scholarly journals Centrosomal P4.1-associated protein (CPAP) positively regulates endocytic vesicular transport and lysosome targeting of EGFR

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Radhika Gudi ◽  
Viswanathan Palanisamy ◽  
Chenthamarakshan Vasu
Keyword(s):  
Cell Surface ◽  
Vesicular Transport ◽  
Critical Role ◽  
Cell Surface Receptor ◽  
Regulatory Effect ◽  
Cellular Functions ◽  
Surface Receptors ◽  
Egfr Activation ◽  
Early Endosomes ◽  
Surface Receptor

AbstractCentrosomal P4.1-associated protein (CPAP) plays a critical role in restricting the centriole length in human cells. Here, we report a novel, positive regulatory influence for CPAP on endocytic vesicular transport (EVT) and lysosome targeting of internalized-cell surface receptor EGFR. We observed that higher CPAP levels cause an increase in the abundance of multi-vesicular body (MVB) and EGFR is detectable in CPAP-overexpression induced puncta. The surface and cellular levels of EGFR are higher under CPAP deficiency and lower under CPAP overexpression. While ligand-engagement induced internalization or routing of EGFR into early endosomes is not influenced by cellular levels of CPAP, we found that targeting of ligand-activated, internalized EGFR to lysosome is impacted by CPAP levels. Transport of ligand-bound EGFR from early endosome to late endosome/MVB and lysosome is diminished in CPAP-depleted cells. Moreover, CPAP depleted cells appear to show a diminished ability to form MVB structures upon EGFR activation. These observations suggest a positive regulatory effect of CPAP on EVT of ligand-bound EGFR-like cell surface receptors to MVB and lysosome. Overall, identification of a non-centriolar function of CPAP in endocytic trafficking provides new insights in understanding the non-canonical cellular functions of CPAP.

scholarly journals Centrosomal P4.1-associated protein (CPAP) positively regulates endocytic vesicular transport and lysosome targeting of EGFR

2020 ◽  
Author(s):  
Radhika Gudi ◽  
Viswanathan Palanisamy ◽  
Chenthamarakshan Vasu
Keyword(s):  
Cell Surface ◽  
Vesicular Transport ◽  
Critical Role ◽  
Early Endosome ◽  
Late Endosome ◽  
Cell Surface Receptor ◽  
Regulatory Role ◽  
Surface Receptors ◽  
Early Endosomes ◽  
Surface Receptor

Centrosomal P4.1-associated protein (CPAP) plays a critical role in restricting the centriole length in human cells. Here, we report a novel, positive regulatory role for CPAP in endocytic vesicular transport (EVT) and lysosome targeting of internalized-cell surface receptor EGFR. We observed that higher CPAP levels cause an increase in the abundance of multi-vesicular body (MVB) and EGFR is detectable in CPAP-overexpression induced puncta. While the surface levels, and total and phosphorylated cellular levels of EGFR are higher under CPAP deficiency, ligand-engagement induced internalization of this receptor is not impacted by CPAP levels. Furthermore, routing of EGFR into early endosomes is not influenced by CPAP. However, most importantly, we found that CPAP is required for targeting ligand-activated, internalized EGFR to lysosome. Transport of ligand-bound EGFR from early endosome to late endosome/MVB and lysosome is severely diminished in CPAP-depleted cells. Moreover, CPAP depleted cells showed diminished ability to form MVB structures upon EGFR activation. These observations show a positive regulatory role for CPAP in early endosome to late endosome transport and lysosome targeting of ligand-bound EGFR-like cell surface receptors. Overall, identification of this regulatory role for CPAP in endocytic trafficking of EGFR provides new insights in understanding the cellular functions of CPAP.

Inhibition of rat ventricular automaticity by adenosine

1985 ◽  
Vol 248 (6) ◽  
pp. H907-H913 ◽  
Author(s):  
L. J. Heller ◽  
R. A. Olsson
Keyword(s):  
Cell Surface ◽  
Cell Surface Receptor ◽  
Chronotropic Effect ◽  
Surface Receptors ◽  
Adenosine Concentration ◽  
Surface Receptor ◽  
Ventricular Automaticity ◽  
Beating Rate ◽  
Chronotropic Effects ◽  
Developed Pressure

This study was designed to characterize adenosine's negative chronotropic effect on ventricular pacemakers. The spontaneous beating rate of isolated, isovolumic rat ventricular preparations perfused with Krebs-Henseleit solution decreased as the adenosine concentration was increased [log M effective concentration 50% (EC50) = -5.22 +/- 0.17]. The lack of effect of propranolol or atropine on this adenosine response eliminates the involvement of endogenous neurotransmitters. Support for the involvement of an external cell surface receptor was provided by findings that theophylline and 8-(4-sulfophenyl)theophylline, an analogue thought to act solely at the cell surface, significantly increased the adenosine log M EC50 to -3.94 +/- 0.22 and -3.61 +/- 0.22, respectively. An increase in spontaneous beating rate induced by theophylline, but not by its analogue, was blocked by the addition of propranolol. The relative chronotropic potency of the adenosine analogues R-PIA, S-PIA, and NECA suggests that the cell surface receptors may be of the Ri type. The negative chronotropic effects of adenosine and its analogues occurred at concentrations that had no effect on the developed pressure of the paced preparation. Electrocardiographic evaluations indicate that at high agonist concentrations, there was an abrupt alteration in electrical properties of the preparation, which could be blocked by theophylline and its analogue.

scholarly journals Topological and Structural Plasticity of the Single Ig Fold and the Double Ig Fold Present in CD19

Biomolecules ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1290 ◽  
Author(s):  
Philippe Youkharibache
Keyword(s):  
Cell Surface ◽  
3D Structure ◽  
Cell Surface Receptor ◽  
Cell Surface Receptors ◽  
Structural Domain ◽  
Surface Receptors ◽  
Surface Receptor ◽  
In Trans ◽  
In Cis ◽  
Ig Domain

The Ig fold has had a remarkable success in vertebrate evolution, with a presence in over 2% of human genes. The Ig fold is not just the elementary structural domain of antibodies and TCRs, it is also at the heart of a staggering 30% of immunologic cell surface receptors, making it a major orchestrator of cell–cell interactions. While BCRs, TCRs, and numerous Ig-based cell surface receptors form homo- or heterodimers on the same cell surface (in cis), many of them interface as ligand-receptors (checkpoints) on interacting cells (in trans) through their Ig domains. New Ig-Ig interfaces are still being discovered between Ig-based cell surface receptors, even in well-known families such as B7. What is largely ignored, however, is that the Ig fold itself is pseudosymmetric, a property that makes the Ig domain a versatile self-associative 3D structure and may, in part, explain its success in evolution, especially through its ability to bind in cis or in trans in the context of cell surface receptor–ligand interactions. In this paper, we review the Ig domains’ tertiary and quaternary pseudosymmetries, with particular attention to the newly identified double Ig fold in the solved CD19 molecular structure to highlight the underlying fundamental folding elements of Ig domains, i.e., Ig protodomains. This pseudosymmetric property of Ig domains gives us a decoding frame of reference to understand the fold, relate all Ig domain forms, single or double, and suggest new protein engineering avenues.

Identifying plant cell-surface receptors: combining ‘classical’ techniques with novel methods

2014 ◽  
Vol 42 (2) ◽  
pp. 395-400 ◽  
Author(s):  
Susanne Uebler ◽  
Thomas Dresselhaus
Keyword(s):  
Cell Surface ◽  
Affinity Purification ◽  
Cell Communication ◽  
Membrane Receptors ◽  
Cell Surface Receptor ◽  
Target Cells ◽  
Surface Receptors ◽  
Success Stories ◽  
Surface Receptor ◽  
Secreted Peptides

Cell–cell communication during development and reproduction in plants depends largely on a few phytohormones and many diverse classes of polymorphic secreted peptides. The peptide ligands are bound at the cell surface of target cells by their membranous interaction partners representing, in most cases, either receptor-like kinases or ion channels. Although knowledge of both the extracellular ligand and its corresponding receptor(s) is necessary to describe the downstream signalling pathway(s), to date only a few ligand–receptor pairs have been identified. Several methods, such as affinity purification and yeast two-hybrid screens, have been used very successfully to elucidate interactions between soluble proteins, but most of these methods cannot be applied to membranous proteins. Experimental obstacles such as low concentration and poor solubility of membrane receptors, as well as instable transient interactions, often hamper the use of these ‘classical’ approaches. However, over the last few years, a lot of progress has been made to overcome these problems by combining classical techniques with new methodologies. In the present article, we review the most promising recent methods in identifying cell-surface receptor interactions, with an emphasis on success stories outside the field of plant research.

scholarly journals Intracellular movement of cell surface receptors after endocytosis: resialylation of asialo-transferrin receptor in human erythroleukemia cells.

1985 ◽  
Vol 100 (3) ◽  
pp. 826-834 ◽  
Author(s):  
M D Snider ◽  
O C Rogers
Keyword(s):  
Sialic Acid ◽  
Cell Surface ◽  
Golgi Complex ◽  
Transferrin Receptor ◽  
Cell Surface Receptor ◽  
Surface Receptors ◽  
Erythroleukemia Cells ◽  
Intracellular Movement ◽  
Surface Receptor ◽  
A Cell

The intracellular movement of cell surface transferrin receptor (TfR) after internalization was studied in K562 cultured human erythroleukemia cells. The sialic acid residues of the TfR glycoprotein were used to monitor transport to the Golgi complex, the site of sialyltransferases. Surface-labeled cells were treated with neuraminidase, and readdition of sialic acid residues, monitored by isoelectric focusing of immunoprecipitated TfR, was used to assess the movement of receptor to sialyltransferase-containing compartments. Asialo-TfR was resialylated by the cells with a half-time of 2-3 h. Resialylation occurred in an intracellular organelle, since it was inhibited by treatments that allow internalization of surface components but block transfer out of the endosomal compartment. Moreover, roughly half of the resialylated molecules were cleaved when cells were retreated with neuraminidase after culturing, indicating that this fraction of the molecules had returned to the cell surface. These results suggest that TfR is transported from the cell surface to the Golgi complex, the intracellular site of sialyltransferases, and then returns to the cell surface. This pathway, which has not been previously described for a cell surface receptor, may be different from the route followed by TfR in iron uptake, since reported rates of transferrin uptake and release are significantly more rapid than the resialylation of asialo-TfR.

scholarly journals SUN-LB130 Identification of IGSF1 Ligands

2020 ◽  
Vol 4 (Supplement_1) ◽  
Author(s):  
Courtney L Smith ◽  
Andrew N Bayne ◽  
Jean-François Trempe ◽  
Daniel J Bernard
Keyword(s):  
Cell Surface ◽  
Transmembrane Domain ◽  
Protein Complexes ◽  
Protein A ◽  
Negative Control ◽  
Cell Surface Receptor ◽  
Immunoglobulin Superfamily ◽  
Central Hypothyroidism ◽  
Surface Receptors ◽  
Surface Receptor

Abstract Immunoglobulin superfamily, member 1 (IGSF1), is an X-linked, type 1 transmembrane glycoprotein that is highly expressed in the anterior pituitary gland and testes. Mutations in the IGSF1 gene cause congenital central hypothyroidism, variable hypoprolactinemia, growth hormone dysregulation, and macroorchidism. Igsf1 knockout mice exhibit reduced pituitary TRH receptor (Trhr1) expression with an associated impairment in TRH-stimulated TSH secretion. The mechanism through which IGSF1 loss leads to reductions in Trhr1 levels is unresolved, at least in part because IGSF1’s cellular functions are unknown. The mature form of the IGSF1 protein consists of seven extracellular Ig loops, a single transmembrane domain containing a positively charged arginine, and a short intracellular carboxy-tail devoid of known functional motifs. Recently, IGSF1 was argued to be a member of the leukocyte receptor cluster (LRC) family. LRC proteins act as cell surface receptors for soluble or membrane-bound proteins. We therefore hypothesized that IGSF1 is a cell surface receptor for a presently undescribed ligand that regulates Trhr1 expression in pituitary thyrotrope cells. To identify candidate IGSF1 ligands, we implemented a new ligand trapping method, Ecto-Fc MS. We fused the extracellular (Ecto) domain of IGSF1 to the fragment crystallizable (Fc) region of human IgG, creating an Ecto-Fc fusion protein. Secreted IGSF1-Fc was purified and used as a ligand trap for bait proteins extracted from rat testes. The protein complexes were affinity purified with protein A beads, trypsin digested into peptides, subjected to orthogonal high-pH fractionation, and identified by tandem LC-MS/MS. More than 700 proteins were enriched in IGSF1-Fc preparations compared to an Fc-only negative control. Several secreted ligands and plasma-membrane proteins were identified, many of which are also expressed in pituitary thyrotrope cells. Identifying the ligand or ligands will enable us to determine IGSF1 function, and may lead to the discovery of novel causes of central hypothyroidism and macroorchidism.

scholarly journals Identification of Amino Acid Residues of Anthrax Protective Antigen Involved in Binding with Lethal Factor

2002 ◽  
Vol 70 (8) ◽  
pp. 4477-4484 ◽  
Author(s):  
Vibha Chauhan ◽  
Rakesh Bhatnagar
Keyword(s):  
Cell Surface ◽  
Protective Antigen ◽  
Lethal Factor ◽  
Lethal Toxin ◽  
Cell Surface Receptor ◽  
Amino Acid Residues ◽  
Anthrax Lethal Toxin ◽  
Mutant Proteins ◽  
Surface Receptors ◽  
Surface Receptor

ABSTRACT Protective antigen (PA) and lethal factor (LF) are the two components of anthrax lethal toxin. PA is responsible for the translocation of LF to the cytosol. The binding of LF to cell surface receptor-bound PA is a prerequisite for the formation of lethal toxin. It has been hypothesized that hydrophobic residues P184, L187, F202, L203, P205, I207, I210, W226, and F236 of domain 1b of PA play an important role in the binding of PA to LF. These residues are normally buried in the 83-kDA version of PA, PA83, as determined by the crystal structure of PA. However, they become exposed due to the conformational change brought about by the cleavage of PA83 to PA63 by a cell surface protease. Mutation of the above-mentioned residues to alanine resulted in mutant proteins that were able to bind to the cell surface receptors and also to be specifically cleaved by the cellular proteases. All the mutant proteins except the F202A, L203A, P205A, and I207A mutants were able to bind to LF and were also toxic to macrophage cells in combination with LF. It was concluded that residues 202, 203, 205, and 207 of PA are essential for the binding of LF to PA.

scholarly journals Heterogeneity in VEGF Receptor-2 mobility and organization on the endothelial cell surface leads to diverse activation models by VEGF

2019 ◽  
Author(s):  
Bruno da Rocha-Azevedo ◽  
Sungsoo Lee ◽  
Aparajita Dasgupta ◽  
Anthony R. Vega ◽  
Luciana R. de Oliveira ◽  
...  
Keyword(s):  
Cell Surface ◽  
Single Molecule ◽  
Receptor Activation ◽  
Cell Surface Receptor ◽  
Vegf Receptor ◽  
Surface Receptors ◽  
Endothelial Cell Surface ◽  
Heterogeneous Nature ◽  
Surface Receptor ◽  
Complex Relationships

SummaryThe nanoscale organization of cell surface receptors plays an important role in signaling. We determined this organization and its relation to receptor activation for VEGF Receptor-2 (VEGFR-2), a critical receptor tyrosine kinase in endothelial cells (ECs), by combining live-cell single-molecule imaging of endogenous VEGFR-2 with rigorous computational analysis. We found that surface VEGFR-2 can be mobile or immobile/confined, and monomeric or non-monomeric, with a complex interplay between the two. The mobility and interaction heterogeneity of VEGFR-2 in the basal state led to heterogeneity in the sequence of steps leading to VEGFR-2 activation by VEGF. Specifically, we found that VEGF can bind to both monomeric and non-monomeric VEGFR-2, and, when binding to monomeric VEGFR-2, promotes dimer formation but only for immobile/confined receptors. Overall, our study highlights the dynamic and heterogeneous nature of cell surface receptor organization and its complex relationships with receptor activation and signaling.

scholarly journals Mutual Potentiation of Plant Immunity by Cell-surface and Intracellular Receptors

2020 ◽  
Author(s):  
Bruno Pok Man Ngou ◽  
Hee-Kyung Ahn ◽  
Pingtao Ding ◽  
Jonathan DG Jones
Keyword(s):  
Immune System ◽  
Cell Surface ◽  
Pseudomonas Syringae ◽  
Plant Immunity ◽  
Cell Surface Receptor ◽  
Hypersensitive Cell Death ◽  
Surface Receptors ◽  
Intracellular Receptor ◽  
Surface Receptor ◽  
Immune Pathways

The plant immune system involves cell-surface receptors that detect intercellular pathogen-derived molecules, and intracellular receptors that activate immunity upon detection of pathogen-secreted effectors that act inside the plant cell. Surface receptor-mediated immunity has been extensively studied but in authentic interactions between plants and microbial pathogens, its presence impedes study of intracellular receptor-mediated immunity alone. How these two immune pathways interact is poorly understood. Here, we reveal mutual potentiation between these two recognition-dependent defense pathways. Recognition by surface receptors activates multiple protein kinases and NADPH oxidases, whereas intracellular receptors primarily elevate abundance of these proteins. Reciprocally, the intracellular receptor-dependent hypersensitive cell death response is strongly enhanced by activation of surface receptors. Activation of either immune system alone is insufficient to provide effective resistance against Pseudomonas syringae. Thus, immune pathways activated by cell-surface and intracellular receptors mutually potentiate to activate strong defense that thwarts pathogens. By studying the activation of intracellular receptors in the absence of surface receptor-mediated immunity, we have dissected the relationship between the two distinct immune systems. These findings reshape our understanding of plant immunity and have broad implications for crop improvement.

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