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1.
Cell ; 152(3): 479-91, 2013 Jan 31.
Artigo em Inglês | MEDLINE | ID: mdl-23374344

RESUMO

Fast axonal transport (FAT) requires consistent energy over long distances to fuel the molecular motors that transport vesicles. We demonstrate that glycolysis provides ATP for the FAT of vesicles. Although inhibiting ATP production from mitochondria did not affect vesicles motility, pharmacological or genetic inhibition of the glycolytic enzyme GAPDH reduced transport in cultured neurons and in Drosophila larvae. GAPDH localizes on vesicles via a huntingtin-dependent mechanism and is transported on fast-moving vesicles within axons. Purified motile vesicles showed GAPDH enzymatic activity and produced ATP. Finally, we show that vesicular GAPDH is necessary and sufficient to provide on-board energy for fast vesicular transport. Although detaching GAPDH from vesicles reduced transport, targeting GAPDH to vesicles was sufficient to promote FAT in GAPDH deficient neurons. This specifically localized glycolytic machinery may supply constant energy, independent of mitochondria, for the processive movement of vesicles over long distances in axons.


Assuntos
Transporte Axonal , Drosophila melanogaster/metabolismo , Glicólise , Neurônios/metabolismo , Trifosfato de Adenosina/metabolismo , Animais , Axônios/metabolismo , Encéfalo/citologia , Células Cultivadas , Drosophila melanogaster/crescimento & desenvolvimento , Gliceraldeído-3-Fosfato Desidrogenases/metabolismo , Camundongos , Mitocôndrias/metabolismo , Ratos
2.
Nucleic Acids Res ; 52(7): 4002-4020, 2024 Apr 24.
Artigo em Inglês | MEDLINE | ID: mdl-38321934

RESUMO

Poly(ADP-ribosylation) (PARylation) is a post-translational modification mediated by a subset of ADP-ribosyl transferases (ARTs). Although PARylation-inhibition based therapies are considered as an avenue to combat debilitating diseases such as cancer and myopathies, the role of this modification in physiological processes such as cell differentiation remains unclear. Here, we show that Tankyrase1 (TNKS1), a PARylating ART, plays a major role in myogenesis, a vital process known to drive muscle fiber formation and regeneration. Although all bona fide PARPs are expressed in muscle cells, experiments using siRNA-mediated knockdown or pharmacological inhibition show that TNKS1 is the enzyme responsible of catalyzing PARylation during myogenesis. Via this activity, TNKS1 controls the turnover of mRNAs encoding myogenic regulatory factors such as nucleophosmin (NPM) and myogenin. TNKS1 mediates these effects by targeting RNA-binding proteins such as Human Antigen R (HuR). HuR harbors a conserved TNKS-binding motif (TBM), the mutation of which not only prevents the association of HuR with TNKS1 and its PARylation, but also precludes HuR from regulating the turnover of NPM and myogenin mRNAs as well as from promoting myogenesis. Therefore, our data uncover a new role for TNKS1 as a key modulator of RBP-mediated post-transcriptional events required for vital processes such as myogenesis.


Assuntos
Desenvolvimento Muscular , Fibras Musculares Esqueléticas , Miogenina , RNA Mensageiro , Tanquirases , Tanquirases/metabolismo , Tanquirases/genética , Humanos , RNA Mensageiro/metabolismo , RNA Mensageiro/genética , Desenvolvimento Muscular/genética , Animais , Fibras Musculares Esqueléticas/metabolismo , Camundongos , Miogenina/genética , Miogenina/metabolismo , Nucleofosmina , Proteína Semelhante a ELAV 1/metabolismo , Proteína Semelhante a ELAV 1/genética , Estabilidade de RNA/genética , Poli ADP Ribosilação/genética , Linhagem Celular , Proteínas Nucleares/metabolismo , Proteínas Nucleares/genética , Diferenciação Celular/genética , Proteínas de Ligação a RNA/metabolismo , Proteínas de Ligação a RNA/genética , Células HEK293
3.
Mol Microbiol ; 121(4): 659-670, 2024 04.
Artigo em Inglês | MEDLINE | ID: mdl-38140856

RESUMO

Since its inception in the 1930s, transmission electron microscopy (TEM) has been a powerful method to explore the cellular structure of parasites. TEM usually requires samples of <100 nm thick and with protozoans being larger than 1 µm, their study requires resin embedding and ultrathin sectioning. During the past decade, several new methods have been developed to improve, facilitate, and speed up the structural characterisation of biological samples, offering new imaging modalities for the study of protozoans. In particular, scanning transmission electron microscopy (STEM) can be used to observe sample sections as thick as 1 µm thus becoming an alternative to conventional TEM. STEM can also be performed under cryogenic conditions in combination with cryo-electron tomography providing access to the study of thicker samples in their native hydrated states in 3D. This method, called cryo-scanning transmission electron tomography (cryo-STET), was first developed in 2014. This review presents the basic concepts and benefits of STEM methods and provides examples to illustrate the potential for new insights into the structure and ultrastructure of protozoans.


Assuntos
Tomografia com Microscopia Eletrônica , Microscopia Eletrônica de Transmissão e Varredura/métodos , Tomografia com Microscopia Eletrônica/métodos , Microscopia Crioeletrônica/métodos , Microscopia Eletrônica de Varredura
4.
Nucleic Acids Res ; 51(3): 1375-1392, 2023 02 22.
Artigo em Inglês | MEDLINE | ID: mdl-36629268

RESUMO

mRNA stability is the mechanism by which cells protect transcripts allowing their expression to execute various functions that affect cell metabolism and fate. It is well-established that RNA binding proteins (RBPs) such as HuR use their ability to stabilize mRNA targets to modulate vital processes such as muscle fiber formation (myogenesis). However, the machinery and the mechanisms regulating mRNA stabilization are still elusive. Here, we identified Y-Box binding protein 1 (YB1) as an indispensable HuR binding partner for mRNA stabilization and promotion of myogenesis. Both HuR and YB1 bind to 409 common mRNA targets, 147 of which contain a U-rich consensus motif in their 3' untranslated region (3'UTR) that can also be found in mRNA targets in other cell systems. YB1 and HuR form a heterodimer that associates with the U-rich consensus motif to stabilize key promyogenic mRNAs. The formation of this complex involves a small domain in HuR (227-234) that if mutated prevents HuR from reestablishing myogenesis in siHuR-treated muscle cells. Together our data uncover that YB1 is a key player in HuR-mediated stabilization of pro-myogenic mRNAs and provide the first indication that the mRNA stability mechanism is as complex as other key cellular processes such as mRNA decay and translation.


Assuntos
Proteína Semelhante a ELAV 1 , Fibras Musculares Esqueléticas , Fatores de Transcrição , Regiões 3' não Traduzidas , Proteínas ELAV/genética , Proteínas ELAV/metabolismo , Proteína Semelhante a ELAV 1/metabolismo , Desenvolvimento Muscular , Fibras Musculares Esqueléticas/metabolismo , Estabilidade de RNA , RNA Mensageiro/metabolismo , Linhagem Celular , Animais , Camundongos , Fatores de Transcrição/metabolismo
5.
Proc Natl Acad Sci U S A ; 116(35): 17261-17270, 2019 08 27.
Artigo em Inglês | MEDLINE | ID: mdl-31405989

RESUMO

Debilitating cancer-induced muscle wasting, a syndrome known as cachexia, is lethal. Here we report a posttranscriptional pathway involving the RNA-binding protein HuR as a key player in the onset of this syndrome. Under these conditions, HuR switches its function from a promoter of muscle fiber formation to become an inducer of muscle loss. HuR binds to the STAT3 (signal transducer and activator of transcription 3) mRNA, which encodes one of the main effectors of this condition, promoting its expression both in vitro and in vivo. While HuR does not affect the stability and the cellular movement of this transcript, HuR promotes the translation of the STAT3 mRNA by preventing miR-330 (microRNA 330)-mediated translation inhibition. To achieve this effect, HuR directly binds to a U-rich element in the STAT3 mRNA-3'untranslated region (UTR) located within the vicinity of the miR-330 seed element. Even though the binding sites of HuR and miR-330 do not overlap, the recruitment of either one of them to the STAT3-3'UTR negatively impacts the binding and the function of the other factor. Therefore, together, our data establish the competitive interplay between HuR and miR-330 as a mechanism via which muscle fibers modulate, in part, STAT3 expression to determine their fate in response to promoters of muscle wasting.


Assuntos
Proteína Semelhante a ELAV 1/metabolismo , MicroRNAs/metabolismo , Atrofia Muscular/metabolismo , Proteínas de Neoplasias/metabolismo , Neoplasias Experimentais/metabolismo , Biossíntese de Proteínas , RNA Neoplásico/metabolismo , Fator de Transcrição STAT3/biossíntese , Regiões 3' não Traduzidas , Animais , Proteína Semelhante a ELAV 1/genética , Masculino , Camundongos , Camundongos Knockout , MicroRNAs/genética , Atrofia Muscular/genética , Proteínas de Neoplasias/genética , Neoplasias Experimentais/genética , Neoplasias Experimentais/patologia , RNA Neoplásico/genética , Fator de Transcrição STAT3/genética
6.
J Cell Physiol ; 236(10): 6836-6851, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-33855709

RESUMO

Idiopathic pulmonary fibrosis (IPF) is a disease of progressive scarring caused by excessive extracellular matrix (ECM) deposition and activation of α-SMA-expressing myofibroblasts. Human antigen R (HuR) is an RNA binding protein that promotes protein translation. Upon translocation from the nucleus to the cytoplasm, HuR functions to stabilize messenger RNA (mRNA) to increase protein levels. However, the role of HuR in promoting ECM production, myofibroblast differentiation, and lung fibrosis is unknown. Human lung fibroblasts (HLFs) treated with transforming growth factor ß1 (TGF-ß1) showed a significant increase in translocation of HuR from the nucleus to the cytoplasm. TGF-ß-treated HLFs that were transfected with HuR small interfering RNA had a significant reduction in α-SMA protein as well as the ECM proteins COL1A1, COL3A, and FN1. HuR was also bound to mRNA for ACTA2, COL1A1, COL3A1, and FN. HuR knockdown affected the mRNA stability of ACTA2 but not that of the ECM genes COL1A1, COL3A1, or FN. In mouse models of pulmonary fibrosis, there was higher cytoplasmic HuR in lung structural cells compared to control mice. In human IPF lungs, there was also more cytoplasmic HuR. This study is the first to show that HuR in lung fibroblasts controls their differentiation to myofibroblasts and consequent ECM production. Further research on HuR could assist in establishing the basis for the development of new target therapy for fibrotic diseases, such as IPF.


Assuntos
Transdiferenciação Celular , Proteína Semelhante a ELAV 1/metabolismo , Matriz Extracelular/metabolismo , Fibroblastos/metabolismo , Fibrose Pulmonar Idiopática/metabolismo , Pulmão/metabolismo , Miofibroblastos/metabolismo , Actinas/genética , Actinas/metabolismo , Animais , Transdiferenciação Celular/efeitos dos fármacos , Células Cultivadas , Modelos Animais de Doenças , Proteína Semelhante a ELAV 1/genética , Matriz Extracelular/efeitos dos fármacos , Matriz Extracelular/patologia , Proteínas da Matriz Extracelular/genética , Proteínas da Matriz Extracelular/metabolismo , Fibroblastos/efeitos dos fármacos , Fibroblastos/patologia , Regulação da Expressão Gênica , Humanos , Fibrose Pulmonar Idiopática/genética , Fibrose Pulmonar Idiopática/patologia , Pulmão/efeitos dos fármacos , Pulmão/patologia , Camundongos , Miofibroblastos/patologia , Fator de Crescimento Transformador beta1/farmacologia
7.
Anal Chem ; 93(16): 6508-6515, 2021 04 27.
Artigo em Inglês | MEDLINE | ID: mdl-33861925

RESUMO

Vaccine adjuvants are immunostimulatory substances used to improve and modulate the immune response induced by antigens. A better understanding of the antigen-adjuvant interactions is necessary to develop future effective vaccine. In this study, Taylor dispersion analysis (TDA) was successfully implemented to characterize the interactions between a polymeric adjuvant (poly(acrylic acid), SPA09) and a vaccine antigen in development for the treatment of Staphylococcus aureus. TDA allowed one to rapidly determine both (i) the size of the antigen-adjuvant complexes under physiological conditions and (ii) the percentage of free antigen in the adjuvant/antigen mixture at equilibrium and finally get the interaction parameters (stoichiometry and binding constant). The complex sizes obtained by TDA were compared to the results obtained by transmission electron microscopy, and the binding parameters were compared to results previously obtained by frontal analysis continuous capillary electrophoresis.


Assuntos
Adjuvantes Imunológicos , Antígenos , Vacinas , Eletroforese Capilar
8.
EMBO Rep ; 19(5)2018 05.
Artigo em Inglês | MEDLINE | ID: mdl-29592859

RESUMO

Cellular senescence is a physiological response by which an organism halts the proliferation of potentially harmful and damaged cells. However, the accumulation of senescent cells over time can become deleterious leading to diseases and physiological decline. Our data reveal a novel interplay between senescence and the stress response that affects both the progression of senescence and the behavior of senescent cells. We show that constitutive exposure to stress induces the formation of stress granules (SGs) in proliferative and presenescent cells, but not in fully senescent cells. Stress granule assembly alone is sufficient to decrease the number of senescent cells without affecting the expression of bona fide senescence markers. SG-mediated inhibition of senescence is associated with the recruitment of the plasminogen activator inhibitor-1 (PAI-1), a known promoter of senescence, to these entities. PAI-1 localization to SGs increases the translocation of cyclin D1 to the nucleus, promotes RB phosphorylation, and maintains a proliferative, non-senescent state. Together, our data indicate that SGs may be targets of intervention to modulate senescence in order to impair or prevent its deleterious effects.


Assuntos
Senescência Celular , Grânulos Citoplasmáticos/metabolismo , Inibidor 1 de Ativador de Plasminogênio/metabolismo , Estresse Fisiológico , Linhagem Celular , Núcleo Celular/metabolismo , Ciclina D1/genética , Ciclina D1/metabolismo , Humanos , Fosforilação , Inibidor 1 de Ativador de Plasminogênio/genética
9.
Nucleic Acids Res ; 46(15): 7643-7661, 2018 09 06.
Artigo em Inglês | MEDLINE | ID: mdl-29939290

RESUMO

RNA processing is critical for proper spatial and temporal control of gene expression. The ubiquitous nuclear polyadenosine RNA binding protein, PABPN1, post-transcriptionally regulates multiple steps of gene expression. Mutations in the PABPN1 gene expanding an N-terminal alanine tract in the PABPN1 protein from 10 alanines to 11-18 alanines cause the muscle-specific disease oculopharyngeal muscular dystrophy (OPMD), which affects eyelid, pharynx, and proximal limb muscles. Previous work revealed that the Pabpn1 transcript is unstable, contributing to low steady-state Pabpn1 mRNA and protein levels in vivo, specifically in skeletal muscle, with even lower levels in muscles affected in OPMD. Thus, low levels of PABPN1 protein could predispose specific tissues to pathology in OPMD. However, no studies have defined the mechanisms that regulate Pabpn1 expression. Here, we define multiple cis-regulatory elements and a trans-acting factor, HuR, which regulate Pabpn1 expression specifically in mature muscle in vitro and in vivo. We exploit multiple models including C2C12 myotubes, primary muscle cells, and mice to determine that HuR decreases Pabpn1 expression. Overall, we have uncovered a mechanism in mature muscle that negatively regulates Pabpn1 expression in vitro and in vivo, which could provide insight to future studies investigating therapeutic strategies for OPMD treatment.


Assuntos
Proteína Semelhante a ELAV 1/genética , Regulação da Expressão Gênica , Proteína I de Ligação a Poli(A)/genética , Proteínas de Ligação a RNA/genética , Animais , Linhagem Celular , Modelos Animais de Doenças , Proteína Semelhante a ELAV 1/metabolismo , Células HEK293 , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Fibras Musculares Esqueléticas/citologia , Fibras Musculares Esqueléticas/metabolismo , Músculo Esquelético/metabolismo , Distrofia Muscular Oculofaríngea/genética , Distrofia Muscular Oculofaríngea/metabolismo , Distrofia Muscular Oculofaríngea/patologia , Mutação , Células NIH 3T3 , Proteína I de Ligação a Poli(A)/metabolismo , Proteínas de Ligação a RNA/metabolismo
10.
J Microsc ; 274(1): 23-31, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30649833

RESUMO

Propagation of structural information through conformational changes in host-encoded amyloid proteins is at the root of many neurodegenerative disorders. Although important breakthroughs have been made in the field, fundamental issues like the 3D-structures of the fibrils involved in some of those disorders are still to be elucidated. To better characterise those nanometric fibrils, a broad range of techniques is currently available. Nevertheless none of them is able to perform direct chemical characterisation of single protein fibrils. In this work, we propose to investigate the structure of the C-terminal region of a bacterial protein called Hfq as a model amyloidogenic protein, using a correlative approach. The complementary techniques used are transmission electron microscopy and a newly developed infrared nanospectroscopy technique called AFM-IR. We introduce and discuss the strategy that we have implemented as well as the protocol, challenges and difficulties encountered during this study to characterise amyloid assemblies at the nearly single-molecule level. LAY DESCRIPTION: Propagation of structural information through conformational changes in amyloid proteins is at the root of many neurodegenerative disorders. Amyloids are nanostructures originating from the aggregation of multiple copies of peptide or protein monomers that eventually form fibrils. Often described as being the cause for the development of various diseases, amyloid fibrils are of major significance in the public health domain. While important breakthroughs have been made in the field, fundamental issues like the 3D-structures of the fibrils implied in some of those disorders are still to be elucidated. To better characterise these fibrils, a broad range of techniques is currently available for the detection and visualisation of amyloid nanostructures. Nevertheless none of them is able to perform direct chemical characterisation of single protein fibrils. In this work, we propose to investigate the structure of model amyloidogenic fibrils using a correlative approach. The complementary techniques used are transmission electron microscopy and a newly developed infrared nanospectroscopy technique called AFM-IR that allows chemical characterisation at the nanometric scale. The strategy, protocol, challenges and difficulties encountered in this approach are introduced and discussed herein.


Assuntos
Amiloide , Microscopia Eletrônica de Transmissão/métodos , Nanotecnologia/métodos , Espectroscopia de Infravermelho com Transformada de Fourier/métodos , Amiloide/química , Amiloide/ultraestrutura , Nanoestruturas/química , Nanoestruturas/ultraestrutura , Compostos de Silício
11.
J Struct Biol ; 202(1): 51-60, 2018 04.
Artigo em Inglês | MEDLINE | ID: mdl-29248600

RESUMO

The protist Trypanosoma brucei is an emerging model for the study of cilia and flagella. Here, we used scanning transmission electron microscopy (STEM) tomography to describe the structure of the trypanosome transition zone (TZ). At the base of the TZ, nine transition fibres irradiate from the B microtubule of each doublet towards the membrane. The TZ adopts a 9 + 0 structure throughout its length of ∼300 nm and its lumen contains an electron-dense structure. The proximal portion of the TZ has an invariant length of 150 nm and is characterised by a collarette surrounding the membrane and the presence of electron-dense material between the membrane and the doublets. The distal portion exhibits more length variation (from 55 to 235 nm) and contains typical Y-links. STEM analysis revealed a more complex organisation of the Y-links compared to what was reported by conventional transmission electron microscopy. Observation of the very early phase of flagellum assembly demonstrated that the proximal portion and the collarette are assembled early during construction. The presence of the flagella connector that maintains the tip of the new flagellum to the side of the old was confirmed and additional filamentous structures making contact with the membrane of the flagellar pocket were also detected. The structure and potential functions of the TZ in trypanosomes are discussed, as well as its mode of assembly.


Assuntos
Cílios/ultraestrutura , Tomografia com Microscopia Eletrônica/métodos , Flagelos/ultraestrutura , Trypanosoma brucei brucei/ultraestrutura , Axonema/metabolismo , Axonema/ultraestrutura , Cílios/metabolismo , Flagelos/metabolismo , Microscopia Eletrônica de Transmissão/métodos , Microtúbulos/metabolismo , Microtúbulos/ultraestrutura , Trypanosoma brucei brucei/metabolismo
12.
Ann Rheum Dis ; 77(9): 1283-1289, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-29886430

RESUMO

OBJECTIVE: To define the role of ultrasound (US) for the assessment of patients with rheumatoid arthritis (RA) in clinical remission, including joint and tendon evaluation. METHODS: A multicentre longitudinal study has been promoted by the US Study Group of the Italian Society for Rheumatology. 25 Italian centres participated, enrolling consecutive patients with RA in clinical remission. All patients underwent complete clinical assessment (demographic data, disease characteristics, laboratory exams, clinical assessment of 28 joints and patient/physician-reported outcomes) and Power Doppler (PD) US evaluation of wrist, metacarpalphalangeal joints, proximal interphalangeal joints and synovial tendons of the hands and wrists at enrolment, 6 and 12 months. The association between clinical and US variables with flare, disability and radiographic progression was evaluated by univariable and adjusted logistic regression models. RESULTS: 361 patients were enrolled, the mean age was 56.20 (±13.31) years and 261 were women, with a mean disease duration of 9.75 (±8.07) years. In the 12 months follow-up, 98/326 (30.1%) patients presented a disease flare. The concurrent presence of PD positive tenosynovitis and joint synovitis predicted disease flare, with an OR (95% CI) of 2.75 (1.45 to 5.20) in crude analyses and 2.09 (1.06 to 4.13) in adjusted analyses. US variables did not predict the worsening of function or radiographic progression. US was able to predict flare at 12 months but not at 6 months. CONCLUSIONS: PD positivity in tendons and joints is an independent risk factor of flare in patients with RA in clinical remission. Musculoskeletal ultrasound evaluation is a valuable tool to monitor and help decision making in patients with RA in clinical remission.


Assuntos
Artrite Reumatoide/diagnóstico por imagem , Sinovite/diagnóstico por imagem , Tenossinovite/diagnóstico por imagem , Adulto , Idoso , Artrite Reumatoide/complicações , Artrite Reumatoide/epidemiologia , Feminino , Articulação da Mão/diagnóstico por imagem , Humanos , Itália/epidemiologia , Estudos Longitudinais , Masculino , Pessoa de Meia-Idade , Prognóstico , Recidiva , Indução de Remissão , Fatores de Risco , Índice de Gravidade de Doença , Sinovite/epidemiologia , Sinovite/etiologia , Tenossinovite/epidemiologia , Tenossinovite/etiologia , Ultrassonografia Doppler/métodos , Articulação do Punho/diagnóstico por imagem
13.
Ophthalmic Res ; 59(3): 164-169, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29587271

RESUMO

BACKGROUND: Due to the presence of speckle Poisson noise, the interpretation of spectral domain-optical coherence tomography (SD-OCT) images frequently requires the use of data averaging to improve the signal-to-noise ratio. This implies long acquisition times and requires patient sedation in some cases. Iterative variance stabilizing transformation (VST) is a possible approach by which to remove speckle Poisson noise on single images. METHODS: We used SD-OCT images of human and murine (LH Beta-Tag mouse model) retinas with and without retinoblastoma acquired with 2 different imaging devices (Bioptigen and Micron IV). These images were processed using a denoising workflow implemented in Matlab. RESULTS: We demonstrated the presence of speckle Poisson noise, which can be removed by a VST-based approach. This approach is robust as it works in all used imaging devices and in both human and mouse retinas, independently of the tumor status. The implemented algorithm is freely available from the authors on demand. CONCLUSIONS: On a single denoised image, the proposed method provides results similar to those expected from the SD-OCT averaging. Because of the friendly user interface, it can be easily used by clinicians and researchers in ophthalmology.


Assuntos
Algoritmos , Processamento de Imagem Assistida por Computador , Retina/patologia , Retinoblastoma/patologia , Tomografia de Coerência Óptica/métodos , Animais , Humanos , Camundongos , Neoplasias Experimentais/patologia , Razão Sinal-Ruído
14.
J Synchrotron Radiat ; 23(Pt 3): 783-94, 2016 May.
Artigo em Inglês | MEDLINE | ID: mdl-27140159

RESUMO

A new multi-platform freeware has been developed for the processing and reconstruction of scanning multi-technique X-ray imaging and tomography datasets. The software platform aims to treat different scanning imaging techniques: X-ray fluorescence, phase, absorption and dark field and any of their combinations, thus providing an easy-to-use data processing tool for the X-ray imaging user community. A dedicated data input stream copes with the input and management of large datasets (several hundred GB) collected during a typical multi-technique fast scan at the Nanoscopium beamline and even on a standard PC. To the authors' knowledge, this is the first software tool that aims at treating all of the modalities of scanning multi-technique imaging and tomography experiments.


Assuntos
Software , Processamento de Imagem Assistida por Computador , Radiografia , Síncrotrons , Tomografia Computadorizada por Raios X , Raios X
15.
Rheumatology (Oxford) ; 55(10): 1826-36, 2016 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-27354688

RESUMO

OBJECTIVES: This study aimed to estimate the prevalence of US-detected tenosynovitis in RA patients in clinical remission and to explore its clinical correlates. METHODS: A total of 427 RA patients in clinical remission were consecutively enrolled from 25 Italian rheumatology centres. Tenosynovitis and synovitis were scored by US grey scale (GS) and power Doppler (PD) semi-quantitative scoring systems at wrist and hand joints. Complete clinical assessment was performed by rheumatologists blinded to the US results. A flare questionnaire was used to assess unstable remission (primary outcome), HAQ for functional disability and radiographic erosions for damage (secondary outcomes). Cross-sectional relationships between the presence of each US finding and outcome variables are presented as odds ratios (ORs) and 95% CIs, both crude and adjusted for pre-specified confounders. RESULTS: The prevalence of tenosynovitis in clinical remission was 52.5% (95% CI 0.48, 0.57) for GS and 22.7% (95% CI 0.19, 0.27) for PD, while the prevalence of synovitis was 71.6% (95% CI 0.67, 0.76) for GS and 42% (95% CI 0.37, 0.47) for PD. Among clinical correlates, PD tenosynovitis associated with lower remission duration and morning stiffness while PD synovitis did not. Only PD tenosynovitis showed a significant association with the flare questionnaire [OR 1.95 (95% CI 1.17, 3.26)]. No cross-sectional associations were found with the HAQ. The presence of radiographic erosions associated with GS and PD synovitis but not with tenosynovitis. CONCLUSIONS: US-detected tenosynovitis is a frequent finding in RA patients in clinical remission and associates with unstable remission.


Assuntos
Artrite Reumatoide/diagnóstico por imagem , Tenossinovite/diagnóstico por imagem , Adolescente , Adulto , Distribuição por Idade , Idoso , Artrite Reumatoide/complicações , Artrite Reumatoide/epidemiologia , Estudos Transversais , Feminino , Humanos , Itália/epidemiologia , Masculino , Pessoa de Meia-Idade , Prevalência , Sinovite/complicações , Sinovite/diagnóstico por imagem , Sinovite/epidemiologia , Tenossinovite/complicações , Tenossinovite/epidemiologia , Ultrassonografia Doppler , Adulto Jovem
16.
Nucleic Acids Res ; 42(13): 8678-91, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-25013173

RESUMO

The sequence of events leading to stress granule assembly in stressed cells remains elusive. We show here, using isotope labeling and ion microprobe, that proportionally more RNA than proteins are present in stress granules than in surrounding cytoplasm. We further demonstrate that the delivery of single strand polynucleotides, mRNA and ssDNA, to the cytoplasm can trigger stress granule assembly. On the other hand, increasing the cytoplasmic level of mRNA-binding proteins like YB-1 can directly prevent the aggregation of mRNA by forming isolated mRNPs, as evidenced by atomic force microscopy. Interestingly, we also discovered that enucleated cells do form stress granules, demonstrating that the translocation to the cytoplasm of nuclear prion-like RNA-binding proteins like TIA-1 is dispensable for stress granule assembly. The results lead to an alternative view on stress granule formation based on the following sequence of events: after the massive dissociation of polysomes during stress, mRNA-stabilizing proteins like YB-1 are outnumbered by the burst of nonpolysomal mRNA. mRNA freed of ribosomes thus becomes accessible to mRNA-binding aggregation-prone proteins or misfolded proteins, which induces stress granule formation. Within the frame of this model, the shuttling of nuclear mRNA-stabilizing proteins to the cytoplasm could dissociate stress granules or prevent their assembly.


Assuntos
Grânulos Citoplasmáticos/metabolismo , Polirribossomos/metabolismo , RNA Mensageiro/metabolismo , Proteínas de Ligação a RNA/metabolismo , Estresse Fisiológico , Animais , Células Cultivadas , Citoplasma/química , Grânulos Citoplasmáticos/química , DNA de Cadeia Simples/metabolismo , Proteínas de Choque Térmico HSP70/antagonistas & inibidores , Inibidores de Proteassoma/farmacologia , Multimerização Proteica , Transporte Proteico , Proteínas/análise , Puromicina/farmacologia , RNA/análise , RNA Mensageiro/fisiologia , Ratos
17.
Biomacromolecules ; 16(10): 3265-74, 2015 Oct 12.
Artigo em Inglês | MEDLINE | ID: mdl-26388179

RESUMO

Biocompatible amphiphilic block copolymers composed of polysarcosine (PSar) and poly(ε-caprolactone) (PCL) were synthesized using ring-opening polymerization of sarcosine N-thiocarboxyanhydride initiated by oxyamine-ended PCL and characterized by NMR, SEC, and DSC. Self-assembling of two triblock copolymers PSar8-b-PCL28-b-PSar8 (CS7) and PSar16-b-PCL40-b-PSar16 (CS10) in dilute solution was studied in detail toward polymersome formation using thin-film hydration and nanoprecipitation techniques. A few giant vesicles were obtained by thin-film hydration from both copolymers and visualized by confocal laser scanning microscope. Unilamellar sheets and nanofibers (with 8-10 nm thickness or diameter) were obtained by nanoprecipitation at room temperature and observed by Cryo-TEM. These lamellae and fibrous structures were transformed into worm-like cylinders and spheres (D∼30-100 nm) after heating to 65 °C (>Tm,PCL). Heating CS10 suspensions to 90 °C led eventually to multilamellar polymersomes (D∼100-500 nm). Mechanism II, where micelles expand to vesicles through water diffusion and hydrophilic core forming, was proposed for polymersome formation. A cell viability test confirmed the self-assemblies were not cytotoxic.


Assuntos
Microscopia Crioeletrônica/métodos , Peptídeos/química , Poliésteres/química , Sarcosina/análogos & derivados , Varredura Diferencial de Calorimetria , Polimerização , Sarcosina/química
18.
EMBO J ; 29(9): 1565-72, 2010 May 05.
Artigo em Inglês | MEDLINE | ID: mdl-20339347

RESUMO

Centrosomes are cellular organelles that have a major role in the spatial organisation of the microtubule network. The centrosome is comprised of two centrioles that duplicate only once during the cell cycle, generating a procentriole from each mature centriole. Despite the essential roles of centrosomes, the detailed structural mechanisms involved in centriole duplication remain largely unknown. Here, we describe human procentriole assembly using cryo-electron tomography. In centrosomes, isolated from human lymphoblasts, we observed that each one of the nine microtubule triplets grows independently around a periodic central structure. The proximal end of the A-microtubule is capped by a conical structure and the B- and C-microtubules elongate bidirectionally from its wall. These observations suggest that the gamma tubulin ring complex (gamma-TuRC) has a fundamental role in procentriole formation by nucleating the A-microtubule that acts as a template for B-microtubule elongation that, in turn, supports C-microtubule growth. This study provides new insights into the initial structural events involved in procentriole assembly and establishes the basis for determining the molecular mechanisms of centriole duplication on the nanometric scale.


Assuntos
Centríolos/metabolismo , Centríolos/ultraestrutura , Tomografia com Microscopia Eletrônica , Linhagem Celular , Humanos , Linfócitos/metabolismo , Linfócitos/ultraestrutura , Microtúbulos/metabolismo , Microtúbulos/ultraestrutura , Modelos Biológicos , Tubulina (Proteína)/metabolismo
19.
FASEB J ; 27(10): 4316-26, 2013 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-23839934

RESUMO

Hepatitis B surface antigen (HBsAg) subvirus particles produced from yeast share immunological determinants with mature viruses, which enable the use of HBsAg as a potent antigen for human vaccination. Because the intimate structure of such pseudoviral particles is still a matter of debate, we investigated the robustness of the external barrier and its structure and dynamics using the noninvasive solid-state NMR technique. This barrier is made of 60% proteins and 40% lipids. Phospholipids represent 83% of all lipids, and chain unsaturation is of 72%. Dynamics was reported by embedding small amounts of deuterium chain-labeled unsaturated phospholipid into the external barrier of entire subviral particles, while controlling particle integrity by cryoelectron microscopy, tomography, and light scattering. Variable preparation modes were used, from mild incubation of small unilamellar vesicles to very stringent incorporation with freeze-drying. A lipid bilayer structure of 4- to 5-nm thickness was evidenced with a higher rigidity than that of synthetic phospholipid vesicles, but nonetheless reflecting a fluid membrane (50-52% of maximum rigidity) in agreement with the elevated unsaturation content. The HBsAg particles of 20- to 24-nm diameter were surprisingly found resistant to lyophilization, in such a way that trapped water inside particles could not be removed. These dual properties bring more insight into the mode of action of native subviral particles and their recombinant counterparts used in vaccines.


Assuntos
Membrana Celular , Microscopia Crioeletrônica , Liofilização , Antígenos de Superfície da Hepatite B/metabolismo , Espectroscopia de Ressonância Magnética , Antígenos de Superfície da Hepatite B/genética , Pichia/metabolismo
20.
Tissue Cell ; 88: 102396, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38703582

RESUMO

By using a unique animal model of type 2 diabetes mellitus, Psammomys obesus induced by a high-calorie diet (HCD) for nine months, we showed for the first time, in the liver, the impact of inflammation on the remodeling of intercellular junction molecules E-cadherins during the progression of steatohepatitis. Under the effect of HCD, the expressions of immunohistochemical markers, Tumor Necrosis Factor alpha (TNFα) and E-cadherins were inversely correlated. Ultrastructural examination revealed the involvement of destabilization and loss of E-cadherins in the process of hepatic pathogenesis. This mechanical maintenance stress was favored by the recruitment of immune cells which contributed to the triggering and progression of fibrosis by the enlargement of the intercellular space and the invasion of collagen fibers. Furthermore to escape cell death, loss of E-cadherins played a major role in mediating fibrosis. Psammomys obesus is a promising model for experimental research, enabling the extrapolation of observed structural and functional alterations in humans, the objective to find new therapeutic targets. The physiological resemblance between Psammomys obesus and humans enhances the precision and relevance of biomedical research efforts.


Assuntos
Caderinas , Diabetes Mellitus Tipo 2 , Modelos Animais de Doenças , Gerbillinae , Fígado , Fator de Necrose Tumoral alfa , Animais , Fator de Necrose Tumoral alfa/metabolismo , Diabetes Mellitus Tipo 2/metabolismo , Diabetes Mellitus Tipo 2/patologia , Caderinas/metabolismo , Fígado/metabolismo , Fígado/patologia , Fígado/ultraestrutura , Doenças Metabólicas/patologia , Doenças Metabólicas/metabolismo , Masculino
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