RESUMEN
Hypoimmune gene edited human pluripotent stem cells (hPSCs) are a promising platform for developing reparative cellular therapies that evade immune rejection. Existing first-generation hypoimmune strategies have used CRISPR/Cas9 editing to modulate genes associated with adaptive (e.g., T cell) immune responses, but have largely not addressed the innate immune cells (e.g., monocytes, neutrophils) that mediate inflammation and rejection processes occurring early after graft transplantation. We identified the adhesion molecule ICAM-1 as a novel hypoimmune target that plays multiple critical roles in both adaptive and innate immune responses post-transplantation. In a series of studies, we found that ICAM-1 blocking or knock-out (KO) in hPSC-derived cardiovascular therapies imparted significantly diminished binding of multiple immune cell types. ICAM-1 KO resulted in diminished T cell proliferation responses in vitro and in longer in vivo retention/protection of KO grafts following immune cell encounter in NeoThy humanized mice. The ICAM-1 KO edit was also introduced into existing first-generation hypoimmune hPSCs and prevented immune cell binding, thereby enhancing the overall hypoimmune capacity of the cells. This novel hypoimmune editing strategy has the potential to improve the long-term efficacy and safety profiles of regenerative therapies for cardiovascular pathologies and a number of other diseases.
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Development of a post-transplant kidney transplant tolerance induction protocol involving a novel total lymphoid irradiation (TLI) conditioning method in a rhesus macaque model is described. We examined the feasibility of acheiving tolerance to MHC 1-haplotype matched kidney transplants by establishing a mixed chimeric state with infusion of donor hematopoietic cells (HC) using TomoTherapy TLI. The chimeric state was hypothesized to permit the elimination of all immunosuppressive (IS) medications while preserving allograft function long-term without development of graft-versus-host-disease (GVHD) or rejection. An experimental group of 11 renal transplant recipients received the tolerance induction protocol and outcomes were compared to a control group (n = 7) that received the same conditioning but without donor HC infusion. Development of mixed chimerism and operational tolerance was accomplished in two recipients in the experimental group. Both recipients were withdrawn from all IS and continued to maintain normal renal allograft function for 4 years without rejection or GVHD. None of the animals in the control group achieved tolerance when IS was eliminated. This novel experimental model demonstrated the feasibility for inducing of long-term operational tolerance when mixed chimerism is achieved using a TLI post-transplant conditioning protocol in 1-haplotype matched non-human primate recipients of combined kidney and HC transplantation.
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Enfermedad Injerto contra Huésped , Trasplante de Células Madre Hematopoyéticas , Trasplante de Riñón , Radioterapia de Intensidad Modulada , Animales , Macaca mulatta , Irradiación Linfática , Tolerancia Inmunológica , Tolerancia al Trasplante , Acondicionamiento Pretrasplante/métodos , Riñón , Quimera por TrasplanteRESUMEN
Development of a new methodology to induce immunological chimerism after allogeneic hematopoietic cell (HC) transplantation in a rhesus macaque model is described. The chimeric state was achieved using a non-myeloablative, helical tomotherapy-based total lymphoid irradiation (TomoTLI) conditioning regimen followed by donor HC infusions between 1-haplotype matched donor/recipient pairs. The technique was tested as a feasibility study in an experimental group of seven rhesus macaques that received the novel TomoTLI tolerance protocol and HC allo-transplants. Two tomotherapy protocols were compared: TomoTLI (n = 5) and TomoTLI/total-body irradiation (TBI) (n = 2). Five of seven animals developed mixed chimerism. Three of five animals given the TomoTLI protocol generated transient mixed chimerism with no graft-versus-host disease (GVHD) with survival of 33, 152 and >180 days. However, the inclusion of belatacept in addition to a single fraction of TBI resulted in total chimerism and fatal GVHD in both animals, indicating an unacceptable conditioning regimen.
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Quimerismo , Trasplante de Células Madre Hematopoyéticas , Tejido Linfoide/efectos de la radiación , Modelos Biológicos , Radioterapia de Intensidad Modulada/métodos , Animales , Enfermedad Injerto contra Huésped , Macaca mulatta , Modelos Animales , Trasplante HomólogoRESUMEN
The reconstruction of anterior skull base defects after carcinologic surgery is challenging. Large defects can require the use of autologous free tissue transfer. Currently, most reconstructions use soft-tissue flaps. We describe the use of an osteocutaneous radial forearm free flap to reconstruct a large defect secondary to a malignant paraganglioma extending into the anterior cranial fossa and both orbits. The surgical resection required endonasal and transcranial approaches. We reconstructed the defect with a free osteocutaneous radial forearm flap. We laid the bone flap across the defect, resting on the orbital roof on each side, and sutured the soft component to the edge of the dura. The pedicle was funnelled from the craniotomy to a prepared cervicotomy and the micro-anastomoses were performed onto the facial artery and two satellite veins. Potential indications and major drawbacks of this technique are briefly discussed. Osteocutaneous radial forearm free flaps can be a valuable reconstructive option for patients with a large defect of the anterior skull base, needing both rigid support and a watertight closure.
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Colgajos Tisulares Libres , Procedimientos de Cirugía Plástica , Craneotomía , Antebrazo/cirugía , Humanos , Base del Cráneo/cirugíaRESUMEN
Maternal microchimerism (MMc) has been associated with development of allospecific transplant tolerance, antitumor immunity, and cross-generational reproductive fitness, but its mode of action is unknown. We found in a murine model that MMc caused exposure to the noninherited maternal antigens in all offspring, but in some, MMc magnitude was enough to cause membrane alloantigen acquisition (mAAQ; "cross-dressing") of host dendritic cells (DCs). Extracellular vesicle (EV)-enriched serum fractions from mAAQ+, but not from non-mAAQ, mice reproduced the DC cross-dressing phenomenon in vitro. In vivo, mAAQ was associated with increased expression of immune modulators PD-L1 (programmed death-ligand 1) and CD86 by myeloid DCs (mDCs) and decreased presentation of allopeptide+self-MHC complexes, along with increased PD-L1, on plasmacytoid DCs (pDCs). Remarkably, both serum EV-enriched fractions and membrane microdomains containing the acquired MHC alloantigens included CD86, but completely excluded PD-L1. In contrast, EV-enriched fractions and microdomains containing allopeptide+self-MHC did not exclude PD-L1. Adoptive transfer of allospecific transgenic CD4 T cells revealed a "split tolerance" status in mAAQ+ mice: T cells recognizing intact acquired MHC alloantigens proliferated, whereas those responding to allopeptide+self-MHC did not. Using isolated pDCs and mDCs for in vitro culture with allopeptide+self-MHC-specific CD4 T cells, we could replicate their normal activation in non-mAAQ mice, and PD-L1-dependent anergy in mAAQ+ hosts. We propose that EVs provide a physiologic link between microchimerism and split tolerance, with implications for tumor immunity, transplantation, autoimmunity, and reproductive success.
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Quimerismo , Células Dendríticas/inmunología , Vesículas Extracelulares/inmunología , Tolerancia Inmunológica , Traslado Adoptivo , Animales , Antígeno B7-2/biosíntesis , Antígeno B7-2/inmunología , Antígeno B7-H1/biosíntesis , Antígeno B7-H1/inmunología , Linfocitos T CD4-Positivos/inmunología , Femenino , Transfusión Fetomaterna/inmunología , Antígenos H-2/genética , Antígenos H-2/inmunología , Antígeno de Histocompatibilidad H-2D/genética , Antígeno de Histocompatibilidad H-2D/inmunología , Antígenos de Histocompatibilidad Clase II/genética , Antígenos de Histocompatibilidad Clase II/inmunología , Isoantígenos/inmunología , Masculino , Intercambio Materno-Fetal/inmunología , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Modelos Inmunológicos , Embarazo , Especificidad del Receptor de Antígeno de Linfocitos TRESUMEN
BACKGROUND: Cognitive behavioural therapy (CBT) is a successful treatment of obsessive compulsive disorder (OCD). It is known to induce changes in cerebral metabolism; however, the dynamics of these changes and their relation to clinical change remain largely unknown, precluding the identification of individualized response biomarkers. METHOD: In order to study the dynamics of treatment response, we performed systematic clinical and functional magnetic resonance imaging (fMRI) evaluation of 35 OCD patients immediately before a 3-month course of CBT, halfway through and at its end, as well as 6 months after. To sensitize fMRI probing, we used an original exposure task using neutral, generic and personalized obsession-inducing images. RESULTS: As expected, CBT produced a significant improvement in OCD. This improvement was continuous over the course of the therapy; therefore, outcome could be predicted by response at mid-therapy (r 2 = 0.67, p < 0.001). Haemodynamic response to the task was located in the anterior cingulate and orbitofrontal cortices and was stronger during exposure to personalized obsession-inducing images. In addition, both the anxiety ratings and the haemodynamic response to the obsession-inducing images in the anterior cingulate and the left but not the right orbitofrontal clusters decreased with symptom improvement. Interestingly, haemodynamic activity continued to decrease after stabilization of clinical symptoms. CONCLUSIONS: Using an innovative and highly sensitive exposure paradigm in fMRI, we showed that clinical and haemodynamic phenotypes have similar time courses during CBT. Our results, which suggest that the initial CBT sessions are crucial, prompt us to investigate the anatomo-functional modifications underlying the very first weeks of the therapy.
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Corteza Cerebral/irrigación sanguínea , Terapia Cognitivo-Conductual/métodos , Trastorno Obsesivo Compulsivo/terapia , Resultado del Tratamiento , Adulto , Corteza Cerebral/fisiopatología , Circulación Cerebrovascular/fisiología , Femenino , Hemodinámica/fisiología , Humanos , Imagen por Resonancia Magnética , Masculino , Trastorno Obsesivo Compulsivo/fisiopatologíaRESUMEN
Long-term harmful effects of immunosuppressive drugs and chronic rejection are a persistent impetus to establish methods to induce immunological tolerance to allografts. PCR-based studies have found evidence that humans and other placental mammals can have prolonged extremely low levels of maternal cells as well as other non-self cells, referred to as microchimerism. The persistence of these cells suggests a mechanism for the maintenance of the regulatory T-cell (Treg) responses frequently detected in offspring to non-inherited maternal antigens. We test the hypothesis that the detection of very low copy levels of insertion/deletion (Indel) alleles consistent with non-inherited maternal genes, will correlate with immune regulation to non-inherited maternal antigens as detected by a trans-vivo Delayed-Type Hypersensitivity (tvDTH) assay in kidney transplant recipients, normal donors and their immediate biological family members. Preliminary data reported here compares qPCR amplification of rare DNA templates in the peripheral blood polymorphonuclear (PMN) fraction of cells, with the results of tvDTH assays for linked suppression of recall antigen responses in the presence of non-inherited maternal antigens [NIMA]. The two assays do not show a definitive correlation.
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Quimerismo , Trasplante de Riñón , Células Cultivadas , Niño , ADN/genética , Femenino , Humanos , Hipersensibilidad Tardía/genética , Leucocitos Mononucleares/metabolismo , Donadores Vivos , Masculino , Persona de Mediana Edad , Linfocitos T Reguladores/metabolismo , Tolerancia al TrasplanteRESUMEN
The incidence of myocardial infarctions and influenza follow similar seasonal patterns. To determine if acute myocardial infarctions (AMIs) and ischaemic strokes are associated with influenza activity, we built time-series models using data from the Nationwide Inpatient Sample. In these models, we used influenza activity to predict the incidence of AMI and ischaemic stroke. We fitted national models as well as models based on four geographical regions and five age groups. Across all models, we found consistent significant associations between AMIs and influenza activity, but not between ischaemic strokes and influenza. Associations between influenza and AMI increased with age, were greatest in those aged >80 years, and were present in all geographical regions. In addition, the natural experiment provided by the second wave of the influenza pandemic in 2009 provided further evidence of the relationship between influenza and AMI, because both series peaked in the same non-winter month.
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Gripe Humana/epidemiología , Infarto del Miocardio/epidemiología , Estaciones del Año , Accidente Cerebrovascular/epidemiología , Adulto , Factores de Edad , Anciano , Anciano de 80 o más Años , Isquemia Encefálica/complicaciones , Isquemia Encefálica/epidemiología , Humanos , Incidencia , Persona de Mediana Edad , Modelos Estadísticos , Pandemias , Análisis de Regresión , Accidente Cerebrovascular/etiología , Estados Unidos/epidemiologíaRESUMEN
We report the results of the recent high power testing of superconducting radio frequency photonic band gap (PBG) accelerator cells. Tests of the two single-cell 2.1 GHz cavities were performed at both 4 and 2 K. An accelerating gradient of 15 MV/m and an unloaded quality factor Q(0) of 4×10(9) were achieved. It has been long realized that PBG structures have great potential in reducing long-range wakefields in accelerators. A PBG structure confines the fundamental TM(01)-like accelerating mode, but does not support higher order modes. Employing PBG cavities to filter out higher order modes in superconducting particle accelerators will allow suppression of dangerous beam instabilities caused by wakefields and thus operation at higher frequencies and significantly higher beam luminosities. This may lead towards a completely new generation of colliders for high energy physics and energy recovery linacs for the free-electron lasers.
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Deep brain stimulation was first developed for movement disorders but is now being offered as a therapeutic alternative in severe psychiatric disorders after the failure of conventional therapies. One of such pathologies is obsessive-compulsive disorder. This disorder which associates intrusive thoughts (obsessions) and repetitive irrepressible rituals (compulsions) is characterized by a dysfunction of a cortico-subcortical loop. After having reviewed the pathophysiological evidence to show why deep brain stimulation was an interesting path to take for severe and resistant cases of obsessive-compulsive disorder, we will present the results of the different clinical trials. Finally, we will provide possible mechanisms for the effects of deep brain stimulation in this pathology.
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Ganglios Basales/fisiopatología , Estimulación Encefálica Profunda , Trastorno Obsesivo Compulsivo/etiología , Trastorno Obsesivo Compulsivo/fisiopatología , Ganglios Basales/patología , Encéfalo/patología , Encéfalo/fisiopatología , Estimulación Encefálica Profunda/efectos adversos , Estimulación Encefálica Profunda/métodos , Humanos , Trastornos Mentales/fisiopatología , Trastornos Mentales/terapia , Modelos Biológicos , Trastorno Obsesivo Compulsivo/patologíaRESUMEN
PURPOSE: The purpose of this study was three-fold: 1) to estimate the organ doses and effective dose (ED) for patients undergoing neuro 3D-imaging protocols, 2) to study the effect of beam collimation on ED, and 3) to derive protocol-specific DAP-to-ED conversion factors. METHODS: A cone-beam CT system (Philips Allura Xper FD20/20) was used to measure the organ doses for seven neuro imaging protocols. Two data sets were obtained: seven protocols with uncollimated beam (FOV: entire head) and four with beam collimation (FOV: roughly from the base to the top of the skull). Measurements were performed on an adult male anthropomorphic phantom (CIRS, Norfolk, VA) with 20 MOSFET detectors (Best Medical Canada, Ottawa, Canada) placed in selected organs. The dose area product (DAP) values were recorded from console. The ED values were computed by multiplying measured organ doses to corresponding ICRP 103 tissue weighting factors. RESULTS: For seven protocols with uncollimated setting, the EDs ranged from 0.16 mSv to 1.6 mSv, and the DAP-to-ED conversion factors range from 0.037 to 0.17 mSv/Gy/cm2 . For four protocols with beam collimation, the ED was reduced approximately by a factor of 2, and the DAP-to-ED conversion factors by approximately 30%. CONCLUSIONS: We have measured ED for standard adult neuro imaging protocols in a 3-D rotational angiography system. Our results provide a simple means of ED estimation using DAP values from console in the C-arm cone-beam CT system. Research was funded in part by Philips Healthcare, the Netherlands.
RESUMEN
Functional and connectivity changes in corticostriatal systems have been reported in the brains of patients with obsessive-compulsive disorder (OCD); however, the relationship between basal ganglia activity and OCD severity has never been adequately established. We recently showed that deep brain stimulation of the subthalamic nucleus (STN), a central basal ganglia nucleus, improves OCD. Here, single-unit subthalamic neuronal activity was analysed in 12 OCD patients, in relation to the severity of obsessions and compulsions and response to STN stimulation, and compared with that obtained in 12 patients with Parkinson's disease (PD). STN neurons in OCD patients had lower discharge frequency than those in PD patients, with a similar proportion of burst-type activity (69 vs 67%). Oscillatory activity was present in 46 and 68% of neurons in OCD and PD patients, respectively, predominantly in the low-frequency band (1-8 Hz). In OCD patients, the bursty and oscillatory subthalamic neuronal activity was mainly located in the associative-limbic part. Both OCD severity and clinical improvement following STN stimulation were related to the STN neuronal activity. In patients with the most severe OCD, STN neurons exhibited bursts with shorter duration and interburst interval, but higher intraburst frequency, and more oscillations in the low-frequency bands. In patients with best clinical outcome with STN stimulation, STN neurons displayed higher mean discharge, burst and intraburst frequencies, and lower interburst interval. These findings are consistent with the hypothesis of a dysfunction in the associative-limbic subdivision of the basal ganglia circuitry in OCD's pathophysiology.
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Ganglios Basales/fisiopatología , Estimulación Encefálica Profunda/métodos , Neuronas/patología , Trastorno Obsesivo Compulsivo/fisiopatología , Enfermedad de Parkinson/fisiopatología , Índice de Severidad de la Enfermedad , Adulto , Ganglios Basales/patología , Ganglios Basales/cirugía , Estimulación Encefálica Profunda/instrumentación , Electrodos Implantados , Humanos , Trastorno Obsesivo Compulsivo/patología , Trastorno Obsesivo Compulsivo/terapia , Enfermedad de Parkinson/patología , Enfermedad de Parkinson/terapia , Resultado del TratamientoRESUMEN
Older Italian-born Australians represent one of the largest migrant populations in Australia. However, there are few valid and reliable Italian-language measures of mood symptomology suitable for use with this group. Following a rigorous translation and adaptation process, an Italian version of the Depression Anxiety Stress Scales was administered to a sample of 103 Italian-born men and women over the age of 55 years and the results were subjected to exploratory factor analysis. Items within the original Depression and Stress scales loaded consistently and strongly on separate factors. However, translated Anxiety items loaded across three separate factors, including a factor comprised solely of somatic expressions of anxiety. The results are explained with reference to cultural factors specific to an older Mediterranean migrant sample, including somatic expressions of distress and "nerves". The results are also discussed in light of the size and nature of the sample. The Depression and Stress scales can be used confidently by clinicians and researchers with this population. However, the Anxiety scale cannot be assumed to be measuring an homogenous construct, and as such, should be used with caution.
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Trastornos de Ansiedad/diagnóstico , Depresión/diagnóstico , Encuestas y Cuestionarios , Anciano , Anciano de 80 o más Años , Trastornos de Ansiedad/fisiopatología , Comparación Transcultural , Depresión/fisiopatología , Femenino , Humanos , Italia/etnología , Masculino , Persona de Mediana Edad , Reproducibilidad de los Resultados , Australia del Sur , Migrantes/psicologíaRESUMEN
Mechanosensitive (MS) ion channels likely underlie myriad force-sensing processes, from basic osmotic regulation to specified sensations of animal hearing and touch. Albeit important, the molecular identities of many eukaryotic MS channels remain elusive, let alone their working mechanisms. This is in stark contrast to our advanced knowledge on voltage- or ligand-sensitive channels. Several members of transient receptor potential (TRP) ion channel family have been implicated to function in mechanosensation and are recognized as promising candidate MS channels. The yeast TRP homolog, TRPY1, is clearly a first-line force transducer. It can be activated by hypertonic shock in vivo and by membrane stretch force in excised patches under patch clamp, making it a useful model for understanding TRP channel mechanosensitivity in general. TRPY1 offers two additional research advantages: (1) It has a large ( approximately 300 pS) unitary conductance and therefore a favorable S/N ratio. (2) Budding yeast allows convenient and efficient genetic and molecular manipulations. In this review, we focus on the current research of TRPY1 and discuss its prospect. We also describe the use of yeast as a system to express and characterize animal TRP channels.
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Mecanotransducción Celular/fisiología , Saccharomyces cerevisiae/fisiología , Canales de Potencial de Receptor Transitorio/fisiología , Animales , Fenómenos Electrofisiológicos/fisiología , Humanos , Activación del Canal Iónico/fisiología , Proteínas de Saccharomyces cerevisiae/fisiologíaRESUMEN
The yeast TRPY1 (Yvc1p) channel is activated by membrane stretch to release vacuolar Ca2+ into the cytoplasm upon osmotic upshock. Exogenously added indole greatly enhances the upshock-induced Ca2+ release in vivo. Indole also reversibly activates the channels under patch clamp. A minimum of 10(-6)M Ca2+ is needed for membrane stretch force to open TPRY1, but indole activation appears to be Ca2+ independent. A deletion of 30 residues at the predicted cytoplasmic domain, 570-600Delta, renders TRPY1 insensitive to stretch force upto 10(-3)M Ca2+. Nonetheless, indole readily activates this mutant channel. Several other aromatic compounds, e.g. the antimicrobial parabens, also activate TRPY1. These compounds likely alter the innate forces in the lipid bilayer received by the channel.
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Hidrocarburos Aromáticos/farmacología , Indoles/farmacología , Proteínas de Saccharomyces cerevisiae/agonistas , Saccharomyces cerevisiae/efectos de los fármacos , Calcio/metabolismo , Canales de Calcio , Técnicas de Placa-Clamp , Saccharomyces cerevisiae/metabolismo , Canales Catiónicos TRPCRESUMEN
Antibody hydrolysis of the superantigenic gp120 site and HIV-1 neutralization was studied as a potential anti-HIV mechanism in uninfected humans. gp120 hydrolysis by purified serum and salivary antibodies was determined by electrophoresis and peptide sequencing, the proteolytic mechanism was analyzed using electrophilic peptide analogs, and viral neutralization was studied using peripheral blood mononuclear cells as hosts. Polyclonal and monoclonal IgA but not IgG preparations selectively catalyzed the cleavage of HIV gp120 at rates sufficient to predict biologically relevant protection against the virus. The IgA hydrolytic reaction proceeded by noncovalent recognition of gp120 residues 421-433, a component of the superantigenic site of gp120, coordinated with peptide bond cleavage via a serine protease-like mechanism. The Lys-432-Ala-433 bond was one of the cleavage sites. Infection of peripheral blood mononuclear cells by a primary isolate of HIV was neutralized by the IgA but not IgG fractions. The neutralizing activity was specifically inhibited by an electrophilic inhibitor of the catalytic activity. The existence of catalytic IgAs to gp120 in uninfected humans suggests their role in resistance to HIV.
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Anticuerpos Catalíticos/metabolismo , Proteína gp120 de Envoltorio del VIH/metabolismo , VIH-1/inmunología , Inmunoglobulina A/metabolismo , Adulto , Anticuerpos Monoclonales/inmunología , Anticuerpos Monoclonales/metabolismo , Femenino , Proteína gp120 de Envoltorio del VIH/inmunología , Haptenos/metabolismo , Humanos , Hidrólisis , Inmunoglobulina A/inmunología , Inmunoglobulina A Secretora/inmunología , Inmunoglobulina G/inmunología , Inmunoglobulina G/metabolismo , Masculino , Pruebas de NeutralizaciónRESUMEN
Transient receptor potential (TRP) channels found in animals, protists, and fungi are primary chemo-, thermo-, or mechanosensors. Current research emphasizes the characteristics of individual channels in each animal TRP subfamily but not the mechanisms common across subfamilies. A forward genetic screen of the TrpY1, the yeast TRP channel, recovered gain-of-function (GOF) mutations with phenotype in vivo and in vitro. Single-channel patch-clamp analyses of these GOF-mutant channels show prominent aberrations in open probability and channel kinetics. These mutations revealed functionally important aromatic amino acid residues in four locations: at the intracellular end of the fifth transmembrane helix (TM5), at both ends of TM6, and at the immediate extension of TM6. These aromatics have counterparts in most TRP subfamilies. The one in TM5 (F380L) aligns precisely with an exceptional Drosophila mutant allele (F550I) that causes constitutive activity in the canonical TRP channel, resulting in rapid and severe retinal degeneration beyond mere loss of phototaxis. Thus, this phenylalanine maintains the balance of various functional states (conformations) of a channel for insect phototransduction as well as one for fungal mechanotransduction. This residue is among a small cluster of phenylalanines found in all known subfamilies of TRP channels. This unique case illustrates that GOF mutations can reveal structure-function principles that can be generalized across different TRP subfamilies. It appears that the conserved aromatics in the four locations have conserved functions in most TRP channels. The possible mechanistic roles of these aromatics and the further use of yeast genetics to dissect TRP channels are discussed.
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Proteínas Fúngicas/genética , Proteínas Fúngicas/fisiología , Canales de Potencial de Receptor Transitorio/genética , Canales de Potencial de Receptor Transitorio/fisiología , Levaduras/metabolismo , Secuencia de Aminoácidos , Aminoácidos Aromáticos/química , Secuencia Conservada , Proteínas Fúngicas/química , Datos de Secuencia Molecular , Mutación , Técnicas de Placa-Clamp , Relación Estructura-Actividad , Canales de Potencial de Receptor Transitorio/química , Levaduras/genéticaRESUMEN
Transient receptor potential (TRP) channels are first elements in sensing chemicals, heat, and force and are widespread among protists and fungi as well as animals. Despite their importance, the arrangement and roles of the amino acids that constitute the TRP channel gate are unknown. The yeast TRPY1 is activated in vivo by osmotically induced vacuolar membrane deformation and by cytoplasmic Ca(2+). After a random mutagenesis, we isolated TRPY1 mutants that responded more strongly to mild osmotic upshocks. One such gain-of-function mutant has a Y458H substitution at the C terminus of the predicted sixth transmembrane helix. Direct patch-clamp examination of vacuolar membranes showed that Y458H channels were already active with little stimulus and showed marked flickers between the open and intraburst closed states. They remained responsive to membrane stretch force and to Ca(2+), indicating primary defects in the gate region but not in the sensing of gating principles. None of the other 18 amino acid replacements engineered here showed normal channel kinetics except the two aromatic substitutions, Y458F and Y458W. The Y458 of TRPY1 has its aromatic counterpart in mammalian TRPM. Furthermore, conserved aromatics one alpha-helical turn downstream from this point are also found in animal TRPC, TRPN, TRPP, and TRPML, suggesting that gate anchoring with aromatics may be common among many TRP channels. The possible roles of aromatics at the end of the sixth transmembrane helix are discussed.
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Mutación , Canales de Potencial de Receptor Transitorio/química , Secuencia de Aminoácidos , Animales , Calcio/metabolismo , Citoplasma/metabolismo , Electrofisiología/métodos , Humanos , Cinética , Datos de Secuencia Molecular , Ósmosis , Estructura Secundaria de Proteína , Homología de Secuencia de Aminoácido , Especificidad de la Especie , Relación Estructura-Actividad , Canales de Potencial de Receptor Transitorio/metabolismoRESUMEN
This study aimed to characterize genetic features of HIV-1 subtype C envelope glycoproteins capable of eliciting cross-reactive neutralizing antibodies during natural infections. The gp160 sequences were determined for 36 HIV-1 subtype C isolates (donor viruses) from infected individuals residing in Malawi, Zimbabwe, Zambia and South Africa, whose sera displayed a range of cross-neutralizing activities against a panel of 5 subtype C and 5 subtype B viruses (panel viruses). Hierarchical clustering analysis of neutralization data of the panel viruses predicted phylogenetic relationships between subtype B and C panel viruses, suggesting some subtype-specific neutralization determinants. A similar comparison of subtype C donor viruses showed no significant correlation; however of three donor sequence pairs resolvable by phylogenetic analysis, two were also associated within the neutralization clustering dendrogram, suggesting that closely related viruses may elicit antibodies targeting common neutralization determinants. Significantly, viruses that had shorter V1-V4 loops induced antibodies that showed more neutralization breadth against the subtype C panel viruses (p=0.0135). This study indicates that that some structural features of envelope, such as shorter variable loops, may facilitate the elicitation of cross-reactive neutralizing antibodies in natural infections. Collectively these data provide some insights into design features of an envelope immunogen aimed at inducing neutralizing antibodies.