scholarly journals Secreted Amyloid Precursor Protein-Alpha Enhances LTP Through the Synthesis and Trafficking of Ca2+-Permeable AMPA Receptors

2021 ◽  
Vol 14 ◽  
Author(s):  
Rhys W. Livingstone ◽  
Megan K. Elder ◽  
Anurag Singh ◽  
Courteney M. Westlake ◽  
Warren P. Tate ◽  
...  
Keyword(s):  
Cell Surface ◽  
Amyloid Precursor Protein ◽  
De Novo ◽  
Hippocampal Slices ◽  
Long Term Potentiation ◽  
Surface Expression ◽  
Receptor Expression ◽  
Precursor Protein ◽  
Cell Surface Expression ◽  
Proximity Ligation Assay

Regulation of AMPA receptor expression by neuronal activity and neuromodulators is critical to the expression of both long-term potentiation (LTP) and memory. In particular, Ca2+-permeable AMPARs (CP-AMPAR) play a unique role in these processes due to their transient, activity-regulated expression at synapses. Secreted amyloid precursor protein-alpha (sAPPα), a metabolite of the parent amyloid precursor protein (APP) has been previously shown to enhance hippocampal LTP as well as memory formation in both normal animals and in Alzheimer’s disease models. In earlier work we showed that sAPPα promotes trafficking of GluA1-containing AMPARs to the cell surface and specifically enhances synthesis of GluA1. To date it is not known whether de novo synthesized GluA1 form CP-AMPARs or how they contribute to sAPPα-mediated plasticity. Here, using fluorescent non-canonical amino acid tagging–proximity ligation assay (FUNCAT-PLA), we show that brief treatment of primary rat hippocampal neurons with sAPPα (1 nM, 30 min) rapidly enhanced the cell-surface expression of de novo GluA1 homomers and reduced levels of de novo GluA2, as well as extant GluA2/3-AMPARs. The de novo GluA1-containing AMPARs were localized to extrasynaptic sites and later internalized by sAPPα-driven expression of the activity-regulated cytoskeletal-associated protein, Arc. Interestingly, longer exposure to sAPPα increased synaptic levels of GluA1/2 AMPARs. Moreover, the sAPPα-mediated enhancement of LTP in area CA1 of acute hippocampal slices was dependent on CP-AMPARs. Together, these findings show that sAPPα engages mechanisms which specifically enhance the synthesis and cell-surface expression of GluA1 homomers, underpinning the sAPPα-driven enhancement of synaptic plasticity in the hippocampus.

scholarly journals Amyloid Precursor Protein Enhances Nav1.6 Sodium Channel Cell Surface Expression

2015 ◽  
Vol 290 (19) ◽  
pp. 12048-12057 ◽  
Author(s):  
Chao Liu ◽  
Francis Chee Kuan Tan ◽  
Zhi-Cheng Xiao ◽  
Gavin S. Dawe
Keyword(s):  
Cell Surface ◽  
Amyloid Precursor Protein ◽  
Sodium Channel ◽  
Surface Expression ◽  
Precursor Protein ◽  
Cell Surface Expression

scholarly journals The Novel Membrane Protein TMEM59 Modulates Complex Glycosylation, Cell Surface Expression, and Secretion of the Amyloid Precursor Protein

2010 ◽  
Vol 285 (27) ◽  
pp. 20664-20674 ◽  
Author(s):  
Sylvia Ullrich ◽  
Anna Münch ◽  
Stephanie Neumann ◽  
Elisabeth Kremmer ◽  
Jörg Tatzelt ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Cell Surface ◽  
Amyloid Precursor Protein ◽  
Surface Expression ◽  
Precursor Protein ◽  
Cell Surface Expression ◽  
The Novel

scholarly journals Neuregulin 1 regulates amyloid precursor protein cell surface expression and non-amyloidogenic processing

2018 ◽  
Vol 137 (2) ◽  
pp. 146-153 ◽  
Author(s):  
Young-Jung Kim ◽  
Ji-Young Yoo ◽  
Ok-Soon Kim ◽  
Han-byeol Kim ◽  
Junghwa Ryu ◽  
...  
Keyword(s):  
Cell Surface ◽  
Amyloid Precursor Protein ◽  
Surface Expression ◽  
Precursor Protein ◽  
Cell Surface Expression ◽  
Neuregulin 1 ◽  
Amyloidogenic Processing ◽  
Protein Cell

Metalloproteinases Are Involved in Lipopolysaccharide– and Tumor Necrosis Factor-–Mediated Regulation of CXCR1 and CXCR2 Chemokine Receptor Expression

Blood ◽  
1999 ◽  
Vol 93 (7) ◽  
pp. 2173-2185 ◽  
Author(s):  
Masud H. Khandaker ◽  
Gordon Mitchell ◽  
Luoling Xu ◽  
Joseph D. Andrews ◽  
Rajkumari Singh ◽  
...  
Keyword(s):  
Tumor Necrosis Factor ◽  
Cell Surface ◽  
Tumor Necrosis ◽  
Inflammatory Responses ◽  
Proteinase Inhibitors ◽  
Surface Expression ◽  
Receptor Expression ◽  
Cell Surface Expression ◽  
Metalloproteinase Inhibitors ◽  
Necrosis Factor

The neutrophil-specific G-protein–coupled chemokine receptors, CXCR1 and CXCR2, bind with high affinity to the potent chemoattractant interleukin-8 (IL-8). The mechanisms of IL-8 receptor regulation are not well defined, although previous studies have suggested a process of ligand-promoted internalization as a putative regulatory pathway. Herein, we provide evidence for two distinct processes of CXCR1 and CXCR2 regulation. Confocal microscopy data showed a redistribution of CXCR1 expression from the cell surface of neutrophils to internal compartments after stimulation with IL-8, whereas stimulation with bacterial lipopolysaccharide (LPS) or tumor necrosis factor- (TNF-) did not induce CXCR1 internalization but instead mediated a significant loss of membrane-proximal CXCR1 staining intensity. To investigate whether proteolytic cleavage was the mechanism responsible for LPS- and TNF-–induced downmodulation of IL-8 receptors, we tested a panel of proteinase inhibitors. The downmodulation of CXCR1 and CXCR2 by LPS and TNF- was most dramatically inhibited by metalloproteinase inhibitors; 1,10-phenanthroline and EDTA significantly attenuated LPS- and TNF-–induced loss of CXCR1 and CXCR2 cell surface expression. Metalloproteinase inhibitors also blocked the release of CXCR1 cleavage fragments into the cell supernatants of LPS- and TNF-–stimulated neutrophils. In addition, while treatment of neutrophils with LPS and TNF- inhibited IL-8 receptor–mediated calcium mobilization and IL-8–directed neutrophil chemotaxis, both 1,10-phenanthroline and EDTA blocked these inhibitory processes. In contrast, metalloproteinase inhibitors did not affect IL-8–mediated downmodulation of CXCR1 and CXCR2 cell surface expression or receptor signaling. Thus, these findings may provide further insight into the mechanisms of leukocyte regulation during immunologic and inflammatory responses.

Prognostic significance of leukopenia at the time of diagnosis in acute myeloid leukemia (AML)

2009 ◽  
Vol 27 (15_suppl) ◽  
pp. 7070-7070
Author(s):  
M. L. Arellano ◽  
E. Winton ◽  
L. Pan ◽  
L. Souza ◽  
S. Sunay ◽  
...  
Keyword(s):  
Cell Surface ◽  
Adhesion Molecules ◽  
De Novo ◽  
Risk Group ◽  
Statistical Significance ◽  
Univariate Analysis ◽  
Prognostic Significance ◽  
Surface Expression ◽  
Cell Surface Expression ◽  
Surface Adhesion

7070 Background: In contrast to the poor prognosis associated with hyperleukocytosis, the prognostic significance of leukopenia at the time of diagnosis of AML is unknown. Methods: Single institution retrospective analysis of 225 consecutive, newly diagnosed AML patients (pts), homogeneously treated between July 1996 and February 2005; and divided into 2 groups based on presenting WBC: < 2,000/uL (30) and > 2,000/uL (195). Simultaneously obtained peripheral blood and marrow blasts were analyzed for cell surface expression of CD34, cKit, CXCR4, PCAM, VLA-2, VLA-3, VLA-4, VLA-5, and FLT3 using flow cytometry. Results: Patients’ characteristics (gender, secondary vs. de novo, and cytogenetic [CTG] risk) were comparable between the 2 groups. Leukopenic AML pts were older (median 56 vs. 53 years, p = 0.02), and had lower induction complete remission [CR] rates: 63% vs. 81% (p = 0.03) by univariate analysis. Induction mortality was 0% for leukopenic and 5% for non-leukopenic pts. In primary refractory pts, median survival was longer for leukopenic (11) vs. non-leukopenic (34) pts: 137 vs. 81 d (p = 0.026). Median follow-up was 22 mos. Event-free (EFS), disease-free (DFS), and overall survivals (OS) were lower in the leukopenic group: 12 vs. 14; 14 vs. 17; and 17 vs. 19 mos, respectively; but did not reach statistical significance. By multivariate analysis, age (p < 0.0001) and CTG risk group (p < 0.0001) were independent predictors of OS, while CTG risk group predicted RFS (p < 0.0001). The level of expression of cell surface adhesion molecules on blood and marrow blasts was comparable for the 2 groups. Conclusions: AML pts presenting with leukopenia have comparable outcomes to those presenting with normal or high WBC despite a lower likelihood of achieving remission. Leukopenic AML did not have over-expression of cell surface adhesion molecules. No significant financial relationships to disclose.

scholarly journals Phosphorylation and internalization of gp130 occur after IL-6 activation of Jak2 kinase in hepatocytes.

1994 ◽  
Vol 5 (7) ◽  
pp. 819-828 ◽  
Author(s):  
Y Wang ◽  
G M Fuller
Keyword(s):  
Protein Synthesis ◽  
Cell Surface ◽  
De Novo ◽  
Cell Types ◽  
Surface Expression ◽  
Cell Surface Expression ◽  
Protein Synthesis Inhibitors ◽  
Different Cell Types ◽  
Kinetics Of

Recent evidence has shown that members of the Jak kinase family are activated after IL-6 binds to its receptor complex, leading to a tyrosine phosphorylation of gp130, the IL-6 signal-transducing subunit. The different members of the IL-6 cytokine subfamily induce distinct patterns of Jak-Tyk phosphorylation in different cell types. Using monospecific antibodies to gp130, Jak2 kinase, and phosphotyrosine, we investigated the kinetics of IL-6 stimulation of members of this pathway in primary hepatocytes. Our findings show that Jak 2 is maximally activated within 2 min of exposure to IL-6, followed by gp130 phosphorylation that reaches its peak in another 2 min then declines to basal level by 60 min. In vitro phosphorylation experiments show that activated Jak 2 is able to phosphorylate both native gp130 and a fusion peptide containing its cytoplasmic domain, demonstrating gp130 is a direct substrate of Jak 2 kinase. Experiments designed to explore the cell surface expression of gp130 show that > or = 2 h are required to get a second round of phosphorylation after the addition of more cytokines. This finding suggests that activated gp130 is internalized from the cell surface after IL-6 stimulation. Additional experiments using protein synthesis inhibitors reveal that new protein synthesis is required to get a second cycle of gp130 phosphorylation indicating gp130 must be synthesized de novo and inserted into the membrane. These findings provide strong evidence that down regulation of the IL-6 signal in hepatocytes involves the internalization and cytosol degradation of gp130.

scholarly journals The PAR2 signal peptide prevents premature receptor cleavage and activation

2019 ◽  
Author(s):  
Belinda Liu ◽  
Grace Lee ◽  
Jiejun Wu ◽  
Janise Deming ◽  
Chester Kuei ◽  
...  
Keyword(s):  
Cell Surface ◽  
Signal Peptide ◽  
Synthetic Peptide ◽  
Surface Expression ◽  
Receptor Expression ◽  
Cell Surface Receptor ◽  
Cell Surface Expression ◽  
Peptide Ligand ◽  
Protease Activated Receptors ◽  
N Terminus

AbstractUnlike closely related GPCRs, protease-activated receptors (PAR1, PAR2, PAR3, and PAR4) have a predicted signal peptide at their N-terminus, which is encoded by a separate exon, suggesting that the signal peptides of PARs may serve an important and unique function, specific for PARs. In this report, we show that the PAR2 signal peptide, when fused to the N-terminus of IgG-Fc, effectively induced IgG-Fc secretion into culture medium, thus behaving like a classical signal peptide. The presence of PAR2 signal peptide has a strong effect on PAR2 cell surface expression, as deletion of the signal peptide (PAR2ΔSP) led to dramatic reduction of the cell surface expression and decreased responses to trypsin or the synthetic peptide ligand (SLIGKV). However, further deletion of the tethered ligand region (SLIGKV) at the N-terminus rescued the cell surface receptor expression and the response to the synthetic peptide ligand, suggesting that the signal peptide of PAR2 may be involved in preventing PAR2 from intracellular protease activation before reaching the cell surface. Supporting this hypothesis, an Arg36Ala mutation on PAR2ΔSP, which disabled the trypsin activation site, increased the receptor cell surface expression and the response to ligand stimulation. Similar effects were observed when PAR2ΔSP expressing cells were treated with protease inhibitors. Our findings indicated that these is a role of the PAR2 signal peptide in preventing the premature activation of PAR2 from intracellular protease cleavage before reaching the cells surface. The same mechanism may also apply to PAR1, PAR3, and PAR4.

Apical membrane and intracellular distribution of endogenous alpha 2A-adrenergic receptors in MDCK cells

1994 ◽  
Vol 267 (3) ◽  
pp. F347-F353 ◽  
Author(s):  
M. D. Okusa ◽  
K. R. Lynch ◽  
D. L. Rosin ◽  
L. Huang ◽  
Y. Y. Wei
Keyword(s):  
Cell Surface ◽  
De Novo ◽  
Mdck Cells ◽  
Specific Binding ◽  
Surface Expression ◽  
Surface Proteins ◽  
Cell Surface Expression ◽  
Surface Binding ◽  
Binding Studies ◽  
Apical Domain

The purpose of the current studies was to characterize the endogenous alpha 2-adrenergic receptor (AR) subtypes present in Madin-Darby canine kidney (MDCK) cells and to determine their level of expression and pattern of distribution. By saturation binding analysis with [3H]MK-912, MDCK cells expressed high levels of alpha 2-ARs with a maximum receptor density (Bmax) of 798 +/- 55 fmol/mg protein and an equilibrium dissociation constant (Kd) of 0.98 +/- 0.32 nM. Competitive binding studies using prazosin, oxymetazoline, phentolamine, and epinephrine to displace [3H]MK-912 demonstrated inhibition constant (Ki) values of 1,270 +/- 250, 5.0 +/- 0.4, 5.5 +/- 0.3, and 392 +/- 150 nM (n = 3), respectively. In Northern blot analysis we found that MDCK cells expressed transcripts encoding alpha 2A-AR and not alpha 2B-AR or alpha 2C-AR. Surface binding experiments suggested that approximately 60% of alpha 2A-ARs are distributed at the cell surface domain. Specific binding of [3H]MK-912 to soluble apical and basolateral surface proteins isolated by surface biotinylation indicated the expression of surface alpha 2A-ARs was limited to the apical domain of MDCK cells. No alpha 2A-ARs were detected on the basolateral surface. We conclude that endogenous alpha 2A-ARs are targeted to the apical domain of MDCK cells and that the intracellular compartment may contain ARs as a reservoir for de novo cell surface expression or, alternatively, may represent internalized receptors.

CD81-Dependent Trafficking of CD19: Restoration of CD19 Surface Expression in Human B Cells Harboring A CD81 Mutation

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 1049-1049
Author(s):  
Shoshana Levy ◽  
Chiung-Chi Kuo ◽  
Yael Sagi ◽  
Homer Chen ◽  
Neta Kela-Madar ◽  
...  
Keyword(s):  
B Cells ◽  
Cell Surface ◽  
B Cell ◽  
Cell Line ◽  
Conflicts Of Interest ◽  
Surface Expression ◽  
Antibody Deficiency ◽  
Cell Surface Expression ◽  
Dominant Negative Effect ◽  
Proximity Ligation Assay

Abstract Abstract 1049 Introduction: A 6-year-old girl, who was diagnosed with a primary antibody deficiency, had B cells lacking surface CD19. However, both her CD19 alleles were normal and the impairment was actually caused by a homozygous exon splice site mutation in CD81 (1). The patient's B cells also lacked surface CD81 and produced an immature glycosylated CD19 protein that was retained intracellularly. Interestingly, this human deficiency differed from that of CD81 knockout mice as the latter still express a low level of CD19 on their B cells. Methods: We used an EBV-transformed B cell line from this patient to better understand i) the difference between the human and mouse CD81 deficiencies and ii) how CD81 controls the trafficking of CD19 to the cell surface. We reasoned that the truncated human CD81 mutant (CD81mut) protein might be expressed intracellularly. Indeed, whereas most anti-CD81 mAbs did not recognize CD81mut, we identified one that bound the mutated form and used it in this study. We also expressed the human CD81mut in a CD81-deficient mouse B cell line to determine if it could negatively regulate CD19 surface expression. Results: We show that the CD81mut protein is indeed expressed intracellularly in the patient's EBV-transformed B cells. We then used a proximity ligation assay to demonstrate that the truncated CD81mut protein interacts intracellularly with CD19. However, this interaction with the CD81mut protein abrogated carbohydrate maturation and the trafficking of CD19 to cell surface. We therefore expressed the CD81mut in CD81KO mouse B cells, which still express low levels of surface CD19, and found that it did not exert a dominant negative effect on CD19 surface expression. Finally, we used this reconstitution system to identify specific CD81 domains that restored carbohydrate maturation and cell surface expression of the CD19 molecule in the patient's B cells. Conclusion: This specific case of antibody deficiency was manifested because of lack of surface expression of CD19, an important B cell signaling molecule. However, the maturation of CD19 and its trafficking to the cell surface require the presence of specific domains of the tetraspanin CD81 molecule. Disclosures: No relevant conflicts of interest to declare.

Sign in / Sign up

Export Citation Format

Share Document