RESUMEN

Patients with a high-risk pregnancy or who immediately give birth are often not provided access to acute care occupational and physical therapy during their hospital admission. The greatest potential for health care crises, including maternal mortality, occurs during the first 6 weeks after birth. Maternal mortality and morbidity, which continue to rise in the United States, are considered indicators of the overall population health of a country. It is estimated that over 80% of pregnancy-related deaths are preventable. The leading causes of death within the first 6 days after birth are hemorrhage, hypertensive disorders, and infection. Implicit biases about childbearing individuals who are perceived to be relatively young, independent, active, and healthy may unintentionally contribute to areas of substandard care that adversely impact maternal health outcomes. It is a professional and ethical imperative that health providers, including occupational and physical therapists, establish themselves as allies to patient groups at high risk for disparate treatment. The Acute Care OB Rehab Implicit Bias Self-Reflection Tool is an instrument designed for health providers to identify stereotypes that may contribute to inequitable access to rehabilitation in the hospital after birth. Including rehabilitation services for the perinatal population in the hospital setting can play a pivotal role in early detection of adverse events with activity that may directly impact the increasing maternal mortality rate in the United States.

RESUMEN

The UK Antimicrobial Registry (UKAR) has been developed to capture data on real world usage of antimicrobial agents with an initial focus on those used to treat drug-resistant infections. Several industry partners have committed support for the study, which is included in the National Institute for Health and Care Research (NIHR) portfolio in England with similar arrangements in the three devolved UK nations. The two antimicrobials in the National Institute for Health and Care Excellence (NICE) subscription model pilot (cefiderocol and ceftazidime/avibactam) are included in the UKAR and future expansion of work in this area is planned. This model decouples payment from usage by using a fixed annual fee. The study will provide information on the characteristics of patients receiving study drugs, the infections being treated, treatment effectiveness and adverse events. UKAR potentially provides a novel resource of enduring value to support healthcare in the UK and more widely and contribute to AMR National Action Plan goals for optimal use of antimicrobials.

RESUMEN

The Mla pathway is believed to be involved in maintaining the asymmetrical Gram-negative outer membrane via retrograde phospholipid transport. The pathway is composed of three components: the outer membrane MlaA-OmpC/F complex, a soluble periplasmic protein, MlaC, and the inner membrane ATPase, MlaFEDB complex. Here, we solve the crystal structure of MlaC in its phospholipid-free closed apo conformation, revealing a pivoting ß-sheet mechanism that functions to open and close the phospholipid-binding pocket. Using the apo form of MlaC, we provide evidence that the inner-membrane MlaFEDB machinery exports phospholipids to MlaC in the periplasm. Furthermore, we confirm that the phospholipid export process occurs through the MlaD component of the MlaFEDB complex and that this process is independent of ATP. Our data provide evidence of an apparatus for lipid export away from the inner membrane and suggest that the Mla pathway may have a role in anterograde phospholipid transport.

Asunto(s)

Proteínas Bacterianas/metabolismo , Membrana Celular/metabolismo , Proteínas de la Membrana/metabolismo , Fosfolípidos/metabolismo , Transportadoras de Casetes de Unión a ATP/genética , Transportadoras de Casetes de Unión a ATP/metabolismo , Proteínas Bacterianas/química , Proteínas Bacterianas/genética , Transporte Biológico , Cristalografía por Rayos X , Bacterias Gramnegativas/metabolismo , Proteínas de la Membrana/genética , Proteínas de Transporte de Membrana/química , Proteínas de Transporte de Membrana/metabolismo , Modelos Biológicos , Complejos Multiproteicos/genética , Complejos Multiproteicos/metabolismo , Periplasma/metabolismo , Unión Proteica , Conformación Proteica en Lámina beta

RESUMEN

Rotavirus (RV) infections cause severe diarrhea in infants and young children worldwide. Vaccines are available but cost prohibitive for many countries and only reduce severe symptoms. Vaccinated infants continue to shed infectious particles, and studies show decreased efficacy of the RV vaccines in tropical and subtropical countries where they are needed most. Continuing surveillance for new RV strains, assessment of vaccine efficacy, and development of cost effective antiviral drugs remain an important aspect of RV studies. This study was to determine the efficacy of antioxidant and anti-inflammatory stilbenoids to inhibit RV replication. Peanut (A. hypogaea) hairy root cultures were induced to produce stilbenoids, which were purified by high performance countercurrent chromatography (HPCCC) and analyzed by HPLC. HT29.f8 cells were infected with RV in the presence stilbenoids. Cell viability counts showed no cytotoxic effects on HT29.f8 cells. Viral infectivity titers were calculated and comparatively assessed to determine the effects of stilbenoid treatments. Two stilbenoids, trans-arachidin-1 and trans-arachidin-3, show a significant decrease in RV infectivity titers. Western blot analyses performed on the infected cell lysates complemented the infectivity titrations and indicated a significant decrease in viral replication. These studies show the therapeutic potential of the stilbenoids against RV replication.

RESUMEN

BACKGROUND: Rotavirus (RV) nonstructural protein 4 (NSP4) is the first described viral enterotoxin, which induces early secretory diarrhea in neonatal rodents. Our previous data show a direct interaction between RV NSP4 and the structural protein of caveolae, caveolin-1 (cav-1), in yeast and mammalian cells. The binding site of cav-1 mapped to the NSP4 amphipathic helix, and led us to examine which helical face was responsible for the interaction. METHODS: A panel of NSP4 mutants were prepared and tested for binding to cav-1 by yeast two hybrid and direct binding assays. The charged residues of the NSP4 amphipathic helix were changed to alanine (NSP446-175-ala6); and three residues in the hydrophobic face were altered to charged amino acids (NSP4(46-175)-HydroMut). In total, twelve mutants of NSP4 were generated to define the cav-1 binding site. Synthetic peptides corresponding to the hydrophobic and charged faces of NSP4 were examined for structural changes by circular dichroism (CD) and diarrhea induction by a neonatal mouse study. RESULTS: Mutations of the hydrophilic face (NSP4(46-175)-Ala6) bound cav-1 akin to wild type NSP4. In contrast, disruption of the hydrophobic face (NSP4(46-175)-HydroMut) failed to bind cav-1. These data suggest NSP4 and cav-1 associate via a hydrophobic interaction. Analyses of mutant synthetic peptides in which the hydrophobic residues in the enterotoxic domain of NSP4 were altered suggested a critical hydrophobic residue. Both NSP4HydroMut112-140, that contains three charged amino acids (aa113, 124, 131) changed from the original hydrophobic residues and NSP4AlaAcidic112-140 that contained three alanine residues substituted for negatively charged (aa114, 125, 132) amino acids failed to induce diarrhea. Whereas peptides NSP4wild type 112-140 and NSP4AlaBasic112-140 that contained three alanine substituted for positively charged (aa115, 119, 133) amino acids, induced diarrhea. CONCLUSIONS: These data show that the cav-1 binding domain is within the hydrophobic face of the NSP4 amphipathic helix. The integrity of the helical structure is important for both cav-1 binding and diarrhea induction implying a connection between NSP4 functional and binding activities.

Asunto(s)

Caveolina 1/metabolismo , Glicoproteínas/genética , Glicoproteínas/metabolismo , Toxinas Biológicas/genética , Toxinas Biológicas/metabolismo , Proteínas no Estructurales Virales/genética , Proteínas no Estructurales Virales/metabolismo , Animales , Animales Recién Nacidos , Sitios de Unión , Análisis Mutacional de ADN , Glicoproteínas/química , Interacciones Huésped-Patógeno , Ratones , Modelos Moleculares , Proteínas Mutantes/genética , Proteínas Mutantes/metabolismo , Unión Proteica , Conformación Proteica , Toxinas Biológicas/química , Técnicas del Sistema de Dos Híbridos , Proteínas no Estructurales Virales/química

RESUMEN

BACKGROUND: Rotavirus NSP4 localizes to multiple intracellular sites and is multifunctional, contributing to RV morphogenesis, replication and pathogenesis. One function of NSP4 is the induction of early secretory diarrhea by binding surface receptors to initiate signaling events. The aims of this study were to determine the transport kinetics of NSP4 to the exofacial plasma membrane (PM), the subsequent release from intact infected cells, and rebinding to naïve and/or neighboring cells in two cell types. METHODS: Transport kinetics was evaluated using surface-specific biotinylation/streptavidin pull-downs and exofacial exposure of NSP4 was confirmed by antibody binding to intact cells, and fluorescent resonant energy transfer. Transfected cells similarly were monitored to discern NSP4 movement in the absence of infection or other viral proteins. Endoglycosidase H digestions, preparation of CY3- or CY5- labeled F(ab)2 fragments, confocal imaging, and determination of preferential polarized transport employed standard laboratory techniques. Mock-infected, mock-biotinylated and non-specific antibodies served as controls. RESULTS: Only full-length (FL), endoglycosidase-sensitive NSP4 was detected on the exofacial surface of two cell types, whereas the corresponding cell lysates showed multiple glycosylated forms. The C-terminus of FL NSP4 was detected on exofacial-membrane surfaces at different times in different cell types prior to its release into culture media. Transport to the PM was rapid and distinct yet FL NSP4 was secreted from both cell types at a time similar to the release of virus. NSP4-containing, clarified media from both cells bound surface molecules of naïve cells, and imaging showed secreted NSP4 from one or more infected cells bound neighboring cell membranes in culture. Preferential sorting to apical or basolateral membranes also was distinct in different polarized cells. CONCLUSIONS: The intracellular transport of NSP4 to the PM, translocation across the PM, exposure of the C-terminus on the cell surface and subsequent secretion occurs via an unusual, complex and likely cell-dependent process. The exofacial exposure of the C-terminus poses several questions and suggests an atypical mechanism by which NSP4 traverses the PM and interacts with membrane lipids. Mechanistic details of the unconventional trafficking of NSP4, interactions with host-cell specific molecules and subsequent release require additional study.

Asunto(s)

Membrana Celular/metabolismo , Glicoproteínas/metabolismo , Rotavirus/patogenicidad , Toxinas Biológicas/metabolismo , Proteínas no Estructurales Virales/metabolismo , Animales , Línea Celular , Humanos , Cinética , Unión Proteica , Transporte de Proteínas , Coloración y Etiquetado/métodos

RESUMEN

BACKGROUND/AIMS: Myofibroblast apoptosis promotes the resolution of liver fibrosis. However, retaining macrophages may enhance reversal. The effects of specifically stimulating myofibroblast apoptosis in vivo were assessed. METHODS: A single chain antibody (C1-3) to an extracellular domain of a myofibroblast membrane protein was injected as a fluorescent- or gliotoxin conjugate into mice with liver fibrosis. RESULTS: C1-3 specifically targeted alpha-smooth muscle actin positive liver myofibroblasts within scar regions of the liver in vivo and did not co-localise with liver monocytes/macrophages. Injection of free gliotoxin stimulated a 2-fold increase in non-parenchymal cell apoptosis and depleted liver myofibroblasts by 30% and monocytes/macrophages by 50% but had no effect on fibrosis severity in the sustained injury model employed. In contrast, C1-3-targeted gliotoxin stimulated a 5-fold increase in non-parenchymal cell apoptosis, depleted liver myofibroblasts by 60%, did not affect the number of monocytes/macrophages and significantly reduced fibrosis severity. Fibrosis reduction was associated with increased metalloproteinase-13 levels. CONCLUSIONS: These data demonstrate that specific targeting of liver myofibroblast apoptosis is the most effective anti-fibrogenic therapy, supporting a role for liver monocytes and/or macrophages in the promotion of liver fibrosis reduction.

Asunto(s)

Anticuerpos Monoclonales/farmacología , Apoptosis/inmunología , Fibroblastos/inmunología , Fibroblastos/patología , Cirrosis Hepática/inmunología , Cirrosis Hepática/patología , Actinas/inmunología , Animales , Especificidad de Anticuerpos , Tetracloruro de Carbono/toxicidad , Epítopos , Gliotoxina/farmacología , Inmunoterapia/métodos , Cirrosis Hepática/inducido químicamente , Macrófagos/inmunología , Masculino , Proteínas de la Membrana/inmunología , Ratones , Monocitos/inmunología , Sinaptofisina/inmunología

RESUMEN

Although low-density lipoprotein (LDL) receptor-mediated cholesterol uptake through clathrin-coated pits is now well understood, the molecular details and organizing principles for selective cholesterol uptake/efflux (reverse cholesterol transport, RCT) from peripheral cells remain to be resolved. It is not yet completely clear whether RCT between serum lipoproteins and the plasma membrane occurs primarily through lipid rafts/caveolae or from non-raft domains. To begin to address these issues, lipid raft/caveolae-, caveolae-, and non-raft-enriched fractions were resolved from purified plasma membranes isolated from L-cell fibroblasts and MDCK cells by detergent-free affinity chromatography and compared with detergent-resistant membranes isolated from the same cells. Fluorescent sterol exchange assays between lipoproteins (VLDL, LDL, HDL, apoA1) and these enriched domains provided new insights into supporting the role of lipid rafts/caveolae and caveolae in plasma membrane/lipoprotein cholesterol dynamics: (i) lipids known to be translocated through caveolae were detected (cholesteryl ester, triacylglycerol) and/or enriched (cholesterol, phospholipid) in lipid raft/caveolae fractions; (ii) lipoprotein-mediated sterol uptake/efflux from lipid rafts/caveolae and caveolae was rapid and lipoprotein specific, whereas that from non-rafts was very slow and independent of lipoprotein class; and (iii) the rate and lipoprotein specificity of sterol efflux from lipid rafts/caveolae or caveolae to lipoprotein acceptors in vitro was slower and differed in specificity from that in intact cells-consistent with intracellular factors contributing significantly to cholesterol dynamics between the plasma membrane and lipoproteins.

Asunto(s)

Caveolas/química , Colesterol/química , Lipoproteínas/química , Animales , Western Blotting , Línea Celular , Cromatografía de Afinidad , Perros , Polarización de Fluorescencia , Ratones

RESUMEN

Sterol carrier protein-2 (SCP-2) was independently discovered as a soluble protein that binds and transfers cholesterol as well as phospholipids (nonspecific lipid transfer protein, nsLTP) in vitro. Physiological functions of this protein are only now beginning to be resolved. The gene encoding SCP-2 also encodes sterol carrier protein-x (SCP-x) arising from an alternate transcription site. In vitro and in vivo SCP-x serves as a peroxisomal 3-ketoacyl-CoA thiolase in oxidation of branched-chain lipids (cholesterol to form bile acids; branched-chain fatty acid for detoxification). While peroxisomal SCP-2 facilitates branched-chain lipid oxidation, the role(s) of extraperoxisomal (up to 50% of total) are less clear. Studies using transfected fibroblasts overexpressing SCP-2 and hepatocytes from SCP-2/SCP-x gene-ablated mice reveal that SCP-2 selectively remodels the lipid composition, structure, and function of lipid rafts/caveolae. Studies of purified SCP-2 and in cells show that SCP-2 has high affinity for and selectively transfers many lipid species involved in intracellular signaling: fatty acids, fatty acyl CoAs, lysophosphatidic acid, phosphatidylinositols, and sphingolipids (sphingomyelin, ceramide, mono-di-and multi-hexosylceramides, gangliosides). SCP-2 selectively redistributes these signaling lipids between lipid rafts/caveolae and intracellular sites. These findings suggest SCP-2 serves not only in cholesterol and phospholipid transfer, but also in regulating multiple lipid signaling pathways in lipid raft/caveolae microdomains of the plasma membrane.

Asunto(s)

Proteínas Portadoras/metabolismo , Membrana Celular/metabolismo , Metabolismo de los Lípidos , Microdominios de Membrana/metabolismo , Transducción de Señal , Animales , Transporte Biológico , Proteínas Portadoras/genética , Línea Celular , Colesterol/metabolismo , Ácidos Grasos/metabolismo , Humanos , Lípidos de la Membrana/metabolismo , Microdominios de Membrana/química , Ratones , Modelos Biológicos , Esteroles/metabolismo , Relación Estructura-Actividad

RESUMEN

Although plasma membrane domains, such as caveolae, provide an organizing principle for signaling pathways and cholesterol homeostasis in the cell, relatively little is known regarding specific mechanisms, whereby intracellular lipid-binding proteins are targeted to caveolae. Therefore, the interaction between caveolin-1 and sterol carrier protein-2 (SCP-2), a protein that binds and transfers both cholesterol and signaling lipids (e.g., phosphatidylinositides and sphingolipids), was examined by yeast two-hybrid, in vitro binding and fluorescence resonance energy transfer (FRET) analyses. Results of the in vivo and in vitro assays identified for the first time the N-terminal amino acids (aa) 1-32 amphipathic alpha helix of SCP-2 functionally interacted with caveolin-1. This interaction was independent of the classic caveolin-1 scaffolding domain, in which many signaling proteins interact. Instead, SCP-2 bound caveolin-1 through a new domain identified in the N-terminal domain of caveolin-1 between aa 34-40. Modeling studies suggested that electrostatic interactions between the SCP-2 N-terminal aa 1-32 amphipathic alpha-helical domain (cationic, positively charged face) and the caveolin-1 N-terminal aa 33-59 alpha helix (anionic, negatively charged face) may significantly contribute to this interaction. These findings provide new insights on how SCP-2 enhances cholesterol retention within the cell as well as regulates the distribution of signaling lipids, such as phosphoinositides and sphingolipids, at plasma membrane caveolae.

Asunto(s)

Proteínas Portadoras/química , Caveolina 1/química , Secuencia de Aminoácidos , Animales , Sitios de Unión , Proteínas Portadoras/análisis , Proteínas Portadoras/metabolismo , Caveolina 1/metabolismo , Línea Celular , Transferencia Resonante de Energía de Fluorescencia , Microdominios de Membrana/química , Datos de Secuencia Molecular , Precursores de Proteínas/química , Estructura Terciaria de Proteína , Técnicas del Sistema de Dos Híbridos

RESUMEN

Rotavirus NSP4 plays multiple roles in viral pathogenesis, morphogenesis and replication. We previously reported a direct interaction between full-length NSP4 and the enterotoxic peptide composed of NSP4 residues 114-135 with full-length caveolin-1, the structural protein of caveolae. Caveolin-1 forms a hairpin loop in the cytoplasmic leaflet of plasma membrane caveolae. This unique orientation results in both termini of caveolin-1 exposed to the cytoplasm. The goal of this study was to map the caveolin-1 residues that interact with NSP4 to obtain a more complete picture of this binding event. Utilizing reverse yeast two-hybrid analyses and direct peptide binding assays, the NSP4 binding site was localized to caveolin-1 residues 2-22 and 161-178, at the amino- and carboxyl-termini, respectively. However, NSP4 binding to one of the termini was sufficient for the interaction.

Asunto(s)

Caveolina 1/química , Caveolina 1/metabolismo , Glicoproteínas/fisiología , Rotavirus/fisiología , Rotavirus/patogenicidad , Toxinas Biológicas/fisiología , Proteínas no Estructurales Virales/fisiología , Secuencia de Aminoácidos , Secuencia de Bases , Sitios de Unión , Caveolina 1/genética , Cartilla de ADN/genética , Glicoproteínas/química , Glicoproteínas/genética , Humanos , Técnicas In Vitro , Datos de Secuencia Molecular , Fragmentos de Péptidos/química , Fragmentos de Péptidos/genética , Fragmentos de Péptidos/metabolismo , Unión Proteica , Estructura Terciaria de Proteína , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Rotavirus/genética , Eliminación de Secuencia , Toxinas Biológicas/química , Toxinas Biológicas/genética , Técnicas del Sistema de Dos Híbridos , Proteínas no Estructurales Virales/química , Proteínas no Estructurales Virales/genética

RESUMEN

Rotavirus NSP4, initially characterized as an endoplasmic reticulum intracellular receptor, is a multifunctional viral enterotoxin that induces diarrhea in murine pups. There have been recent reports of the secretion of a cleaved NSP4 fragment (residues 112 to 175) and of the association of NSP4 with LC3-positive autophagosomes, raft membranes, and microtubules. To determine if NSP4 traffics to a specific subset of rafts at the plasma membrane, we isolated caveolae from plasma membrane-enriched material that yielded caveola membranes free of endoplasmic reticulum and nonraft plasma membrane markers. Analyses of the newly isolated caveolae from rotavirus-infected MDCK cells revealed full-length, high-mannose glycosylated NSP4. The lack of Golgi network-specific processing of the caveolar NSP4 glycans supports studies showing that NSP4 bypasses the Golgi apparatus. Confocal imaging showed the colocalization of NSP4 with caveolin-1 early and late in infection, elucidating the temporal and spatial NSP4-caveolin-1 association during infection. These data were extended with fluorescent resonance energy transfer analyses that confirmed the NSP4 and caveolin-1 interaction in that the specific fluorescently tagged antibodies were within 10 nm of each other during infection. Cells transfected with NSP4 showed patterns of staining and colocalization with caveolin-1 similar to those of infected cells. This study presents an endoplasmic reticulum contaminant-free caveola isolation protocol; describes the presence of full-length, endoglycosidase H-sensitive NSP4 in plasma membrane caveolae; provides confirmation of the NSP4-caveolin interaction in the presence and absence of other viral proteins; and provides a final plasma membrane destination for Golgi network-bypassing NSP4 transport.

Asunto(s)

Caveolas/metabolismo , Glicoproteínas/metabolismo , Microdominios de Membrana/metabolismo , Toxinas Biológicas/metabolismo , Proteínas no Estructurales Virales/metabolismo , Animales , Caveolas/ultraestructura , Caveolas/virología , Línea Celular , Perros , Glicoproteínas/aislamiento & purificación , Glicosilación , Células HT29 , Humanos , Microdominios de Membrana/virología , Octoxinol , Rotavirus/metabolismo , Toxinas Biológicas/aislamiento & purificación , Proteínas no Estructurales Virales/aislamiento & purificación

RESUMEN

Rotavirus nonstructural protein 4 (NSP4) is known to function as an intracellular receptor at the endoplasmic reticulum (ER) critical to viral morphogenesis and is the first characterized viral enterotoxin. Exogenously added NSP4 induces diarrhea in rodent pups and stimulates secretory chloride currents across intestinal segments as measured in Ussing chambers. Circular dichroism studies further reveal that intact NSP4 and the enterotoxic peptide (NSP4(114-135)) that is located within the extended, C-terminal amphipathic helix preferentially interact with caveola-like model membranes. We now show colocalization of NSP4 and caveolin-1 in NSP4-transfected and rotavirus-infected mammalian cells in reticular structures surrounding the nucleus (likely ER), in the cytosol, and at the cell periphery by laser scanning confocal microscopy. A direct interaction between NSP4 residues 112 to 140 and caveolin-1 was determined by the Pro-Quest yeast two-hybrid system with full-length NSP4 and seven overlapping deletion mutants as bait, caveolin-1 as prey, and vice versa. Coimmunoprecipitation of NSP4-caveolin-1 complexes from rotavirus-infected mammalian cells demonstrated that the interaction occurs during viral infection. Finally, binding of caveolin-1 from mammalian cell lysates to Sepharose-bound, NSP4-specific synthetic peptides confirmed the yeast two-hybrid data and further delineated the binding domain to amino acids 114 to 135. We propose that the association of NSP4 and caveolin-1 contributes to NSP4 intracellular trafficking from the ER to the cell surface and speculate that exogenously added NSP4 stimulates signaling molecules located in caveola microdomains.

Asunto(s)

Caveolas/metabolismo , Caveolina 1/metabolismo , Glicoproteínas/metabolismo , Rotavirus/metabolismo , Toxinas Biológicas/metabolismo , Proteínas no Estructurales Virales/metabolismo , Animales , Células CACO-2 , Línea Celular , Retículo Endoplásmico/metabolismo , Glicoproteínas/química , Glicoproteínas/genética , Humanos , Inmunoprecipitación , Péptidos/metabolismo , Toxinas Biológicas/química , Toxinas Biológicas/genética , Transfección , Técnicas del Sistema de Dos Híbridos , Proteínas no Estructurales Virales/química , Proteínas no Estructurales Virales/genética

Asunto(s)

Enterotoxinas/fisiología , Glicoproteínas/fisiología , Rotavirus/fisiología , Proteínas no Estructurales Virales/fisiología , Animales , Enterotoxinas/metabolismo , Glicoproteínas/genética , Glicoproteínas/metabolismo , Humanos , Interferencia de ARN , Virus Reordenados/aislamiento & purificación , Receptores Virales , Proteínas Recombinantes/inmunología , Rotavirus/inmunología , Toxinas Biológicas/genética , Toxinas Biológicas/metabolismo , Proteínas no Estructurales Virales/genética , Proteínas no Estructurales Virales/metabolismo , Replicación Viral

RESUMEN

HDL-mediated reverse-cholesterol transport as well as phosphoinositide signaling are mediated through plasma membrane microdomains termed caveolae/lipid rafts. However, relatively little is known regarding mechanism(s) whereby these lipids traffic to or are targeted to caveolae/lipid rafts. Since sterol carrier protein-2 (SCP-2) binds both cholesterol and phosphatidylinositol, the possibility that SCP-2 might interact with caveolin-1 and caveolae was examined. Double immunolabeling and laser scanning fluorescence microscopy showed that a small but significant portion of SCP-2 colocalized with caveolin-1 primarily at the plasma membrane of L-cells and more so within intracellular punctuate structures in hepatoma cells. In SCP-2 overexpressing L-cells, SCP-2 was detected in close proximity to caveolin, 48 +/- 4 A, as determined by fluorescence resonance energy transfer (FRET) and immunogold electron microscopy. Cell fractionation of SCP-2 overexpressing L-cells and Western blotting detected SCP-2 in purified plasma membranes, especially in caveolae/ lipid rafts as compared to the nonraft fraction. SCP-2 and caveolin-1 were coimmunoprecipitated from cell lysates by anti-caveolin-1 and anti-SCP-2. Finally, a yeast two-hybrid assay demonstrated that SCP-2 directly interacts with caveolin-1 in vivo. These interactions of SCP-2 with caveolin-1 were specific since a functionally related protein, phosphatidyinositol transfer protein (PITP), colocalized much less well with caveolin-1, was not in close proximity to caveolin-1 (i.e., >120 A), and was not coimmunoprecipitated by anti-caveolin-1 from cell lysates. In summary, it was shown for the first time that SCP-2 (but not PITP) selectively interacted with caveolin-1, both within the cytoplasm and at the plasma membrane. These data contribute significantly to our understanding of the role of SCP-2 in cholesterol and phosphatidylinositol targeted from intracellular sites of synthesis in the endoplasmic reticulum to caveolae/lipid rafts at the cell surface plasma membrane.

Asunto(s)

Proteínas Portadoras/metabolismo , Caveolinas/metabolismo , Animales , Carcinoma Hepatocelular/metabolismo , Carcinoma Hepatocelular/patología , Proteínas Portadoras/genética , Caveolina 1 , Caveolinas/genética , Línea Celular , Membrana Celular/metabolismo , Técnica del Anticuerpo Fluorescente , Regulación de la Expresión Génica , Vectores Genéticos/genética , Proteínas de la Membrana/metabolismo , Ratones , Microscopía Confocal , Microscopía Electrónica de Rastreo , Proteínas de Transferencia de Fosfolípidos , Pruebas de Precipitina , Unión Proteica , Fracciones Subcelulares/metabolismo , Técnicas del Sistema de Dos Híbridos , Levaduras

RESUMEN

A 1.78 kb sequence, including the E, M, 5a and 5b genes, and the intergenic region between the M and 5a genes, of six US strains of infectious bronchitis (corona)virus (IBV) were sequenced and compared to the published sequences for two additional strains. The overall identities as determined through pairwise analyses of nucleotide sequences of the entire 1.78kb region ranged from 90 to 99%, with the 5b open reading frame (ORF) having the greatest identity (94-99%) while the identities of the E, 5a and M ORFs ranged from 87 to 100%. Nucleotide sequencing of recent field isolates from Alabama (Ala1) and California (Cal3) revealed distinct shifts in homology in the M gene, indicating two apparent recombination events between the Holland 52/Mass41-like strain and an Ark-like strain, both origins of commonly used vaccine strains. Putative sites of recombination could also be identified in both the E and M ORFs of laboratory strains of IBV.

Asunto(s)

Virus de la Bronquitis Infecciosa/clasificación , Virus de la Bronquitis Infecciosa/genética , Proteínas del Envoltorio Viral/genética , Alabama , Animales , Secuencia de Bases , California , Embrión de Pollo , Secuencia Conservada , Infecciones por Coronavirus/diagnóstico , Infecciones por Coronavirus/veterinaria , Cartilla de ADN , Virus de la Bronquitis Infecciosa/aislamiento & purificación , Proteínas de la Membrana/química , Proteínas de la Membrana/genética , Datos de Secuencia Molecular , Sistemas de Lectura Abierta , Filogenia , Reacción en Cadena de la Polimerasa , Enfermedades de las Aves de Corral/virología , Recombinación Genética , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Alineación de Secuencia , Homología de Secuencia de Ácido Nucleico , Proteínas del Envoltorio Viral/química , Proteínas Virales/química , Proteínas Virales/genética

RESUMEN

Cytosine-5 DNA methylation is a critical signal defining heritable epigenetic states of transcription. As aberrant methylation patterns often accompany disease states, the ability to target cytosine methylation to preselected regions could prove valuable in re-establishing proper gene regulation. We employ the strategy of targeted gene methylation in yeast, which has a naturally unmethylated genome, selectively directing de novo DNA methylation via the fusion of C5 DNA methyltransferases to heterologous DNA-binding proteins. The zinc-finger proteins Zif268 and Zip53 can target DNA methylation by M.CviPI or M.SssI 5-52 nt from single zinc-factor binding sites. Modification at specific GC (M.CviPI) or CG (M.SssI) sites is enhanced as much as 20-fold compared with strains expressing either the free enzyme or a fusion protein with the zinc-finger protein moiety unable to bind to DNA. Interestingly, methylation is also selectively targeted as far as 353 nt from the zinc-finger protein binding sites, possibly indicative of looping, nucleosomes or higher-order chromatin structure. These data demonstrate that methylation can be targeted in vivo to a potentially broad range of sequences using specifically engineered zinc-finger proteins. Further more, the selective targeting of methylation by zinc-finger proteins demonstrates that binding of distinct classes of factors can be monitored in living cells.

Asunto(s)

5-Metilcitosina/metabolismo , Metilación de ADN , Proteínas de Unión al ADN/metabolismo , ADN-Citosina Metilasas/metabolismo , Factores de Transcripción/metabolismo , Sitios de Unión/genética , Proteínas de Unión al ADN/genética , ADN-Citosina Metilasas/genética , Mutación , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/crecimiento & desarrollo , Saccharomyces cerevisiae/metabolismo , Factores de Transcripción/genética , Dedos de Zinc/genética

RESUMEN

An optimized donor/shuttle vector, pENTR-His-ccdB, was generated that readily produces a histidine-tagged recombinant protein in multiple expression systems using Gateway Technology. In the current Gateway System, six histidines and the tobacco etch virus protease cleavage site are encoded upstream of the attR1 recombination site such that the histidine-tagged destination/expression vector adds 15 residues to the amino-terminus of recombinant proteins. Our new vector introduces the histidine tag at the donor level and places the multiple cloning sites within the attL recombination sites producing cleavable histidine-tagged proteins with a short, neutral linker of five residues. Two histidine-tagged clones were produced and fusion proteins expressed using the newly engineered vector.

Asunto(s)

Clonación Molecular/métodos , ARN Polimerasas Dirigidas por ADN , Vectores Genéticos , Ingeniería de Proteínas/métodos , Proteínas Recombinantes de Fusión/genética , Secuencia de Aminoácidos , Animales , Proteínas Bacterianas/genética , Toxinas Bacterianas/genética , Secuencia de Bases , Caveolina 1 , Caveolinas/genética , Células Cultivadas , Histidina/genética , Datos de Secuencia Molecular , Proteínas Recombinantes de Fusión/metabolismo , Recombinación Genética , Spodoptera/citología , Spodoptera/genética , Proteínas no Estructurales Virales/genética