis responsible for HGF-dependent Met activation.

Hepatocyte Growth Factor and Macrophage-stimulating Protein “Hinge” Analogs to Treat Pancreatic Cancer

2019 ◽  
Vol 19 (10) ◽  
pp. 782-795
Author(s):  
John W. Wright ◽  
Kevin J. Church ◽  
Joseph W. Harding
Keyword(s):  
Pancreatic Cancer ◽  
Signal Transduction ◽  
Growth Factor ◽  
Hepatocyte Growth Factor ◽  
Tumor Growth ◽  
Receptor Activation ◽  
Signal Transduction Pathways ◽  
Met Receptor ◽  
Macrophage Stimulating Protein ◽  
Hepatocyte Growth

Pancreatic cancer (PC) ranks twelfth in frequency of diagnosis but is the fourth leading cause of cancer related deaths with a 5 year survival rate of less than 7 percent. This poor prognosis occurs because the early stages of PC are often asymptomatic. Over-expression of several growth factors, most notably vascular endothelial growth factor (VEGF), has been implicated in PC resulting in dysfunctional signal transduction pathways and the facilitation of tumor growth, invasion and metastasis. Hepatocyte growth factor (HGF) acts via the Met receptor and has also received research attention with ongoing efforts to develop treatments to block the Met receptor and its signal transduction pathways. Macrophage-stimulating protein (MSP), and its receptor Ron, is also recognized as important in the etiology of PC but is less well studied. Although the angiotensin II (AngII)/AT1 receptor system is best known for mediating blood pressure and body water/electrolyte balance, it also facilitates tumor vascularization and growth by stimulating the expression of VEGF. A metabolite of AngII, angiotensin IV (AngIV) has sequence homology with the “hinge regions” of HGF and MSP, key structures in the growth factor dimerization processes necessary for Met and Ron receptor activation. We have developed AngIV-based analogs designed to block dimerization of HGF and MSP and thus receptor activation. Norleual has shown promise as tested utilizing PC cell cultures. Results indicate that cell migration, invasion, and pro-survival functions were suppressed by this analog and tumor growth was significantly inhibited in an orthotopic PC mouse model.

scholarly journals Structural Basis and Functional Consequence of Helicobacter pylori CagA Multimerization in Cells

2006 ◽  
Vol 281 (43) ◽  
pp. 32344-32352 ◽  
Author(s):  
Shumei Ren ◽  
Hideaki Higashi ◽  
Huaisheng Lu ◽  
Takeshi Azuma ◽  
Masanori Hatakeyama
Keyword(s):  
Helicobacter Pylori ◽  
Tyrosine Phosphorylation ◽  
Cell Shape ◽  
Host Cells ◽  
Structural Basis ◽  
Sequence Motif ◽  
Wild Type ◽  
Src Homology 2 ◽  
Src Homology ◽  
In Cells

Helicobacter pylori cagA-positive strains are associated with gastric adenocarcinoma. The cagA gene product CagA is delivered into gastric epithelial cells where it localizes to the plasma membrane and undergoes tyrosine phosphorylation at the EPIYA-repeat region, which contains the EPIYA-A segment, EPIYA-B segment, and Western CagA-specific EPIYA-C or East Asian CagA-specific EPIYA-D segment. In host cells, CagA specifically binds to and deregulates SHP-2 phosphatase via the tyrosine-phosphorylated EPIYA-C or EPIYA-D segment, thereby inducing an elongated cell shape known as the hummingbird phenotype. In this study, we found that CagA multimerizes in cells in a manner independent of its tyrosine phosphorylation. Using a series of CagA mutants, we identified a conserved amino acid sequence motif (FPLXRXXXVXDLSKVG), which mediates CagA multimerization, within the EPIYA-C segment as well as in a sequence that located immediately downstream of the EPIYA-C or EPIYA-D segment. We also found that a phosphorylation-resistant CagA, which multimerizes but cannot bind SHP-2, inhibits the wild-type CagA-SHP-2 complex formation and abolishes induction of the hummingbird phenotype. Thus, SHP-2 binds to a preformed and tyrosinephosphorylated CagA multimer via its two Src homology 2 domains. These results, in turn, indicate that CagA multimerization is a prerequisite for CagA-SHP-2 interaction and subsequent deregulation of SHP-2. The present work raises the possibility that inhibition of CagA multimerization abolishes pathophysiological activities of CagA that promote gastric carcinogenesis.

scholarly journals Axonal Neuregulin Signals Cells of the Oligodendrocyte Lineage through Activation of HER4 and Schwann Cells through HER2 and HER3

1997 ◽  
Vol 137 (1) ◽  
pp. 211-220 ◽  
Author(s):  
Timothy Vartanian ◽  
Andrew Goodearl ◽  
Andrea Viehöver ◽  
Gerald Fischbach
Keyword(s):  
Progenitor Cells ◽  
Tyrosine Phosphorylation ◽  
Schwann Cells ◽  
Egf Receptor ◽  
Receptor Activation ◽  
Dorsal Root Ganglion Neurons ◽  
Physical Interaction ◽  
Biological Responses ◽  
Glial Growth Factor ◽  
Ganglion Neurons

We are interested in the signaling between axons and glia that leads to myelination and maintenance of the myelin internode, and we have focused on the role of neuregulins and their receptors. Neuregulins are a family of ligands that includes heregulin, neu differentiation factor, glial growth factor, and the acetylcholine receptor–inducing activity. Three signal transducing transmembrane receptors for neuregulins, which bear significant homology to the EGF receptor, are currently known: HER2 (erbB2), HER3 (erbB3), and HER4 (erbB4). We have found that oligodendrocite–type II astrocyte (O2A) progenitor cells and mature oligodendrocytes express HER2 and HER4 but no HER3. Schwann cells express HER2 and HER3 but little HER4. In O2A progenitor cells and oligodendrocytes, recombinant neuregulin induces the rapid tyrosine phosphorylation of only HER4. HER2 is not phosphorylated in cells of the oligodendrocyte lineage, but a physical interaction between HER2 and HER4 was detected in coimmunoprecipitation experiments. In Schwann cells, neuregulin induces the phosphorylation of both HER2 and HER3. Coimmunoprecipitation experiments indicate that receptor activation in Schwann cells results in the formation of HER2:HER3 heterodimers. Neuregulin localized immunocytochemically was present on neurites of cultured dorsal root ganglion neurons, and it was released into the medium in a form that promoted receptor tyrosine phosphorylation. Neuregulins therefore meet important criteria expected of molecules involved in axonal-glial signaling. The use of unique neuregulin receptor combinations in oligodendrocytes and Schwann cells likely results in recruitment of different signaling pathways and thus provides a basis for different biological responses.

scholarly journals Pak4, a Novel Gab1 Binding Partner, Modulates Cell Migration and Invasion by the Met Receptor

2009 ◽  
Vol 29 (11) ◽  
pp. 3018-3032 ◽  
Author(s):  
Grigorios N. Paliouras ◽  
Monica A. Naujokas ◽  
Morag Park
Keyword(s):  
Cell Migration ◽  
Epithelial Cell ◽  
Migration And Invasion ◽  
Cell Periphery ◽  
Met Receptor ◽  
Interacting Protein ◽  
Biological Responses ◽  
Novel Association ◽  
P21 Activated Kinase ◽  
Hepatocyte Growth

ABSTRACT Hepatocyte growth factor (HGF), the ligand for the Met receptor tyrosine kinase, induces epithelial cell dispersal, invasion, and morphogenesis, events that require remodeling of the actin cytoskeleton. The scaffold protein Gab1 is essential for these biological responses downstream from Met. We have identified p21-activated kinase 4 (Pak4) as a novel Gab1-interacting protein. We show that in response to HGF, Gab1 and Pak4 associate and colocalize at the cell periphery within lamellipodia. The association between Pak4 and Gab1 is dependent on Gab1 phosphorylation but independent of Pak4 kinase activity. The interaction is mediated through a region in Gab1, which displays no homology to known Gab1 interaction motifs and through the guanine exchange factor-interacting domain of Pak4. In response to HGF, Gab1 and Pak4 synergize to enhance epithelial cell dispersal, migration, and invasion, whereas knockdown of Pak4 attenuates these responses. A Gab1 mutant unable to recruit Pak4 fails to promote epithelial cell dispersal and an invasive morphogenic program in response to HGF, demonstrating a physiological requirement for Gab1-Pak4 association. These data demonstrate a novel association between Gab1 and Pak4 and identify Pak4 as a key integrator of cell migration and invasive growth downstream from the Met receptor.

Modeling targeted inhibition of wild type and mutated c-MET receptor

2007 ◽  
Vol 25 (18_suppl) ◽  
pp. 14010-14010
Author(s):  
P. C. Ma ◽  
S. Jiang ◽  
R. Du ◽  
S. Dietrich ◽  
Z. Tang ◽  
...  
Keyword(s):  
Tyrosine Kinase ◽  
Kinase Inhibitor ◽  
Receptor Activation ◽  
Kinase Domain ◽  
Cell System ◽  
Tyrosine Kinase Domain ◽  
Wild Type ◽  
Juxtamembrane Domain ◽  
Met Receptor

14010 Background: c-MET belongs to the semaphorin superfamily of signaling proteins, containing three protein families (semaphorins, plexins, c-MET and RON) that have central roles in cell signaling. The c-MET receptor tyrosine kinase is involved in regulating cell growth/proliferation, survival, angiogenesis, cell scattering, cell motility and migration. Mutations in c-MET have been identified in various human cancers including lung cancer and papillary renal cell carcinomas. c-MET mutations occur within the extracellular seven-blade β-propeller fold sema domain (E168D, L229F, S325G, N375S), juxtamembrane domain (R988C, T1010I), and kinase domain (M1268T). We hypothesized that these mutations would have differential effects on the kinase inhibition. Methods: We modeled the various c-MET mutations from different functional domains of the receptor using a G418-resistant stable Cos-7 transfection cell system to determine their effect on sensitivity to a selective c-MET kinase inhibitor SU11274. Sensitivity to SU11274 inhibition was assayed by phospho-immunoblotting using phospho- specific antibody against the major tyrosine kinase phosphorylation epitopes pY1234/1235 of the c-MET kinase in vitro. Results: First, we identified that mutations in the sema and juxtamembrane domain were activating as defined by ligand-independent constitutive receptor activation. SU11274 was capable of inhibiting ligand induced signaling through the wild-type c-MET as well as mutant c-MET receptors harboring mutations in the sema, juxtamembrane and tyrosine kinase domain. However, SU11274 inhibition of mutant c-MET was mutation-dependent, with the juxtamembrane domain mutations R988C and T1010I resulting in a receptor form that was less sensitive to SU11274. Mutations in the sema and kinase domain also resulted in varying sensitivity to inhibition by SU11274 inhibition. Conclusions: Mutations in the sema and juxtamembrane domain of c-MET result in receptor activation. The small molecule inhibitor SU11274 is active against wild type and mutated c- MET receptor. Further studies to characterize the signaling effects and the mechanism of sensitivity and resistance of c-MET mutations to specific inhibitors are crucial in the successful development of therapeutic c-MET and mutant c-MET inhibitors. No significant financial relationships to disclose.

Agonistic monoclonal antibodies against the Met receptor dissect the biological responses to HGF

1998 ◽  
Vol 111 (2) ◽  
pp. 237-247 ◽  
Author(s):  
M. Prat ◽  
T. Crepaldi ◽  
S. Pennacchietti ◽  
F. Bussolino ◽  
P.M. Comoglio
Keyword(s):  
Monoclonal Antibodies ◽  
Growth Factor ◽  
Hepatocyte Growth Factor ◽  
Receptor Activation ◽  
Receptor Dimerization ◽  
Full Agonist ◽  
Biological Responses ◽  
Type Plasminogen Activator ◽  
Urokinase Type Plasminogen Activator ◽  
Hepatocyte Growth

Hepatocyte growth factor, also known as scatter factor, is a pleiotropic cytokine, which stimulates cell motility, invasion, proliferation, survival and morphogenesis, and induces the expression of specific genes by activating its receptor tyrosine kinase. In this work we have isolated, characterized and used as agonists two monoclonal antibodies (mAbs) directed against the extracellular domain of HGF receptor to investigate the requirements for receptor activation and for the different biological responses. The two mAbs display similar affinities, react with epitopes different from the hepatocyte growth factor binding site, and behave as either full or partial agonists. The full agonist mAb (DO-24) triggers all the biological effects elicited by hepatocyte growth factor, namely motility, proliferation, cell survival, invasion, tubulogenesis and angiogenesis. The partial agonist mAb (DN-30) induces only motility. Only the full agonist mAb is able to induce and sustain the expression of urokinase-type plasminogen activator receptor for prolonged periods of time, while both mAbs up-regulate the constitutive expression of urokinase-type plasminogen activator. Both mAbs activate receptor phosphorylation, which, being strictly dependent on mAb bivalence, requires receptor dimerization. Since simple receptor dimerization is not sufficient to trigger full biological responses, we propose that the region on the ss chain of the receptor recognized by the full agonist mAb is crucial for optimal receptor activation.

State of the structure address on MET receptor activation by HGF

2021 ◽  
Author(s):  
Edmond M. Linossi ◽  
Gabriella O. Estevam ◽  
Masaya Oshima ◽  
James S. Fraser ◽  
Eric A. Collisson ◽  
...  
Keyword(s):  
Conformational Changes ◽  
Complex Structure ◽  
Bound State ◽  
Receptor Activation ◽  
Current View ◽  
Met Receptor ◽  
Signaling Axis ◽  
Hepatocyte Growth ◽  
A Current ◽  
Important Drug

The MET receptor tyrosine kinase (RTK) and its cognate ligand hepatocyte growth factor (HGF) comprise a signaling axis essential for development, wound healing and tissue homeostasis. Aberrant HGF/MET signaling is a driver of many cancers and contributes to drug resistance to several approved therapeutics targeting other RTKs, making MET itself an important drug target. In RTKs, homeostatic receptor signaling is dependent on autoinhibition in the absence of ligand binding and orchestrated set of conformational changes induced by ligand-mediated receptor dimerization that result in activation of the intracellular kinase domains. A fundamental understanding of these mechanisms in the MET receptor remains incomplete, despite decades of research. This is due in part to the complex structure of the HGF ligand, which remains unknown in its full-length form, and a lack of high-resolution structures of the complete MET extracellular portion in an apo or ligand-bound state. A current view of HGF-dependent MET activation has evolved from biochemical and structural studies of HGF and MET fragments and here we review what these findings have thus far revealed.

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