scholarly journals Kinetics of cytokine receptor trafficking determine signaling and functional selectivity

2019 ◽  
Author(s):  
J. Martinez-Fabregas ◽  
S. Wilmes ◽  
L. Wang ◽  
M. Hafer ◽  
E. Pohler ◽  
...  
Keyword(s):  
Receptor Binding ◽  
Ex Vivo ◽  
Treg Cells ◽  
Cytokine Receptor ◽  
Binding Kinetics ◽  
Functional Selectivity ◽  
Gene Expression Response ◽  
Surface Receptors ◽  
Downstream Signaling ◽  
Stat3 Phosphorylation

ABSTRACTCytokines activate downstream signaling networks via assembly of cell surface receptors, but it is unclear whether modulation of cytokine-receptor binding parameters can modify biological outcomes. We have engineered variants of IL-6 with different affinities to the gp130 receptor chain to investigate how cytokine receptor binding kinetics influence functional selectivity. Engineered IL-6 variants showed a range of signaling amplitudes, from minimal to full agonist, and induced biased signaling, with changes in receptor binding kinetics affecting more profoundly STAT1 than STAT3 phosphorylation. We show that this differential signaling arises from defective translocation of ligand-gp130 complexes to the endosomal compartment and competitive STAT1/STAT3 binding to phospho-tyrosines in gp130, and results in unique patterns of STAT3 binding to chromatin. This, in turn, leads to a graded gene expression response and substantial differences in ex vivo differentiation of Th17, Th1 and Treg cells. These results provide a molecular understanding of signaling biased by cytokine receptors, and demonstrate that manipulation of signaling thresholds is a useful strategy to decouple cytokine functional pleiotropy.

scholarly journals Kinetics of cytokine receptor trafficking determine signaling and functional selectivity

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Jonathan Martinez-Fabregas ◽  
Stephan Wilmes ◽  
Luopin Wang ◽  
Maximillian Hafer ◽  
Elizabeth Pohler ◽  
...  
Keyword(s):  
Receptor Binding ◽  
Ex Vivo ◽  
Treg Cells ◽  
Cytokine Receptor ◽  
Functional Selectivity ◽  
Gene Expression Response ◽  
Surface Receptors ◽  
Stat3 Phosphorylation ◽  
Biased Signaling ◽  
Expression Response

Cytokines activate signaling via assembly of cell surface receptors, but it is unclear whether modulation of cytokine-receptor binding parameters can modify biological outcomes. We have engineered IL-6 variants with different affinities to gp130 to investigate how cytokine receptor binding dwell-times influence functional selectivity. Engineered IL-6 variants showed a range of signaling amplitudes and induced biased signaling, with changes in receptor binding dwell-times affecting more profoundly STAT1 than STAT3 phosphorylation. We show that this differential signaling arises from defective translocation of ligand-gp130 complexes to the endosomal compartment and competitive STAT1/STAT3 binding to phospho-tyrosines in gp130, and results in unique patterns of STAT3 binding to chromatin. This leads to a graded gene expression response and differences in ex vivo differentiation of Th17, Th1 and Treg cells. These results provide a molecular understanding of signaling biased by cytokine receptors, and demonstrate that manipulation of signaling thresholds is a useful strategy to decouple cytokine functional pleiotropy.

scholarly journals SAT-604 The Role of the Focal Adhesion Kinase Family in Leptin Receptor Signaling

2020 ◽  
Vol 4 (Supplement_1) ◽  
Author(s):  
Colleen Hadley ◽  
Isin Cakir ◽  
Roger D Cone
Keyword(s):  
Food Intake ◽  
Focal Adhesion Kinase ◽  
Focal Adhesion ◽  
Leptin Receptor ◽  
Kinase Activity ◽  
Cytokine Receptor ◽  
Receptor Signaling ◽  
Kinase Family ◽  
Stat3 Phosphorylation

Abstract Overweight and obesity are global concerns affecting nearly one third of the world population. These conditions are characterized by increased adiposity and are accompanied by a proportional increase in circulating leptin, an anorexigenic adipokine. Leptin is responsible for signaling peripheral energy status to the central nervous system to modulate food intake and energy expenditure. As such, neurons within the hypothalamus expressing the long isoform of leptin receptor (LepRb), a type I cytokine receptor, are primarily responsible for mediating the effects of leptin, which signal predominantly through the JAK2-STAT3 transduction mechanism. STAT3 is a latent transcription factor activated upon phosphorylation, which triggers its homodimerization and nuclear translocation. Evidence, however, for JAK2-independent, STAT3-dependent leptin receptor signaling mechanisms exist. FAK (focal adhesion kinase, Ptk2) and Pyk2 (protein tyrosine kinase 2b, Ptk2b) are a subset of nonreceptor protein tyrosine kinases and comprise the focal adhesion kinase family. FAK and Pyk2 are implicated in the regulation of cytokine receptor signaling. Furthermore, Pyk2 knockout mice have an obesity prone phenotype. Here, we studied the role of the focal adhesion kinases in leptin receptor signaling using genetic and pharmacological approaches. We found that overexpression of Pyk2 or FAK increased STAT3 phosphorylation (activation). Overexpression of a FAK or Pyk2 construct with impaired kinase activity, however, attenuated STAT3 phosphorylation, suggesting the increase in STAT3 phosphorylation is largely dependent upon kinase activity of FAK/Pyk2. Treatment of cells with a small molecule dual inhibitor of FAK and Pyk2 (PF431396) attenuated leptin-induced STAT3 phosphorylation in a mouse hypothalamic cell line. Importantly, this effect is independent of JAK2, as PF treatment of two independent JAK2-deficient cell lines exhibited similar attenuation of leptin-induced STAT3 phosphorylation. To assess the physiological relevance of FAK/Pyk2 in leptin receptor signaling in vivo, we administered PF compound to the lateral ventricle of 24-hour fasted lean wild-type mice followed by peripheral leptin administration. Intracerebroventricular (ICV) administration of PF suppressed the anorectic effect of leptin as evidenced by impaired inhibition of food intake upon refeeding. Accordingly, analysis of total hypothalamic lysates from these mice showed ICV PF impaired leptin-induced STAT3 phosphorylation. Taken together, these data suggest that Pyk2 and/or FAK play a role in leptin signal transduction.

scholarly journals FOXP3 expression accurately defines the population of intratumoral regulatory T cells that selectively accumulate in metastatic melanoma lesions

Blood ◽  
2008 ◽  
Vol 112 (13) ◽  
pp. 4953-4960 ◽  
Author(s):  
Mojgan Ahmadzadeh ◽  
Aloisio Felipe-Silva ◽  
Bianca Heemskerk ◽  
Daniel J. Powell ◽  
John R. Wunderlich ◽  
...  
Keyword(s):  
T Cells ◽  
Tumor Microenvironment ◽  
Metastatic Melanoma ◽  
Treg Cell ◽  
Peripheral Blood ◽  
Ex Vivo ◽  
Production Capacity ◽  
Biological Marker ◽  
Foxp3 Expression ◽  
Treg Cells

Abstract Regulatory T (Treg) cells are often found in human tumors; however, their functional characteristics have been difficult to evaluate due to low cell numbers and the inability to adequately distinguish between activated and Treg cell populations. Using a novel approach, we examined the intracellular cytokine production capacity of tumor-infiltrating T cells in the single-cell suspensions of enzymatically digested tumors to differentiate Treg cells from effector T cells. Similar to Treg cells in the peripheral blood of healthy individuals, tumor-infiltrating FOXP3+CD4 T cells, unlike FOXP3− T cells, were unable to produce IL-2 and IFN-γ upon ex vivo stimulation, indicating that FOXP3 expression is a valid biological marker for human Treg cells even in the tumor microenvironment. Accordingly, we enumerated FOXP3+CD4 Treg cells in intratumoral and peritumoral sections of metastatic melanoma tumors and found a significant increase in proportion of FOXP3+CD4 Treg cells in the intratumoral compared with peritumoral areas. Moreover, their frequencies were 3- to 5-fold higher in tumors than in peripheral blood from the same patients or healthy donors, respectively. These findings demonstrate that the tumor-infiltrating CD4 Treg cell population is accurately depicted by FOXP3 expression, they selectively accumulate in tumors, and their frequency in peripheral blood does not properly reflect tumor microenvironment.

Activated Protein C Strengthens Cardiac Tolerance to Ischemic Insults in Aging

2021 ◽  
Author(s):  
Di Ren ◽  
Julia Fedorova ◽  
Kayla Davitt ◽  
Tran Ngoc Van Le ◽  
John H Griffin ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Protein C ◽  
Ex Vivo ◽  
Activated Protein C ◽  
Wild Type ◽  
Endothelial Protein C Receptor ◽  
Cardiac Damage ◽  
Downstream Signaling ◽  
Cardioprotective Effects ◽  
Epcr Shedding

Background: Activated protein C (APC) is a plasma serine protease with anticoagulant and anti-inflammatory activities. Endothelial protein C receptor (EPCR) is associated with APC's activity and mediates its downstream signaling events. APC exerts cardioprotective effects during ischemia and reperfusion (I/R). This study aims to characterize the role of the APC-EPCR axis in ischemic insults in aging. Methods: Young (3-4 months) and aged (24-26 months) wild type C57BL/6J mice, as well as EPCR point mutation (EPCR R84A/R84A ) knock-in C57BL/6J mice incapable of interaction with APC and its wild type of littermate C57BL/6J mice, were subjected to I/R. Wild type APC, signaling-selective APC-2Cys, or anticoagulant-selective APC-E170A were administrated before reperfusion. Results: The results demonstrated that cardiac I/R reduces APC activity, and the APC activity was impaired in the aged versus young hearts possibly attributable to the declined EPCR level with aging. Serum EPCR measurement showed that I/R triggered the shedding of membrane EPCR into circulation, while administration of APC attenuated the I/R-induced EPCR shedding in both young and aged hearts. Subsequent echocardiography showed that APC and APC-2Cys but not APC-E170A ameliorated cardiac dysfunction during I/R in both young and aged mice. Importantly, APC elevated the resistance of the aged heart to ischemic insults through stabilizing EPCR. However, all these cardioprotective effects of APC were blunted in the EPCR R84A/R84A mice versus its wild-type littermates. The ex vivo working heart and metabolomics results demonstrated that AMP-activated protein kinase (AMPK) mediates acute adaptive response while protein kinase B (AKT) is involved in chronic metabolic programming in the hearts with APC treatment. Conclusions: I/R stress causes shedding of the membrane EPCR in the heart, and administration of APC prevents I/R-induced cardiac EPCR shedding that is critical for limiting cardiac damage in aging.

scholarly journals Vav Family Proteins Couple to Diverse Cell Surface Receptors

2000 ◽  
Vol 20 (17) ◽  
pp. 6364-6373 ◽  
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.

scholarly journals Baicalin suppresses lung cancer growth by targeting PDZ-binding kinase/T-LAK cell-originated protein kinase

2019 ◽  
Vol 39 (4) ◽  
Author(s):  
Xin Diao ◽  
Danfen Yang ◽  
Yu Chen ◽  
Wentian Liu
Keyword(s):  
Lung Cancer ◽  
Protein Kinase ◽  
Cancer Cells ◽  
Ex Vivo ◽  
Lung Cancer Cells ◽  
Cancer Growth ◽  
Downstream Signaling ◽  
Lak Cell

AbstractBaicalin is the main bioactive component extracted from the traditional Chinese medicine Baical Skullcap Root, and its anti-tumor activity has been studied in previous studies. PDZ-binding kinase/T-LAK cell-originated protein kinase (PBK/TOPK), a serine/threonine protein kinase, is highly expressed in many cancer cells and stimulates the tumorigenic properties, and so, it is a pivotal target for agent to cure cancers. We reported for the first time that baicalin suppressed PBK/TOPK activities by directly binding with PBK/TOPK in vitro and in vivo. Ex vivo studies showed that baicalin suppressed PBK/TOPK activity in JB6 Cl41 cells and H441 lung cancer cells. Moreover, knockdown of PBK/TOPK in H441 cells decreased their sensitivity to baicalin. In vivo study indicated that injection of baicalin in H441 tumor-bearing mice effectively suppressed cancer growth. The PBK/TOPK downstream signaling molecules Histone H3 and ERK2 in tumor tissues were also decreased after baicalin treatment. Taken together, baicalin can inhibit proliferation of lung cancer cells as a PBK/TOPK inhibitor both in vitro and in vivo.

Glycosylation of Erythropoietin Affects Receptor Binding Kinetics:  Role of Electrostatic Interactions

Biochemistry ◽  
2002 ◽  
Vol 41 (49) ◽  
pp. 14524-14531 ◽  
Author(s):  
Ryan J. Darling ◽  
Uma Kuchibhotla ◽  
Wolfgang Glaesner ◽  
Radmila Micanovic ◽  
Derrick R. Witcher ◽  
...  
Keyword(s):  
Receptor Binding ◽  
Electrostatic Interactions ◽  
Binding Kinetics

Ex-vivo expanded baboon CD4+ CD25Hi Treg cells suppress baboon anti-pig T and B cell immune response

2012 ◽  
Vol 19 (2) ◽  
pp. 102-111 ◽  
Author(s):  
Avneesh K. Singh ◽  
Caleb N. Seavey ◽  
Keith A. Horvath ◽  
Muhammad M. Mohiuddin
Keyword(s):  
Immune Response ◽  
B Cell ◽  
Ex Vivo ◽  
Treg Cells ◽  
Cell Immune Response

Quantitative Assessment of Pulmonary Targeting of Inhaled Corticosteroids Using Ex Vivo Receptor Binding Studies

2020 ◽  
Vol 22 (2) ◽  
Author(s):  
Jie Shao ◽  
James Talton ◽  
Yaning Wang ◽  
Lawrence Winner ◽  
Guenther Hochhaus
Keyword(s):  
Receptor Binding ◽  
Quantitative Assessment ◽  
Inhaled Corticosteroids ◽  
Ex Vivo ◽  
Binding Studies
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