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1.
J Med Virol ; 92(12): 3665-3673, 2020 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-32297984

RESUMEN

OBJECTIVE: Recipients of allogeneic hematopoietic stem cell transplantation (allo-HCT) with positive cytomegalovirus (CMV) serology are at increased risk of morbidity and mortality. The primary objective of this study was to assess the association between treated CMV infection and overall mortality within 1 year after allo-HCT in adult CMV-seropositive Recipients (R+). Secondary objectives included overall 5-year mortality after allo-HCT, risk factors for treated CMV infection, associations between treated CMV infection and allo-HCT complications and medical costs. METHODS: A multicenter retrospective cohort study was conducted in adult CMV-seropositive recipients (R+) who underwent to allo-HCT between 1st January 2010 and 31st December 2014. RESULTS: Five hundred seventy two CMV-seropositive patients (mean age, 50.2 years) undergoing allo-HCT between 2010 and 2014 were included; 55.9% of donors were CMV seropositive. CMV infection treated with antiviral therapy was reported in 227 patients (39.7%) after transplantation. One-year overall mortality was significantly increased in patients with treated CMV infections (hazard ratio, 1.86; 95% CI, 1.16-3.00; P = .011). Mean medical costs during the first post-HCT year were higher in patients with CMV infection (€46 853 vs €31 318; P < .0001). CONCLUSION: In this large cohort of CMV-seropositive patients undergoing allo-HCT, treated CMV infection was significantly associated with an increased 1-year risk of overall mortality, with increased length of stay and with hospitalization cost. The burden of CMV disease in allo-HCT could be reduced in the future by appropriate prophylactic strategies.

2.
Europace ; 22(7): 1071-1082, 2020 07 01.
Artículo en Inglés | MEDLINE | ID: mdl-32424395

RESUMEN

AIMS: Cost-effectiveness data on the remote monitoring (RM) of implantable cardioverter-defibrillators (ICDs) compared to the current standard of care (SC) remains limited. This meta-analysis was performed to assess the economic burden, and to develop an integrated economic model evaluating the efficiency of the RM strategy vs. SC in the context of French healthcare. METHODS AND RESULTS: Randomized controlled trials, comparing RM to SC in patients implanted with ICDs with or without resynchronization therapy (±CRT-D), were identified through a systematic search of scientific literature databases dating from 2005. Seventeen trials (10 229 patients) reporting data on clinical outcomes, quality of life, cost, and/or utility, either as primary or secondary endpoints were identified. Compared to SC, RM resulted in significant reductions in annual costs per patient for direct healthcare costs (seven studies, difference in means -276.1, 95% standard error [SE]: 66.0, I2 = 76.3%) and for labour costs (two studies, difference in means -11.3, 95% SE: 1.4, I2 = 96.3%). A three-state Markov Model showed that RM resulted in cost-savings of €4142 per patient over a 5-year time horizon, with a quality-adjusted life year (QALY) gain of 0.29. The incremental cost-effectiveness ratio was -14 136 €/QALY, in favour of RM. Furthermore, probabilistic sensitivity analyses confirmed that the RM strategy was dominant over SC in 70% of cases. CONCLUSION: Our economic model demonstrates that once implemented, RM of ICD ± CRT-D patients would result in increased effectiveness for lower costs over a 5-year period, compared to the current SC in France.


Asunto(s)
Desfibriladores Implantables , Análisis Costo-Beneficio , Francia , Humanos , Modelos Económicos , Calidad de Vida , Ensayos Clínicos Controlados Aleatorios como Asunto
3.
EMBO J ; 31(18): 3730-44, 2012 Sep 12.
Artículo en Inglés | MEDLINE | ID: mdl-22892567

RESUMEN

Calcium current through voltage-gated calcium channels (VGCC) controls gene expression. Here, we describe a novel signalling pathway in which the VGCC Cacnb4 subunit directly couples neuronal excitability to transcription. Electrical activity induces Cacnb4 association to Ppp2r5d, a regulatory subunit of PP2A phosphatase, followed by (i) nuclear translocation of Cacnb4/Ppp2r5d/PP2A, (ii) association with the tyrosine hydroxylase (TH) gene promoter through the nuclear transcription factor thyroid hormone receptor alpha (TRα), and (iii) histone binding through association of Cacnb4 with HP1γ concomitantly with Ser(10) histone H3 dephosphorylation by PP2A. This signalling cascade leads to TH gene repression by Cacnb4 and is controlled by the state of interaction between the SH3 and guanylate kinase (GK) modules of Cacnb4. The human R482X CACNB4 mutation, responsible for a form of juvenile myoclonic epilepsy, prevents association with Ppp2r5 and nuclear targeting of the complex by altering Cacnb4 conformation. These findings demonstrate that an intact VGCC subunit acts as a repressor recruiting platform to control neuronal gene expression.


Asunto(s)
Canales de Calcio/biosíntesis , Canales de Calcio/genética , Epilepsias Mioclónicas/metabolismo , Regulación de la Expresión Génica , Transporte Activo de Núcleo Celular , Animales , Biofisica/métodos , Canales de Calcio/metabolismo , Electrofisiología/métodos , Proteínas Fluorescentes Verdes/metabolismo , Células HEK293 , Histonas/metabolismo , Humanos , Ratones , Mutación , Proteína Fosfatasa 2/metabolismo , Transducción de Señal , Receptores alfa de Hormona Tiroidea/metabolismo , Transcripción Genética
4.
Int Arch Allergy Immunol ; 166(3): 231-40, 2015.
Artículo en Inglés | MEDLINE | ID: mdl-25924687

RESUMEN

BACKGROUND: Disease stratification, using phenotypic characterization performed either by hypothesis- or data-driven methods, was developed to improve clinical decisions. However, cluster analysis has not been used for allergic rhinitis. OBJECTIVE: To define clusters in allergic rhinitis and to compare them with ARIA (Allergic Rhinitis and Its Impact on Asthma), a hypothesis-driven approach. METHODS: A French observational prospective multicenter study (EVEIL: Echelle visuelle analogique dans la rhinite allergique) was carried out on 990 patients consulting general practitioners for allergic rhinitis and treated as per clinical practice. In this study, changes in symptom scores, visual analogue scales and quality of life were measured at baseline and after 14 days of treatment. A post hoc analysis was performed to identify clusters of patients with allergic rhinitis ­ using Ward's hierarchical method ­ and to define their clinical relevance at baseline and after 14 days of treatment. The cluster approach was compared to the ARIA approach. RESULTS: Patients were clustered into 4 phenotypes which partly followed the ARIA classes. These phenotypes differed in their disease severity including symptoms and quality of life. Physicians in real-life practice prescribed medication regardless of the phenotype and severity, with the exception of patients with ocular symptoms. Prescribed treatments were comparable in hypothesis- and data-driven analyses. The prevalence of uncontrolled patients during treatment was similar in the 4 clusters, but was significantly different according to the ARIA classes. CONCLUSION: Cluster analysis using demographic and clinical parameters only does not appear to add relevant information for disease stratification in allergic rhinitis.


Asunto(s)
Evaluación de Resultado en la Atención de Salud , Rinitis Alérgica/tratamiento farmacológico , Adulto , Análisis por Conglomerados , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estudios Prospectivos , Calidad de Vida , Rinitis Alérgica/genética , Rinitis Alérgica/inmunología , Índice de Severidad de la Enfermedad , Encuestas y Cuestionarios , Adulto Joven
5.
Crit Rev Oncol Hematol ; 173: 103646, 2022 May.
Artículo en Inglés | MEDLINE | ID: mdl-35344913

RESUMEN

Approximately 8-10% of metastatic colorectal cancer (mCRC) tumours harbour BRAFV600E mutations. Eleven randomised controlled trials (RCTs) and 24 non-RCTs were identified. Seven studies evaluated BRAF inhibitors. Single-agent BRAF inhibitors had minimal efficacy, whereas BRAF inhibitor plus anti-EGFR therapy improved outcomes. In BEACON CRC, overall survival (OS) was significantly longer for patients receiving encorafenib plus cetuximab ± binimetinib when compared with irinotecan/FOLFIRI plus cetuximab as second- and third-line therapy. Seven prospective non-RCTs reported worse OS and progression-free survival (PFS) for patients with BRAFV600E-mutant vs BRAF wild-type mCRC. Eight RCTs reported that PFS and OS were generally shorter for patients with BRAFV600E-mutant mCRC vs those with KRAS or RAS wild-type mCRC. Patients with BRAFV600E-mutant mCRC have worse outcomes with conventional therapy vs patients with BRAF wild-type tumours. BRAF inhibitors in conjunction with anti-EGFR therapy improves outcomes for patients with BRAFV600E-mutant mCRC vs conventional therapy or a BRAF inhibitor alone.


Asunto(s)
Neoplasias Colorrectales , Proteínas Proto-Oncogénicas B-raf , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Cetuximab/uso terapéutico , Neoplasias Colorrectales/tratamiento farmacológico , Neoplasias Colorrectales/genética , Neoplasias Colorrectales/patología , Humanos , Mutación , Estudios Observacionales como Asunto , Supervivencia sin Progresión , Proteínas Proto-Oncogénicas B-raf/genética , Ensayos Clínicos Controlados Aleatorios como Asunto
6.
Ther Adv Musculoskelet Dis ; 10(10): 201-207, 2018 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-30327686

RESUMEN

Immunoglobulin (Ig) therapy is used to treat a wide range of immunodeficiencies and autoimmune diseases; While, its clinical benefit has been demonstrated in several studies, Ig therapy is associated with a risk of systemic adverse effects. As such, Onset of renal impairment, including acute renal failure, osmotic nephrosis and renal insufficiency, after immunoglobulin administration is rare, but is one of the most significant concerns related to intravenous Ig use at immunomodulatory doses. However, only few studies have investigated the safety of subcutaneous Ig (SCIg) in relation to these rare conditions. The aim of this prospective study is to describe the safety of SCIg (Gammanorm), specifically with regards to renal function, in inflammatory myopathies including mainly polymyositis (PM), dermatomyositis (DM) and inclusion body myositis (IBM). Twenty-four cases were included: 10 patients with PM, 6 with IBM, 5 with DM, 2 with mixed connective-tissue disease (MCTD) and 1 patient with scleromyositis. SCIg was given two to three times per week at 2 g/kg/month in all patients. Patients were treated for a mean duration of 24.6 ± 11.4 months (range 8-37 months) and received a median of 78 SCIg infusions. Renal function was stable over the study period in all patients. High-dose SCIg was well tolerated; the treatment was not withdrawn during the first year in any patient for safety issues. These results suggest that the use of high-dose SCIg is generally feasible and safe in patients with inflammatory myopathies.

7.
ESC Heart Fail ; 5(1): 75-86, 2018 02.
Artículo en Inglés | MEDLINE | ID: mdl-28741873

RESUMEN

AIMS: Although left ventricular assist devices (LVADs) are currently approved for coverage and reimbursement in France, no French cost-effectiveness (CE) data are available to support this decision. This study aimed at estimating the CE of LVAD compared with medical management in the French health system. METHODS AND RESULTS: Individual patient data from the 'French hospital discharge database' (Medicalization of information systems program) were analysed using Kaplan-Meier method. Outcomes were time to death, time to heart transplantation (HTx), and time to death after HTx. A micro-costing method was used to calculate the monthly costs extracted from the Program for the Medicalization of Information Systems. A multistate Markov monthly cycle model was developed to assess CE. The analysis over a lifetime horizon was performed from the perspective of the French healthcare payer; discount rates were 4%. Probabilistic and deterministic sensitivity analyses were performed. Outcomes were quality-adjusted life years (QALYs) and incremental CE ratio (ICER). Mean QALY for an LVAD patient was 1.5 at a lifetime cost of €190 739, delivering a probabilistic ICER of €125 580/QALY [95% confidence interval: 105 587 to 150 314]. The sensitivity analysis showed that the ICER was mainly sensitive to two factors: (i) the high acquisition cost of the device and (ii) the device performance in terms of patient survival. CONCLUSIONS: Our economic evaluation showed that the use of LVAD in patients with end-stage heart failure yields greater benefit in terms of survival than medical management at an extra lifetime cost exceeding the €100 000/QALY. Technological advances and device costs reduction shall hence lead to an improvement in overall CE.


Asunto(s)
Insuficiencia Cardíaca/cirugía , Corazón Auxiliar/economía , Alta del Paciente/estadística & datos numéricos , Adulto , Anciano , Análisis Costo-Beneficio , Femenino , Estudios de Seguimiento , Francia/epidemiología , Insuficiencia Cardíaca/economía , Insuficiencia Cardíaca/epidemiología , Humanos , Masculino , Cadenas de Markov , Persona de Mediana Edad , Prevalencia , Calidad de Vida , Estudios Retrospectivos , Adulto Joven
8.
Autoimmun Rev ; 17(9): 873-881, 2018 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-30005853

RESUMEN

We reviewed the efficacy of SCIg administration in terms of muscle strength maintenance and patient satisfaction comparing with IVIg in the treatment of auto-immune neuromuscular diseases. A systematic review was conducted, and identified studies from databases (PUBMED, EMBASE, EBSCO, Web of Science and Google Scholar) which were analyzed. The methodological quality of the selected publications was evaluated using the Newcastle-Ottawa Scale. Data were extracted from a total of 11 studies Fixed and random-effect model meta-analyses were performed. For the maintenance of muscle strength, Overall Neuropathy Limitations Scale (ONLS) data from 100 patients diagnosed with multifocal mononeuropathy (MMN) or chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) were pooled together. Switching to subcutaneous immunoglobulin administration led to a significant improvement (fixed effects model, p = 0.002). In data collected using the Medical Research Council Scale for Muscle Strength data from 140 patients with a wider range of disorders, a small but significant improvement in overall strength was observed in the SCIg group (p < 0.0001). In addition, the results of two studies measuring health-related quality of life and patient satisfaction were pooled. Data from 49 patients suffering from MMN, CIDP, and a variety of different myopathies demonstrated a small but significant increase in the mean 36-Item Short Form Survey (SF-36) scores (p < 0.0001). A highly significant difference was revealed when comparing data from 119 patients' responses to the Life Quality Index questionnaire (LQI) assessing patient satisfaction (p < 0.0001). This is the first analysis showing that SCIg is more effective than IVIg in improving Patient Reported Outcomes in auto-immune neuromuscular disease. These results should permit a broad range of patients to self-administer immunoglobulin treatments at home, potentially improving patient acceptability while reducing hospital visits and healthcare costs for the treatment of chronic auto-immune neuropathies.


Asunto(s)
Enfermedades Autoinmunes/tratamiento farmacológico , Inmunoglobulinas Intravenosas/uso terapéutico , Inmunoterapia/métodos , Enfermedades Neuromusculares/tratamiento farmacológico , Polirradiculoneuropatía Crónica Inflamatoria Desmielinizante/tratamiento farmacológico , Calidad de Vida/psicología , Humanos , Inmunoglobulinas Intravenosas/farmacología , Satisfacción del Paciente
9.
Biochim Biophys Acta ; 1758(3): 308-19, 2006 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-16545341

RESUMEN

Maurocalcine (MCa) is a 33-amino acid residue peptide toxin initially isolated from the scorpion Scorpio maurus maurus. Its structural and functional features make it resembling many Cell Penetrating Peptides. In particular, MCa exhibits a characteristic positively charged face that may interact with membrane lipids. External application of MCa is known to produce Ca2+-release from intracellular stores within seconds. MCa binds directly to the skeletal muscle isoform of the ryanodine receptor, an intracellular channel target of the endoplasmic reticulum, and induces long-lasting channel openings in a mode of smaller conductance. The binding sites for MCa have been mapped within the cytoplasmic domain of the ryanodine receptor. In this manuscript, we further investigated how MCa proceeds to cross biological membranes in order to reach its target. A biotinylated derivative of MCa (MCab) was chemically synthesized, coupled to a fluorescent streptavidin indicator (Cy3 or Cy5) and the cell penetration of the entire complex followed by confocal microscopy and FACS analysis. The data provide evidence that MCa allows the penetration of the macro proteic complex and therefore may be used as a vector for the delivery of proteins in the cytoplasm as well as in the nucleus. Using both FACS and confocal analysis, we show that the cell penetration of the fluorescent complex is observed at concentrations as low as 10 nM, is sensitive to membrane potential and is partly inhibited by heparin. We also show that MCa interacts with the disialoganglioside GD3, the most abundant charged lipid in natural membranes. Despite its action on ryanodine receptor, MCa showed no sign of cell toxicity on HEK293 cells suggesting that it may have a wider application range. These data indicate that MCa may cross the plasma membrane directly by cell translocation and has a promising future as a carrier of various drugs and agents of therapeutic, diagnostic and technological value.


Asunto(s)
Portadores de Fármacos/metabolismo , Canal Liberador de Calcio Receptor de Rianodina/metabolismo , Venenos de Escorpión/metabolismo , Secuencia de Aminoácidos , Carbocianinas/análisis , Carbocianinas/metabolismo , Membrana Celular/metabolismo , Núcleo Celular/química , Núcleo Celular/metabolismo , Células Cultivadas , Citoplasma/química , Citoplasma/metabolismo , Portadores de Fármacos/química , Endocitosis , Citometría de Flujo , Humanos , Lípidos de la Membrana/metabolismo , Potenciales de la Membrana , Microscopía Confocal , Datos de Secuencia Molecular , Proteína Oncogénica pp60(v-src)/metabolismo , Fragmentos de Péptidos/metabolismo , Péptidos/metabolismo , Conformación Proteica , Transporte de Proteínas , Venenos de Escorpión/química , Venenos de Escorpión/toxicidad
10.
J Med Case Rep ; 11(1): 58, 2017 Mar 04.
Artículo en Inglés | MEDLINE | ID: mdl-28257650

RESUMEN

BACKGROUND: Antisynthetase syndrome is a rare and debilitating multiorgan disease characterized by inflammatory myopathy, interstitial lung disease, cutaneous involvement, and frequent chronic inflammation of the joints. Standard treatments include corticosteroids and immunosuppressants. In some cases, treatment resistance may develop. Administration of immunoglobulins intravenously is recommended in patients with drug-resistant antisynthetase syndrome. CASE PRESENTATION: Here, we describe the case of a 56-year-old woman of Algerian origin. She is the first case of a patient with multidrug-resistant antisynthetase syndrome featuring pulmonary involvement and arthropathy, and chronic secondary immune deficiency with recurrent infections, after anti-CD20 treatment, in which her primary antisynthetase syndrome-related symptoms and secondary immune deficiency were treated successfully with subcutaneous administration of immunoglobulin. The administration of immunoglobulin subcutaneously was introduced at a dose of 2 g/kg per month and was well tolerated. Clinical improvement was observed within 3 months of initiation of subcutaneous administration of immunoglobulin. After 22 months of treatment, she showed a significant improvement in terms of muscle strength, pulmonary involvement, arthralgia, and immunodeficiency. Her serum creatine phosphokinase and C-reactive protein levels remained normal. Finally, she was compliant and entirely satisfied with the treatment. CONCLUSIONS: Taken together, these observations suggest that administration of immunoglobulin subcutaneously may be a useful therapeutic approach to tackle steroid-refractory antisynthetase syndrome while ensuring minimal side effects and improved treatment compliance. This treatment also allowed, in our case, for the regression of the chronic immunodeficiency secondary to rituximab treatment.


Asunto(s)
Inmunoglobulinas/administración & dosificación , Miositis/terapia , Agammaglobulinemia/complicaciones , Femenino , Humanos , Síndromes de Inmunodeficiencia/complicaciones , Inmunosupresores/uso terapéutico , Enfermedades Pulmonares Intersticiales/complicaciones , Enfermedades Pulmonares Intersticiales/diagnóstico por imagen , Imagen por Resonancia Magnética , Metotrexato/uso terapéutico , Persona de Mediana Edad , Miositis/complicaciones , Miositis/diagnóstico por imagen , Absorción Subcutánea
11.
J Pain Symptom Manage ; 49(2): 183-191.e2, 2015 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-24945492

RESUMEN

CONTEXT: Patients with gastrointestinal cancer are at high risk for deterioration of nutrition. Home parenteral nutrition (HPN) could improve nutritional status and quality of life (QoL). OBJECTIVES: The purpose of this study was 1) to evaluate the impact of HPN on QoL, 2) to assess changes in nutritional status, and 3) to assess proxy perception of patient well-being. METHODS: We conducted a prospective, observational, and a multicenter study. Inclusion criteria were adult patients with gastrointestinal cancer, for whom HPN was indicated and prescribed for at least 14 days. The physician, the patient, and a family member completed questionnaires at inclusion and 28 days later. The QoL was assessed by the patients using the Functional Assessment of Cancer Therapy-General questionnaire, at inclusion and 28 days later. RESULTS: The study included 370 patients with gastrointestinal cancer. The HPN was indicated for cancer-related undernutrition in 89% of the patients and was used as a complement to oral intake in 84%. After 28 days of parenteral intake, global QoL was significantly increased (48.9 at inclusion vs. 50.3, P=0.007). The patients' weight improved significantly by 2.7% (P<0.001). The nutrition risk screening also decreased significantly (3.2±1.1 vs. 2.8±1.3, P=0.003). CONCLUSION: HPN could provide benefit for malnourished patients with gastrointestinal cancer. However, randomized controlled studies are required to confirm this benefit and the safety profile.


Asunto(s)
Neoplasias Gastrointestinales/dietoterapia , Neoplasias Gastrointestinales/fisiopatología , Desnutrición/dietoterapia , Desnutrición/fisiopatología , Nutrición Parenteral en el Domicilio , Calidad de Vida , Anciano , Peso Corporal , Femenino , Neoplasias Gastrointestinales/psicología , Humanos , Masculino , Desnutrición/psicología , Persona de Mediana Edad , Estado Nutricional , Satisfacción del Paciente , Estudios Prospectivos , Encuestas y Cuestionarios , Resultado del Tratamiento
12.
Bull Cancer ; 101(3): 243-9, 2014 Mar.
Artículo en Francés | MEDLINE | ID: mdl-24691188

RESUMEN

Malnutrition is a bad prognostic factor that reduces the quality of life (QoL) in patients with cancer. The objective was to assess the impact of home parenteral nutrition (HPN) on the QoL of elderly malnourished patients with cancer. This French prospective observational study included patients, aged 70 years or older, with cancer, for whom HPN was prescribed for at least 14 days. The patient, the physician and a family member or home caregiver had to fill in a questionnaire at inclusion and 28 days later. Included patients (n = 221) were mainly suffering from a digestive cancer. After HPN intake, improved weight was noticed in 68% and 14% of patients had reached the target weight. Improved global QoL was reported in 59% of patients. Physicians noticed a significant improvement for the same compounds. These results suggest a benefit of the HPN on the nutritional status and QoL in elderly patients with cancer. Further controlled randomised trials are needed to prove the benefit of HPN in the routine management of these patients.


Asunto(s)
Desnutrición/terapia , Neoplasias/complicaciones , Nutrición Parenteral en el Domicilio , Calidad de Vida , Anciano , Anciano de 80 o más Años , Neoplasias del Sistema Digestivo/complicaciones , Femenino , Francia , Humanos , Masculino , Desnutrición/etiología , Estado Nutricional , Neoplasias Orofaríngeas/complicaciones , Nutrición Parenteral en el Domicilio/efectos adversos , Estudios Prospectivos , Neoplasias del Sistema Respiratorio/complicaciones , Encuestas y Cuestionarios , Aumento de Peso
13.
Pflugers Arch ; 454(1): 115-29, 2007 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-17171365

RESUMEN

Direct regulation of N-type calcium channels by G-proteins is essential to control neuronal excitability and neurotransmitter release. Binding of the G(betagamma) dimer directly onto the channel is characterized by a marked current inhibition ("ON" effect), whereas the pore opening- and time-dependent dissociation of this complex from the channel produce a characteristic set of biophysical modifications ("OFF" effects). Although G-protein dissociation is linked to channel opening, the contribution of channel inactivation to G-protein regulation has been poorly studied. Here, the role of channel inactivation was assessed by examining time-dependent G-protein de-inhibition of Ca(v)2.2 channels in the presence of various inactivation-altering beta subunit constructs. G-protein activation was produced via mu-opioid receptor activation using the DAMGO agonist. Whereas the "ON" effect of G-protein regulation is independent of the type of beta subunit, the "OFF" effects were critically affected by channel inactivation. Channel inactivation acts as a synergistic factor to channel activation for the speed of G-protein dissociation. However, fast inactivating channels also reduce the temporal window of opportunity for G-protein dissociation, resulting in a reduced extent of current recovery, whereas slow inactivating channels undergo a far more complete recovery from inhibition. Taken together, these results provide novel insights on the role of channel inactivation in N-type channel regulation by G-proteins and contribute to the understanding of the physiological consequence of channel inactivation in the modulation of synaptic activity by G-protein coupled receptors.


Asunto(s)
Canales de Calcio Tipo N/fisiología , Proteínas de Unión al GTP/fisiología , Animales , Canales de Calcio Tipo N/metabolismo , Conductividad Eléctrica , Electrofisiología , Proteínas de Unión al GTP/metabolismo , Cinética , Isoformas de Proteínas/metabolismo , Isoformas de Proteínas/fisiología , Conejos , Ratas , Receptores Opioides mu/fisiología , Factores de Tiempo
14.
Eur J Neurosci ; 23(9): 2311-20, 2006 May.
Artículo en Inglés | MEDLINE | ID: mdl-16706839

RESUMEN

An increase in intracellular Ca2+ due to voltage-gated Ca2+ (CaV) channel opening represents an important trigger for a number of second-messenger-mediated effects ranging from neurotransmitter release to gene activation. Ca2+ entry occurs through the principal pore-forming protein but several ancillary subunits are known to more precisely tune ion influx. Among them, the CaVbeta subunits are perhaps the most important, given that they largely influence the biophysical and pharmacological properties of the channel. Notably, several functional features may be associated with specific structural regions of the CaVbeta subunits emphasizing the relevance of intramolecular domains in the physiology of these proteins. In the current report, we show that CaVbeta3 contains two PEST motifs and undergoes Ca2+ -dependent degradation which can be prevented by the specific calpain inhibitor calpeptin. Using mutant constructs lacking the PEST motifs, we present evidence that they are necessary for the cleavage of CaVbeta3 by calpain. Furthermore, the deletion of the PEST sequences did not affect the binding of CaVbeta3 to the ion-conducting CaV2.2 subunit and, when expressed in human embryonic kidney-293 cells, the PEST motif-deleted CaVbeta3 significantly increased whole-cell current density and retarded channel inactivation. Consistent with this observation, calpeptin treatment of human embryonic kidney-293 cells expressing wild-type CaVbeta3 resulted in an increase in current amplitude. Together, these findings suggest that calpain-mediated CaVbeta3 proteolysis may be an essential process for Ca2+ channel functional regulation.


Asunto(s)
Canales de Calcio/química , Canales de Calcio/metabolismo , Señalización del Calcio/fisiología , Proteínas de Unión al Calcio/metabolismo , Calcio/metabolismo , Proteínas de Microfilamentos/metabolismo , Western Blotting/métodos , Canales de Calcio/genética , Proteínas de Unión al Calcio/antagonistas & inhibidores , Línea Celular , Dipéptidos/farmacología , Relación Dosis-Respuesta en la Radiación , Estimulación Eléctrica/métodos , Humanos , Inmunoprecipitación/métodos , Potenciales de la Membrana/efectos de los fármacos , Potenciales de la Membrana/fisiología , Potenciales de la Membrana/efectos de la radiación , Proteínas de Microfilamentos/antagonistas & inhibidores , Mutación/fisiología , Técnicas de Placa-Clamp/métodos , Conformación Proteica , Subunidades de Proteína , Proteínas Recombinantes de Fusión/química , Proteínas Recombinantes de Fusión/genética , Proteínas Recombinantes de Fusión/metabolismo , Factores de Tiempo , Transfección/métodos , Calponinas
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