Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 243
Filtrar
Más filtros

Bases de datos
País/Región como asunto
Tipo del documento
Intervalo de año de publicación
1.
Cell ; 187(1): 95-109.e26, 2024 01 04.
Artículo en Inglés | MEDLINE | ID: mdl-38181745

RESUMEN

DddA-derived cytosine base editors (DdCBEs) and transcription activator-like effector (TALE)-linked deaminases (TALEDs) catalyze targeted base editing of mitochondrial DNA (mtDNA) in eukaryotic cells, a method useful for modeling of mitochondrial genetic disorders and developing novel therapeutic modalities. Here, we report that A-to-G-editing TALEDs but not C-to-T-editing DdCBEs induce tens of thousands of transcriptome-wide off-target edits in human cells. To avoid these unwanted RNA edits, we engineered the substrate-binding site in TadA8e, the deoxy-adenine deaminase in TALEDs, and created TALED variants with fine-tuned deaminase activity. Our engineered TALED variants not only reduced RNA off-target edits by >99% but also minimized off-target mtDNA mutations and bystander edits at a target site. Unlike wild-type versions, our TALED variants were not cytotoxic and did not cause developmental arrest of mouse embryos. As a result, we obtained mice with pathogenic mtDNA mutations, associated with Leigh syndrome, which showed reduced heart rates.


Asunto(s)
ADN Mitocondrial , Efectores Tipo Activadores de la Transcripción , Animales , Humanos , Ratones , Adenina , Citosina , ADN Mitocondrial/genética , Edición Génica , ARN , Efectores Tipo Activadores de la Transcripción/metabolismo , Ingeniería de Proteínas
2.
Cell ; 153(4): 797-811, 2013 May 09.
Artículo en Inglés | MEDLINE | ID: mdl-23663779

RESUMEN

All metazoan guts are subjected to immunologically unique conditions in which an efficient antimicrobial system operates to eliminate pathogens while tolerating symbiotic commensal microbiota. However, the molecular mechanisms controlling this process are only partially understood. Here, we show that bacterial-derived uracil acts as a ligand for dual oxidase (DUOX)-dependent reactive oxygen species generation in Drosophila gut and that the uracil production in bacteria causes inflammation in the gut. The acute and controlled uracil-induced immune response is required for efficient elimination of bacteria, intestinal cell repair, and host survival during infection of nonresident species. Among resident gut microbiota, uracil production is absent in symbionts, allowing harmonious colonization without DUOX activation, whereas uracil release from opportunistic pathobionts provokes chronic inflammation. These results reveal that bacteria with distinct abilities to activate uracil-induced gut inflammation, in terms of intensity and duration, act as critical factors that determine homeostasis or pathogenesis in gut-microbe interactions.


Asunto(s)
Drosophila/inmunología , Drosophila/microbiología , Inmunidad Mucosa , Pectobacterium carotovorum/fisiología , Simbiosis , Uracilo/metabolismo , Animales , Tracto Gastrointestinal/inmunología , Tracto Gastrointestinal/microbiología , Tracto Gastrointestinal/fisiología , Homeostasis , Humanos , Inflamación/inmunología , Inflamación/microbiología , Enfermedades Inflamatorias del Intestino/inmunología , Enfermedades Inflamatorias del Intestino/microbiología , NADPH Oxidasas/metabolismo , Especies Reactivas de Oxígeno/metabolismo , Células Madre/metabolismo
3.
Nature ; 593(7860): 570-574, 2021 05.
Artículo en Inglés | MEDLINE | ID: mdl-33953396

RESUMEN

A balanced intake of macronutrients-protein, carbohydrate and fat-is essential for the well-being of organisms. An adequate calorific intake but with insufficient protein consumption can lead to several ailments, including kwashiorkor1. Taste receptors (T1R1-T1R3)2 can detect amino acids in the environment, and cellular sensors (Gcn2 and Tor)3 monitor the levels of amino acids in the cell. When deprived of dietary protein, animals select a food source that contains a greater proportion of protein or essential amino acids (EAAs)4. This suggests that food selection is geared towards achieving the target amount of a particular macronutrient with assistance of the EAA-specific hunger-driven response, which is poorly understood. Here we show in Drosophila that a microbiome-gut-brain axis detects a deficit of EAAs and stimulates a compensatory appetite for EAAs. We found that the neuropeptide CNMamide (CNMa)5 was highly induced in enterocytes of the anterior midgut during protein deprivation. Silencing of the CNMa-CNMa receptor axis blocked the EAA-specific hunger-driven response in deprived flies. Furthermore, gnotobiotic flies bearing an EAA-producing symbiotic microbiome exhibited a reduced appetite for EAAs. By contrast, gnotobiotic flies with a mutant microbiome that did not produce leucine or other EAAs showed higher expression of CNMa and a greater compensatory appetite for EAAs. We propose that gut enterocytes sense the levels of diet- and microbiome-derived EAAs and communicate the EAA-deprived condition to the brain through CNMa.


Asunto(s)
Aminoácidos Esenciales/administración & dosificación , Eje Cerebro-Intestino , Drosophila/fisiología , Preferencias Alimentarias , Microbioma Gastrointestinal , Aminoácidos Esenciales/deficiencia , Fenómenos Fisiológicos Nutricionales de los Animales , Animales , Animales Modificados Genéticamente , Apetito , Enterocitos , Femenino , Vida Libre de Gérmenes , Hambre , Leucina , Simbiosis
4.
Biochem Biophys Res Commun ; 704: 149596, 2024 Apr 16.
Artículo en Inglés | MEDLINE | ID: mdl-38430697

RESUMEN

PHD finger protein 7 (Phf7) is a member of the PHF family proteins, which plays important roles in spermiogenesis. Phf7 is expressed in the adult testes and its deficiency causes male infertility. In this study, we tried to find the causal relationship between Phf7 deficiency and reduced growth retardation which were found in null knock-out (Phf7-/-) mice. Phf7-/- mice were born normally in the Mendelian ratio. However, the Phf7-/- males showed decreased body weight gain, bone mineral density, and bone mineral content compared to those in wild-type (WT) mice. Histological analysis for tibia revealed increased number of osteoclast cells in Phf7-/- mice compared with that in WT mice. When we analyzed the expressions for marker genes for the initial stage of osteoclastogenesis, such as receptor activator of nuclear factor kappa B (Rank) in tibia, there was no difference in the mRNA levels between Phf7-/- and WT mice. However, the expression of tartrate-resistant acid phosphatase (Trap), a mature stage marker gene, was significantly higher in Phf7-/- mice than in WT mice. In addition, the levels of testosterone and dihydrotestosterone (DHT), more potent and active form of testosterone, were significantly reduced in the testes of Phf7-/- mice compared to those in WT mice. Furthermore, testicular mRNA levels for steroidogenesis marker genes, namely Star, Cyp11a1, Cyp17a1 and 17ß-hsd, were significantly lower in Phf7-/- mice than in WT mice. In conclusion, these results suggest that Phf7 deficiency reduces the production of male sex hormones and thereby impairs associated bone remodeling.


Asunto(s)
Hormonas Testiculares , Animales , Masculino , Ratones , Remodelación Ósea , Osteoclastos/metabolismo , ARN Mensajero/metabolismo , Hormonas Testiculares/metabolismo , Testosterona/metabolismo
5.
J Biol Chem ; 298(12): 102682, 2022 12.
Artículo en Inglés | MEDLINE | ID: mdl-36356900

RESUMEN

Liraglutide, a glucagon-like peptide-1 analog, has beneficial metabolic effects in patients with type 2 diabetes and obesity. Although the high efficacy of liraglutide as an anti-diabetic and anti-obesity drug is well known, liraglutide-induced metabolic alterations in diverse tissues remain largely unexplored. Here, we report the changes in metabolic profiles induced by a 2-week subcutaneous injection of liraglutide in diet-induced obese mice fed a high-fat diet for 8 weeks. Our comprehensive metabolomic analyses of the hypothalamus, plasma, liver, and skeletal muscle showed that liraglutide intervention led to various metabolic alterations in comparison with diet-induced obese or nonobese mice. We found that liraglutide remarkably coordinated not only fatty acid metabolism in the hypothalamus and skeletal muscle but also amino acid and carbohydrate metabolism in plasma and liver. Comparative analyses of metabolite dynamics revealed that liraglutide rewired intertissue metabolic correlations. Our study points to a previously unappreciated metabolic alteration by liraglutide in several tissues, which may underlie its therapeutic effects within and across the tissues.


Asunto(s)
Diabetes Mellitus Tipo 2 , Liraglutida , Animales , Ratones , Diabetes Mellitus Tipo 2/tratamiento farmacológico , Diabetes Mellitus Tipo 2/metabolismo , Dieta Alta en Grasa , Péptido 1 Similar al Glucagón , Hipoglucemiantes/farmacología , Hipoglucemiantes/uso terapéutico , Liraglutida/farmacología , Liraglutida/uso terapéutico , Ratones Obesos , Obesidad/inducido químicamente , Obesidad/tratamiento farmacológico
6.
BMC Med ; 21(1): 248, 2023 07 10.
Artículo en Inglés | MEDLINE | ID: mdl-37424001

RESUMEN

BACKGROUND: The COVID-19 Vaccine Introduction and deployment Costing (CVIC) tool was developed to assist countries to estimate incremental financial costs to roll out COVID-19 vaccines. This article describes the purposes, assumptions and methods used in the CVIC tool and presents the estimated financial costs of delivering COVID-19 vaccines in the Lao People's Democratic Republic (Lao PDR). METHODS: From March to September 2021, a multidisciplinary team in Lao PDR was involved in the costing exercise of the National Deployment and Vaccination Plan for COVID-19 vaccines to develop potential scenarios and gather inputs using the CVIC tool. Financial costs of introducing COVID-19 vaccines for 3 years from 2021 to 2023 were projected from the government perspective. All costs were collected in 2021 Lao Kip and presented in United States dollar. RESULTS: From 2021 to 2023, the financial cost required to vaccinate all adults in Lao PDR with primary series of COVID-19 vaccines (1 dose for Ad26.COV2.S (recombinant) vaccine and 2 doses for the other vaccine products) is estimated to be US$6.44 million (excluding vaccine costs) and additionally US$1.44 million and US$1.62 million to include teenagers and children, respectively. These translate to financial costs of US$0.79-0.81 per dose, which decrease to US$0.6 when two boosters are introduced to the population. Capital and operational cold-chain costs contributed 15-34% and 15-24% of the total costs in all scenarios, respectively. 17-26% went to data management, monitoring and evaluation, and oversight, and 13-22% to vaccine delivery. CONCLUSIONS: With the CVIC tool, costs of five scenarios were estimated with different target population and booster dose use. These facilitated Lao PDR to refine their strategic planning for COVID-19 vaccine rollout and to decide on the level of external resources needed to mobilize and support outreach services. The results may further inform inputs in cost-effectiveness or cost-benefit analyses and potentially be applied and adjusted in similar low- and middle-income settings.


Asunto(s)
Vacunas contra la COVID-19 , COVID-19 , Vacunación , Adolescente , Adulto , Niño , Humanos , Ad26COVS1 , Análisis Costo-Beneficio , COVID-19/epidemiología , COVID-19/prevención & control , Vacunas contra la COVID-19/economía , Laos/epidemiología , Vacunación/economía
7.
Biomacromolecules ; 24(6): 2409-2432, 2023 06 12.
Artículo en Inglés | MEDLINE | ID: mdl-37155361

RESUMEN

Twenty years ago, this journal published a review entitled "Biofabrication with Chitosan" based on the observations that (i) chitosan could be electrodeposited using low voltage electrical inputs (typically less than 5 V) and (ii) the enzyme tyrosinase could be used to graft proteins (via accessible tyrosine residues) to chitosan. Here, we provide a progress report on the coupling of electronic inputs with advanced biological methods for the fabrication of biopolymer-based hydrogel films. In many cases, the initial observations of chitosan's electrodeposition have been extended and generalized: mechanisms have been established for the electrodeposition of various other biological polymers (proteins and polysaccharides), and electrodeposition has been shown to allow the precise control of the hydrogel's emergent microstructure. In addition, the use of biotechnological methods to confer function has been extended from tyrosinase conjugation to the use of protein engineering to create genetically fused assembly tags (short sequences of accessible amino acid residues) that facilitate the attachment of function-conferring proteins to electrodeposited films using alternative enzymes (e.g., transglutaminase), metal chelation, and electrochemically induced oxidative mechanisms. Over these 20 years, the contributions from numerous groups have also identified exciting opportunities. First, electrochemistry provides unique capabilities to impose chemical and electrical cues that can induce assembly while controlling the emergent microstructure. Second, it is clear that the detailed mechanisms of biopolymer self-assembly (i.e., chitosan gel formation) are far more complex than anticipated, and this provides a rich opportunity both for fundamental inquiry and for the creation of high performance and sustainable material systems. Third, the mild conditions used for electrodeposition allow cells to be co-deposited for the fabrication of living materials. Finally, the applications have been expanded from biosensing and lab-on-a-chip systems to bioelectronic and medical materials. We suggest that electro-biofabrication is poised to emerge as an enabling additive manufacturing method especially suited for life science applications and to bridge communication between our biological and technological worlds.


Asunto(s)
Quitosano , Quitosano/química , Monofenol Monooxigenasa/química , Hidrogeles , Proteínas , Biopolímeros
8.
FASEB J ; 35(8): e21794, 2021 08.
Artículo en Inglés | MEDLINE | ID: mdl-34314059

RESUMEN

While biglycan (BGN) is suggested to direct diverse signaling cascades, the effects of soluble BGN as a ligand on metabolic traits have not been studied. Herein, we tested the effects of BGN on obesity in high-fat diet (HFD)-induced obese animals and glucose metabolism, with the underlying mechanism responsible for observed effects in vitro. Our results showed that BGN administration (1 mg/kg body weight, intraperitoneally) significantly prevented HFD-induced obesity, and this was mainly attributed to reduced food intake. Also, intracerebroventricular injection of BGN reduced food intake and body weight. The underlying mechanism includes modulation of neuropeptides gene expression involved in appetite in the hypothalamus in vitro and in vivo. In addition, BGN regulates glucose metabolism as shown by improved glucose tolerance in mice as well as AMPK/AKT dual pathway-driven enhanced glucose uptake and GLUT4 translocation in L6 myoblast cells. In conclusion, our results suggest BGN as a potential therapeutic target to treat risk factors for metabolic diseases.


Asunto(s)
Proteínas Quinasas Activadas por AMP/metabolismo , Biglicano/administración & dosificación , Glucosa/metabolismo , Músculo Esquelético/efectos de los fármacos , Obesidad/tratamiento farmacológico , Proteínas Proto-Oncogénicas c-akt/metabolismo , Animales , Línea Celular , Conducta Alimentaria , Ratones , Ratones Endogámicos ICR , Ratas
9.
Int J Health Plann Manage ; 36(2): 482-497, 2021 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-33326170

RESUMEN

The study aims to examine the effect of catastrophic health expenditure (CHE) on exit from poverty among the poor at the poverty line of less than 40% of median income level (MIL), analysing data from the Korean Welfare Panel Study 2008-2016 through a discrete time event history analysis. Effects of CHE on poverty exit were different between exit to near-poverty and exit to non-poverty. Households facing CHE were less likely to exit from poverty to near-poverty at the CHE thresholds of 20%-30%; however, effects of CHE were not associated with exiting from poverty to non-poverty. Considering the majority of types of exit from poverty were exit to near-poverty (about 70%), this result would raise concerns that occurrences of CHE may pose a big threat to their already limited household budget of the poor. Combined loss of income due to ill health and financial burden due to health care may force the poor to be stuck at poverty. The study was the first exploratory study in South Korea to examine the effect of CHE on exit from poverty. This study is expected to contribute to better understanding of the economic consequences of out-of-pocket payments due to health care among the poor over time. Reduction in the incidence of CHE by expanding the benefits coverage of the national health insurance in Korea can be an important step to reduce poverty.


Asunto(s)
Enfermedad Catastrófica , Gastos en Salud , Composición Familiar , Humanos , Pobreza , República de Corea
10.
Angew Chem Int Ed Engl ; 60(5): 2446-2454, 2021 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-33089921

RESUMEN

Long-lived room temperature phosphorescence from organic molecular crystals attracts great attention. Persistent luminescence depends on the electronic properties of the molecular components, mainly π-conjugated donor-acceptor (D-A) chromophores, and their molecular packing. Here, a strategy is developed by designing two isomeric molecular phosphors incorporating and combining a bridge for σ-conjugation between the D and A units and a structure-directing unit for H-bond-directed supramolecular self-assembly. Calculations highlight the critical role played by the two degrees of freedom of the σ-conjugated bridge on the chromophore optical properties. The molecular crystals exhibit RTP quantum yields up to 20 % and lifetimes up to 520 ms. The crystal structures of the efficient phosphorescent materials establish the existence of an unprecedented well-organization of the emitters into 2D rectangular columnar-like supramolecular structure stabilized by intermolecular H-bonding.

11.
Appl Environ Microbiol ; 86(5)2020 02 18.
Artículo en Inglés | MEDLINE | ID: mdl-31836580

RESUMEN

Melanin is a pigment produced by organisms throughout all domains of life. Due to its unique physicochemical properties, biocompatibility, and biostability, there has been an increasing interest in the use of melanin for broad applications. In the vast majority of studies, melanin has been either chemically synthesized or isolated from animals, which has restricted its use to small-scale applications. Using bacteria as biocatalysts is a promising and economical alternative for the large-scale production of biomaterials. In this study, we engineered the marine bacterium Vibrio natriegens, one of the fastest-growing organisms, to synthesize melanin by expressing a heterologous tyrosinase gene and demonstrated that melanin production was much faster than in previously reported heterologous systems. The melanin of V. natriegens was characterized as a polymer derived from dihydroxyindole-2-carboxylic acid (DHICA) and, similarly to synthetic melanin, exhibited several characteristic and useful features. Electron microscopy analysis demonstrated that melanin produced from V. natriegens formed nanoparticles that were assembled as "melanin ghost" structures, and the photoprotective properties of these particles were validated by their protection of cells from UV irradiation. Using a novel electrochemical reverse engineering method, we observed that melanization conferred redox activity to V. natriegens Moreover, melanized bacteria were able to quickly adsorb the organic compound trinitrotoluene (TNT). Overall, the genetic tractability, rapid division time, and ease of culture provide a set of attractive properties that compare favorably to current E. coli production strains and warrant the further development of this chassis as a microbial factory for natural product biosynthesis.IMPORTANCE Melanins are macromolecules that are ubiquitous in nature and impart a large variety of biological functions, including structure, coloration, radiation resistance, free radical scavenging, and thermoregulation. Currently, in the majority of investigations, melanins are either chemically synthesized or extracted from animals, which presents significant challenges for large-scale production. Bacteria have been used as biocatalysts to synthesize a variety of biomaterials due to their fast growth and amenability to genetic engineering using synthetic biology tools. In this study, we engineered the extremely fast-growing bacterium V. natriegens to synthesize melanin nanoparticles by expressing a heterologous tyrosinase gene with inducible promoters. Characterization of the melanin produced from V. natriegens-produced tyrosinase revealed that it exhibited physical and chemical properties similar to those of natural and chemically synthesized melanins, including nanoparticle structure, protection against UV damage, and adsorption of toxic compounds. We anticipate that producing and controlling melanin structures at the nanoscale in this bacterial system with synthetic biology tools will enable the design and rapid production of novel biomaterials for multiple applications.


Asunto(s)
Bacillus megaterium/genética , Biopolímeros/metabolismo , Melaninas/biosíntesis , Microorganismos Modificados Genéticamente/metabolismo , Monofenol Monooxigenasa/genética , Vibrio/metabolismo , Biopolímeros/genética , Microorganismos Modificados Genéticamente/genética , Monofenol Monooxigenasa/metabolismo , Vibrio/genética
12.
Cardiovasc Ultrasound ; 18(1): 44, 2020 Nov 10.
Artículo en Inglés | MEDLINE | ID: mdl-33172479

RESUMEN

BACKGROUND: With an increasing clinical importance of the treatment of the heart failure (HF) with preserved ejection fraction (HFpEF), it is important to be certain of the diagnosis of HF. We investigated global and regional left ventricular (LV) strains using speckle tracking echocardiography (STE) in patients with HFpEF and compared those parameters with that of patients with hypertension and normal subjects. METHODS: Peak longitudinal, circumferential and radial strains were assessed globally and regionally for each study groups using STE. Diastolic strain rate was also determined. RESULTS: There were 50 patients in HFpEF group, 56 patients in hypertension group and 46 age-matched normal subjects. In patients with HFpEF, global peak longitudinal, circumferential and radial strain and strain rate were reduced compared to both hypertension patients and normal controls (- 15.5 ± 5.3 vs - 17.7 ± 3.1 and - 19.9 ± 2.0; - 9.7 ± 2.2 vs - 19.3 ± 3.1 and - 20.5 ± 3.3; 17.7 ± 8.2 vs 38.4 ± 12.4 and 43.6 ± 11.9, respectively, P <  0.001, for all). The diagnostic performance of global circumferential strain to predict the HFpEF was greatest among strain parameters (area under the curve = 0.997). CONCLUSIONS: In the speckle tracking echocardiography, impaired peak global strain and homogeneously reduced regional strain was observed in HFpEF patients compared to the hypertension patients and normal subjects in decreasing order. This can provide early information on the initiation of LV deformation of HFpEF in patients with hypertension or normal subjects.


Asunto(s)
Insuficiencia Cardíaca/fisiopatología , Ventrículos Cardíacos/diagnóstico por imagen , Hipertensión/fisiopatología , Contracción Miocárdica/fisiología , Volumen Sistólico/fisiología , Función Ventricular Izquierda/fisiología , Adulto , Anciano , Anciano de 80 o más Años , Diástole , Femenino , Insuficiencia Cardíaca/diagnóstico , Ventrículos Cardíacos/fisiopatología , Humanos , Masculino , Persona de Mediana Edad , Estudios Prospectivos
13.
Biomacromolecules ; 20(2): 969-978, 2019 02 11.
Artículo en Inglés | MEDLINE | ID: mdl-30616349

RESUMEN

Biomacromolecules often possess information to self-assemble through low energy competing interactions which can make self-assembly responsive to environmental cues and can also confer dynamic properties. Here, we coupled self-assembling systems to create biofunctional multilayer films that can be cued to disassemble through either molecular or electrical signals. To create functional multilayers, we: (i) electrodeposited the pH-responsive self-assembling aminopolysaccharide chitosan, (ii) allowed the lectin Concanavalin A (ConA) to bind to the chitosan-coated electrode (presumably through electrostatic interactions), (iii) performed layer-by-layer self-assembly by sequential contacting with glycogen and ConA, and (iv) conferred biological (i.e., enzymatic) function by assembling glycoprotein (i.e., enzymes) to the ConA-terminated multilayer. Because the ConA tetramer dissociates at low pH, this multilayer can be triggered to disassemble by acidification. We demonstrate two approaches to induce acidification: (i) glucose oxidase can induce multilayer disassembly in response to molecular cues, and (ii) anodic reactions can induce multilayer disassembly in response to electrical cues.


Asunto(s)
Sustancias Macromoleculares/química , Quitosano/química , Concanavalina A/química , Electricidad , Electrodos , Glucosa Oxidasa/química , Glucógeno/química , Glicoproteínas/química , Lectinas/química , Electricidad Estática
14.
Proc IEEE Inst Electr Electron Eng ; 107(7): 1402-1424, 2019 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-32095023

RESUMEN

Biology is well-known for its ability to communicate through (i) molecularly-specific signaling modalities and (ii) a globally-acting electrical modality associated with ion flow across biological membranes. Emerging research suggests that biology uses a third type of communication modality associated with a flow of electrons through reduction/oxidation (redox) reactions. This redox signaling modality appears to act globally and has features of both molecular and electrical modalities: since free electrons do not exist in aqueous solution, the electrons must flow through molecular intermediates that can be switched between two states - with electrons (reduced) or without electrons (oxidized). Importantly, this global redox modality is easily accessible through its electrical features using convenient electrochemical instrumentation. In this review, we explain this redox modality, describe our electrochemical measurements, and provide four examples demonstrating that redox enables communication between biology and electronics. The first two examples illustrate how redox probing can acquire biologically relevant information. The last two examples illustrate how redox inputs can transduce biologically-relevant transitions for patterning and the induction of a synbio transceiver for two-hop molecular communication. In summary, we believe redox provides a unique ability to bridge bio-device communication because simple electrochemical methods enable global access to biologically meaningful information. Further, we envision that redox may facilitate the application of information theory to the biological sciences.

15.
J Biol Chem ; 292(33): 13795-13808, 2017 08 18.
Artículo en Inglés | MEDLINE | ID: mdl-28655770

RESUMEN

In the adult brain, programmed death of neural stem cells is considered to be critical for tissue homeostasis and cognitive function and is dysregulated in neurodegeneration. Previously, we have reported that adult rat hippocampal neural (HCN) stem cells undergo autophagic cell death (ACD) following insulin withdrawal. Because the apoptotic capability of the HCN cells was intact, our findings suggested activation of unique molecular mechanisms linking insulin withdrawal to ACD rather than apoptosis. Here, we report that phosphorylation of autophagy-associated protein p62 by AMP-activated protein kinase (AMPK) drives ACD and mitophagy in HCN cells. Pharmacological inhibition of AMPK or genetic ablation of the AMPK α2 subunit by clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 genome editing suppressed ACD, whereas AMPK activation promoted ACD in insulin-deprived HCN cells. We found that following insulin withdrawal AMPK phosphorylated p62 at a novel site, Ser-293/Ser-294 (in rat and human p62, respectively). Phosphorylated p62 translocated to mitochondria and induced mitophagy and ACD. Interestingly, p62 phosphorylation at Ser-293 was not required for staurosporine-induced apoptosis in HCN cells. To the best of our knowledge, this is the first report on the direct phosphorylation of p62 by AMPK. Our data suggest that AMPK-mediated p62 phosphorylation is an ACD-specific signaling event and provide novel mechanistic insight into the molecular mechanisms in ACD.


Asunto(s)
Proteínas Quinasas Activadas por AMP/metabolismo , Autofagia , Hipocampo/metabolismo , Células-Madre Neurales/metabolismo , Procesamiento Proteico-Postraduccional , Proteína Sequestosoma-1/metabolismo , Proteínas Quinasas Activadas por AMP/antagonistas & inhibidores , Proteínas Quinasas Activadas por AMP/química , Proteínas Quinasas Activadas por AMP/genética , Células Madre Adultas/citología , Células Madre Adultas/efectos de los fármacos , Células Madre Adultas/metabolismo , Sustitución de Aminoácidos , Animales , Autofagia/efectos de los fármacos , Proteína 7 Relacionada con la Autofagia/antagonistas & inhibidores , Proteína 7 Relacionada con la Autofagia/genética , Proteína 7 Relacionada con la Autofagia/metabolismo , Supervivencia Celular/efectos de los fármacos , Células Cultivadas , Activación Enzimática/efectos de los fármacos , Eliminación de Gen , Hipocampo/citología , Hipocampo/efectos de los fármacos , Humanos , Proteínas del Tejido Nervioso/antagonistas & inhibidores , Proteínas del Tejido Nervioso/genética , Proteínas del Tejido Nervioso/metabolismo , Células-Madre Neurales/citología , Células-Madre Neurales/efectos de los fármacos , Fosforilación/efectos de los fármacos , Mutación Puntual , Inhibidores de Proteínas Quinasas/farmacología , Procesamiento Proteico-Postraduccional/efectos de los fármacos , Transporte de Proteínas/efectos de los fármacos , Interferencia de ARN , Ratas , Proteínas Recombinantes de Fusión/química , Proteínas Recombinantes de Fusión/metabolismo , Proteína Sequestosoma-1/antagonistas & inhibidores , Proteína Sequestosoma-1/genética
16.
Biomacromolecules ; 19(8): 3502-3514, 2018 08 13.
Artículo en Inglés | MEDLINE | ID: mdl-29928797

RESUMEN

Recent studies showed that melanin-mimetic catechol-chitosan films are redox-active and their ability to exchange electrons confers pro-oxidant activities for the sustained, in situ generation of reactive oxygen species for antimicrobial bandages. Here we electrofabricated catechol-chitosan films, demonstrate these films are redox-active, and show their ability to exchange electrons confers sustained radical scavenging activities that could be useful for protective coatings. Electrofabrication was performed in two steps: cathodic electrodeposition of a chitosan film followed by anodic grafting of catechol to chitosan. Spectroelectrochemical reverse engineering methods were used to characterize the catechol-chitosan films and demonstrate the films are redox-active and can donate electrons to quench oxidative free radicals and can accept electrons to quench reductive free radicals. Electrofabricated catechol-chitosan films that were peeled from the electrode were also shown to be capable of donating electrons to quench an oxidative free radical, but this radical scavenging activity decayed upon depletion of electrons from the film (i.e., as the film became oxidized). However, the radical scavenging activity could be recovered by a regeneration step in which the films were contacted with the biological reducing agent ascorbic acid. These results demonstrate that catecholic materials offer important redox-based and context-dependent properties for possible applications as protective coatings.


Asunto(s)
Materiales Biomiméticos/química , Catecoles/química , Quitosano/química , Depuradores de Radicales Libres/química
17.
Anal Chem ; 89(3): 1583-1592, 2017 02 07.
Artículo en Inglés | MEDLINE | ID: mdl-28035805

RESUMEN

Oxidative stress is implicated in many diseases yet no simple, rapid, and robust measurement is available at the point-of-care to assist clinicians in detecting oxidative stress. Here, we report results from a discovery-based research approach in which a redox mediator is used to probe serum samples for chemical information relevant to oxidative stress. Specifically, we use an iridium salt (K2IrCl6) to probe serum for reducing activities that can transfer electrons to iridium and thus generate detectable optical and electrochemical signals. We show that this Ir-reducing assay can detect various biological reductants and is especially sensitive to glutathione (GSH) compared to alternative assays. We performed an initial clinical evaluation using serum from 10 people diagnosed with schizophrenia, a mental health disorder that is increasingly linked to oxidative stress. The measured Ir-reducing capacity was able to discriminate people with schizophrenia from healthy controls (p < 0.005), and correlations were observed between Ir-reducing capacity and independent measures of symptom severity.


Asunto(s)
Cloruros/química , Iridio/química , Estrés Oxidativo , Área Bajo la Curva , Técnicas Electroquímicas , Glutatión/química , Humanos , Oxidación-Reducción , Curva ROC , Esquizofrenia/diagnóstico , Esquizofrenia/metabolismo , Compuestos de Sulfhidrilo/sangre , Compuestos de Sulfhidrilo/química
18.
Biomacromolecules ; 18(12): 4084-4098, 2017 Dec 11.
Artículo en Inglés | MEDLINE | ID: mdl-29032671

RESUMEN

Melanins are ubiquitous in nature but their biological activities and functions have been difficult to discern. Conventional approaches to determine material function start by resolving structure and then characterize relevant properties. These approaches have been less successful for melanins because of their complex structure and insolubility, and because their relevant properties are not readily characterized by conventional methods. Here, we report a novel spectroelectrochemical reverse engineering approach that focuses on redox and radical scavenging activities. In this method, the melanin is immobilized in a permeable hydrogel film adjacent to an electrode and this immobilized melanin is probed using diffusible mediators and complex electrical inputs. Response characteristics are measured using two modalities, electrochemical currents associated with the reaction of diffusible mediators, and optical absorbance associated with the presence of diffusible free radicals. Using this method, we observed that both Sepia and fungal melanins are redox active and can repeatedly exchange electrons to be switched between oxidized and reduced states. Further, we observed that these melanins can quench radicals either by donating or accepting electrons. Finally, we demonstrate that the melanins' radical scavenging activities are dependent on their redox state such that a melanin must be reduced to have donatable electrons to quench oxidative free radicals, or must be oxidized to accept electrons from reductive free radicals. While the observation that melanin is redox-active is consistent with their well-accepted beneficial (radical-scavenging) and detrimental (pro-oxidant) activities, these observations may also support less well-accepted proposed functions for melanin in energy harvesting and redox communication.


Asunto(s)
Radicales Libres/química , Melaninas/química , Especies Reactivas de Oxígeno/química , Análisis Espectral/métodos , Animales , Hongos/química , Hidrogel de Polietilenoglicol-Dimetacrilato/química , Oxidación-Reducción , Sepia
19.
Electrochem commun ; 79: 33-36, 2017 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-28729810

RESUMEN

We investigate gold, TiN, and platinum in combination with a chitosan-catechol-based redox-cycling system (RCS) for electrochemical detection of the antipsychotic clozapine. We have previously demonstrated the RCS for detection of clozapine in serum, but challenges remain regarding low signal-to-noise ratios. This can be mitigated by selection of electrode materials with beneficial surface morphologies and/or compositions. We employ cyclic voltammetry to assess the redox current generated by clozapine, and differentiate solely surface-area-based effects from clozapine-specific ones using a standard redox couple. We find that nano- and microstructured platinum greatly amplifies the clozapine signal compared to gold (up to 1490-fold for platinum black). However, the material performs poorly in the presence of chloride ions, and RCS modification provides no further amplification. The RCS combined with atomic-layer-deposited (ALD) TiN, on the other hand, increases the signal by 7.54 times, versus 2.86 times for RCS on gold, with a 9.2-fold lower variability, indicating that the homogenous and chemically inert properties of ALD-TiN may make it an ideal electrode material.

20.
J Gerontol Nurs ; 43(2): 55-64, 2017 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-27845807

RESUMEN

Institutionalized older adults are known to be at high risk of malnutrition, but few nutritional interventions have been used for older adults in long-term care (LTC) settings. The purpose of the current study was to investigate the effects of implementing a nutritional intervention involving nursing staff education, facilitation, and a shared algorithm (NIEFA) for institutionalized older adults in Korea. A quasi-experimental pre- and posttest design was used. Patients in two LTC facilities were assigned to an intervention (n = 23) or control (n = 22) group. After completion of the 4-week NIEFA program, significant improvements were found in the intervention group's daily energy intake (t = 3.832, p < 0.001), total lymphocytes (t = 3.87, p < 0.001), hemoglobin levels (t = 4.991, p < 0.001), hematocrit levels (t = 4.305, p < 0.001), and Mini Nutritional Assessment scores (t = 10.223, p < 0.001). Implementation of NIEFA in a LTC facility may be effective in improving the nutritional status of older adults with or at risk of malnutrition. [Journal of Gerontological Nursing, 43(2), 55-64.].


Asunto(s)
Dietética , Casas de Salud , Anciano , Estudios de Casos y Controles , Ingestión de Energía , Femenino , Humanos , Cuidados a Largo Plazo , Masculino , República de Corea
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA