RESUMO
A review of the literature published in 2019 on topics relating to gaseous emissions from wastewater facilities is presented. This review is divided into the following sections: odorant emissions from Water Resource Recovery Facilities (WRRFs); greenhouse gas (GHG) emissions; gaseous emissions from wastewater collection systems; physiochemical odor/emissions control methods; biological odor/emissions control methods; odor/GHG characterization and monitoring; and odor impacts/risk assessments. © 2020 Water Environment Federation PRACTITIONER POINTS: Provide a quick reference list for readers who do not have time to go through the 2019 published articles. This prescreening of relevant literatures will save them time and effort. Utilities, engineers, and researchers can identify knowledge gaps, which help them to plan for future testing and R&D needs. Designers can make use of the lit review findings to support their design.
Assuntos
Gases de Efeito Estufa , Águas Residuárias , Gases/análise , Efeito Estufa , Gases de Efeito Estufa/análise , Eliminação de Resíduos Líquidos , Recursos HídricosRESUMO
A review of the literature published in 2017 on topics relating to gaseous emissions from wastewater facilities is presented. This review is divided into the following sections: odorant emissions from wastewater treatment plants (WWTPs); greenhouse gas (GHG) emissions from WWTPs; gaseous emissions from wastewater collection systems; physiochemical odor/emissions control methods; biological odor/emissions control methods; odor/GHG characterization/monitoring/ modeling; and odor impacts/risk assessments.
Assuntos
Gases/análise , Eliminação de Resíduos Líquidos/métodos , Águas Residuárias/química , Gases de Efeito Estufa/análise , OdorantesRESUMO
A review of the literature published in 2016 on topics relating to gaseous emissions from wastewater facilities is presented. This review is divided into the following sections: odorant emissions from wastewater treatment plants (WWTPs); greenhouse gas (GHG) emissions from WWTPs; gaseous emissions from wastewater collection systems; physiochemical odor/emissions control methods; biological odor/emissions control methods; odor characterization/monitoring; and odor impacts/ risk assessments.
Assuntos
Poluentes Atmosféricos/análise , Eliminação de Resíduos Líquidos/estatística & dados numéricos , Poluição do Ar/estatística & dados numéricos , Gases , Efeito Estufa , Águas Residuárias/químicaRESUMO
This research systematically studied the behavior of aeration diffuser efficiency over time, and its relation to the energy usage per diffuser. Twelve diffusers were selected for a one year fouling study. Comprehensive aeration efficiency projections were carried out in two WRRFs with different influent rates, and the influence of operating conditions on aeration diffusers' performance was demonstrated. This study showed that the initial energy use, during the first year of operation, of those aeration diffusers located in high rate systems (with solids retention time - SRT-less than 2 days) increased more than 20% in comparison to the conventional systems (2 > SRT). Diffusers operating for three years in conventional systems presented the same fouling characteristics as those deployed in high rate processes for less than 15 months. A new procedure was developed to accurately project energy consumption on aeration diffusers; including the impacts of operation conditions, such SRT and organic loading rate, on specific aeration diffusers materials (i.e. silicone, polyurethane, EPDM, ceramic). Furthermore, it considers the microbial colonization dynamics, which successfully correlated with the increase of energy consumption (r2:0.82 ± 7). The presented energy model projected the energy costs and the potential savings for the diffusers after three years in operation in different operating conditions. Whereas the most efficient diffusers provided potential costs spanning from 4900 USD/Month for a small plant (20 MGD, or 74,500 m3/d) up to 24,500 USD/Month for a large plant (100 MGD, or 375,000 m3/d), other diffusers presenting less efficiency provided spans from 18,000USD/Month for a small plant to 90,000 USD/Month for large plants. The aim of this methodology is to help utilities gain more insight into process mechanisms and design better energy efficiency strategies at existing facilities to reduce energy consumption.
Assuntos
Difusão , Oxigênio , Reatores Biológicos , Cerâmica , Eliminação de Resíduos LíquidosRESUMO
A review of the literature published in 2015 on topics relating to gaseous emissions from wastewater facilities is presented. This review is divided into the following sections: odorant emissions from wastewater treatment plants (WWTPs); greenhouse gas (GHG) emissions from WWTPs; gaseous emissions from wastewater collection systems; physiochemical odor/emissions control methods; biological odor/emissions control methods; odor characterization/monitoring; and odor impacts/ risk assessments.
Assuntos
Poluição do Ar/prevenção & controle , Gases de Efeito Estufa/análise , Eliminação de Resíduos Líquidos/métodos , Águas Residuárias/química , Poluição do Ar/estatística & dados numéricos , Odorantes/análiseRESUMO
We report the synthesis of a gadolinium hydroxide (Gd(OH)3) nanorod based doxorubicin (Dox) delivery system that can enhance both magnetic resonance imaging contrast and radiation sensitivity. A simple and cost effective wet-chemical method was utilized in the presence of manganese (Mn) ions and Dox to produce the Gd(OH)3:Mn·Dox nanocluster structure. The Gd(OH)3:Mn·Dox nanocluster was composed of Mn-doped Gd(OH)3 nanorods arranged in parallel with Dox as a linker molecule between the adjacent nanorods. No other studies have utilized Dox as both the linker and therapeutic molecule in a nanostructure to date. The Gd(OH)3 nanorod is reported to have no significant cellular or in vivo toxicity, which makes it an ideal base material for this biomedical application. The Gd(OH)3:Mn·Dox nanocluster exhibited paramagnetic behavior and was stable in a colloidal solution. The nanocluster also enabled high Dox loading capacity and specifically released Dox in a sustained and pH-dependent manner. The positively charged Gd(OH)3:Mn·Dox nanoclusters were readily internalized into MDA-MB-231 breast cancer cells via endocytosis, which resulted in intracellular release of Dox. The released Dox in cells was effective in conferring cytotoxicity and inhibiting proliferation of cancer cells. Furthermore, a synergistic anticancer effect could be observed with radiation treatment. Overall, the Gd(OH)3:Mn·Dox nanocluster drug delivery system described herein may have potential utility in clinics as a multifunctional theranostic nanoparticle with combined benefits in both diagnosis and therapy in the management of cancer.
Assuntos
Gadolínio/química , Doxorrubicina , Sistemas de Liberação de Medicamentos , Imageamento por Ressonância Magnética , Nanopartículas , Nanomedicina TeranósticaRESUMO
Aeration is commonly identified as the largest contributor to process energy needs in the treatment of wastewater and therefore garners significant focus in reducing energy use. Fine-pore diffusers are the most common aeration system in municipal wastewater treatment. These diffusers are subject to fouling and scaling, resulting in loss in transfer efficiency as biofilms form and change material properties producing larger bubbles, hindering mass transfer and contributing to increased plant energy costs. This research establishes a direct correlation and apparent mechanistic link between biofilm DNA concentration and reduced aeration efficiency caused by biofilm fouling. Although the connection between biofilm growth and fouling has been implicit in discussions of diffuser fouling for many years, this research provides measured quantitative connection between the extent of biofouling and reduced diffuser efficiency. This was clearly established by studying systematically the deterioration of aeration diffusers efficiency during a 1.5 year period, concurrently with the microbiological study of the biofilm fouling in order to understand the major factors contributing to diffuser fouling. The six different diffuser technologies analyzed in this paper included four different materials which were ethylene-propylene-diene monomer (EPDM), polyurethane, silicone and ceramic. While all diffusers foul eventually, some novel materials exhibited fouling resistance. The material type played a major role in determining the biofilm characteristics (i.e., growth rate, composition, and microbial density) which directly affected the rate and intensity at what the diffusers were fouled, whereas diffuser geometry exerted little influence. Overall, a high correlation between the increase in biofilm DNA and the decrease in αF was evident (CV < 14.0 ± 2.0%). By linking bacterial growth with aeration efficiency, the research was able to show quantitatively the causal connection between bacterial fouling and energy wastage during aeration.
Assuntos
Biofilmes , Eliminação de Resíduos Líquidos/métodos , Purificação da Água/métodos , Incrustação Biológica , Cerâmica/química , DNA Bacteriano/análise , Desoxirribonucleases/química , Difusão , Elastômeros/química , Desenho de Equipamento , Etilenos/química , Consórcios Microbianos , Microscopia Confocal , Oxigênio/química , Pressão , Esgotos/química , Águas Residuárias , Microbiologia da ÁguaRESUMO
Recent studies have found BCL10 can localize to the nucleus and that this is linked to tumor aggression and poorer prognosis. These studies suggest that BCL10 localization plays a novel role in the nucleus that may contribute to cellular transformation and carcinogenesis. In this study, we show that BCL10 functions as part of the DNA damage response (DDR). We found that BCL10 facilitates the rapid recruitment of RPA, BRCA1 and RAD51 to sites of DNA damage. Furthermore, we also found that ATM phosphorylates BCL10 in response to DNA damage. Functionally, BCL10 promoted DNA double-strand breaks repair, enhancing cell survival after DNA damage. Taken together our results suggest a novel role for BCL10 in the repair of DNA lesions.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Quebras de DNA de Cadeia Dupla , Dano ao DNA/fisiologia , Proteínas Adaptadoras de Transdução de Sinal/genética , Proteína 10 de Linfoma CCL de Células B , Sítios de Ligação/fisiologia , Linhagem Celular Tumoral , Sobrevivência Celular/fisiologia , HumanosRESUMO
A review of the literature published in 2014 on topics relating to gaseous emissions from wastewater facilities is presented. This review is divided into the following sections: odorant emissions from wastewater treatment plants (WWTPs); greenhouse gas (GHG) emissions from WWTPs; gaseous emissions from wastewater collection systems; physiochemical odor/emissions control methods; biological odor/emissions control methods; odor characterization/monitoring; and odor impacts/risk assessments.
RESUMO
Specific expression patterns of microRNA (miRNA) molecules have been linked to cancer initiation, progression, and metastasis. The accumulating evidence for the role of oncogenic or tumor-suppressing miRNAs identified the need for nano-scaled platform that can help deliver nucleotides to modulate miRNAs. Here we report the synthesis of novel layered gadolinium hydroxychloride (LGdH) nanoparticles, a member of the layered double hydroxide (LDH) family, with physiochemical properties suitable for cell uptake and tracing via magnetic resonance (MR) imaging. As a proof of concept, we demonstrate the inhibition of mature miRNA-10b in metastatic breast cancer cell line using LGdH nanoparticle as a delivery platform. Through characterization analysis, we show that nanoparticles are easily and stably loaded with anti-miRNA oligonucleotides (AMO) and efficiently penetrate cell membranes. We demonstrate that AMOs delivered by LGdH nanoparticles remain functional by inducing changes in the expression of its downstream effector and by curbing the invasive properties. Furthermore, we demonstrate the traceability of LGdH nanoparticles via T1 weighted MR imaging. LGdH nanoparticles, which are biocompatible with cells in vitro, provide a promising multifunctional platform for microRNA therapeutics through their diagnostic, imaging, and therapeutic potentials.
Assuntos
Neoplasias da Mama/tratamento farmacológico , Sistemas de Liberação de Medicamentos/instrumentação , Gadolínio/química , Nanopartículas Metálicas/química , MicroRNAs/uso terapêutico , Materiais Biocompatíveis/síntese química , Neoplasias da Mama/ultraestrutura , Linhagem Celular Tumoral , Feminino , Gadolínio/uso terapêutico , Humanos , Imageamento por Ressonância Magnética/instrumentação , Nanopartículas Metálicas/uso terapêutico , Oligonucleotídeos Antissenso/química , Oligonucleotídeos Antissenso/uso terapêuticoRESUMO
BACKGROUND: The mucin MUC1, a type I transmembrane glycoprotein, is overexpressed in breast cancer and has been correlated with increased metastasis. We were the first to report binding between MUC1 and Intercellular adhesion molecule-1 (ICAM-1), which is expressed on stromal and endothelial cells throughout the migratory tract of a metastasizing breast cancer cell. Subsequently, we found that MUC1/ICAM-1 binding results in pro-migratory calcium oscillations, cytoskeletal reorganization, and simulated transendothelial migration. These events were found to involve Src kinase, a non-receptor tyrosine kinase also implicated in breast cancer initiation and progression. Here, we further investigated the mechanism of MUC1/ICAM-1 signalling, focusing on the role of MUC1 dimerization in Src recruitment and pro-metastatic signalling. METHODS: To assay MUC1 dimerization, we used a chemical crosslinker which allowed for the detection of dimers on SDS-PAGE. We then generated MUC1 constructs containing an engineered domain which allowed for manipulation of dimerization status through the addition of ligands to the engineered domain. Following manipulation of dimerization, we immunoprecipitated MUC1 to investigate recruitment of Src, or assayed for our previously observed ICAM-1 binding induced events. To investigate the nature of MUC1 dimers, we used both non-reducing SDS-PAGE and generated a mutant construct lacking cysteine residues. RESULTS: We first demonstrate that the previously observed MUC1/ICAM-1 signalling events are dependent on the activity of Src kinase. We then report that MUC1 forms constitutive cytoplasmic domain dimers which are necessary for Src recruitment, ICAM-1 induced calcium oscillations and simulated transendothelial migration. The dimers are not covalently linked constitutively or following ICAM-1 binding. In contrast to previously published reports, we found that membrane proximal cysteine residues were not involved in dimerization or ICAM-1 induced signalling. CONCLUSIONS: Our data implicates non-cysteine linked MUC1 dimerization in cell signalling pathways required for cancer cell migration.
Assuntos
Neoplasias da Mama/patologia , Carcinoma/patologia , Molécula 1 de Adesão Intercelular/metabolismo , Mucina-1/fisiologia , Multimerização Proteica/fisiologia , Quinases da Família src/metabolismo , Neoplasias da Mama/genética , Neoplasias da Mama/metabolismo , Carcinoma/genética , Carcinoma/metabolismo , Linhagem Celular Tumoral , Cisteína/genética , Cisteína/metabolismo , Feminino , Células HEK293 , Humanos , Modelos Biológicos , Mucina-1/química , Mucina-1/genética , Mucina-1/metabolismo , Invasividade Neoplásica , Ligação Proteica/efeitos dos fármacos , Ligação Proteica/genética , RNA Interferente Pequeno/farmacologia , Quinases da Família src/genéticaRESUMO
OBJECTIVE: Soluble matrix metalloproteinases (MMPs) facilitate the egress of hematopoietic stem/progenitor cells (HSPC) from the bone marrow (BM) during granulocyte colony-stimulating factor (G-CSF)-induced mobilization. Because membrane-type (MT)1-MMP, which is localized on the leading edge of migrating cells, activates the latent forms of soluble MMPs, we investigated its role in HSPC mobilization. MATERIALS AND METHODS: We examined the effect of G-CSF on the expression of MT1-MMP and its activities (proMMP-2 activation and migration) in hematopoietic cells. We also investigated the subcellular localization of MT1-MMP and the signaling pathways that regulate its expression and function in hematopoietic cells after exposure to G-CSF. RESULTS: We found that G-CSF increases MT1-MMP transcription and protein synthesis in hematopoietic cells; proMMP-2 activation in cocultures of HSPC with BM fibroblasts; chemoinvasion across reconstituted basement membrane Matrigel toward a stromal cell-derived factor-1 gradient, which is reduced by small interfering RNA silencing of MT1-MMP; and localization of MT1-MMP to membrane lipid rafts through a mechanism that is regulated by the phosphatidylinositol 3-kinase signaling pathway. Disruption of raft formation (by the cholesterol-sequestering agent methyl-beta-cyclodextrin) abrogated phosphatidylinositol 3-kinase phosphorylation and MT1-MMP incorporation into lipid rafts resulting in reduced proMMP-2 activation and HSPC migration. CONCLUSION: G-CSF-induced upregulation of MT1-MMP in hematopoietic cells and its enhanced incorporation into membrane lipid rafts contributes to proMMP-2 activation, which facilitates mobilization of HSPC.
Assuntos
Regulação Enzimológica da Expressão Gênica/efeitos dos fármacos , Fator Estimulador de Colônias de Granulócitos/farmacologia , Mobilização de Células-Tronco Hematopoéticas , Células-Tronco Hematopoéticas/enzimologia , Metaloproteinase 14 da Matriz/biossíntese , Microdomínios da Membrana/enzimologia , Regulação para Cima/efeitos dos fármacos , Movimento Celular , Células Cultivadas , Técnicas de Cocultura , Ativação Enzimática/efeitos dos fármacos , Precursores Enzimáticos/metabolismo , Fibroblastos/citologia , Fibroblastos/metabolismo , Gelatinases/metabolismo , Células-Tronco Hematopoéticas/citologia , Humanos , Fosfatidilinositol 3-Quinases/metabolismo , Fosforilação/efeitos dos fármacos , Transdução de Sinais/efeitos dos fármacos , Células Estromais/citologia , Células Estromais/metabolismo , beta-Ciclodextrinas/farmacologiaRESUMO
Lipid rafts are dynamic assemblies of cholesterol and glycolipid that form detergent-insoluble microdomains within membrane lipid bilayers. Because rafts can be separated by flotation on sucrose gradients, interrogation by mass spectrometry (MS) provides a valuable new insight into lipid raft function. Here we combine liquid chromatography (LC) electrospray ionization (ESI) and matrix-assisted laser desorption ionization (MALDI) MS/MS to corroborate and extend our previous description of lipid raft proteomes derived from the monocytic cell line THP-1. Interestingly, LC-ESI and MALDI MS/MS identify largely non-overlapping, and therefore, potentially complementary protein populations. Using the combined approach, we detected 277 proteins compared to 52 proteins obtained with the original gel-based MALDI MS. We confirmed the presence of 47 of the original 52 proteins demonstrating the consistency of the lipid raft preparations. We demonstrated by immunoblotting that Rac 1 and Rac 2, two of the 52 proteins we failed to confirm, were indeed absent from the lipid raft fractions. The majority of new proteins were cytoskeletal proteins and their regulators, proteins implicated in membrane fusion and vesicular trafficking or signaling molecules. Our results therefore, confirm and extend previous evidence indicating lipid rafts of monocytic cells are specialized for cytoskeletal assembly and vesicle trafficking. Of particular interest, we detected SNAP-23, basigin, Glut-4 and pantophysin in lipid rafts. Since these proteins are implicated in both vesicular trafficking and gamete fusion, lipid rafts may play a common role in these processes. It is evident that the combination of LC-ESI and LC-MALDI MS/MS increases the proteome coverage which allows better understanding of the lipid raft function.
Assuntos
Microdomínios da Membrana/química , Monócitos/citologia , Proteoma/análise , Animais , Bovinos , Linhagem Celular , Cromatografia Líquida , Guanosina Trifosfato/metabolismo , Humanos , Peso Molecular , Monócitos/química , Peptídeos/análise , Peptídeos/química , Proteoma/química , Proteoma/metabolismo , Espectrometria de Massas por Ionização por Electrospray , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz , Espectrometria de Massas em Tandem , Proteínas rac de Ligação ao GTP/análise , Proteínas rac de Ligação ao GTP/metabolismo , Proteínas rac1 de Ligação ao GTP/análise , Proteínas rac1 de Ligação ao GTP/metabolismo , Proteína RAC2 de Ligação ao GTPRESUMO
MUC1, a transmembrane glycoprotein of the mucin family, when aberrantly expressed on breast cancer cells is correlated with increased lymph node metastases. We have previously shown that MUC1 binds intercellular adhesion molecule-1 (ICAM-1) on surrounding accessory cells and facilitates transendothelial migration of MUC1-bearing cells. Nevertheless, the underlying molecular mechanism is still obscure. In the present study, we used a novel assay of actin cytoskeletal reorganization to show that by ligating ICAM-1, MUC1 triggers Rac1- and Cdc42-dependent actin cytoskeletal protrusive activity preferentially at the heterotypic cell-cell contact sites. Further, we show that these MUC1/ICAM-1 interaction-initiated lamellipodial and filopodial protrusions require Src family kinase and CT10 regulator of kinase like (CrkL) accompanied by the rapid formation of a Src-CrkL signaling complex at the MUC1 cytoplasmic domain. Through inhibition of Src kinase activity, we further revealed that Src is required for recruiting CrkL to the MUC1 cytoplasmic domain as well as mediating the observed actin cytoskeleton dynamics. These findings suggest a novel MUC1-Src-CrkL-Rac1/Cdc42 signaling cascade following ICAM-1 ligation, through which MUC1 regulates cytoskeletal reorganization and directed cell motility during cell migration.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Movimento Celular , Citoesqueleto/enzimologia , Molécula 1 de Adesão Intercelular/metabolismo , Mucina-1/metabolismo , Proteínas Nucleares/metabolismo , Proteínas Proto-Oncogênicas pp60(c-src)/metabolismo , Proteína cdc42 de Ligação ao GTP/metabolismo , Actinas/metabolismo , Animais , Linhagem Celular Tumoral , Humanos , Camundongos , Células NIH 3T3 , Ligação Proteica , Transdução de Sinais , Fosfolipases Tipo C/metabolismo , Proteínas rac1 de Ligação ao GTP/metabolismo , Quinases da Família src/metabolismoRESUMO
Changes in the level of membrane cholesterol regulate a variety of signaling processes including those mediated by acylated signaling molecules that localize to lipid rafts. Recently several types of ion channels have been shown to have cholesterol-dependent activity and to localize to lipid rafts. In this study, we have investigated the role of cholesterol in the regulation of ion transport in colonic epithelial cells. We observed that methyl-beta-cyclodextrin (MbetaCD), a cholesterol-sequestering molecule, activated transepithelial short circuit current (Isc), but only from the basolateral side. Similar results were obtained with a cholesterol-binding agent, filipin, and with the sphingomyelin-degrading enzyme, sphingomyelinase. Experiments with DeltaF508CFTR mutant mice indicated that raft disruption affected CFTR-mediated anion secretion, while pharmacological studies showed that this effect was due to activation of basolateral large conductance Ca2+-activated K+ (BK) channels. Sucrose density gradient centrifugation studies demonstrated that BK channels were normally present in the high-density fraction containing the detergent-insoluble cytoskeleton, and that following treatment with MbetaCD, BK channels redistributed into detergent-soluble fractions. Our evidence therefore implicates novel high-density cholesterol-enriched plasma membrane microdomains in the modulation of BK channel activation and anion secretion in colonic epithelia.
Assuntos
Membrana Celular/química , Colesterol/análise , Colo/citologia , Canais de Potássio/metabolismo , Amilorida/farmacologia , Animais , Permeabilidade da Membrana Celular/efeitos dos fármacos , Colesterol/metabolismo , Fibrose Cística/metabolismo , Regulador de Condutância Transmembrana em Fibrose Cística/metabolismo , Epitélio/metabolismo , Filipina/farmacologia , Microdomínios da Membrana/metabolismo , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Camundongos Mutantes , Ouabaína/farmacologia , Técnicas de Patch-Clamp , Compostos de Amônio Quaternário/farmacologia , Água/química , beta-Ciclodextrinas/farmacologiaRESUMO
Lipid rafts are glycolipid- and cholesterol-enriched membrane microdomains implicated in membrane signaling and trafficking. The highly hydrophobic nature of lipid raft proteins pose significant problems of solubilization and recovery that hinder analysis by mass spectrometry (MS) and may under-report the composition of lipid rafts. In a previous investigation of the monocyte lipid raft in which proteins were digested with trypsin following polyacrylamide gel electrophoresis we identified 52 proteins. Here we report the development of a sodium dodecyl sulfate (SDS)-aided approach in which proteins are digested in solution and examined by high-performance liquid chromatography-matrix-assisted laser desorption/ionization-tandem mass spectrometry (HPLC-MALDI-MS/MS) using a novel LC-MALDI interface thereby circumventing the need to separate proteins on gels. Using this approach we identified 71 proteins in the lipid raft, 45 of which were not detected using in-gel digestion. Among the new proteins are alpha- and beta-tubulin, tubulinspecific chaperone A, a folding protein involved in tubulin dimer assembly, and KIF13, a microtubule motor protein indicating that proteins involved in microtubule assembly and trafficking are more readily detected using an in-solution approach. To investigate why tubulin was not identified by in-gel digestion, we compared the distribution of alpha-tubulin and the raft marker flotillin-2 in buoyant density gradients before and after separation on SDS-gels. Both proteins were present in the raft fractions, but tubulin was selectively lost following separation on SDS-gels. Assemblies of cytoskeletal proteins with lipid rafts may therefore be resolved using in-solution digestion that would be missed using gel-based approaches.
Assuntos
Cromatografia Líquida/métodos , Microdomínios da Membrana/química , Proteômica , Transporte Biológico , Ácidos Carboxílicos/metabolismo , Linhagem Celular , Centrifugação com Gradiente de Concentração , Colesterol/química , Cromatografia Líquida de Alta Pressão , Citoesqueleto/química , Citoesqueleto/metabolismo , Citosol/metabolismo , Detergentes/farmacologia , Dimerização , Eletroforese em Gel Bidimensional , Eletroforese em Gel de Poliacrilamida , Glicolipídeos/química , Humanos , Lipídeos/química , Espectrometria de Massas , Proteínas de Membrana/química , Octoxinol/farmacologia , Peptídeos/química , Dobramento de Proteína , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz/métodos , Fatores de Tempo , Tripsina/farmacologia , Tubulina (Proteína)/químicaRESUMO
CD20 is a B cell-specific membrane protein that functions in store-operated calcium entry and serves as a useful target for antibody-mediated therapeutic depletion of B cells. Antibody binding to CD20 induces a diversity of biological effects, some of which are dependent on lipid rafts. Rafts are isolated as low density detergent-resistant membranes, initially characterized using Triton X-100. We have previously reported that CD20 is soluble in 1% Triton but that antibodies induce the association of CD20 with Triton-resistant rafts. However, by using several other detergents to isolate rafts and by microscopic co-localization with a glycosylphosphatidylinositol-linked protein, we show in this report that CD20 is constitutively raft-associated. CD20 was distributed in a punctate pattern on the cell surface as visualized by fluorescence imaging and was also localized to microvilli by electron microscopy. The mechanism underlying antibody-induced association of CD20 with Triton-resistant rafts was investigated and found not to require cellular ATP, kinase activity, actin polymerization, or antibody cross-linking but was dependent on the epitope recognized. Thus, antibody-induced insolubility in 1% Triton most likely reflects a transition from relatively weak to strong raft association that occurs as a result of a conformational change in the CD20 protein.
Assuntos
Antígenos CD20/metabolismo , Microdomínios da Membrana/metabolismo , Microvilosidades/metabolismo , Actinas/química , Trifosfato de Adenosina/química , Antígenos CD59/biossíntese , Linhagem Celular Tumoral , Membrana Celular/metabolismo , Reagentes de Ligações Cruzadas/farmacologia , Citocalasina D/farmacologia , Detergentes/farmacologia , Epitopos/química , Citometria de Fluxo , Humanos , Microscopia Eletrônica , Microscopia de Fluorescência , Modelos Químicos , Octoxinol/farmacologia , Conformação Proteica , Fatores de Tempo , TransfecçãoRESUMO
Lipid rafts are liquid-ordered cholesterol and glycolipid-enriched membrane microdomains that act as sorting devices for the accumulation of acylated signaling molecules. Lipid rafts are implicated in receptor signaling, protein and membrane trafficking, cytoskeletal re-organization and the entry of infectious organisms into cells. Several recent studies have investigated the composition of the lipid raft proteome by mass spectrometry. Here, those studies and the insights they afford into raft function are reviewed. Lipid rafts contain hydrophobic proteins, posing problems of isolation, recovery and analysis. Recent advances in proteome preparation that extend the boundaries of protein detection in lipid rafts are described and their implications for the exploration of the functional proteome are discussed.
Assuntos
Microdomínios da Membrana/metabolismo , Proteoma , Humanos , Microdomínios da Membrana/química , Fagossomos/metabolismo , Transporte Proteico/fisiologia , Proteínas/química , Proteínas/metabolismo , Transdução de Sinais/fisiologia , Linfócitos T/metabolismoRESUMO
Lipid rafts are membrane microdomains of unique lipid composition that segregate proteins with poorly understood consequences for membrane organization. Identification of raft associated proteins could therefore provide novel insight into raft-dependent functions. Monocytes process antigens for presentation to T cells by ingesting pathogens into calcium-dependent plasma membrane invaginations called "phagosomes" which develop by sequential fusion with the endoplasmic reticulum, early and late endosomes. We investigated the protein composition of Triton X-100 insoluble low density membranes of the monocyte cell-line THP-1 by matrix-assisted laser desorption/ionization-time of flight and tandem mass spectrometry. The ganglioside GM1 colocalized on the plasma membrane with the raft markers flotillin 1 and 2, which were enriched in low buoyant density fractions containing 52 identifiable proteins, 28 of which have not been reported in rafts, and nine of which are associated with the endoplasmic reticulum (ER). Remarkably, 27 of the 52 proteins are components of phagosomes, including the ER protein calnexin which we demonstrate is phosphorylated on serine 562, a switch controlling calcium homeostasis. The presence of the early and late endosome trafficking proteins Rab-1, and Rab-7 together with the late endosome protein LIMPII, indicate lipid rafts are present throughout endosome maturation. Identification of vacuolar ATP synthase, and synaptosomal-associated protein-23, proteins implicated in membrane fusion, together with the cytoskeletal proteins actin, alpha-actinin, and vimentin, and Rac 1, 2, and 3, regulators of cytoskeletal assembly, indicate monocyte lipid rafts contain the machinery to direct vesicular fusion and actin based vesicular migration throughout phagosome development.
Assuntos
Vesículas Citoplasmáticas/metabolismo , Microdomínios da Membrana/química , Proteínas de Membrana/análise , Monócitos/química , Monócitos/citologia , Fagossomos/metabolismo , Transporte Biológico Ativo , Calnexina/química , Calnexina/metabolismo , Linhagem Celular , Proteínas do Citoesqueleto/análise , Proteínas do Citoesqueleto/química , Retículo Endoplasmático/química , Glucose/metabolismo , Glicosilfosfatidilinositóis/metabolismo , Fusão de Membrana , Proteínas de Membrana/química , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por MatrizRESUMO
Small cell lung carcinoma (SCLC) is a highly metastatic disease with a poor prognosis due to its resistance to current modes of therapy. SCLC cells appear to arise by oncogenic transformation of self-renewing pulmonary neuroendocrine cells, which have the potential to differentiate into a variety of lung epithelial cell lineages. Epithelial-mesenchymal conversion involved in such cell type transitions leads to the acquisition of an invasive and metastatic phenotype and may be critical for neoplastic progression and its eventual resistance to therapy. In order to investigate mechanisms involved in such transitions, a SCLC cell line was exposed to 5-bromodeoxyuridine. This treatment induced a dramatic conversion from non-substrate-adherent aggregates to monolayers of cells exhibiting an epithelioid phenotype. The phenotypic transition was concomitant with downregulation of vimentin, upregulation of cytokeratins, and cell-cell and cell-matrix adhesion molecules as well as redistribution of the actin cytoskeleton. The changes in the levels and organization of cell-cell and cell-matrix adhesion molecules were correlated with an in vivo loss of tumorigenicity.