Integrated analysis of ERBB receptor activation and downstream signaling with EXTassays

AbstractThe kappa opioid receptor (KOR) has emerged as a promising therapeutic target for pain and itch treatment. There is growing interest in biased agonists that preferentially activate select signaling pathways downstream of KOR activation on the cellular level due to their therapeutic promise in retaining the analgesic and antipruritic effects and eliminating the sedative and dysphoric effects of KOR signaling on the physiological level. The concept of ligand-selective signaling includes that biased ligands promote KOR to selectively recruit one transducer or regulator protein over another, introducing bias into the signaling cascade at the very receptor-proximal level. Measuring agonist effects directly at the receptor has remained challenging and previous studies have focused on inferring agonist-selective KOR engagement with G protein relative to β-arrestin based on downstream signaling readouts. Here we discuss novel strategies to directly assess ligand-selective effects on receptor activation using KOR-interacting biosensors. The conformation-specific cytoplasmic biosensors are disconnected from the endogenous signaling machinery and provide a direct receptor-proxy readout of ligand effects in living cells. Receptor–biosensor interaction is ligand concentration dependent and can be used to determine relative ligand potency and efficacy. In addition, the biosensors reveal the existence of two dimensions of agonist bias in the cellular context: Firstly, agonists can selectively produce discrete protein-engaged KOR states and secondly, agonists can differ in the precise subcellular location at which they activate KOR. We discuss the value and the limitations of using orthogonal receptor-interacting biosensors in the quest to understand functional selectivity amongst KOR agonists in the cellular context.

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Role of Ca2+ in Mediating Plant Responses to Extracellular ATP and ADP

International Journal of Molecular Sciences ◽

10.3390/ijms19113590 ◽

2018 ◽

Vol 19 (11) ◽

pp. 3590 ◽

Cited By ~ 8

Author(s):

Greg Clark ◽

Stanley Roux

Keyword(s):

Cytosolic Calcium ◽

Defense Responses ◽

Receptor Activation ◽

Extracellular Atp ◽

Extracellular Nucleotides ◽

Nucleoside Triphosphate ◽

Plant Responses ◽

Downstream Signaling ◽

Nucleoside Triphosphate Diphosphohydrolase

Among the most recently discovered chemical regulators of plant growth and development are extracellular nucleotides, especially extracellular ATP (eATP) and extracellular ADP (eADP). Plant cells release ATP into their extracellular matrix under a variety of different circumstances, and this eATP can then function as an agonist that binds to a specific receptor and induces signaling changes, the earliest of which is an increase in the concentration of cytosolic calcium ([Ca2+]cyt). This initial change is then amplified into downstream-signaling changes that include increased levels of reactive oxygen species and nitric oxide, which ultimately lead to major changes in the growth rate, defense responses, and leaf stomatal apertures of plants. This review presents and discusses the evidence that links receptor activation to increased [Ca2+]cyt and, ultimately, to growth and diverse adaptive changes in plant development. It also discusses the evidence that increased [Ca2+]cyt also enhances the activity of apyrase (nucleoside triphosphate diphosphohydrolase) enzymes that function in multiple subcellular locales to hydrolyze ATP and ADP, and thus limit or terminate the effects of these potent regulators.

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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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erbB-1 and erbB-4 Receptors Act in Concert to Facilitate Female Sexual Development and Mature Reproductive Function

Endocrinology ◽

10.1210/en.2004-1146 ◽

2005 ◽

Vol 146 (3) ◽

pp. 1465-1472 ◽

Cited By ~ 47

Author(s):

Vincent Prevot ◽

Alejandro Lomniczi ◽

Gabriel Corfas ◽

Sergio R. Ojeda

Keyword(s):

Glial Cells ◽

Sexual Development ◽

Double Mutant ◽

Reproductive Function ◽

Receptor Activation ◽

Dominant Negative ◽

Reproductive Capacity ◽

Erbb Receptor ◽

Signaling Systems ◽

Lhrh Release

Glial erbB-1 and erbB-4 receptors are key components of the process by which neuroendocrine glial cells control LHRH secretion and the onset of female puberty. We now provide evidence that these two signaling systems work in a coordinated fashion to control reproductive function. To generate animals carrying functionally impaired erbB-1 and erbB-4 receptors, we crossed Waved 2 (Wa-2+/+) mice harboring a point mutation of the erbB-1 receptor with mice expressing a dominant-negative erbB-4 receptor in astrocytes. In comparison to single-deficient mice, double-mutant animals exhibited a further delay in the onset of puberty and a strikingly diminished adult reproductive capacity. Ligand-dependent erbB receptor phosphorylation and erbB-mediated MAPK (ERK 1/2) phosphorylation were impaired in mutant astrocytes. Wa-2+/+ or double-mutant astrocytes failed to respond to TGFα with production of prostaglandin E2, one of the factors mediating the stimulatory effect of astroglial erbB receptor activation on LHRH release. Medium conditioned by Wa-2+/+ or double-mutant astrocytes treated with TGFα failed to stimulate LHRH release from GT1–7 cells. The LH response to ovariectomy was significantly attenuated in mutant mice in comparison with wild-type controls. Although the Wa-2 mutation affects all cells bearing erbB-1 receptors, these results suggest that a major defect underlying the reproductive defects of animals with impaired erbB signaling is a decreased ability of glial cells to stimulate LHRH release. Thus, a coordinated involvement of erbB-1 and erbB-4 signaling systems is required for the normalcy of sexual development and the maintenance of mature female reproductive function.

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Neuregulin-Heparan-sulfate Proteoglycan Interactions Produce Sustained erbB Receptor Activation Required for the Induction of Acetylcholine Receptors in Muscle

Journal of Biological Chemistry ◽

10.1074/jbc.m104485200 ◽

2001 ◽

Vol 276 (41) ◽

pp. 38068-38075 ◽

Cited By ~ 2

Author(s):

Qunfang Li ◽

Jeffrey A. Loeb

Keyword(s):

Heparan Sulfate ◽

Acetylcholine Receptors ◽

Receptor Activation ◽

Heparan Sulfate Proteoglycan ◽

Erbb Receptor ◽

Sulfate Proteoglycan

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Effects of Prednisolone on Serum and Tissue Fluid IGF-I Receptor Activation and Post-Receptor Signaling in Humans

The Journal of Clinical Endocrinology & Metabolism ◽

10.1210/jc.2017-00696 ◽

2017 ◽

Vol 102 (11) ◽

pp. 4031-4040 ◽

Cited By ~ 9

Author(s):

Nilani Ramshanker ◽

Maiken Aagaard ◽

Rikke Hjortebjerg ◽

Thomas Schmidt Voss ◽

Niels Møller ◽

...

Keyword(s):

Messenger Rna ◽

Protein A ◽

Receptor Activation ◽

Tissue Fluid ◽

Igf Binding Proteins ◽

Downstream Signaling ◽

Specific Effects ◽

Igf I ◽

Underlying Mechanisms ◽

Double Blinded

Abstract Context Short-term glucocorticoid exposure increases serum insulinlike growth factor I (IGF-I) concentrations but antagonizes IGF-I tissue signaling. The underlying mechanisms remain unknown. Objective To identify at which levels glucocorticoid inhibits IGF-I signaling. Design and Methods Nineteen healthy males received prednisolone (37.5 mg/d) and placebo for 5 days in a randomized, double-blinded, placebo-controlled crossover study. Serum was collected on days 1, 3, and 5, and abdominal skin suction blister fluid (SBF; ~interstitial fluid) was taken on day 5 (n = 9) together with muscle biopsy specimens (n = 19). The ability of serum and SBF to activate the IGF-I receptor (IGF-IR) (bioactive IGF) and its downstream signaling proteins was assessed using IGF-IR–transfected cells. Results Prednisolone increased IGF-I concentrations and bioactive IGF in serum (P ≤ 0.001) but not in SBF, which, compared with serum, contained less bioactive IGF (~28%) after prednisolone (P < 0.05). This observation was unexplained by SBF concentrations of IGFs and IGF-binding proteins (IGFBPs) 1 to 4. However, following prednisolone treatment, SBF contained less IGFBP-4 fragments (P < 0.05) generated by pregnancy-associated plasma protein A (PAPP-A). Concomitantly, prednisolone increased SBF levels of stanniocalcin 2 (STC2) (P = 0.02) compared with serum. STC2 blocks PAPP-A from cleaving IGFBP-4. Finally, prednisolone suppressed post–IGF-IR signaling pathways at the level of insulin receptor substrate 1 (P < 0.05) but did not change skeletal muscle IGF-IR, IGF-I, or STC2 messenger RNA. Conclusion Prednisolone increased IGF-I concentrations and IGF bioactivity in serum but not in tissue fluid. The latter may relate to a STC2-mediated inhibition of PAPP-A in tissue fluids. Furthermore, prednisolone induced post–IGF-IR resistance. Thus, glucocorticoid may exert distinct, compartment-specific effects on IGF action.

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Staphylococcus aureus secretes immunomodulatory RNA and DNA via membrane vesicles

Scientific Reports ◽

10.1038/s41598-020-75108-3 ◽

2020 ◽

Vol 10 (1) ◽

Cited By ~ 1

Author(s):

Blanca V. Rodriguez ◽

Meta J. Kuehn

Keyword(s):

Staphylococcus Aureus ◽

Nucleic Acids ◽

Immune Modulation ◽

Membrane Vesicle ◽

Membrane Vesicles ◽

Receptor Activation ◽

Host Cells ◽

Downstream Signaling ◽

Host Immune Responses ◽

Rna And Dna

Abstract Bacterial-derived RNA and DNA can function as ligands for intracellular receptor activation and induce downstream signaling to modulate the host response to bacterial infection. The mechanisms underlying the secretion of immunomodulatory RNA and DNA by pathogens such as Staphylococcus aureus and their delivery to intracellular host cell receptors are not well understood. Recently, extracellular membrane vesicle (MV) production has been proposed as a general secretion mechanism that could facilitate the delivery of functional bacterial nucleic acids into host cells. S. aureus produce membrane-bound, spherical, nano-sized, MVs packaged with a select array of bioactive macromolecules and they have been shown to play important roles in bacterial virulence and in immune modulation through the transmission of biologic signals to host cells. Here we show that S. aureus secretes RNA and DNA molecules that are mostly protected from degradation by their association with MVs. Importantly, we demonstrate that MVs can be delivered into cultured macrophage cells and subsequently stimulate a potent IFN-β response in recipient cells via activation of endosomal Toll-like receptors. These findings advance our understanding of the mechanisms by which bacterial nucleic acids traffic extracellularly to trigger the modulation of host immune responses.

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ErbB Receptor Activation, Cell Morphology Changes, and Apoptosis Induced by Anti-Her2 Monoclonal Antibodies

Biochemical and Biophysical Research Communications ◽

10.1006/bbrc.1996.1311 ◽

1996 ◽

Vol 226 (1) ◽

pp. 59-69 ◽

Cited By ~ 20

Author(s):

Yoshiko Kita ◽

Julia Tseng ◽

Thomas Horan ◽

Jie Wen ◽

John Philo ◽

...

Keyword(s):

Monoclonal Antibodies ◽

Cell Morphology ◽

Receptor Activation ◽

Erbb Receptor ◽

Morphology Changes

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Evidence for Activation of Toll-Like Receptor and Receptor for Advanced Glycation End Products in Preterm Birth

Mediators of Inflammation ◽

10.1155/2010/490406 ◽

2010 ◽

Vol 2010 ◽

pp. 1-10 ◽

Cited By ~ 23

Author(s):

Taketoshi Noguchi ◽

Toshiyuki Sado ◽

Katsuhiko Naruse ◽

Hiroshi Shigetomi ◽

Akira Onogi ◽

...

Keyword(s):

Preterm Birth ◽

Advanced Glycation End Products ◽

Expression Profiles ◽

Receptor Activation ◽

Advanced Glycation ◽

Specific Expression ◽

Downstream Signaling ◽

Glycation End Products ◽

End Products ◽

Rage Expression

Objective. Individuals with inflammation have a myriad of pregnancy aberrations including increasing their preterm birth risk. Toll-like receptors (TLRs) and receptor for advanced glycation end products (RAGE) and their ligands were all found to play a key role in inflammation. In the present study, we reviewed TLR and RAGE expression, their ligands, and signaling in preterm birth.Research Design and Methods. A systematic search was performed in the electronic databases PubMed and ScienceDirect up to July 2010, combining the keywords “preterm birth,” “TLR”, “RAGE”, “danger signal”, “alarmin”, “genomewide,” “microarray,” and “proteomics” with specific expression profiles of genes and proteins.Results. This paper provides data on TLR and RAGE levels and critical downstream signaling events including NF-kappaB-dependent proinflammatory cytokine expression in preterm birth. About half of the genes and proteins specifically present in preterm birth have the properties of endogenous ligands “alarmin” for receptor activation. The interactions between the TLR-mediated acute inflammation and RAGE-mediated chronic inflammation have clear implications for preterm birth via the TLR and RAGE system, which may be acting collectively.Conclusions. TLR and RAGE expression and their ligands, signaling, and functional activation are increased in preterm birth and may contribute to the proinflammatory state.

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