scholarly journals Focal cholesterol depletion during Fcγ receptor-mediated phagocytosis contributes to Lyn kinase regulation

2018 ◽  
Author(s):  
Stella M. Lu ◽  
Allen Volchuk ◽  
Gregory D. Fairn
Keyword(s):  
Cholesterol Depletion ◽  
Membrane Domains ◽  
Kinase Signaling ◽  
Protein Markers ◽  
Fcγ Receptor ◽  
Lyn Kinase ◽  
Selective Depletion ◽  
Summary Statement ◽  
Specific Membrane ◽  
Genetically Encoded Biosensor

AbstractCholesterol-rich nanodomains, historically referred to as lipid rafts, have previously been reported to be critical for proper Fcγ Receptor and Lyn kinase signaling during phagocytosis. Throughout the initial stages of phagocytosis, the nascent phagosome is actively remodeled by localized lipid metabolism and exocytosis. However, to date, little is known about the dynamics of cholesterol during this stage of particle engulfment. Using a genetically-encoded biosensor for cholesterol, we find that cholesterol is depleted from the nascent phagosome prior to sealing. Additionally, protein markers of both cholesterol-rich and cholesterol-poor nanodomains also clear from the site of phagocytosis arguing against the selective depletion of specific membrane domains. Consistent with previous studies we find that exocytosis contributes to the remodeling of the nascent phagosome. The displacement of cholesterol from the forming phagosome was paralleled by Lyn kinase helping to explain the reduction of phosphotyrosine signal in the nascent phagosome. This diminution of cholesterol and Lyn from the base of the cup may aid in the processivity of the phagocytic signal during pseudopod extension, and provide an unappreciated mechanism by which Lyn kinase signaling is regulated during phagocytosis.Summary Statement: Localized exocytosis dilutes cholesterol from the phagocytic cup leading to the displacement of Lyn kinase and an attenuation of signaling.

scholarly journals Utility of Three-Protein Panels in the Separation of Aggressive Prostate Cancer from Non-Aggressive Tumors

2021 ◽  
Author(s):  
Qing Kay Li ◽  
Tung-shing Mamie Lih ◽  
Yuefan Wang ◽  
Yingwei Hu ◽  
Naseruddin Hoti ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Diagnostic Utility ◽  
Prostate Specific Membrane Antigen ◽  
Potential Utility ◽  
Protein Markers ◽  
Detection Ability ◽  
Galectin 3 ◽  
Individual Marker ◽  
Aggressive Tumors ◽  
Specific Membrane

Abstract Background Prostate cancer (PCa) is a heterogeneous group of tumors, including non-aggressive (NAG) and aggressive (AG) subtypes, with variable clinical outcomes. We assessed the diagnostic utility of selected protein markers to identify AG tumors. Methods The TMA was constructed, including NAG and AG. 12 protein markers were evaluated using the TMA by IHC stains. The makers were also evaluated for their potential utility as single or panels for distinguishing AG from NAG tumors. Results The higher expressions of four protein markers, including prostate specific membrane antigen (PSMA), phospho-EGFR, androgen receptor (AR), and P16, were identified in AG tumors of Gleason score 4 and 5. In contrast, Galectin-3, DPP4 and MAN1B1 revealed stronger staining patterns in NAG tumors. Sensitivity and specificity of individual marker varied widely. In tow-marker panels, especially in the panel of DPP4 and PSMA, the specificity was 38.46% at 95% sensitivity. To further improve the detection ability, we combined DPP4 and PSMA with either Galectin-3 or phospho-EGFR into three-marker panels. The specificity achieved >46% at 95% sensitivity and AUC was >0.85. Conclusions Our panels can be used to improve the separation of AG from NAG tumor and to add in the optimization of the treatment strategy for patients.

scholarly journals Expression of Sugar Transporters by In Vivo Electroporation and Particle Gun Methods in the Rat Liver: Localization to Specific Membrane Domains.

2001 ◽  
Vol 34 (1) ◽  
pp. 15-24 ◽  
Author(s):  
Yasuo Shinoda ◽  
Takeshi Suzuki ◽  
Minako Sugawara-Yokoo ◽  
Shinya Nagamatsu ◽  
Hiroyuki Kuwano ◽  
...  
Keyword(s):  
Rat Liver ◽  
Membrane Domains ◽  
Particle Gun ◽  
In Vivo Electroporation ◽  
Sugar Transporters ◽  
Specific Membrane

scholarly journals Sphingomyelin homeostasis is required to form functional enzymatic domains at the trans-Golgi network

2014 ◽  
Vol 206 (5) ◽  
pp. 609-618 ◽  
Author(s):  
Josse van Galen ◽  
Felix Campelo ◽  
Emma Martínez-Alonso ◽  
Margherita Scarpa ◽  
José Ángel Martínez-Menárguez ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Hela Cells ◽  
Transmembrane Proteins ◽  
Short Chain ◽  
Membrane Domains ◽  
Trans Golgi Network ◽  
And Function ◽  
Golgi Network ◽  
Specific Membrane

Do lipids such as sphingomyelin (SM) that are known to assemble into specific membrane domains play a role in the organization and function of transmembrane proteins? In this paper, we show that disruption of SM homeostasis at the trans-Golgi network (TGN) by treatment of HeLa cells with d-ceramide-C6, which was converted together with phosphatidylcholine to short-chain SM and diacylglycerol by SM synthase, led to the segregation of Golgi-resident proteins from each other. We found that TGN46, which cycles between the TGN and the plasma membrane, was not sialylated by a sialyltransferase at the TGN and that this enzyme and its substrate TGN46 could not physically interact with each other. Our results suggest that SM organizes transmembrane proteins into functional enzymatic domains at the TGN.

scholarly journals Phosphorylation and dephosphorylation of Ser852 and Ser889 control clustering, localization, and function of PAR-3

2020 ◽  
Author(s):  
Kazunari Yamashita ◽  
Keiko Mizuno ◽  
Kana Furukawa ◽  
Hiroko Hirose ◽  
Natsuki Sakurai ◽  
...  
Keyword(s):  
Tight Junction ◽  
Cell Polarity ◽  
Phosphorylation Site ◽  
Cell Junction ◽  
Unique Role ◽  
Cellular Events ◽  
A Cell ◽  
Summary Statement ◽  
And Function ◽  
Specific Membrane

AbstractCell polarity is essential for various asymmetric cellular events, where the partitioning defective (PAR) protein, PAR3, plays a unique role as a cellular landmark to establish polarity. In epithelial cells, PAR3 localizes at the subapical border such as the tight junction in vertebrates and functions as an apical determinant. Although there is much information about the regulators of PAR3 localization, the mechanism involved in PAR3 concentration and localization to the specific membrane domain remains an important question to be clarified. In this study, we demonstrate that ASPP2, a stimulator of PAR3 localization, can link PAR3 and protein phosphatase 1 (PP1). The ASPP2–PP1 complex dephosphorylates a novel phosphorylation site, Ser852, of PAR3. Furthermore, Ser852- or Ser889-unphosphorylatable PAR3 mutants form protein clusters and ectopically localize to the lateral membrane. Concomitance of clustering and ectopic localization suggests that PAR3 localization is a consequence of local clustering. We also demonstrate that unphosphorylatable forms of PAR3 are static in molecular turnover and fail to coordinate rapid reconstruction of the tight junction, supporting that both phosphorylated and dephosphorylated states are essential for the functional integrity of PAR3.Summary statementWe show that phosphorylation and dephosphorylation regulate clustering of PAR-3, a cell polarity-regulating factor, and how the clustering regulation affects localization of PAR-3 and cell-cell junction formation.

scholarly journals Tissue factor in microvesicles shed from U87MG human glioblastoma cells induces coagulation, platelet aggregation, and thrombogenesis

Blood ◽  
1984 ◽  
Vol 64 (1) ◽  
pp. 177-184 ◽  
Author(s):  
E Bastida ◽  
A Ordinas ◽  
G Escolar ◽  
GA Jamieson
Keyword(s):  
Platelet Aggregation ◽  
Tissue Factor ◽  
Bovine Brain ◽  
Membrane Domains ◽  
Extrinsic Pathway ◽  
Intact Cells ◽  
Human Glioblastoma ◽  
Single Protein ◽  
Specific Membrane

Abstract Microvesicles (diameter ca 200 nm) from the cell-free supernatant of U87MG human glioblastoma cell caused platelet aggregation and coagulation in a manner identical with that previously shown for the intact cells. Both activities were inhibited by dansylarginine -N-(3- ethyl-1,5-pentanediyl) amide (DAPA), confirming the thrombin-dependent nature of both activities. The specific activities per microgram of protein were 2–10 times greater in the microvesicles than in the plasma membrane fraction, suggesting localization in specific membrane domains. Sucrose density centrifugation gave a single protein peak (density 1.14) with congruent procoagulant and platelet aggregating activities. Both activities required the extrinsic pathway, as shown by studies with factor-deficient plasmas, and both were inhibited by heating (60 min/100 degrees C), by reduction and alkylation, and by incubation of the microvesicles with rabbit anti-bovine brain tissue factor antibody. These observations were confirmed using microvesicles from the HL-60 human promyelocytic leukemia cells, which are known to contain tissue factor activity. The results suggest that both procoagulant and proaggregating activities are causally related through the presence of tissue factor in the microvesicles. Studies with the Baumgartner perfusion apparatus showed that U87MG microvesicles increased the size of adherent thrombi nearly tenfold and that these thrombi were associated with nucleated cells from the blood. The increase in adherent thrombi did not occur if perfusion was carried out in the presence of DAPA, confirming the role of thrombin in their formation.

scholarly journals Pollen Aperture Factor INP1 Acts Late in Aperture Formation by Excluding Specific Membrane Domains from Exine Deposition

2017 ◽  
Vol 176 (1) ◽  
pp. 326-339 ◽  
Author(s):  
Anna A. Dobritsa ◽  
Andrew B. Kirkpatrick ◽  
Sarah H. Reeder ◽  
Peng Li ◽  
Heather A. Owen
Keyword(s):  
Membrane Domains ◽  
Specific Membrane

scholarly journals Exclusion of CD45 inhibits activity of p56lck associated with glycolipid-enriched membrane domains.

1996 ◽  
Vol 135 (6) ◽  
pp. 1515-1523 ◽  
Author(s):  
W Rodgers ◽  
J K Rose
Keyword(s):  
Kinase Activity ◽  
Specific Activity ◽  
Peptide Mapping ◽  
Tyrosine Phosphatase ◽  
T Cell Development ◽  
Jurkat Cells ◽  
Membrane Domains ◽  
Membrane Bound ◽  
Triton X ◽  
Specific Membrane

p56lck (Lck) is a lymphoid-specific Src family tyrosine kinase that is critical for T-cell development and activation. Lck is also a membrane protein, and approximately half of the membrane-associated Lck is associated with a glycolipid-enriched membrane (GEM) fraction that is resistant to solubilization by Triton X-100 (TX-100). To compare the membrane-associated Lck present in the GEM and TX-100-soluble fractions of Jurkat cells, Lck from each fraction was immunoblotted with antibody to phosphotyrosine. Lck in the GEM fraction was found to be hyperphosphorylated on tyrosine, and this correlated with a lower kinase specific activity relative to the TX-100-soluble Lck. Peptide mapping and phosphatase diagests showed that the hyperphosphorylation and lower kinase activity of GEM-associated Lck was due to phosphorylation of the regulatory COOH-terminal Tyr505. In addition, we determined that the membrane-bound tyrosine phosphatase CD45 was absent from the GEM fraction. Cells lacking CD45 showed identical phosphorylation of Lck in GEM and TX-100-soluble membranes. We propose that the GEM fraction represents a specific membrane domain present in T-cells, and that the hyperphosphorylation of tyrosine and lower kinase activity of GEM-associated Lck is due to exclusion of CD45 from these domains. Lck associated with the GEM domains may therefore consitute a reservoir of enzyme that can be readily activated.

scholarly journals Membrane Domain Specificity in the Spatial Distribution of Aquaporins 5, 7, 9, and 11 in Efferent Ducts and Epididymis of Rats

2008 ◽  
Vol 56 (12) ◽  
pp. 1121-1135 ◽  
Author(s):  
Louis Hermo ◽  
Morgan Schellenberg ◽  
Lauren Ye Liu ◽  
Bama Dayanandan ◽  
Tong Zhang ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Plasma Membranes ◽  
Water Channel ◽  
Wide Field ◽  
Membrane Domains ◽  
Efferent Ducts ◽  
Specific Manner ◽  
Basal Plasma ◽  
A Cell ◽  
Specific Membrane

Water content within the epididymis of the male reproductive system is stringently regulated to promote sperm maturation. Several members of the aquaporin (AQP) family of water channel-forming integral membrane proteins have been identified in epididymal cells, but expression profiling for this epithelium is presently incomplete, and no AQP isoform has yet been identified on basolateral plasma membranes of these cells. In this study, we explored AQP expression by RT-PCR and light microscopy immunolocalizations using peroxidase and wide-field fluorescence techniques. The results indicate that several AQPs are coexpressed in the epididymis including AQP 5, 7, 9, and 11. Immunolocalizations suggested complex patterns in the spatial distribution of these AQPs. In principal cells, AQP 9 and 11 were present mainly on microvilli, whereas AQP 7 was localized primarily to lateral and then to basal plasma membranes in a region-specific manner. AQP 5 was also expressed regionally but was associated with membranes of endosomes. Additionally, AQPs were expressed by some but not all basal (AQP 7 and 11), clear (AQP 7 and 9), and halo (AQP 7 and 11) cells. These findings indicate unique associations of AQPs with specific membrane domains in a cell type- and region-specific manner within the epididymis of adult animals.

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