scholarly journals Sorting nexin 27 rescues neuroligin 2 from lysosomal degradation to control inhibitory synapse number

2019 ◽  
Vol 476 (2) ◽  
pp. 293-306 ◽  
Author(s):  
Caroline S. Binda ◽  
Yasuko Nakamura ◽  
Jeremy M. Henley ◽  
Kevin A. Wilkinson
Keyword(s):  
Adaptor Protein ◽  
Inhibitory Synapse ◽  
Endosomal Trafficking ◽  
Dependent Manner ◽  
Lysosomal Degradation ◽  
Sorting Nexin ◽  
The Core ◽  
Cargo Proteins ◽  
Vacuolar Protein ◽  
Zona Occludens

Abstract Retromer is an evolutionarily conserved endosomal trafficking complex that mediates the retrieval of cargo proteins from a degradative pathway for sorting back to the cell surface. To promote cargo recycling, the core retromer trimer of VPS (vacuolar protein sorting)26, VPS29 and VPS35 recognises cargo either directly, or through an adaptor protein, the most well characterised of which is the PDZ [postsynaptic density 95 (PSD95), disk large, zona occludens] domain-containing sorting nexin SNX27. Neuroligins (NLGs) are postsynaptic trans-synaptic scaffold proteins that function in the clustering of postsynaptic proteins to maintain synaptic stability. Here, we show that each of the NLGs (NLG1–3) bind to SNX27 in a direct PDZ ligand-dependent manner. Depletion of SNX27 from neurons leads to a decrease in levels of each NLG protein and, for NLG2, this occurs as a result of enhanced lysosomal degradation. Notably, while depletion of the core retromer component VPS35 leads to a decrease in NLG1 and NLG3 levels, NLG2 is unaffected, suggesting that, for this cargo, SNX27 acts independently of retromer. Consistent with loss of SNX27 leading to enhanced lysosomal degradation of NLG2, knockdown of SNX27 results in fewer NLG2 clusters in cultured neurons, and loss of SNX27 or VPS35 reduces the size and number of gephyrin clusters. Together, these data indicate that NLGs are SNX27–retromer cargoes and suggest that SNX27–retromer controls inhibitory synapse number, at least in part through trafficking of NLG2.

The β-appendages of the four adaptor-protein (AP) complexes: structure and binding properties, and identification of sorting nexin 9 as an accessory protein to AP-2

2002 ◽  
Vol 362 (3) ◽  
pp. 597-607 ◽  
Author(s):  
Richard LUNDMARK ◽  
Sven R. CARLSSON
Keyword(s):  
Intracellular Transport ◽  
Adaptor Protein ◽  
Cd Spectroscopy ◽  
Functional Domain ◽  
Sequence Alignments ◽  
Sorting Nexin ◽  
Essential Components ◽  
Cargo Proteins ◽  
Src Homology ◽  
Partial Overlap

Adaptor protein (AP) complexes are essential components for the formation of coated vesicles and the recognition of cargo proteins for intracellular transport. Each AP complex exposes two appendage domains with that function to bind regulatory accessory proteins in the cytosol. Secondary structure predictions, sequence alignments and CD spectroscopy were used to relate the β-appendages of all human AP complexes to the previously published crystal structure of AP-2. The results suggested that the β-appendages of AP-1, AP-2 and AP-3 have similar structures, consisting of two subdomains, whereas that of AP-4 lacks the inner subdomain. Pull-down and overlay assays showed partial overlap in the binding specificities of the β-appendages of AP-1 and AP-2, whereas the corresponding domain of AP-3 displayed a unique binding pattern. That AP-4 may have a truncated, non-functional domain was indicated by its apparent inability to bind any proteins from cytosol. Of several novel β-appendage-binding proteins detected, one that had affinity exclusively for AP-2 was identified as sorting nexin 9 (SNX9). SNX9, which contains a phox and an Src homology 3 domain, was found in large complexes and was at least partially associated with AP-2 in the cytosol. SNX9 may function to assist AP-2 in its role at the plasma membrane.

scholarly journals Distinct claudins and associated PDZ proteins form different autotypic tight junctions in myelinating Schwann cells

2002 ◽  
Vol 159 (2) ◽  
pp. 361-372 ◽  
Author(s):  
Sebastian Poliak ◽  
Sean Matlis ◽  
Christoph Ullmer ◽  
Steven S. Scherer ◽  
Elior Peles
Keyword(s):  
Tight Junction ◽  
Tight Junctions ◽  
Schwann Cells ◽  
Pdz Domain ◽  
Adaptor Protein ◽  
Dependent Manner ◽  
Guanylate Kinase ◽  
Pdz Proteins ◽  
Junction Protein ◽  
Zona Occludens

The apposed membranes of myelinating Schwann cells are joined by several types of junctional specializations known as autotypic or reflexive junctions. These include tight, gap, and adherens junctions, all of which are found in regions of noncompact myelin: the paranodal loops, incisures of Schmidt-Lanterman, and mesaxons. The molecular components of autotypic tight junctions have not been established. Here we report that two homologues of Discs Lost–multi PDZ domain protein (MUPP)1, and Pals-associated tight junction protein (PATJ), are differentially localized in myelinating Schwann cells and associated with different claudins. PATJ is mainly found at the paranodal loops, where it colocalized with claudin-1. MUPP1 and claudin-5 colocalized in the incisures, and the COOH-terminal region of claudin-5 interacts with MUPP1 in a PSD-95/Disc Large/zona occludens (ZO)-1 (PDZ)-dependent manner. In developing nerves, claudin-5 and MUPP1 appear together in incisures during the first postnatal week, suggesting that they coassemble during myelination. Finally, we show that the incisures also contain four other PDZ proteins that are found in epithelial tight junctions, including three membrane-associated guanylate-kinase proteins (membrane-associated guanylate-kinase inverted-2, ZO-1, and ZO-2) and the adaptor protein Par-3. The presence of these different tight junction proteins in regions of noncompact myelin may be required to maintain the intricate cytoarchitecture of myelinating Schwann cells.

scholarly journals Proteomic identification and structural basis for the interaction between sorting nexin SNX17 and PDLIM family proteins

2021 ◽  
Author(s):  
Michael D Healy ◽  
Joanna Sacharz ◽  
Kerrie E McNally ◽  
Calum McConville ◽  
Ryan J Hall ◽  
...  
Keyword(s):  
Pdz Domain ◽  
Structural Basis ◽  
Binding Motif ◽  
Endosomal Trafficking ◽  
Pdz Domains ◽  
Sorting Nexin ◽  
Affinity Enrichment ◽  
C Terminus ◽  
Loop Sequence ◽  
Cargo Proteins

The sorting nexin SNX17 controls endosome-to-cell surface recycling of diverse transmembrane cargo proteins including integrins, the amyloid precursor protein and lipoprotein receptors. This requires association with the multi-subunit Commander trafficking complex, which depends on the C-terminus of SNX17 through unknown mechanisms. Using affinity enrichment proteomics, we find that a C-terminal peptide of SNX17 is not only sufficient for Commander interaction but also associates with members of the actin-associated PDZ and LIM domain (PDLIM) family. We show that SNX17 contains a type III PSD95/Dlg/Zo1 (PDZ) binding motif (PDZbm) that binds specifically to the PDZ domains of PDLIM family proteins but not to other PDZ domains tested. The structure of the PDLIM7 PDZ domain bound to the SNX17 C-terminus was determined by NMR spectroscopy and reveals an unconventional perpendicular peptide interaction. Mutagenesis confirms the interaction is mediated by specific electrostatic contacts and a uniquely conserved proline-containing loop sequence in the PDLIM protein family. Our results define the mechanism of SNX17-PDLIM interaction and suggest that the PDLIM proteins may play a role in regulating the activity of SNX17 in conjunction with Commander and actin-rich endosomal trafficking domains.

scholarly journals Cargo-selective SNX-BAR proteins mediate retromer trimer independent retrograde transport

2017 ◽  
Vol 216 (11) ◽  
pp. 3677-3693 ◽  
Author(s):  
Arunas Kvainickas ◽  
Ana Jimenez-Orgaz ◽  
Heike Nägele ◽  
Zehan Hu ◽  
Jörn Dengjel ◽  
...  
Keyword(s):  
Quantitative Proteomics ◽  
Retrograde Transport ◽  
Dependent Manner ◽  
Sorting Nexin ◽  
Trans Golgi Network ◽  
The Core ◽  
Retromer Complex ◽  
Mannose 6 Phosphate ◽  
Golgi Network

The retromer complex, which recycles the cation-independent mannose 6-phosphate receptor (CI-MPR) from endosomes to the trans-Golgi network (TGN), is thought to consist of a cargo-selective VPS26–VPS29–VPS35 trimer and a membrane-deforming subunit of sorting nexin (SNX)–Bin, Amphyphysin, and Rvs (BAR; SNX-BAR) proteins. In this study, we demonstrate that heterodimers of the SNX-BAR proteins, SNX1, SNX2, SNX5, and SNX6, are the cargo-selective elements that mediate the retrograde transport of CI-MPR from endosomes to the TGN independently of the core retromer trimer. Using quantitative proteomics, we also identify the IGF1R, among more potential cargo, as another SNX5 and SNX6 binding receptor that recycles through SNX-BAR heterodimers, but not via the retromer trimer, in a ligand- and activation-dependent manner. Overall, our data redefine the mechanics of retromer-based sorting and call into question whether retromer indeed functions as a complex of SNX-BAR proteins and the VPS26–VPS29–VPS35 trimer.

scholarly journals Sorting nexin 27 regulates basal and stimulated brush border trafficking of NHE3

2015 ◽  
Vol 26 (11) ◽  
pp. 2030-2043 ◽  
Author(s):  
Varsha Singh ◽  
Jianbo Yang ◽  
Boyoung Cha ◽  
Tiane-e Chen ◽  
Rafiquel Sarker ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Epithelial Cells ◽  
Pdz Domain ◽  
Surface Expression ◽  
Dependent Manner ◽  
Intestinal Epithelial ◽  
Pdz Domains ◽  
Sorting Nexin ◽  
C Terminus ◽  
Cargo Proteins

Sorting nexin 27 (SNX27) contains a PDZ domain that is phylogenetically related to the PDZ domains of the NHERF proteins. Studies on nonepithelial cells have shown that this protein is located in endosomes, where it regulates trafficking of cargo proteins in a PDZ domain–dependent manner. However, the role of SNX27 in trafficking of cargo proteins in epithelial cells has not been adequately explored. Here we show that SNX27 directly interacts with NHE3 (C-terminus) primarily through the SNX27 PDZ domain. A combination of knockdown and reconstitution experiments with wild type and a PDZ domain mutant (GYGF → GAGA) of SNX27 demonstrate that the PDZ domain of SNX27 is required to maintain basal NHE3 activity and surface expression of NHE3 in polarized epithelial cells. Biotinylation-based recycling and degradation studies in intestinal epithelial cells show that SNX27 is required for the exocytosis (not endocytosis) of NHE3 from early endosome to plasma membrane. SNX27 is also required to regulate the retention of NHE3 on the plasma membrane. The findings of the present study extend our understanding of PDZ-mediated recycling of cargo proteins from endosome to plasma membrane in epithelial cells.

scholarly journals Propofol suppresses cell viability, cell cycle progression and motility and induces cell apoptosis of ovarian cancer cells through suppressing MEK/ERK signaling via targeting circVPS13C/miR-145 axis

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Huan Lu ◽  
Guanlin Zheng ◽  
Xiang Gao ◽  
Chanjuan Chen ◽  
Min Zhou ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Ovarian Cancer ◽  
Cancer Cells ◽  
Rna Binding ◽  
Erk Signaling ◽  
Luciferase Reporter ◽  
Migration And Invasion ◽  
Ovarian Cancer Cells ◽  
Dependent Manner ◽  
Vacuolar Protein

Abstract Background Propofol is a kind of common intravenous anaesthetic agent that plays an anti-tumor role in a variety of cancers, including ovarian cancer. However, the working mechanism of Propofol in ovarian cancer needs further exploration. Methods The viability and metastasis of ovarian cancer cells were assessed by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and transwell assays. Flow cytometry was used to evaluate the cell cycle and apoptosis. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to examine the abundance of circular RNA vacuolar protein sorting 13 homolog C (circVPS13C) and microRNA-145 (miR-145). The target relationship between miR-145 and circVPS13C was predicted by circinteractome database and verified by dual-luciferase reporter assay, RNA-binding protein immunoprecipitation (RIP) assay and RNA-pull down assay. Western blot assay was used to detect the levels of phosphorylated extracellular regulated MAP kinase (p-ERK), ERK, p-MAP kinse-ERK kinase (p-MEK) and MEK, in ovarian cancer cells. Results Propofol treatment suppressed the viability, cell cycle and motility and elevated the apoptosis rate of ovarian cancer cells. Propofol up-regulated miR-145 in a dose-dependent manner. Propofol exerted an anti-tumor role partly through up-regulating miR-145. MiR-145 was a direct target of circVPS13C. Propofol suppressed the progression of ovarian cancer through up-regulating miR-145 via suppressing circVPS13C. Propofol functioned through circVPS13C/miR-145/MEK/ERK signaling in ovarian cancer cells. Conclusion Propofol suppressed the proliferation, cell cycle, migration and invasion and induced the apoptosis of ovarian cancer cells through circVPS13C/miR-145/MEK/ERK signaling in vitro.

scholarly journals Rapid whole cell imaging reveals a calcium-APPL1-dynein nexus that regulates cohort trafficking of stimulated EGF receptors

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
H. M. York ◽  
A. Patil ◽  
U. K. Moorthi ◽  
A. Kaur ◽  
A. Bhowmik ◽  
...  
Keyword(s):  
Signal Processing ◽  
Growth Factor ◽  
Leucine Zipper ◽  
Adaptor Protein ◽  
Endosomal Trafficking ◽  
Egf Receptors ◽  
Ph Domain ◽  
Cell Level ◽  
Whole Cell ◽  
Light Sheet Microscopy

AbstractThe endosomal system provides rich signal processing capabilities for responses elicited by growth factor receptors and their ligands. At the single cell level, endosomal trafficking becomes a critical component of signal processing, as exemplified by the epidermal growth factor (EGF) receptors. Activated EGFRs are trafficked to the phosphatase-enriched peri-nuclear region (PNR), where they are dephosphorylated and degraded. The details of the mechanisms that govern the movements of stimulated EGFRs towards the PNR, are not completely known. Here, exploiting the advantages of lattice light-sheet microscopy, we show that EGFR activation by EGF triggers a transient calcium increase causing a whole-cell level redistribution of Adaptor Protein, Phosphotyrosine Interacting with PH Domain And Leucine Zipper 1 (APPL1) from pre-existing endosomes within one minute, the rebinding of liberated APPL1 directly to EGFR, and the dynein-dependent translocation of APPL1-EGF-bearing endosomes to the PNR within ten minutes. The cell spanning, fast acting network that we reveal integrates a cascade of events dedicated to the cohort movement of activated EGF receptors. Our findings support the intriguing proposal that certain endosomal pathways have shed some of the stochastic strategies of traditional trafficking and have evolved processes that provide the temporal predictability that typify canonical signaling.

TRAF6-mediated ubiquitination of APPL1 enhances hepatic actions of insulin by promoting the membrane translocation of Akt

2013 ◽  
Vol 455 (2) ◽  
pp. 207-216 ◽  
Author(s):  
Kenneth K. Y. Cheng ◽  
Karen S. L. Lam ◽  
Yu Wang ◽  
Donghai Wu ◽  
Mingliang Zhang ◽  
...  
Keyword(s):  
Hepatic Glucose Production ◽  
Adaptor Protein ◽  
Glucose Production ◽  
Membrane Localization ◽  
Dependent Manner ◽  
Membrane Translocation ◽  
Insulin Stimulation ◽  
Akt Activation ◽  
Hepatic Glucose ◽  
Impaired Insulin

The adaptor protein APPL1 undergoes ubiquitination upon insulin stimulation in a TRAF6-dependent manner. Abrogation of APPL1 ubiquitination blocks insulin-evoked membrane localization of the APPL1–Akt complex, leading to impaired insulin actions on Akt activation and suppression of hepatic glucose production.

scholarly journals TBC-2 Regulates RAB-5/RAB-7-mediated Endosomal Trafficking inCaenorhabditis elegans

2010 ◽  
Vol 21 (13) ◽  
pp. 2285-2296 ◽  
Author(s):  
Laëtitia Chotard ◽  
Ashwini K. Mishra ◽  
Marc-André Sylvain ◽  
Simon Tuck ◽  
David G. Lambright ◽  
...  
Keyword(s):  
Rab Gtpase ◽  
Endosomal Trafficking ◽  
Dependent Manner ◽  
Nucleotide Exchange ◽  
Late Endosomes ◽  
Arginine Finger ◽  
Endosome Maturation ◽  
Hops Complex

During endosome maturation the early endosomal Rab5 GTPase is replaced with the late endosomal Rab7 GTPase. It has been proposed that active Rab5 can recruit and activate Rab7, which in turn could inactivate and remove Rab5. However, many of the Rab5 and Rab7 regulators that mediate endosome maturation are not known. Here, we identify Caenorhabditis elegans TBC-2, a conserved putative Rab GTPase-activating protein (GAP), as a regulator of endosome to lysosome trafficking in several tissues. We show that tbc-2 mutant animals accumulate enormous RAB-7–positive late endosomes in the intestine containing refractile material. RAB-5, RAB-7, and components of the homotypic fusion and vacuole protein sorting (HOPS) complex, a RAB-7 effector/putative guanine nucleotide exchange factor (GEF), are required for the tbc-2(−) intestinal phenotype. Expression of activated RAB-5 Q78L in the intestine phenocopies the tbc-2(−) large late endosome phenotype in a RAB-7 and HOPS complex-dependent manner. TBC-2 requires the catalytic arginine-finger for function in vivo and displays the strongest GAP activity on RAB-5 in vitro. However, TBC-2 colocalizes primarily with RAB-7 on late endosomes and requires RAB-7 for membrane localization. Our data suggest that TBC-2 functions on late endosomes to inactivate RAB-5 during endosome maturation.

scholarly journals Sorting nexin 27 interactome in T-lymphocytes identifies zona occludens-2 dynamic redistribution at the immune synapse

Traffic ◽  
2017 ◽  
Vol 18 (8) ◽  
pp. 491-504 ◽  
Author(s):  
María Tello-Lafoz ◽  
Gonzalo Martínez-Martínez ◽  
Cristina Rodríguez-Rodríguez ◽  
Juan Pablo Albar ◽  
Morgan Huse ◽  
...  
Keyword(s):  
T Lymphocytes ◽  
Immune Synapse ◽  
Sorting Nexin ◽  
Zona Occludens
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