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1.
Opt Express ; 32(2): 1314-1324, 2024 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-38297686

RESUMO

Nitrogen-containing high-energy organic compounds represent a class of materials with critical implications in various fields, including military, aerospace, and chemical industries. The precise characterization and analysis of these compounds are essential for both safety and performance considerations. Spectroscopic characterization in the far-infrared region has great potential for non-destructive investigation of high energetic and related compounds. This research article presents a comprehensive study of common organic energetic materials in the far-infrared region (5-200 cm-1), aiming to enhance security measures through the utilization of cutting-edge spectroscopic techniques. Broadband terahertz time-domain spectroscopy and ultra-low frequency Raman spectroscopy are employed as powerful tools to probe the vibrational and rotational modes of various explosive materials. One of the key objectives of this present work is unveiling the characteristic spectral features and optical parameters of five common nitrogen based high energy organic compounds towards rapid and accurate identification. Further, we have explored the potential of terahertz reflection imaging for non-contact through barrier sensing, a critical requirement in security applications. Based on the spectral features obtained from the spectroscopic studies and using advanced imaging algorithms we have been able to detect these compounds under various barriers including paper, cloth, backpack, etc. Subsequently, this study highlights the capabilities of the two techniques offering a pathway to enhance their utility over a wide range of practical security applications.

2.
Nature ; 556(7701): 376-380, 2018 04.
Artigo em Inglês | MEDLINE | ID: mdl-29643507

RESUMO

Ribosome-associated mRNA quality control mechanisms ensure the fidelity of protein translation1,2. Although these mechanisms have been extensively studied in yeast, little is known about their role in mammalian tissues, despite emerging evidence that stem cell fate is controlled by translational mechanisms3,4. One evolutionarily conserved component of the quality control machinery, Dom34 (in higher eukaryotes known as Pelota (Pelo)), rescues stalled ribosomes 5 . Here we show that Pelo is required for mammalian epidermal homeostasis. Conditional deletion of Pelo in mouse epidermal stem cells that express Lrig1 results in hyperproliferation and abnormal differentiation of these cells. By contrast, deletion of Pelo in Lgr5-expressing stem cells has no effect and deletion in Lgr6-expressing stem cells induces only a mild phenotype. Loss of Pelo results in accumulation of short ribosome footprints and global upregulation of translation, rather than affecting the expression of specific genes. Translational inhibition by rapamycin-mediated downregulation of mTOR (mechanistic target of rapamycin kinase) rescues the epidermal phenotype. Our study reveals that the ribosome-rescue machinery is important for mammalian tissue homeostasis and that it has specific effects on different stem cell populations.


Assuntos
Evolução Biológica , Epiderme/metabolismo , Homeostase , Ribossomos/metabolismo , Células-Tronco/metabolismo , Animais , Proteínas de Ciclo Celular/deficiência , Proteínas de Ciclo Celular/genética , Diferenciação Celular , Proliferação de Células , Progressão da Doença , Endonucleases , Células Epidérmicas , Epiderme/patologia , Feminino , Homeostase/genética , Masculino , Glicoproteínas de Membrana/metabolismo , Camundongos , Proteínas dos Microfilamentos/deficiência , Proteínas dos Microfilamentos/genética , Mutação , Proteínas do Tecido Nervoso/metabolismo , Fenótipo , Biossíntese de Proteínas , RNA Mensageiro/metabolismo , Receptores Acoplados a Proteínas G/metabolismo , Células-Tronco/citologia , Serina-Treonina Quinases TOR/antagonistas & inibidores , Serina-Treonina Quinases TOR/metabolismo
3.
Proc Natl Acad Sci U S A ; 117(36): 22173-22182, 2020 09 08.
Artigo em Inglês | MEDLINE | ID: mdl-32843345

RESUMO

While the lipids of the outer layers of mammalian epidermis and their contribution to barrier formation have been extensively described, the role of individual lipid species in the onset of keratinocyte differentiation remains unknown. A lipidomic analysis of primary human keratinocytes revealed accumulation of numerous lipid species during suspension-induced differentiation. A small interfering RNA screen of 258 lipid-modifying enzymes identified two genes that on knockdown induced epidermal differentiation: ELOVL1, encoding elongation of very long-chain fatty acids protein 1, and SLC27A1, encoding fatty acid transport protein 1. By intersecting lipidomic datasets from suspension-induced differentiation and knockdown keratinocytes, we pinpointed candidate bioactive lipid subspecies as differentiation regulators. Several of these-ceramides and glucosylceramides-induced differentiation when added to primary keratinocytes in culture. Our results reveal the potential of lipid subspecies to regulate exit from the epidermal stem cell compartment.


Assuntos
Diferenciação Celular/fisiologia , Queratinócitos/fisiologia , Células-Tronco/fisiologia , Células Cultivadas , Epiderme , Humanos , Metabolismo dos Lipídeos
4.
Monaldi Arch Chest Dis ; 93(4)2023 Feb 02.
Artigo em Inglês | MEDLINE | ID: mdl-36786163

RESUMO

Serratia marcescens is an aerobic, Gram-negative bacillus predominantly seen in patients with intravenous drug use, immunosuppression, previous antibiotic exposure, and indwelling catheterization. Gram-negative organism causing infective endocarditis (IE) is rare. Serratia marcescens IE is uncommon and is reported to be seen in 0.14% of all cases. In this report, we discuss in detail about a 38-year-old man with a history of intravenous drug abuse presenting with S. marcescens related prosthetic valve IE.


Assuntos
Endocardite Bacteriana , Serratia , Adulto , Humanos , Masculino , Antibacterianos , Endocardite Bacteriana/diagnóstico , Endocardite Bacteriana/tratamento farmacológico , Serratia marcescens
5.
Ann Hematol ; 101(9): 2107-2110, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-35723711

RESUMO

Methemoglobin is a form of hemoglobin that has been oxidized, changing its heme iron configuration from the ferrous to the ferric state. Unlike normal hemoglobin, methemoglobin does not bind oxygen and as a result, cannot deliver oxygen to the tissues. At the presentation in the emergency department, an electrocardiogram (EKG) is usually performed as a reflex for patients admitted for shortness of breath to rule out acute coronary syndrome. Very limited data is available on EKG abnormalities in patients with methemoglobinemia. In this study, we retrospectively analyzed the pattern of EKG changes in patients with methemoglobinemia.


Assuntos
Metemoglobinemia , Eletrocardiografia , Humanos , Metemoglobina , Metemoglobinemia/diagnóstico , Oxigênio , Estudos Retrospectivos
6.
Genomics ; 113(4): 2350-2364, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-34051324

RESUMO

Long non-coding RNAs (lncRNAs) are a highly heterogeneous class of non-protein-encoding transcripts that play an essential regulatory role in diverse biological processes, including stress responses. The severe stunting disease caused by Citrus bark cracking viroid (CBCVd) poses a major threat to the production of Humulus lupulus (hop) plants. In this study, we systematically investigate the characteristics of the lncRNAs in hop and their role in CBCVd-infection using RNA-sequencing data. Following a stringent filtration criterion, a total of 3598 putative lncRNAs were identified with a high degree of certainty, of which 19% (684) of the lncRNAs were significantly differentially expressed (DE) in CBCVd-infected hop, which were predicted to be mainly involved in plant-pathogen interactions, kinase cascades, secondary metabolism and phytohormone signal transduction. Besides, several lncRNAs and CBCVd-responsive lncRNAs were identified as the precursor of microRNAs and predicted as endogenous target mimics (eTMs) for hop microRNAs involved in CBCVd-infection.


Assuntos
Citrus , Humulus , RNA Longo não Codificante , Viroides , Citrus/genética , Perfilação da Expressão Gênica , Humulus/genética , Casca de Planta , Doenças das Plantas/genética , RNA Longo não Codificante/genética , Viroides/genética
7.
Int J Mol Sci ; 23(2)2022 Jan 14.
Artigo em Inglês | MEDLINE | ID: mdl-35055083

RESUMO

Verticillium nonalfalfae (V. nonalfalfae) is one of the most problematic hop (Humulus lupulus L.) pathogens, as the highly virulent fungal pathotypes cause severe annual yield losses due to infections of entire hop fields. In recent years, the RNA interference (RNAi) mechanism has become one of the main areas of focus in plant-fungal pathogen interaction studies and has been implicated as one of the major contributors to fungal pathogenicity. MicroRNA-like RNAs (milRNAs) have been identified in several important plant pathogenic fungi; however, to date, no milRNA has been reported in the V. nonalfalfae species. In the present study, using a high-throughput sequencing approach and extensive bioinformatics analysis, a total of 156 milRNA precursors were identified in the annotated V. nonalfalfae genome, and 27 of these milRNA precursors were selected as true milRNA candidates, with appropriate microRNA hairpin secondary structures. The stem-loop RT-qPCR assay was used for milRNA validation; a total of nine V. nonalfalfae milRNAs were detected, and their expression was confirmed. The milRNA expression patterns, determined by the absolute quantification approach, imply that milRNAs play an important role in the pathogenicity of highly virulent V. nonalfalfae pathotypes. Computational analysis predicted milRNA targets in the V. nonalfalfae genome and in the host hop transcriptome, and the activity of milRNA-mediated RNAi target cleavage was subsequently confirmed for two selected endogenous fungal target gene models using the 5' RLM-RACE approach.


Assuntos
Ascomicetos/genética , Sequenciamento de Nucleotídeos em Larga Escala , MicroRNAs/genética , RNA Fúngico , Pequeno RNA não Traduzido/genética , Biologia Computacional/métodos , Perfilação da Expressão Gênica , Regulação Fúngica da Expressão Gênica , Ontologia Genética , Interações Hospedeiro-Patógeno , Conformação de Ácido Nucleico , Filogenia , Doenças das Plantas/microbiologia , Reação em Cadeia da Polimerase em Tempo Real , Reprodutibilidade dos Testes
8.
Int J Mol Sci ; 23(15)2022 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-35955640

RESUMO

The mimosoid legumes are a clade of ~40 genera in the Caesalpinioideae subfamily of the Fabaceae that grow in tropical and subtropical regions. Unlike the better studied Papilionoideae, there are few genomic resources within this legume group. The tree Prosopis cineraria is native to the Near East and Indian subcontinent, where it thrives in very hot desert environments. To develop a tool to better understand desert plant adaptation mechanisms, we sequenced the P. cineraria genome to near-chromosomal assembly, with a total sequence length of ~691 Mb. We predicted 77,579 gene models (76,554 CDS, 361 rRNAs and 664 tRNAs) from the assembled genome, among them 55,325 (~72%) protein-coding genes that were functionally annotated. This genome was found to consist of over 58% repeat sequences, primarily long terminal repeats (LTR-)-retrotransposons. We find an expansion of terpenoid metabolism genes in P. cineraria and its relative Prosopis alba, but not in other legumes. We also observed an amplification of NBS-LRR disease-resistance genes correlated with LTR-associated retrotransposition, and identified 410 retrogenes with an active burst of chimeric retrogene creation that approximately occurred at the same time of divergence of P. cineraria from a common lineage with P. alba~23 Mya. These retrogenes include many biotic defense responses and abiotic stress stimulus responses, as well as the early Nodulin 93 gene. Nodulin 93 gene amplification is consistent with an adaptive response of the species to the low nitrogen in arid desert soil. Consistent with these results, our differentially expressed genes show a tissue specific expression of isoprenoid pathways in shoots, but not in roots, as well as important genes involved in abiotic salt stress in both tissues. Overall, the genome sequence of P. cineraria enriches our understanding of the genomic mechanisms of its disease resistance and abiotic stress tolerance. Thus, it is a very important step in crop and legume improvement.


Assuntos
Fabaceae , Prosopis , Resistência à Doença/genética , Fabaceae/genética , Genes de Plantas , Genoma de Planta , Prosopis/genética , Árvores/genética
9.
Monaldi Arch Chest Dis ; 93(3)2022 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-36226557

RESUMO

Takotsubo cardiomyopathy (TTC) is a non-ischemic cardiomyopathy precipitated by stress. Various infections are reported to precipitate this form of cardiomyopathy. We report a patient presenting with TTC secondary to influenza.  In this article, we also discuss the various infections reported to precipitate this form of reversible cardiomyopathy in literature. We have also included the recent reports of TTC among patients with COVID-19.


Assuntos
COVID-19 , Cardiomiopatia de Takotsubo , Humanos , Cardiomiopatia de Takotsubo/etiologia , Cardiomiopatia de Takotsubo/complicações , COVID-19/complicações
10.
Monaldi Arch Chest Dis ; 93(2)2022 Sep 05.
Artigo em Inglês | MEDLINE | ID: mdl-36063088

RESUMO

Coronavirus disease (COVID-19) can cause circulatory shock refractory to medical therapy. Such patients can be managed with mechanical circulatory support (MCS) devices like IABP, Impella, VA ECMO, and Left Ventricular Assist Devices (LVADs). Moreover, patients on long-term durable LVADs are a special population having increased susceptibility and mortality to COVID-19 infection. In this narrative review, we searched PubMed and Medline for studies on COVID-19 patients on short-term MCS devices. We found 36 papers with 110 patients who met our review criteria, including 89 LVAD patients and 21 COVID-19 patients who needed MCS device therapy. These studies were used to extract patient demographics, clinical presentation, MCS device details, management, and outcomes. Mean age of patients with COVID-19 infection on LVADs was 60, 73% were male, and HeartMate 3 was the most common device (53%). Most patients (77.5%) needed hospitalization, and mortality was 23.6%. Among the 21 reported cases of critically ill COVID-19 patients who required MCS, the mean age was 49.8 years, 52% were women, and the most common MCS device used was VA ECMO (62%) in conjunction with an Impella for LV venting. Comorbidities were not present in 43%, but 71% had abnormal ventricular function on echocardiography. MCS is a viable option for managing severe COVID-19 infection with shock, with many reported cases of favorable outcomes.


Assuntos
COVID-19 , Coração Auxiliar , Humanos , Masculino , Feminino , Pessoa de Meia-Idade , Coração Auxiliar/efeitos adversos , Mortalidade Hospitalar , Hospitalização , Estudos Retrospectivos , Resultado do Tratamento
11.
J Biol Chem ; 295(30): 10138-10152, 2020 07 24.
Artigo em Inglês | MEDLINE | ID: mdl-32385113

RESUMO

Mitochondrial dysfunction has long been implicated in the neurodegenerative disorder Parkinson's disease (PD); however, it is unclear how mitochondrial impairment and α-synuclein pathology are coupled. Using specific mitochondrial inhibitors, EM analysis, and biochemical assays, we report here that intramitochondrial protein homeostasis plays a major role in α-synuclein aggregation. We found that interference with intramitochondrial proteases, such as HtrA2 and Lon protease, and mitochondrial protein import significantly aggravates α-synuclein seeding. In contrast, direct inhibition of mitochondrial complex I, an increase in intracellular calcium concentration, or formation of reactive oxygen species, all of which have been associated with mitochondrial stress, did not affect α-synuclein pathology. We further demonstrate that similar mechanisms are involved in amyloid-ß 1-42 (Aß42) aggregation. Our results suggest that, in addition to other protein quality control pathways, such as the ubiquitin-proteasome system, mitochondria per se can influence protein homeostasis of cytosolic aggregation-prone proteins. We propose that approaches that seek to maintain mitochondrial fitness, rather than target downstream mitochondrial dysfunction, may aid in the search for therapeutic strategies to manage PD and related neuropathologies.


Assuntos
Peptídeos beta-Amiloides/metabolismo , Mitocôndrias/metabolismo , Doença de Parkinson/metabolismo , Fragmentos de Peptídeos/metabolismo , Proteostase , alfa-Sinucleína/metabolismo , Peptídeos beta-Amiloides/genética , Animais , Linhagem Celular Tumoral , Feminino , Serina Peptidase 2 de Requerimento de Alta Temperatura A/genética , Serina Peptidase 2 de Requerimento de Alta Temperatura A/metabolismo , Humanos , Mitocôndrias/genética , Mitocôndrias/patologia , Proteínas do Tecido Nervoso/genética , Proteínas do Tecido Nervoso/metabolismo , Doença de Parkinson/genética , Doença de Parkinson/patologia , Fragmentos de Peptídeos/genética , Ratos , Ratos Sprague-Dawley , Fatores de Processamento de Serina-Arginina/genética , Fatores de Processamento de Serina-Arginina/metabolismo , alfa-Sinucleína/genética
12.
Physiol Plant ; 173(4): 1481-1494, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33963568

RESUMO

Salt stress disturbs the cellular osmotic and ionic balance, which then creates a negative impact on plant growth and development. The Na+ and Cl- ions can enter into plant cells through various membrane transporters, including specific and non-specific Na+ , K+ , and Ca2+ transporters. Therefore, it is important to understand Na+ and K+ transport mechanisms in plants along with the isolation of genes, their characterization, the structural features, and their post-translation regulation under salt stress. This review summarizes the molecular insights of plant ion transporters, including non-selective cation transporters, cyclic nucleotide-gated cation transporters, glutamate-like receptors, membrane intrinsic proteins, cation proton antiporters, and sodium proton antiporter families. Further, we discussed the K+ transporter families such as high-affinity K+ transporters, HAK/KUP/KT transporters, shaker type K+ transporters, and K+ efflux antiporters. Besides the ion transport process, we have shed light on available literature on epigenetic regulation of transport processes under salt stress. Recent advancements of salt stress sensing mechanisms and various salt sensors within signaling transduction pathways are discussed. Further, we have compiled salt-stress signaling pathways, and their crosstalk with phytohormones.


Assuntos
Proteínas de Transporte de Cátions , Regulação da Expressão Gênica de Plantas , Plantas , Estresse Salino , Proteínas de Transporte de Cátions/genética , Epigênese Genética , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Potássio/metabolismo
13.
Chaos ; 31(9): 093136, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34598461

RESUMO

We study the propagation of rare or extreme events in a network of coupled nonlinear oscillators, where counter-rotating oscillators play the role of the malfunctioning agents. The extreme events originate from the coupled counter-oscillating pair of oscillators through a mechanism of saddle-node bifurcation. A detailed study of the propagation and the destruction of the extreme events and how these events depend on the strength of the coupling is presented. Extreme events travel only when nearby oscillators are in synchronization. The emergence of extreme events and their propagation are observed in a number of excitable systems for different network sizes and for different topologies.

14.
Monaldi Arch Chest Dis ; 91(3)2021 Mar 23.
Artigo em Inglês | MEDLINE | ID: mdl-33759445

RESUMO

Although the most frequent presentation of the novel Coronavirus disease-2019 (COVID-19) is a respiratory syndrome, cardiac involvement is being increasingly recognized. One such entity is takotsubo cardiomyopathy. We sought to review the various cases of takotsubo cardiomyopathy reported during the COVID-19 pandemic and consolidate the information available on its clinical features, evaluation and treatment. We performed a PubMed search using the MeSH terms "Takotsubo Cardiomyopathy" or "Stress Cardiomyopathy" and "COVID-19", and identified 16 case reports, two case series, and one retrospective cohort study. There was a total of 24 reported patients with COVID-19 infection, who developed takotsubo cardiomyopathy, and two patients without COVID-19 who developed takotsubo cardiomyopathy due to the emotional stress associated with the global pandemic. The mean age of the patients was 67.19 years (SD 15.83) and 16(59.3%) were women. Chest pain was reported in only ten patients (38.46 %) and ST-elevation was seen in 11 patients (42.3%). While most patients had typical takotsubo cardiomyopathy, four patients had inverted(reverse) takotsubo cardiomyopathy, two had bi-ventricular involvement, one had median takotsubo and another had global takotsubo with apical sparing variant. Most patients had a positive outcome with complete or near-complete reversal of cardiac dysfunction at the time of discharge. Five deaths (19.23%) were reported. Takotsubo cardiomyopathy is a rare, but increasingly reported reversible cardiomyopathy that can be seen in patients with COVID-19 infection and the diagnosis must be actively sought for in these patients.


Assuntos
COVID-19 , Cardiomiopatia de Takotsubo , Idoso , Ecocardiografia , Feminino , Humanos , Pandemias , Estudos Retrospectivos , SARS-CoV-2 , Cardiomiopatia de Takotsubo/diagnóstico , Cardiomiopatia de Takotsubo/epidemiologia , Cardiomiopatia de Takotsubo/etiologia
15.
Monaldi Arch Chest Dis ; 91(2)2021 Apr 16.
Artigo em Inglês | MEDLINE | ID: mdl-33926176

RESUMO

COVID-19 has involved numerous countries across the globe and the disease burden, susceptible age group; mortality rate has been variable depending on the demographical profile, economic status, and health care infrastructure. In the current clinical environment, COVID-19 is one of the most important clinical differential diagnoses in patients presenting with respiratory symptoms. The optimal mechanical ventilation strategy for these patients has been a constant topic of discussion and very importantly so, since a great majority of these patients require invasive mechanical ventilation and often for an extended period of time. In this report we highlight our experience with a COVID-19 patient who most likely suffered barotrauma either as a result of traumatic endotracheal intubation or primarily due to COVID-19 itself. We also aim to highlight the current literature available to suggest the management strategy for these patients for a favorable outcome. The cases described are diverse in terms of age variance and other comorbidities. According to the literature, certain patients, with COVID-19 disease and spontaneous pneumothorax were noted to be managed conservatively and oxygen supplementation with nasal cannula sufficed. Decision regarding need and escalation to invasive mechanical ventilation should be taken early in the disease to avoid complications such as patient self-inflicted lung injury (P-SILI) and barotrauma sequelae such as pneumothorax and pneumomediastinum Recent systematic review further supports the fact that the use of non-invasive ventilation (NIV) in certain patients with COVID-19 pneumonia may give a false sense of security and clinical stabilization but has no overall benefit to avoid intubation. While invasive mechanical ventilation may be associated with higher rates of barotrauma, this should not mean that intubation and invasive mechanical ventilation should be delayed. This becomes an important consideration when non-intensivists or personnel with less experience provide care for this vulnerable patient population who may rely too heavily on NIV to avoid intubation and mechanical ventilation.


Assuntos
COVID-19/complicações , COVID-19/terapia , Enfisema Mediastínico/diagnóstico , Pneumotórax/diagnóstico , Idoso , COVID-19/diagnóstico , Humanos , Intubação Intratraqueal/efeitos adversos , Enfisema Mediastínico/etiologia , Enfisema Mediastínico/terapia , Pneumotórax/etiologia , Pneumotórax/terapia , Respiração Artificial/efeitos adversos
17.
Monaldi Arch Chest Dis ; 91(3)2021 May 17.
Artigo em Inglês | MEDLINE | ID: mdl-34006041

RESUMO

Austrian syndrome occurs in 1.2% of all patients with pneumococcal infective endocarditis. It presents with the triad of meningitis, pneumonia, and endocarditis. It is commonly seen in elderly males with a history of alcohol abuse, an immunocompromised state, or recent valve surgery. We present a case of Austrian syndrome presenting with paravalvular complications in the form of aortic root fistula. In this report, we describe the second patient with the community-acquired, pneumococcal, native, aortic valve, endocarditis with Austrian syndrome complicated by the development of an aortic fistula.


Assuntos
Endocardite Bacteriana , Fístula , Meningite Pneumocócica , Pneumonia Pneumocócica , Idoso , Valva Aórtica/diagnóstico por imagem , Valva Aórtica/cirurgia , Áustria , Endocardite Bacteriana/complicações , Endocardite Bacteriana/diagnóstico , Humanos , Masculino
18.
Monaldi Arch Chest Dis ; 91(1)2021 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-33567816

RESUMO

Esophageal perforation is a fatal entity if not diagnosed in a timely fashion. Once diagnosed, it requires collaborative effort of team of doctors including radiologists, thoracic surgeons and general surgeons. We share hereby our experience with esophageal perforation and successful outcome.


Assuntos
Perfuração Esofágica , Perfuração Esofágica/diagnóstico por imagem , Perfuração Esofágica/etiologia , Humanos
19.
J Biol Chem ; 294(5): 1478-1487, 2019 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-30504224

RESUMO

The 42-amino-acid ß-amyloid (Aß42) is a critical causative agent in the pathology of Alzheimer's disease. The hereditary Arctic mutation of Aß42 (E22G) leads to increased intracellular accumulation of ß-amyloid in early-onset Alzheimer's disease. However, it remains largely unknown how the Arctic mutant variant leads to aggressive protein aggregation and increased intracellular toxicity. Here, we constructed stable cell lines expressing fluorescent-tagged wildtype (WT) and E22G Aß42 to study the aggregation kinetics of the Arctic Aß42 mutant peptide and its heterogeneous structural forms. Arctic-mutant peptides assemble and form fibrils at a much faster rate than WT peptides. We identified five categories of intracellular aggregate-oligomers, single fibrils, fibril bundles, clusters, and aggresomes-that underline the heterogeneity of these Aß42 aggregates and represent the progression of Aß42 aggregation within the cell. Fluorescence-lifetime imaging (FLIM) and 3D structural illumination microscopy (SIM) showed that all aggregate species displayed highly compact structures with strong affinity between individual fibrils. We also found that aggregates formed by Arctic mutant Aß42 were more resistant to intracellular degradation than their WT counterparts. Our findings uncover the structural basis of the progression of Arctic mutant Aß42 aggregation in the cell.


Assuntos
Peptídeos beta-Amiloides/química , Microscopia Confocal/métodos , Microscopia de Fluorescência/métodos , Mutação , Imagem Óptica/métodos , Multimerização Proteica , Peptídeos beta-Amiloides/genética , Peptídeos beta-Amiloides/ultraestrutura , Humanos , Cinética , Modelos Moleculares , Conformação Proteica
20.
J Am Chem Soc ; 142(14): 6661-6674, 2020 04 08.
Artigo em Inglês | MEDLINE | ID: mdl-32182066

RESUMO

Mitochondria play a key role in oncogenesis and constitute one of the most important targets for cancer treatments. Although the most effective way to deliver drugs to mitochondria is by covalently linking them to a lipophilic cation, the in vivo delivery of free drugs still constitutes a critical bottleneck. Herein, we report the design of a mitochondria-targeted metal-organic framework (MOF) that greatly increases the efficacy of a model cancer drug, reducing the required dose to less than 1% compared to the free drug and ca. 10% compared to the nontargeted MOF. The performance of the system is evaluated using a holistic approach ranging from microscopy to transcriptomics. Super-resolution microscopy of MCF-7 cells treated with the targeted MOF system reveals important mitochondrial morphology changes that are clearly associated with cell death as soon as 30 min after incubation. Whole transcriptome analysis of cells indicates widespread changes in gene expression when treated with the MOF system, specifically in biological processes that have a profound effect on cell physiology and that are related to cell death. We show how targeting MOFs toward mitochondria represents a valuable strategy for the development of new drug delivery systems.


Assuntos
Sistemas de Liberação de Medicamentos/métodos , Estruturas Metalorgânicas/metabolismo , Mitocôndrias/metabolismo , Humanos
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