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2.
Glia ; 71(1): 91-102, 2023 01.
Artigo em Inglês | MEDLINE | ID: mdl-35411970

RESUMO

In the central nervous system, oligodendrocytes synthesize the myelin, a specialized membrane to wrap axons in a discontinuous way allowing a rapid saltatory nerve impulse conduction. Oligodendrocytes express a number of growth factors and neurotransmitters receptors that allow them to sense the environment and interact with neurons and other glial cells. Depending on the cell cycle stage, oligodendrocytes may respond to these signals by regulating their survival, proliferation, migration, and differentiation. Among these signals are the endocannabinoids, lipidic molecules synthesized from phospholipids in the plasma membrane in response to cell activation. Here, we discuss the evidence showing that oligodendrocytes express a full endocannabinoid signaling machinery involved in physiological oligodendrocyte functions that can be therapeutically exploited to promote remyelination in central nervous system pathologies.


Assuntos
Endocanabinoides , Oligodendroglia , Endocanabinoides/metabolismo , Oligodendroglia/metabolismo , Bainha de Mielina/metabolismo , Axônios/metabolismo , Sistema Nervoso Central/metabolismo , Diferenciação Celular/fisiologia
3.
Mol Med ; 28(1): 40, 2022 04 09.
Artigo em Inglês | MEDLINE | ID: mdl-35397534

RESUMO

BACKGROUND: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has already caused 6 million deaths worldwide. While asymptomatic individuals are responsible of many potential transmissions, the difficulty to identify and isolate them at the high peak of infection constitutes still a real challenge. Moreover, SARS-CoV-2 provokes severe vascular damage and thromboembolic events in critical COVID-19 patients, deriving in many related deaths and long-hauler symptoms. Understanding how these processes are triggered as well as the potential long-term sequelae, even in asymptomatic individuals, becomes essential. METHODS: We have evaluated, by application of a proteomics-based quantitative approach, the effect of serum from COVID-19 asymptomatic individuals over circulating angiogenic cells (CACs). Healthy CACs were incubated ex-vivo with the serum of either COVID-19 negative (PCR -/IgG -, n:8) or COVID-19 positive asymptomatic donors, at different infective stages: PCR +/IgG - (n:8) and PCR -/IgG + (n:8). Also, a label free quantitative approach was applied to identify and quantify protein differences between these serums. Finally, machine learning algorithms were applied to validate the differential protein patterns in CACs. RESULTS: Our results confirmed that SARS-CoV-2 promotes changes at the protein level in the serum of infected asymptomatic individuals, mainly correlated with altered coagulation and inflammatory processes (Fibrinogen, Von Willebrand Factor, Thrombospondin-1). At the cellular level, proteins like ICAM-1, TLR2 or Ezrin/Radixin were only up-regulated in CACs treated with the serum of asymptomatic patients at the highest peak of infection (PCR + /IgG -), but not with the serum of PCR -/IgG + individuals. Several proteins stood out as significantly discriminating markers in CACs in response to PCR or IgG + serums. Many of these proteins particiArticle title: Kindly check and confirm the edit made in the article title.pate in the initial endothelial response against the virus. CONCLUSIONS: The ex vivo incubation of CACs with the serum of asymptomatic COVID-19 donors at different stages of infection promoted protein changes representative of the endothelial dysfunction and inflammatory response after viral infection, together with activation of the coagulation process. The current approach constitutes an optimal model to study the response of vascular cells to SARS-CoV-2 infection, and an alternative platform to test potential inhibitors targeting either the virus entry pathway or the immune responses following SARS-CoV-2 infection.


Assuntos
COVID-19 , Humanos , Imunoglobulina G , Técnicas de Amplificação de Ácido Nucleico , SARS-CoV-2
4.
J Strength Cond Res ; 36(7): 1936-1943, 2022 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-32740285

RESUMO

ABSTRACT: Neto, FR, Dorneles, JR, Luna, RM, Spina, MA, Gonçalves, CW, and Gomes Costa, RR. Performance differences between the arched and flat bench press in beginner and experienced Paralympic powerlifters. J Strength Cond Res 36(7): 1936-1943, 2022-The present study aimed to verify the differences of the total load, trajectory of the barbell in the sagittal plane, and mean velocity of the barbell between the arched and flat techniques of the bench press in beginner (BG) and experienced (EG) Paralympic powerlifters. Twenty beginners (age: 34.4 years; experience: 3.3 months) and 23 experienced (age: 35.5 years; experience: 9.8 months) Paralympic powerlifters were selected from a Rehabilitation Hospital Network and a Paralympic sports center. Subjects were assessed in the one-maximum repetition test of the bench press exercise using the flat and arched bench press techniques (48-72-hour interval between sessions). Maximum strength, trajectory of the barbell in the sagittal plane, and mean velocity of the barbell were measured to compare the techniques and the groups. The total load corrected with the Haleczko formula was significantly higher in EG compared with BG (∆ = 21.1%; effect sizes [ES] = 0.39, p ≤ 0.05). There were no significant differences for all analyzed outcomes comparing the arched and flat techniques. During the eccentric phase of the bench press, all assessed differences ranged from -16.6 to 23.1% and presented ES of trivial to moderate. On the concentric phase, the assessed differences ranged from -20.7 to 13.9% and presented ES of trivial to moderate. The total load, trajectory of the barbell in the sagittal plane, and mean velocity of the barbell were not significantly different between the arched and flat techniques for experienced and beginner powerlifting athletes during both the eccentric and concentric phase of the movement. However, further analyses are essential to determine the best technique for athletes.


Assuntos
Treinamento Resistido , Levantamento de Peso , Adulto , Terapia por Exercício , Humanos , Movimento , Força Muscular , Treinamento Resistido/métodos
5.
J Neurochem ; 158(3): 640-656, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-33942314

RESUMO

CB1 cannabinoid receptor is widely expressed in the central nervous system of animals from late prenatal development to adulthood. Appropriate activation and signaling of CB1 cannabinoid receptors in cortical interneurons are crucial during perinatal/postnatal ages and adolescence, when long-lasting changes in brain activity may elicit subsequent appearance of disorders in the adult brain. Here we used an optimized immunoprecipitation protocol based on specific antibodies followed by shot-gun proteomics to find CB1 interacting partners in postnatal rat GABAergic cortical neurons in vitro at two different stages of maturation. Besides describing new proteins associated with CB1 like dihydrolipoyllysine-residue acetyltransferase component of pyruvate dehydrogenase complex (DLAT), fatty acid synthase (FASN), tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein zeta (YWHAZ), voltage-dependent anion channel 1 (VDAC1), myosin phosphatase Rho-interacting protein (MPRIP) or usher syndrome type-1C protein-binding protein 1 (USHBP1), we show that the signaling complex of CB1 is different between maturational stages. Interestingly, the CB1 signaling complex is enriched at the more immature stage in mitochondrial associated proteins and metabolic molecular functions, whereas at more mature stage, CB1 complex is increased in maturation and synaptic-associated proteins. We describe also interacting partners specifically immunoprecipitated with either N-terminal or C-terminal CB1 directed antibodies. Our results highlight new players that may be affected by altered cannabinoid signaling at this critical window of postnatal cortical development.


Assuntos
Córtex Cerebral/embriologia , Córtex Cerebral/metabolismo , Neurônios GABAérgicos/fisiologia , Receptor CB1 de Canabinoide/genética , Receptor CB1 de Canabinoide/metabolismo , Animais , Células Cultivadas , Feminino , Gravidez , Ratos , Ratos Wistar , Transdução de Sinais/fisiologia
7.
Appl Opt ; 60(17): 5153-5160, 2021 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-34143087

RESUMO

We present a method for calibration and data extraction for a Stokes polarimeter working with three different wavelengths simultaneously. In the Stokes polarimeter considered in this work, we use two liquid crystal variable retarders (LCVRs) combined with a Glan-Thompson linear polarizer. A recently developed fitting calibration procedure is used. We use the same calibration samples and LCVR voltages for all three wavelengths, giving simultaneous measurement and calibration. We compare the performance of the polarimeter, after calibration, using four or six calibration samples in our experiment. To generate the four known calibration beams, we use a linear polarizer oriented at 130° and 30° with respect to the horizontal, a horizontal linear polarizer followed by a half-wave plate (at 632 nm) with its fast axis at 30°, and a horizontal linear polarizer followed by a quarter-wave plate (at 632 nm) with its fast axis at 30°. For calibration with six reference beams, we add two known calibration beams by setting the fast axis of the half- and quarter-wave plates at 130°. Experimental results show good agreement with the expected results, with the fitting calibration procedure giving an approximately 50% reduction in total RMS error with four calibration samples. There is a negligible reduction in the error when six calibration samples are used compared to the case with four samples.

8.
Int J Mol Sci ; 21(15)2020 Jul 24.
Artigo em Inglês | MEDLINE | ID: mdl-32722151

RESUMO

In atherosclerosis, circulating angiogenic cells (CAC), also known as early endothelial progenitor cells (eEPC), are thought to participate mainly in a paracrine fashion by promoting the recruitment of other cell populations such as late EPC, or endothelial colony-forming cells (ECFC), to the injured areas. There, ECFC replace the damaged endothelium, promoting neovascularization. However, despite their regenerative role, the number and function of EPC are severely affected under pathological conditions, being essential to further understand how these cells react to such environments in order to implement their use in regenerative cell therapies. Herein, we evaluated the effect of direct incubation ex vivo of healthy CAC with the secretome of atherosclerotic arteries. By using a quantitative proteomics approach, 194 altered proteins were identified in the secretome of pre-conditioned CAC, many of them related to inhibition of angiogenesis (e.g., endostatin, thrombospondin-1, fibulins) and cell migration. Functional assays corroborated that healthy CAC released factors enhanced ECFC angiogenesis, but, after atherosclerotic pre-conditioning, the secretome of pre-stimulated CAC negatively affected ECFC migration, as well as their ability to form tubules on a basement membrane matrix assay. Overall, we have shown here, for the first time, the effect of atherosclerotic factors over the paracrine role of CAC ex vivo. The increased release of angiogenic inhibitors by CAC in response to atherosclerotic factors induced an angiogenic switch, by blocking ECFC ability to form tubules in response to pre-conditioned CAC. Thus, we confirmed here that the angiogenic role of CAC is highly affected by the atherosclerotic environment.


Assuntos
Aterosclerose/metabolismo , Movimento Celular , Proliferação de Células , Células Progenitoras Endoteliais/metabolismo , Neovascularização Fisiológica , Comunicação Parácrina , Transdução de Sinais , Aterosclerose/patologia , Células Progenitoras Endoteliais/patologia , Humanos
9.
Nucleic Acids Res ; 44(18): 8704-8713, 2016 Oct 14.
Artigo em Inglês | MEDLINE | ID: mdl-27325740

RESUMO

ATF4 is a pro-oncogenic transcription factor whose translation is activated by eIF2 phosphorylation through delayed re-initiation involving two uORFs in the mRNA leader. However, in yeast, the effect of eIF2 phosphorylation can be mimicked by eIF5 overexpression, which turns eIF5 into translational inhibitor, thereby promoting translation of GCN4, the yeast ATF4 equivalent. Furthermore, regulatory protein termed eIF5-mimic protein (5MP) can bind eIF2 and inhibit general translation. Here, we show that 5MP1 overexpression in human cells leads to strong formation of 5MP1:eIF2 complex, nearly comparable to that of eIF5:eIF2 complex produced by eIF5 overexpression. Overexpression of eIF5, 5MP1 and 5MP2, the second human paralog, promotes ATF4 expression in certain types of human cells including fibrosarcoma. 5MP overexpression also induces ATF4 expression in Drosophila The knockdown of 5MP1 in fibrosarcoma attenuates ATF4 expression and its tumor formation on nude mice. Since 5MP2 is overproduced in salivary mucoepidermoid carcinoma, we propose that overexpression of eIF5 and 5MP induces translation of ATF4 and potentially other genes with uORFs in their mRNA leaders through delayed re-initiation, thereby enhancing the survival of normal and cancer cells under stress conditions.


Assuntos
Fator 4 Ativador da Transcrição/metabolismo , Proteínas de Ligação a DNA/metabolismo , Fator de Iniciação 2 em Eucariotos/metabolismo , Fator de Iniciação 5 em Eucariotos/metabolismo , Iniciação Traducional da Cadeia Peptídica , Animais , Carcinogênese/patologia , Linhagem Celular Tumoral , Drosophila melanogaster/metabolismo , Fator de Iniciação 3 em Eucariotos , Fibrossarcoma/patologia , Técnicas de Silenciamento de Genes , Células HEK293 , Células HeLa , Humanos , Masculino , Espectrometria de Massas , Camundongos Nus
10.
Opt Lett ; 42(9): 1780-1783, 2017 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-28454159

RESUMO

A modal interferometer by a single mechanically induced long-period fiber grating (MI-LPFG) using a half-length coating fiber is presented. The coating material used for this Letter is a film of silica nanoparticles doped with an organic chromophore. The silica nanoparticles, with diameters within the range of 40-50 nm, were deposited over 3.5 cm length of fiber by the dip-coating method, forming a film with a thickness between 500 and 1250 nm. Then the modal interferometer was implemented by inscribing the MI-LPFG over the coated fiber section and a similar fiber length of the uncoated fiber. The experimental results show high-contrast transmission bands, where the position and depth of the absorption envelope band are finely selected by the grating period, the pressure applied, and the film thickness. The novel modal interferometer architecture based on a single MI-LPFG, combined with a functionalized nanoparticles coating film, offers an attractive platform for the development of fiber sensors and other fiber-based devices.

11.
Proc Natl Acad Sci U S A ; 111(28): 10137-42, 2014 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-24982174

RESUMO

Endothelial colony-forming cells (ECFCs) are endothelial precursors that circulate in peripheral blood. Studies have demonstrated that human ECFCs have robust vasculogenic properties. However, whether ECFCs can exert trophic functions in support of specific stem cells in vivo remains largely unknown. Here, we sought to determine whether human ECFCs can function as paracrine mediators before the establishment of blood perfusion. We used two xenograft models of human mesenchymal stem cell (MSC) transplantation and studied how the presence of ECFCs modulates MSC engraftment and regenerative capacity in vivo. Human MSCs were isolated from white adipose tissue and bone marrow aspirates and were s.c. implanted into immunodeficient mice in the presence or absence of cord blood-derived ECFCs. MSC engraftment was regulated by ECFC-derived paracrine factors via platelet-derived growth factor BB (PDGF-BB)/platelet-derived growth factor receptor (PDGFR)-ß signaling. Cotransplanting ECFCs significantly enhanced MSC engraftment by reducing early apoptosis and preserving stemness-related properties of PDGFR-ß(+) MSCs, including the ability to repopulate secondary grafts. MSC engraftment was negligible in the absence of ECFCs and completely impaired in the presence of Tyrphostin AG1296, an inhibitor of PDGFR kinase. Additionally, transplanted MSCs displayed fate-restricted potential in vivo, with adipose tissue-derived and bone marrow-derived MSCs contributing exclusive differentiation along adipogenic and osteogenic lineages, respectively. This work demonstrates that blood-derived ECFCs can serve as paracrine mediators and regulate the regenerative potential of MSCs via PDGF-BB/PDGFR-ß signaling. Our data suggest the systematic use of ECFCs as a means to improve MSC transplantation.


Assuntos
Células Endoteliais/metabolismo , Células-Tronco Mesenquimais/metabolismo , Comunicação Parácrina , Proteínas Proto-Oncogênicas c-sis/metabolismo , Receptor beta de Fator de Crescimento Derivado de Plaquetas/metabolismo , Animais , Becaplermina , Células Cultivadas , Técnicas de Cocultura , Células Endoteliais/citologia , Feminino , Xenoenxertos , Humanos , Masculino , Transplante de Células-Tronco Mesenquimais , Células-Tronco Mesenquimais/citologia , Camundongos , Receptor beta de Fator de Crescimento Derivado de Plaquetas/antagonistas & inibidores , Tirfostinas/farmacologia
12.
Proc Natl Acad Sci U S A ; 111(21): E2182-90, 2014 May 27.
Artigo em Inglês | MEDLINE | ID: mdl-24782546

RESUMO

Breast cancer is the leading cause of cancer-related mortality in women worldwide, with an estimated 1.7 million new cases and 522,000 deaths around the world in 2012 alone. Cancer stem cells (CSCs) are essential for tumor reoccurrence and metastasis which is the major source of cancer lethality. G protein-coupled receptor chemokine (C-X-C motif) receptor 4 (CXCR4) is critical for tumor metastasis. However, stromal cell-derived factor 1 (SDF-1)/CXCR4-mediated signaling pathways in breast CSCs are largely unknown. Using isotope reductive dimethylation and large-scale MS-based quantitative phosphoproteome analysis, we examined protein phosphorylation induced by SDF-1/CXCR4 signaling in breast CSCs. We quantified more than 11,000 phosphorylation sites in 2,500 phosphoproteins. Of these phosphosites, 87% were statistically unchanged in abundance in response to SDF-1/CXCR4 stimulation. In contrast, 545 phosphosites in 266 phosphoproteins were significantly increased, whereas 113 phosphosites in 74 phosphoproteins were significantly decreased. SDF-1/CXCR4 increases phosphorylation in 60 cell migration- and invasion-related proteins, of them 43 (>70%) phosphoproteins are unrecognized. In addition, SDF-1/CXCR4 upregulates the phosphorylation of 44 previously uncharacterized kinases, 8 phosphatases, and 1 endogenous phosphatase inhibitor. Using computational approaches, we performed system-based analyses examining SDF-1/CXCR4-mediated phosphoproteome, including construction of kinase-substrate network and feedback regulation loops downstream of SDF-1/CXCR4 signaling in breast CSCs. We identified a previously unidentified SDF-1/CXCR4-PKA-MAP2K2-ERK signaling pathway and demonstrated the feedback regulation on MEK, ERK1/2, δ-catenin, and PPP1Cα in SDF-1/CXCR4 signaling in breast CSCs. This study gives a system-wide view of phosphorylation events downstream of SDF-1/CXCR4 signaling in breast CSCs, providing a resource for the study of CSC-targeted cancer therapy.


Assuntos
Neoplasias da Mama/genética , Quimiocina CXCL12/metabolismo , Retroalimentação Fisiológica/fisiologia , Metástase Neoplásica/fisiopatologia , Células-Tronco Neoplásicas/metabolismo , Receptores CXCR4/metabolismo , Transdução de Sinais/genética , Animais , Neoplasias da Mama/metabolismo , Linhagem Celular Tumoral , Feminino , Humanos , Camundongos , Camundongos SCID , Fosforilação , Proteômica/métodos
13.
Proc Natl Acad Sci U S A ; 111(31): E3187-95, 2014 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-25049413

RESUMO

The interaction of the eukaryotic translation initiation factor eIF4E with the initiation factor eIF4G recruits the 40S ribosomal particle to the 5' end of mRNAs, facilitates scanning to the AUG start codon, and is crucial for eukaryotic translation of nearly all genes. Efficient recruitment of the 40S particle is particularly important for translation of mRNAs encoding oncoproteins and growth-promoting factors, which often harbor complex 5' UTRs and require efficient initiation. Thus, inhibiting the eIF4E/eIF4G interaction has emerged as a previously unpursued route for developing anticancer agents. Indeed, we discovered small-molecule inhibitors of this eIF4E/eIF4G interaction (4EGIs) that inhibit translation initiation both in vitro and in vivo and were used successfully in numerous cancer-biology and neurobiology studies. However, their detailed molecular mechanism of action has remained elusive. Here, we show that the eIF4E/eIF4G inhibitor 4EGI-1 acts allosterically by binding to a site on eIF4E distant from the eIF4G binding epitope. Data from NMR mapping and high-resolution crystal structures are congruent with this mechanism, where 4EGI-1 attaches to a hydrophobic pocket of eIF4E between ß-sheet2 (L60-T68) and α-helix1 (E69-N77), causing localized conformational changes mainly in the H78-L85 region. It acts by unfolding a short 310-helix (S82-L85) while extending α-helix1 by one turn (H78-S82). This unusual helix rearrangement has not been seen in any previous eIF4E structure and reveals elements of an allosteric inhibition mechanism leading to the dislocation of eIF4G from eIF4E.


Assuntos
Fator de Iniciação 4E em Eucariotos/química , Fator de Iniciação 4E em Eucariotos/metabolismo , Fator de Iniciação Eucariótico 4G/metabolismo , Hidrazonas/química , Hidrazonas/metabolismo , Tiazóis/química , Tiazóis/metabolismo , Regulação Alostérica , Sítios de Ligação , Cristalografia por Raios X , Fator de Iniciação 4E em Eucariotos/antagonistas & inibidores , Fator de Iniciação Eucariótico 4G/química , Humanos , Ligantes , Espectroscopia de Ressonância Magnética , Modelos Moleculares , Mutagênese Sítio-Dirigida , Peptídeos/química , Peptídeos/metabolismo , Estrutura Quaternária de Proteína , Estrutura Secundária de Proteína , Capuzes de RNA/metabolismo , Soluções
14.
J Biol Chem ; 290(44): 26361-72, 2015 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-26350461

RESUMO

Triacylglycerols (TGs) stored in lipid droplets (LDs) are hydrolyzed in a highly regulated metabolic process called lipolysis to free fatty acids that serve as energy substrates for ß-oxidation, precursors for membrane lipids and signaling molecules. Comparative gene identification-58 (CGI-58) stimulates the enzymatic activity of adipose triglyceride lipase (ATGL), which catalyzes the hydrolysis of TGs to diacylglycerols and free fatty acids. In adipose tissue, protein-protein interactions between CGI-58 and the LD coating protein perilipin 1 restrain the ability of CGI-58 to activate ATGL under basal conditions. Phosphorylation of perilipin 1 disrupts these interactions and mobilizes CGI-58 for the activation of ATGL. We have previously demonstrated that the removal of a peptide at the N terminus (residues 10-31) of CGI-58 abrogates CGI-58 localization to LDs and CGI-58-mediated activation of ATGL. Here, we show that this tryptophan-rich N-terminal peptide serves as an independent LD anchor, with its three tryptophans serving as focal points of the left (harboring Trp(21) and Trp(25)) and right (harboring Trp(29)) anchor arms. The solution state NMR structure of a peptide comprising the LD anchor bound to dodecylphosphocholine micelles as LD mimic reveals that the left arm forms a concise hydrophobic core comprising tryptophans Trp(21) and Trp(25) and two adjacent leucines. Trp(29) serves as the core of a functionally independent anchor arm. Consequently, simultaneous tryptophan alanine permutations in both arms abolish localization and activity of CGI-58 as opposed to tryptophan substitutions that occur in only one arm.


Assuntos
1-Acilglicerol-3-Fosfato O-Aciltransferase/metabolismo , Lipase/metabolismo , Gotículas Lipídicas/metabolismo , 1-Acilglicerol-3-Fosfato O-Aciltransferase/genética , Motivos de Aminoácidos , Sequência de Aminoácidos , Animais , Células COS , Chlorocebus aethiops , Ativação Enzimática , Humanos , Lipase/genética , Deleção de Sequência , Triglicerídeos/genética , Triglicerídeos/metabolismo
15.
RNA ; 20(2): 150-67, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24335188

RESUMO

In the current model of translation initiation by the scanning mechanism, eIF1 promotes an open conformation of the 40S subunit competent for rapidly loading the eIF2·GTP·Met-tRNAi ternary complex (TC) in a metastable conformation (POUT) capable of sampling triplets entering the P site while blocking accommodation of Met-tRNAi in the PIN state and preventing completion of GTP hydrolysis (Pi release) by the TC. All of these functions should be reversed by eIF1 dissociation from the preinitiation complex (PIC) on AUG recognition. We tested this model by selecting eIF1 Ssu(-) mutations that suppress the elevated UUG initiation and reduced rate of TC loading in vivo conferred by an eIF1 (Sui(-)) substitution that eliminates a direct contact of eIF1 with the 40S subunit. Importantly, several Ssu(-) substitutions increase eIF1 affinity for 40S subunits in vitro, and the strongest-binding variant (D61G), predicted to eliminate ionic repulsion with 18S rRNA, both reduces the rate of eIF1 dissociation and destabilizes the PIN state of TC binding in reconstituted PICs harboring Sui(-) variants of eIF5 or eIF2. These findings establish that eIF1 dissociation from the 40S subunit is required for the PIN mode of TC binding and AUG recognition and that increasing eIF1 affinity for the 40S subunit increases initiation accuracy in vivo. Our results further demonstrate that the GTPase-activating protein eIF5 and ß-subunit of eIF2 promote accuracy by controlling eIF1 dissociation and the stability of TC binding to the PIC, beyond their roles in regulating GTP hydrolysis by eIF2.


Assuntos
Fator de Iniciação 1 em Eucariotos/metabolismo , Subunidades Ribossômicas Menores de Eucariotos/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/metabolismo , Iniciação da Transcrição Genética , Sequência de Aminoácidos , Códon de Iniciação , Fator de Iniciação 1 em Eucariotos/química , Fator de Iniciação 1 em Eucariotos/genética , Fator de Iniciação 2 em Eucariotos/genética , Fator de Iniciação 2 em Eucariotos/metabolismo , Fator de Iniciação 5 em Eucariotos/química , Fator de Iniciação 5 em Eucariotos/metabolismo , Técnicas de Inativação de Genes , Guanosina Trifosfato/química , Guanosina Trifosfato/metabolismo , Hidrólise , Dados de Sequência Molecular , Mutação de Sentido Incorreto , Ligação Proteica , Estabilidade Proteica , Subunidades Ribossômicas Menores de Eucariotos/química , Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/química , Proteínas de Saccharomyces cerevisiae/genética
16.
J Biol Chem ; 288(38): 27546-27562, 2013 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-23893413

RESUMO

Recognition of the translation initiation codon is thought to require dissociation of eIF1 from the 40 S ribosomal subunit, enabling irreversible GTP hydrolysis (Pi release) by the eIF2·GTP·Met-tRNAi ternary complex (TC), rearrangement of the 40 S subunit to a closed conformation incompatible with scanning, and stable binding of Met-tRNAi to the P site. The crystal structure of a Tetrahymena 40 S·eIF1 complex revealed several basic amino acids in eIF1 contacting 18 S rRNA, and we tested the prediction that their counterparts in yeast eIF1 are required to prevent premature eIF1 dissociation from scanning ribosomes at non-AUG triplets. Supporting this idea, substituting Lys-60 in helix α1, or either Lys-37 or Arg-33 in ß-hairpin loop-1, impairs binding of yeast eIF1 to 40 S·eIF1A complexes in vitro, and it confers increased initiation at UUG codons (Sui(-) phenotype) or lethality, in a manner suppressed by overexpressing the mutant proteins or by an eIF1A mutation (17-21) known to impede eIF1 dissociation in vitro. The eIF1 Sui(-) mutations also derepress translation of GCN4 mRNA, indicating impaired ternary complex loading, and this Gcd(-) phenotype is likewise suppressed by eIF1 overexpression or the 17-21 mutation. These findings indicate that direct contacts of eIF1 with 18 S rRNA seen in the Tetrahymena 40 S·eIF1 complex are crucial in yeast to stabilize the open conformation of the 40 S subunit and are required for rapid TC loading and ribosomal scanning and to impede rearrangement to the closed complex at non-AUG codons. Finally, we implicate the unstructured N-terminal tail of eIF1 in blocking rearrangement to the closed conformation in the scanning preinitiation complex.


Assuntos
Códon de Iniciação/metabolismo , Fator de Iniciação 1 em Eucariotos/metabolismo , Iniciação Traducional da Cadeia Peptídica/fisiologia , RNA de Transferência de Metionina/metabolismo , Subunidades Ribossômicas Menores de Eucariotos/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/metabolismo , Fatores de Transcrição de Zíper de Leucina Básica/biossíntese , Fatores de Transcrição de Zíper de Leucina Básica/genética , Códon de Iniciação/genética , Fator de Iniciação 1 em Eucariotos/genética , Mutação , Estrutura Secundária de Proteína , Estrutura Terciária de Proteína , Proteínas de Protozoários/genética , Proteínas de Protozoários/metabolismo , RNA Fúngico/genética , RNA Fúngico/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , RNA de Transferência de Metionina/genética , Subunidades Ribossômicas Menores de Eucariotos/genética , Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/biossíntese , Proteínas de Saccharomyces cerevisiae/genética , Tetrahymena thermophila/genética , Tetrahymena thermophila/metabolismo
17.
J Pediatr ; 164(3): 566-571, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-24315508

RESUMO

OBJECTIVE: Endothelial colony-forming cells (ECFCs) are a subset of circulating endothelial progenitor cells that are particularly abundant in umbilical cord blood. We sought to determine whether ECFC abundance in cord blood is associated with maternal body-mass index (BMI) in nonpathologic pregnancies. STUDY DESIGN: We measured the level of ECFCs in the cord blood of neonates (n = 27) born from non-obese healthy mothers with nonpathologic pregnancies and examined whether ECFC abundance correlated with maternal BMI. We also examined the effect of maternal BMI on ECFC phenotype and function using angiogenic and vasculogenic assays. RESULTS: We observed variation in ECFC abundance among subjects and found a positive correlation between prepregnancy maternal BMI and ECFC content (r = 0.51, P = .007), which was independent of other obstetric factors. Despite this variation, ECFC phenotype and functionality were deemed normal and highly similar between subjects with maternal BMI <25 kg/m(2) and BMI between 25-30 kg/m(2), including the ability to form vascular networks in vivo. CONCLUSIONS: This study underlines the need to consider maternal BMI as a potential confounding factor for cord blood levels of ECFCs in future comparative studies between healthy and pathologic pregnancies.


Assuntos
Índice de Massa Corporal , Células Endoteliais/citologia , Sangue Fetal/citologia , Células-Tronco/citologia , Adulto , Células Cultivadas , Feminino , Humanos , Recém-Nascido , Masculino , Gravidez , Nascimento Prematuro/sangue
18.
Langmuir ; 30(40): 11985-92, 2014 Oct 14.
Artigo em Inglês | MEDLINE | ID: mdl-25233063

RESUMO

The origin of the odd-even effect in properties of self-assembled monolayers (SAMs) and/or technologies derived from them is poorly understood. We report that hydrophobicity and, hence, surface wetting of SAMs are dominated by the nature of the substrate (surface roughness and identity) and SAM tilt angle, which influences surface dipoles/orientation of the terminal moiety. We measured static contact angles (θs) made by water droplets on n-alkanethiolate SAMs with an odd (SAM(O)) or even (SAM(E)) number of carbons (average θs range of 105.8-112.1°). When SAMs were fabricated on smooth "template-stripped" metal (M(TS)) surfaces [root-mean-square (rms) roughness = 0.36 ± 0.01 nm for Au(TS) and 0.60 ± 0.04 nm for Ag(TS)], the odd-even effect, characterized by a zigzag oscillation in values of θs, was observed. We, however, did not observe the same effect with rougher "as-deposited" (M(AD)) surfaces (rms roughness = 2.27 ± 0.16 nm for Au(AD) and 5.13 ± 0.22 nm for Ag(AD)). The odd-even effect in hydrophobicity inverts when the substrate changes from Au(TS) (higher θs for SAM(E) than SAM(O), with average Δθs |n - (n + 1)| ≈ 3°) to Ag(TS) (higher θs for SAM(O) than SAM(E), with average Δθs |n - (n + 1)| ≈ 2°). A comparison of hydrophobicity across Ag(TS) and Au(TS) showed a statistically significant difference (Student's t test) between SAM(E) (Δθs |Ag evens - Au evens| ≈ 5°; p < 0.01) but failed to show statistically significant differences on SAM(O) (Δθs |Ag odds - Au odds| ≈ 1°; p > 0.1). From these results, we deduce that the roughness of the metal substrate (from comparison of M(AD) versus M(TS)) and orientation of the terminal -CH2CH3 (by comparing SAM(E) and SAM(O) on Au(TS) versus Ag(TS)) play major roles in the hydrophobicity and, by extension, general wetting properties of n-alkanethiolate SAMs.


Assuntos
Alcanos/química , Ouro/química , Prata/química , Compostos de Sulfidrila/química , Interações Hidrofóbicas e Hidrofílicas , Água/química , Molhabilidade
19.
Appl Opt ; 53(16): 3393-8, 2014 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-24922413

RESUMO

The generation of circularly polarized light with a high circularity degree and low azimuthal error sensitivity was analyzed using a system composed by two waveplates. It is shown how the high circularity degree is achieved using a combination of a half- (λ/2) and a quarter- (λ/4) waveplate λ/2+λ/4 configuration. However, the lowest azimuthal sensitivity under small variations in the azimuths of the waveplates is obtained by employing a λ/4+λ/2 configuration. Analytical calculus particularized for quartz and MgF2 waveplates is presented.

20.
Int Forum Allergy Rhinol ; 14(7): 1245-1248, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38268107

RESUMO

KEY POINTS: T-cell activation in patients with chronic rhinosinusitis with nasal polyps (CRSwNP) is enriched by late cytotoxic T cells. The proportion of early and intermediate activated cytotoxic T cells decreases in nasal polyps of patients with CRSwNP. Our results identify late activated cytotoxic T cells as potential biomarkers or therapeutic targets for patients with CRSwNP.


Assuntos
Imunofenotipagem , Ativação Linfocitária , Pólipos Nasais , Rinite , Sinusite , Humanos , Pólipos Nasais/imunologia , Sinusite/imunologia , Rinite/imunologia , Doença Crônica , Ativação Linfocitária/imunologia , Masculino , Adulto , Pessoa de Meia-Idade , Feminino , Linfócitos T Citotóxicos/imunologia , Idoso , Rinossinusite
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