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1.
Lancet Infect Dis ; 22(9): 1356-1364, 2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-35716700

RESUMO

BACKGROUND: Acute febrile illness is a common presentation for patients at hospitals globally. Assays that can diagnose a variety of common pathogens in blood could help to establish a diagnosis for targeted disease management. We aimed to evaluate the performance of the BioFire Global Fever Panel (GF Panel), a multiplex nucleic acid amplification test performed on whole blood specimens run on the BioFire FilmArray System, in the diagnosis of several pathogens that cause acute febrile illness. METHODS: We did a prospective, multicentre, cross-sectional diagnostic accuracy study to evaluate the GF Panel. Consenting adults and children older than 6 months presenting with fever in the previous 2 days were enrolled consecutively in sub-Saharan Africa (Ghana, Kenya, Tanzania, Uganda), southeast Asia (Cambodia, Thailand), central and South America (Honduras, Peru), and the USA (Washington, DC; St Louis, MO). We assessed the performance of six analytes (chikungunya virus, dengue virus [serotypes 1-4], Leptospira spp, Plasmodium spp, Plasmodium falciparum, and Plasmodium vivax or Plasmodium ovale) on the GF Panel. The performance of the GF Panel was assessed using comparator PCR assays with different primers followed by bidirectional sequencing on nucleic acid extracts from the same specimen. We calculated the positive percent agreement and negative percent agreement of the GF Panel with respect to the comparator assays. This study is registered with ClinicalTrials.gov, NCT02968355. FINDINGS: From March 26, 2018, to Sept 30, 2019, 1965 participants were enrolled at ten sites worldwide. Of the 1875 participants with analysable results, 980 (52·3%) were female and the median age was 22 years (range 0-100). At least one analyte was detected in 657 (35·0%) of 1875 specimens. The GF Panel had a positive percent agreement for the six analytes evaluated as follows: chikungunya virus 100% (95% CI 86·3-100), dengue virus 94·0% (90·6-96·5), Leptospira spp 93·8% (69·8-99·8), Plasmodium spp 98·3% (96·3-99·4), P falciparum 92·7% (88·8-95·6), and P vivax or P ovale 92·7% (86·7-96·6). The GF Panel had a negative percent agreement equal to or greater than 99·2% (98·6-99·6) for all analytes. INTERPRETATION: This 1 h sample-to-answer, molecular device can detect common causative agents of acute febrile illness with excellent positive percent agreement and negative percent agreement directly in whole blood. The targets of the assay are prevalent in tropical and subtropical regions globally, and the assay could help to provide both public health surveillance and individual diagnoses. FUNDING: BioFire Defense, Joint Project Manager for Medical Countermeasure Systems and US Army Medical Materiel Development Activity, and National Institute of Allergy and Infectious Diseases.


Assuntos
Febre de Chikungunya , Vírus Chikungunya , Dengue , Leptospirose , Malária , Plasmodium , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Criança , Pré-Escolar , Estudos Transversais , Feminino , Febre , Humanos , Lactente , Recém-Nascido , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Adulto Jovem
2.
Indian J Palliat Care ; 27(1): 183-185, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34035638

RESUMO

Rural populations are unique compared to their urban and suburban counterparts in relation to both healthcare mindsets and spiritual needs. Rural populations tend to be more religious, more accepting of death, and less likely to pursue aggressive care at the end-of-life. This research project looked at the utilization of chaplaincy services among a rural, southwestern hospice population. It also examined outcomes related to patient and family satisfaction surrounding spiritual themes. Results were compared to 1700 other hospice programs. Areas where there were significant statistical differences from benchmarks were highlighted. It appears that overall hospice satisfaction and assistance with feelings of sadness and anxiety could be related to increased spiritual utilization.

3.
Malar J ; 20(1): 133, 2021 Mar 06.
Artigo em Inglês | MEDLINE | ID: mdl-33676502

RESUMO

BACKGROUND: Rapid and sensitive diagnostics are critical tools for clinical case management and public health control efforts. Both capillary and venous blood are currently used for malaria detection and while diagnostic technologies may not be equally sensitive with both materials, the published data on this subject are scarce and not conclusive. METHODS: Paired clinical samples of venous and capillary blood from 141 febrile individuals in Bo, Sierra Leone, were obtained between January and May 2019 and tested for the presence of Plasmodium parasites using two multiplexed PCR assays: the FilmArray-based Global Fever Panel (GFP) and the TaqMan-based Malaria Multiplex Sample Ready (MMSR) assay. RESULTS: No significant differences in Plasmodium parasite detection between capillary and venous blood for both assays were observed. The GFP assay was more sensitive than MMSR for all markers that could be compared (Plasmodium spp. and Plasmodium falciparum) in both venous and capillary blood. CONCLUSIONS: No difference was found in malaria detection between venous and capillary blood using two different PCR-based detection assays. This data gives support for use of capillary blood, a material which can be obtained easier by less invasive methods, for PCR-based malaria diagnostics, independent of the platform.


Assuntos
Capilares/parasitologia , Testes Diagnósticos de Rotina/estatística & dados numéricos , Malária/diagnóstico , Reação em Cadeia da Polimerase Multiplex/estatística & dados numéricos , Plasmodium/isolamento & purificação , Veias/parasitologia , Adolescente , Adulto , Criança , Pré-Escolar , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Sensibilidade e Especificidade , Serra Leoa , Especificidade da Espécie , Adulto Jovem
4.
Dimens Crit Care Nurs ; 38(1): 50-53, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30499792

RESUMO

Although it is common to promote direct care nurses to management positions in nursing, it is important to have a well-defined process. Excelling in clinical skills at the bedside does not always translate into management and leadership abilities. Having a way to internally identify and develop frontline leaders for future management positions is important in succession planning, creating organizational culture, decreasing costs, and increasing employee engagement.


Assuntos
Mobilidade Ocupacional , Enfermeiros Administradores , Cultura Organizacional , Seleção de Pessoal , Competência Clínica , Humanos , Liderança
5.
Dimens Crit Care Nurs ; 36(2): 106-109, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28151788

RESUMO

There is growing recognition that electronic medical record triggers in the intensive care unit (ICU) have led to an increase in palliative care consultations. One suburban health care system adopted triggers unique to their culture and setting in a pilot study and saw an increase in palliative consultations in the ICU. Implementing triggers is often a complex and multifaceted process to adopt. This review shares the steps from concept to implementation of establishing palliative prompts in 1 ICU within an integrated health care system.


Assuntos
Enfermagem de Cuidados Críticos , Enfermagem de Cuidados Paliativos na Terminalidade da Vida , Seleção de Pacientes , Encaminhamento e Consulta , Idoso , Humanos , Kentucky , Modelos Organizacionais , Ohio , Cultura Organizacional , Projetos Piloto
6.
Elife ; 52016 12 02.
Artigo em Inglês | MEDLINE | ID: mdl-27911261

RESUMO

Protein Kinase A (PKA) mediates synaptic plasticity and is widely implicated in learning and memory. The hippocampal dentate gyrus (DG) is thought to be responsible for processing and encoding distinct contextual associations in response to highly similar inputs. The mossy fiber (MF) axons of the dentate granule cells convey strong excitatory drive to CA3 pyramidal neurons and express presynaptic, PKA-dependent forms of plasticity. Here, we demonstrate an essential role for the PKA anchoring protein, AKAP7, in mouse MF axons and terminals. Genetic ablation of AKAP7 specifically from dentate granule cells results in disruption of MF-CA3 LTP directly initiated by cAMP, and the AKAP7 mutant mice are selectively deficient in pattern separation behaviors. Our results suggest that the AKAP7/PKA complex in the MF projections plays an essential role in synaptic plasticity and contextual memory formation.


Assuntos
Proteínas de Ancoragem à Quinase A/deficiência , Região CA3 Hipocampal/fisiologia , Núcleos Cerebelares/fisiologia , Técnicas de Inativação de Genes , Fibras Musgosas Hipocampais/fisiologia , Comportamento Espacial , Animais , Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , Camundongos
7.
Home Healthc Nurse ; 31(4): 184-8, 2013 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-23549249

RESUMO

Evidence-based practice has become the accepted phrase relative to healthcare quality and outcomes. Hospice providers have begun to express an interest in applying evidence to practice. Evidence-based practice, with its tiers of evidence, ranks quantitative research methods at the top. However, there is concern that applying evidence-based practice to a subjective concept like pain and suffering may be problematic. A more balanced approach to quality outcomes in hospice care may need to involve patient experience and qualitative research.


Assuntos
Prática Clínica Baseada em Evidências , Cuidados Paliativos na Terminalidade da Vida/normas , Hospitais para Doentes Terminais/normas , Humanos , Dor/prevenção & controle , Manejo da Dor/normas , Pesquisa Qualitativa , Estresse Psicológico/prevenção & controle
9.
Front Neurosci ; 6: 180, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-23248581

RESUMO

The pituitary receptor for thyrotropin-releasing hormone (TRH) is a calcium-mobilizing G protein-coupled receptor (GPCR) that signals through Gq/11, elevating calcium, and activating protein kinase C. TRH receptor signaling is quickly desensitized as a consequence of receptor phosphorylation, arrestin binding, and internalization. Following activation, TRH receptors are phosphorylated at multiple Ser/Thr residues in the cytoplasmic tail. Phosphorylation catalyzed by GPCR kinase 2 (GRK2) takes place rapidly, reaching a maximum within seconds. Arrestins bind to two phosphorylated regions, but only arrestin bound to the proximal region causes desensitization and internalization. Phosphorylation at Thr365 is critical for these responses. TRH receptors internalize in clathrin-coated vesicles with bound arrestin. Following endocytosis, vesicles containing phosphorylated TRH receptors soon merge with rab5-positive vesicles. Over approximately 20 min these form larger endosomes rich in rab4 and rab5, early sorting endosomes. After TRH is removed from the medium, dephosphorylated receptors start to accumulate in rab4-positive, rab5-negative recycling endosomes. The mechanisms responsible for sorting dephosphorylated receptors to recycling endosomes are unknown. TRH receptors from internal pools help repopulate the plasma membrane. Dephosphorylation of TRH receptors begins when TRH is removed from the medium regardless of receptor localization, although dephosphorylation is fastest when the receptor is on the plasma membrane. Protein phosphatase 1 is involved in dephosphorylation but the details of how the enzyme is targeted to the receptor remain obscure. It is likely that future studies will identify biased ligands for the TRH receptor, novel arrestin-dependent signaling pathways, mechanisms responsible for targeting kinases and phosphatases to the receptor, and principles governing receptor trafficking.

10.
Proc Natl Acad Sci U S A ; 109(42): 17099-104, 2012 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-23035250

RESUMO

Protein kinase A (PKA) is activated during sympathetic stimulation of the heart and phosphorylates key proteins involved in cardiac Ca(2+) handling, including the L-type Ca(2+) channel (Ca(V)1.2) and phospholamban (PLN). This results in acceleration and amplification of the beat-to-beat changes in cytosolic Ca(2+) in cardiomyocytes and, in turn, an increased rate and force of contraction. PKA is held in proximity to its substrates by protein scaffolds called A kinase anchoring proteins (AKAPs). It has been suggested that the short and long isoforms of AKAP7 (also called AKAP15/18) localize PKA in complexes with Ca(V)1.2 and PLN, respectively. We generated an AKAP7 KO mouse in which all isoforms were deleted and tested whether Ca(2+) current, intracellular Ca(2+) concentration, or Ca(2+) reuptake were impaired in isolated adult ventricular cardiomyocytes following stimulation with the ß-adrenergic agonist isoproterenol. KO cardiomyocytes responded normally to adrenergic stimulation, as measured by whole-cell patch clamp or a fluorescent intracellular Ca(2+) indicator. Phosphorylation of Ca(V)1.2 and PLN were also unaffected by genetic deletion of AKAP7. Immunoblot and RT-PCR revealed that only the long isoforms of AKAP7 were detectable in ventricular cardiomyocytes. The results indicate that AKAP7 is not required for regulation of Ca(2+) handling in mouse cardiomyocytes.


Assuntos
Proteínas de Ancoragem à Quinase A/metabolismo , Agonistas Adrenérgicos beta/farmacologia , Cálcio/metabolismo , Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , Isoproterenol/farmacologia , Contração Miocárdica/fisiologia , Miócitos Cardíacos/efeitos dos fármacos , Proteínas de Ancoragem à Quinase A/genética , Animais , Southern Blotting , Primers do DNA/genética , Immunoblotting , Imunoprecipitação , Camundongos , Camundongos Knockout , Miócitos Cardíacos/metabolismo , Técnicas de Patch-Clamp , Fosforilação , Reação em Cadeia da Polimerase Via Transcriptase Reversa
11.
Dimens Crit Care Nurs ; 30(5): 231-5, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-21841410

RESUMO

Pediatric hospice and palliative care continue to be an underutilized model of care. There is much confusion over the differences between hospice and palliative care. Nurses and physicians continue to need specialized training regarding end-of-life care and the pediatric population. Children and their families may needlessly be suffering during the dying process. Many barriers exist that prevent its use among medical professionals. This article discusses some of these barriers and strategies to reduce them. Recent changes in health care law will allow both curative and hospice care to be provided at the same time.


Assuntos
Serviços de Saúde da Criança , Necessidades e Demandas de Serviços de Saúde , Hospitais para Doentes Terminais , Cuidados Paliativos , Atitude do Pessoal de Saúde , Criança , Humanos , Reembolso de Seguro de Saúde , Manejo da Dor , Espiritualidade , Estados Unidos
12.
Mol Interv ; 10(2): 86-97, 2010 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-20368369

RESUMO

A-Kinase Anchoring Proteins (AKAPs) orchestrate and synchronize cellular events by tethering the cAMP-dependent protein kinase (PKA) and other signaling enzymes to organelles and membranes. The control of kinases and phosphatases that are held in proximity to activators, effectors, and substrates favors the rapid dissemination of information from one cellular location to the next. This article charts the inception of the PKA-anchoring hypothesis, the characterization of AKAPs and their nomenclature, and the physiological roles of context-specific AKAP signaling complexes.


Assuntos
Proteínas de Ancoragem à Quinase A/fisiologia , Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , Enzimas Imobilizadas/metabolismo , Regulação Enzimológica da Expressão Gênica , Humanos , Modelos Biológicos , Modelos Moleculares
13.
Mol Pharmacol ; 77(2): 288-97, 2010 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-19906838

RESUMO

The thyrotropin-releasing hormone (TRH) receptor undergoes rapid and extensive agonist-dependent phosphorylation attributable to G protein-coupled receptor (GPCR) kinases (GRKs), particularly GRK2. Like many GPCRs, the TRH receptor is predicted to form an amphipathic helix, helix 8, between the NPXXY motif at the cytoplasmic end of the seventh transmembrane domain and palmitoylation sites at Cys335 and Cys337. Mutation of all six lysine and arginine residues between the NPXXY and residue 340 to glutamine (6Q receptor) did not prevent the receptor from stimulating inositol phosphate turnover but almost completely prevented receptor phosphorylation in response to TRH. Phosphorylation at all sites in the cytoplasmic tail was inhibited. The phosphorylation defect was not reversed by long incubation times or high TRH concentrations. As expected for a phosphorylation-defective receptor, the 6Q-TRH receptor did not recruit arrestin, undergo the typical arrestin-dependent increase in agonist affinity, or internalize well. Lys326, directly before phenylalanine in the common GPCR motif NPXXY(X)(5-6)F(R/K), was critical for phosphorylation. The 6Q-TRH receptor was not phosphorylated effectively in cells overexpressing GRK2 or in in vitro kinase assays containing purified GRK2. Phosphorylation of the 6Q receptor was partially restored by coexpression of a receptor with an intact helix 8 but without phosphorylation sites. Phosphorylation was inhibited but not completely prevented by alanine substitution for cysteine palmitoylation sites. Positively charged amino acids in the proximal tail of the beta2-adrenergic receptor were also important for GRK-dependent phosphorylation. The results indicate that positive residues in helix 8 of GPCRs are important for GRK-dependent phosphorylation.


Assuntos
Quinases de Receptores Acoplados a Proteína G/química , Quinases de Receptores Acoplados a Proteína G/fisiologia , Receptores do Hormônio Liberador da Tireotropina/química , Receptores do Hormônio Liberador da Tireotropina/fisiologia , Sequência de Aminoácidos , Animais , Linhagem Celular , Humanos , Camundongos , Dados de Sequência Molecular , Fosforilação/fisiologia , Estrutura Secundária de Proteína/fisiologia
14.
Am J Hosp Palliat Care ; 27(3): 187-90, 2010 May.
Artigo em Inglês | MEDLINE | ID: mdl-19837970

RESUMO

This article attempts to find a correlation between certain disease types and increased needs for bereavement services for survivors. Data were examined from those requesting increased bereavement services from a hospice provider in Kentucky, over a 2-year span. The survivors were then matched with the disease type of their loved one to see whether there was a connection between the two. Although limited in its scope and focus, the study revealed that patients surviving Alzheimer disease, lung cancer, and renal failure consistently (at least 50% of the time) required increased bereavement services after the death of their loved one. Other disease types indicated more erratic patterns for increased grief services.


Assuntos
Luto , Aconselhamento , Família/psicologia , Cuidados Paliativos na Terminalidade da Vida , Avaliação das Necessidades/organização & administração , Sobreviventes/psicologia , Adaptação Psicológica , Doença de Alzheimer/mortalidade , Atitude Frente a Saúde , Cuidadores/educação , Cuidadores/psicologia , Aconselhamento/organização & administração , Pesquisa sobre Serviços de Saúde , Cuidados Paliativos na Terminalidade da Vida/organização & administração , Cuidados Paliativos na Terminalidade da Vida/psicologia , Humanos , Kentucky/epidemiologia , Falência Renal Crônica/mortalidade , Tempo de Internação/estatística & dados numéricos , Neoplasias Pulmonares/mortalidade , Alocação de Recursos , Inquéritos e Questionários , Sobreviventes/estatística & dados numéricos
15.
Mol Endocrinol ; 23(9): 1466-78, 2009 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-19541745

RESUMO

Activation of the G protein-coupled TRH receptor leads to its phosphorylation and internalization. These studies addressed the fundamental question of whether phosphorylation regulates receptor trafficking or endosomal localization regulates the phosphorylation state of the receptor. Trafficking of phosphorylated and dephosphorylated TRH receptors was characterized using phosphosite-specific antibody after labeling surface receptors with antibody to an extracellular epitope tag. Rab5 and phosphoreceptor did not colocalize at the plasma membrane immediately after TRH addition but overlapped extensively by 15 min. Dominant-negative Rab5-S34N inhibited receptor internalization. Later, phosphoreceptor was in endosomes containing Rab5 and Rab4. Dephosphorylated receptor colocalized with Rab4 but not with Rab5. Dominant-negative Rab4, -5, or -11 did not affect receptor phosphorylation or dephosphorylation, showing that phosphorylation determines localization in Rab4(+)/Rab5(-) vesicles and not vice versa. No receptor colocalized with Rab7; a small amount of phosphoreceptor colocalized with Rab11. To characterize recycling, surface receptors were tagged with antibody, or surface receptors containing an N-terminal biotin ligase acceptor sequence were labeled with biotin. Most recycling receptors did not return to the plasma membrane for more than 2 h after TRH was removed, whereas the total cell surface receptor density was largely restored in less than 1 h, indicating that recruited receptors contribute heavily to early repopulation of the plasma membrane.


Assuntos
Receptores do Hormônio Liberador da Tireotropina/metabolismo , Membrana Celular/metabolismo , Endocitose , Endossomos/metabolismo , Genes Dominantes , Humanos , Lisossomos/metabolismo , Microscopia Confocal/métodos , Modelos Biológicos , Fosforilação , Transporte Proteico , Transdução de Sinais , Fatores de Tempo , Proteínas rab de Ligação ao GTP/metabolismo
16.
Mol Pharmacol ; 74(1): 195-202, 2008 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-18413662

RESUMO

Arrestin binding to agonist-occupied phosphorylated G protein-coupled receptors typically increases the affinity of agonist binding, increases resistance of receptor-bound agonist to removal with high acid/salt buffer, and leads to receptor desensitization and internalization. We tested whether thyrotropin-releasing hormone (TRH) receptors lacking phosphosites in the C-terminal tail could form stable and functional complexes with arrestin. Fibroblasts from mice lacking arrestins 2 and 3 were used to distinguish between arrestin-dependent and -independent effects. Arrestin did not promote internalization or desensitization of a receptor that had key Ser/Thr phosphosites mutated to Ala (4Ala receptor). Nevertheless, arrestin greatly increased acid/salt resistance and the affinity of 4Ala receptor for TRH. Truncation of 4Ala receptor just distal to the key phosphosites (4AlaStop receptor) abolished arrestin-dependent acid/salt resistance but not the effect of arrestin on agonist affinity. Arrestin formed stable complexes with activated wild-type and 4Ala receptors but not with 4AlaStop receptor, as measured by translocation of arrestin-green fluorescent protein to the plasma membrane or chemical cross-linking. An arrestin mutant that does not interact with clathrin and AP2 did not internalize receptor but still promoted high affinity TRH binding, acid/salt resistance, and desensitization. A sterically restricted arrestin mutant did not cause receptor internalization or desensitization but did promote acid/salt resistance and high agonist affinity. The results demonstrate that arrestin binds to proximal or distal phosphosites in the receptor tail. Arrestin binding at either site causes increased agonist affinity and acid/salt resistance, but only the proximal phosphosites evoke the necessary conformational changes in arrestin for receptor desensitization and internalization.


Assuntos
Arrestina/metabolismo , Receptores do Hormônio Liberador da Tireotropina/metabolismo , Animais , Arrestina/química , Arrestina/genética , Linhagem Celular , Células Cultivadas , Embrião de Mamíferos , Fibroblastos/metabolismo , Proteínas de Fluorescência Verde/metabolismo , Hemaglutininas/metabolismo , Humanos , Fosfatos de Inositol/biossíntese , Rim/citologia , Ligantes , Camundongos , Modelos Biológicos , Mutação , Fosforilação , Estrutura Terciária de Proteína , Receptores do Hormônio Liberador da Tireotropina/química , Transfecção
17.
Proc Natl Acad Sci U S A ; 104(46): 18303-8, 2007 Nov 13.
Artigo em Inglês | MEDLINE | ID: mdl-17989235

RESUMO

The G protein-coupled thyrotropin (TSH)-releasing hormone (TRH) receptor forms homodimers. Regulated receptor dimerization increases TRH-induced receptor endocytosis. These studies test whether dimerization increases receptor phosphorylation, which could potentiate internalization. Phosphorylation at residues 355-365, which is critical for internalization, was measured with a highly selective phospho-site-specific antibody. Two strategies were used to drive receptor dimerization. Dimerization of a TRH receptor-FK506-binding protein (FKBP) fusion protein was stimulated by a dimeric FKBP ligand. The chemical dimerizer caused a large increase in TRH-dependent phosphorylation within 1 min, whereas a monomeric FKBP ligand had no effect. The dimerizer did not alter phoshorylation of receptors lacking the FKBP domain. Dimerization of receptors containing an N-terminal HA epitope also was induced with anti-HA antibody. Anti-HA IgG strongly increased TRH-induced phosphorylation, whereas monomeric Fab fragments had no effect. Anti-HA antibody did not alter phosphorylation in receptors lacking an HA tag. Furthermore, two phosphorylation-defective TRH receptors functionally complemented one another and permitted phosphorylation. Receptors with a D71A mutation in the second transmembrane domain do not signal, whereas receptors with four Ala mutations in the 355-365 region signal normally but lack phosphorylation sites. When D71A- and 4Ala-TRH receptors were expressed alone, neither underwent TRH-dependent phosphorylation. When they were expressed together, D71A receptor was phosphorylated by G protein-coupled receptor kinases in response to TRH. These results suggest that the TRH receptor is phosphorylated preferentially when it is in dimers or when preexisting receptor dimers are driven into microaggregates. Increased receptor phosphorylation may amplify desensitization.


Assuntos
Receptores do Hormônio Liberador da Tireotropina/metabolismo , Dimerização , Ensaio de Imunoadsorção Enzimática , Imunofluorescência , Fosforilação , Receptores do Hormônio Liberador da Tireotropina/química
18.
J Biol Chem ; 282(17): 12893-906, 2007 Apr 27.
Artigo em Inglês | MEDLINE | ID: mdl-17329249

RESUMO

To study phosphorylation of the endogenous type I thyrotropin-releasing hormone receptor in the anterior pituitary, we generated phosphosite-specific polyclonal antibodies. The major phosphorylation site of receptor endogenously expressed in pituitary GH3 cells was Thr(365) in the receptor tail; distal sites were more phosphorylated in some heterologous models. beta-Arrestin 2 reduced thyrotropin-releasing hormone (TRH)-stimulated inositol phosphate production and accelerated internalization of the wild type receptor but not receptor mutants where the critical phosphosites were mutated to Ala. Phosphorylation peaked within seconds and was maximal at 100 nm TRH. Based on dominant negative kinase and small interfering RNA approaches, phosphorylation was mediated primarily by G protein-coupled receptor kinase 2. Phosphorylated receptor, visualized by immunofluorescence microscopy, was initially at the plasma membrane, and over 5-30 min it moved to intracellular vesicles in GH3 cells. Dephosphorylation was rapid (t((1/2)) approximately 1 min) if agonist was removed while receptor was at the surface. Dephosphorylation was slower (t((1/2)) approximately 4 min) if agonist was withdrawn after receptor had internalized. After agonist removal and dephosphorylation, a second pulse of agonist caused extensive rephosphorylation, particularly if most receptor was still on the plasma membrane. Phosphorylated receptor staining was visible in prolactin- and thyrotropin-producing cells in rat pituitary tissue from untreated rats and much stronger in tissue from animals injected with TRH. Our results show that the TRH receptor can rapidly cycle between a phosphorylated and nonphosphorylated state in response to changing agonist concentrations and that phosphorylation can be used as an indicator of receptor activity in vivo.


Assuntos
Hipófise/metabolismo , Processamento de Proteína Pós-Traducional/fisiologia , Receptores do Hormônio Liberador da Tireotropina/metabolismo , Animais , Anticorpos Monoclonais/química , Anticorpos Monoclonais/imunologia , Arrestinas/metabolismo , Células CHO , Cricetinae , Cricetulus , Feminino , Quinase 2 de Receptor Acoplado a Proteína G , Hormônios/farmacologia , Humanos , Imuno-Histoquímica , Fosfatos de Inositol/metabolismo , Mutação , Hipófise/citologia , Prolactina/metabolismo , Processamento de Proteína Pós-Traducional/efeitos dos fármacos , Ratos , Ratos Sprague-Dawley , Receptores do Hormônio Liberador da Tireotropina/genética , Receptores do Hormônio Liberador da Tireotropina/imunologia , Hormônio Liberador de Tireotropina/farmacologia , Fatores de Tempo , Quinases de Receptores Adrenérgicos beta/antagonistas & inibidores , Quinases de Receptores Adrenérgicos beta/metabolismo , beta-Arrestina 2 , beta-Arrestinas
19.
J Biol Chem ; 280(46): 38346-54, 2005 Nov 18.
Artigo em Inglês | MEDLINE | ID: mdl-16183993

RESUMO

The G protein-coupled thyrotropin-releasing hormone (TRH) receptor is phosphorylated and binds to beta-arrestin after agonist exposure. To define the importance of receptor phosphorylation and beta-arrestin binding in desensitization, and to determine whether beta-arrestin binding and receptor endocytosis are required for receptor dephosphorylation, we expressed TRH receptors in fibroblasts from mice lacking beta-arrestin-1 and/or beta-arrestin-2. Apparent affinity for [(3)H]MeTRH was increased 8-fold in cells expressing beta-arrestins, including a beta-arrestin mutant that did not permit receptor internalization. TRH caused extensive receptor endocytosis in the presence of beta-arrestins, but receptors remained primarily on the plasma membrane without beta-arrestin. beta-Arrestins strongly inhibited inositol 1,4,5-trisphosphate production within 10 s. At 30 min, endogenous beta-arrestins reduced TRH-stimulated inositol phosphate production by 48% (beta-arrestin-1), 71% (beta-arrestin-2), and 84% (beta-arrestins-1 and -2). In contrast, receptor phosphorylation, detected by the mobility shift of deglycosylated receptor, was unaffected by beta-arrestins. Receptors were fully phosphorylated within 15 s of TRH addition. Receptor dephosphorylation was identical with or without beta-arrestins and almost complete 20 min after TRH withdrawal. Blocking endocytosis with hypertonic sucrose did not alter the rate of receptor phosphorylation or dephosphorylation. Expressing receptors in cells lacking Galpha(q) and Galpha(11) or inhibiting protein kinase C pharmacologically did not prevent receptor phosphorylation or dephosphorylation. Overexpression of dominant negative G protein-coupled receptor kinase-2 (GRK2), however, retarded receptor phosphorylation. Receptor activation caused translocation of endogenous GRK2 to the plasma membrane. The results show conclusively that receptor dephosphorylation can take place on the plasma membrane and that beta-arrestin binding is critical for desensitization and internalization.


Assuntos
Arrestinas/fisiologia , Receptores do Hormônio Liberador da Tireotropina/fisiologia , Fosfatase Alcalina/metabolismo , Animais , Arrestinas/química , Arrestinas/metabolismo , Células CHO , Células COS , Canais de Cálcio/metabolismo , Linhagem Celular , Membrana Celular/metabolismo , Chlorocebus aethiops , Cricetinae , DNA Complementar/metabolismo , Relação Dose-Resposta a Droga , Endocitose , Fibroblastos/metabolismo , Quinase 2 de Receptor Acoplado a Proteína G , Subunidades alfa Gq-G11 de Proteínas de Ligação ao GTP/metabolismo , Proteínas de Ligação ao GTP/metabolismo , Glicosilação , Proteínas de Fluorescência Verde/metabolismo , Immunoblotting , Imunoglobulina G/química , Imunoprecipitação , Inositol 1,4,5-Trifosfato/metabolismo , Receptores de Inositol 1,4,5-Trifosfato , Fosfatos de Inositol/química , Fosfatos de Inositol/metabolismo , Cinética , Camundongos , Camundongos Knockout , Mutação , Fosfatos/química , Fosforilação , Plasmídeos/metabolismo , Ligação Proteica , Proteína Quinase C/antagonistas & inibidores , Proteína Quinase C/metabolismo , Estrutura Terciária de Proteína , Transporte Proteico , Receptores Citoplasmáticos e Nucleares/metabolismo , Receptores do Hormônio Liberador da Tireotropina/química , Sacarose/química , Sacarose/farmacologia , Fatores de Tempo , Transfecção , Quinases de Receptores Adrenérgicos beta/metabolismo , beta-Arrestina 1 , beta-Arrestina 2 , beta-Arrestinas
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