Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 139
Filtrar
1.
PLoS Genet ; 18(11): e1010273, 2022 11.
Artigo em Inglês | MEDLINE | ID: mdl-36383567

RESUMO

Animal behavior is influenced by the competing drives to maintain energy and to reproduce. The balance between these evolutionary pressures and how nutrient signaling pathways intersect with mating remains unclear. The nutrient sensor O-GlcNAc transferase, which post-translationally modifies intracellular proteins with a single monosaccharide, is responsive to cellular nutrient status and regulates diverse biological processes. Though essential in most metazoans, O-GlcNAc transferase (ogt-1) is dispensable in Caenorhabditis elegans, allowing genetic analysis of its physiological roles. Compared to control, ogt-1 males had a four-fold reduction in mean offspring, with nearly two thirds producing zero progeny. Interestingly, we found that ogt-1 males transferred sperm less often, and virgin males had reduced sperm count. ogt-1 males were also less likely to engage in mate-searching and mate-response behaviors. Surprisingly, we found normal fertility for males with hypodermal expression of ogt-1 and for ogt-1 strains with catalytic-dead mutations. This suggests OGT-1 serves a non-catalytic function in the hypodermis impacting male fertility and mating behavior. This study builds upon research on the nutrient sensor O-GlcNAc transferase and demonstrates a role it plays in the interplay between the evolutionary drives for reproduction and survival.


Assuntos
Caenorhabditis elegans , Sêmen , Animais , Masculino , Caenorhabditis elegans/genética , Caenorhabditis elegans/metabolismo , Sêmen/metabolismo , N-Acetilglucosaminiltransferases/genética , N-Acetilglucosaminiltransferases/metabolismo , Fertilidade/genética
2.
J Synchrotron Radiat ; 31(Pt 4): 670-680, 2024 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-38838166

RESUMO

Deflectometric profilometers are used to precisely measure the form of beam shaping optics of synchrotrons and X-ray free-electron lasers. They often utilize autocollimators which measure slope by evaluating the displacement of a reticle image on a detector. Based on our privileged access to the raw image data of an autocollimator, novel strategies to reduce the systematic measurement errors by using a set of overlapping images of the reticle obtained at different positions on the detector are discussed. It is demonstrated that imaging properties such as, for example, geometrical distortions and vignetting, can be extracted from this redundant set of images without recourse to external calibration facilities. This approach is based on the fact that the properties of the reticle itself do not change - all changes in the reticle image are due to the imaging process. Firstly, by combining interpolation and correlation, it is possible to determine the shift of a reticle image relative to a reference image with minimal error propagation. Secondly, the intensity of the reticle image is analysed as a function of its position on the CCD and a vignetting correction is calculated. Thirdly, the size of the reticle image is analysed as a function of its position and an imaging distortion correction is derived. It is demonstrated that, for different measurement ranges and aperture diameters of the autocollimator, reductions in the systematic errors of up to a factor of four to five can be achieved without recourse to external measurements.

3.
Nat Rev Mol Cell Biol ; 13(5): 312-21, 2012 04 23.
Artigo em Inglês | MEDLINE | ID: mdl-22522719

RESUMO

O-GlcNAcylation, which is a nutrient-sensitive sugar modification, participates in the epigenetic regulation of gene expression. The enzymes involved in O-linked ß-D-N-acetylglucosamine (O-GlcNAc) cycling - O-GlcNAc transferase (OGT) and O-GlcNAcase (OGA) - target key transcriptional and epigenetic regulators including RNA polymerase II, histones, histone deacetylase complexes and members of the Polycomb and Trithorax groups. Thus, O-GlcNAc cycling may serve as a homeostatic mechanism linking nutrient availability to higher-order chromatin organization. In response to nutrient availability, O-GlcNAcylation is poised to influence X chromosome inactivation and genetic imprinting, as well as embryonic development. The wide range of physiological functions regulated by O-GlcNAc cycling suggests an unexplored nexus between epigenetic regulation in disease and nutrient availability.


Assuntos
Acetilglucosamina/metabolismo , Epigênese Genética , Estado Nutricional/genética , Processamento de Proteína Pós-Traducional , Acetilglucosaminidase/química , Acetilglucosaminidase/metabolismo , Acetilglucosaminidase/fisiologia , Animais , Cromatina/genética , Cromatina/metabolismo , Glicosilação , Humanos , Redes e Vias Metabólicas , N-Acetilgalactosaminiltransferases/química , N-Acetilgalactosaminiltransferases/metabolismo , N-Acetilgalactosaminiltransferases/fisiologia , Conformação Proteica
4.
Genome Res ; 30(8): 1154-1169, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32817236

RESUMO

The characterization of de novo mutations in regions of high sequence and structural diversity from whole-genome sequencing data remains highly challenging. Complex structural variants tend to arise in regions of high repetitiveness and low complexity, challenging both de novo assembly, in which short reads do not capture the long-range context required for resolution, and mapping approaches, in which improper alignment of reads to a reference genome that is highly diverged from that of the sample can lead to false or partial calls. Long-read technologies can potentially solve such problems but are currently unfeasible to use at scale. Here we present Corticall, a graph-based method that combines the advantages of multiple technologies and prior data sources to detect arbitrary classes of genetic variant. We construct multisample, colored de Bruijn graphs from short-read data for all samples, align long-read-derived haplotypes and multiple reference data sources to restore graph connectivity information, and call variants using graph path-finding algorithms and a model for simultaneous alignment and recombination. We validate and evaluate the approach using extensive simulations and use it to characterize the rate and spectrum of de novo mutation events in 119 progeny from four Plasmodium falciparum experimental crosses, using long-read data on the parents to inform reconstructions of the progeny and to detect several known and novel nonallelic homologous recombination events.


Assuntos
Genoma de Protozoário/genética , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Mutação/genética , Plasmodium falciparum/genética , Sequenciamento Completo do Genoma/métodos , Algoritmos , Sequência de Bases , Variação Genética/genética , Alinhamento de Sequência , Análise de Sequência de DNA/métodos , Software
5.
J Microsc ; 289(1): 20-31, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36219478

RESUMO

X-ray-computed tomography with sub-micron resolution (nano-CT) is one of the most useful techniques to examine the 3D microstructure of materials down to voxel sizes 10 nm. However, since size and shape of samples have considerable influence on acquisition time and data quality, adapted and universally applicable workflows are needed. Three novel workflows for sample preparation using ultra-short pulsed lasers are presented which allow for reproducible fabrication, safe extraction and mounting of samples. Their application potential is illustrated via nano-CT measurements of glass ceramics as well as a laser-modified glass. Since the according sample geometries take also the requirements of other analytical techniques such as transmission electron microscopy into account, samples prepared according to the new workflows can be furthermore seen as a starting point for correlative microstructural analyses involving multiple techniques.

6.
Anal Chem ; 94(27): 9508-9513, 2022 07 12.
Artigo em Inglês | MEDLINE | ID: mdl-35729701

RESUMO

The family of deubiquitinases (DUBs) comprises ∼100 enzymes that cleave ubiquitin from substrate proteins and thereby regulate key aspects of human physiology. DUBs have recently emerged as disease-relevant and chemically tractable, although currently there are no approved DUB-targeting drugs and most preclinical small molecules are low-potency and/or multitargeted. We paired a novel capillary electrophoresis microchip containing an integrated, "on-chip" C18 bed (SPE-ZipChip) with a TMT version of our recently described PRM-LIVE acquisition scheme on a timsTOF Pro mass spectrometer to facilitate rapid activity-based protein profiling of DUB inhibitors. We demonstrate the ability of the SPE-ZipChip to improve proteome coverage of complex samples as well as the quantitation integrity of CE-PRM-LIVE for TMT labeled samples. These technologies provide a platform to accurately quantify competitive binding of covalent and reversible inhibitors in a multiplexed assay that spans 49 endogenous DUBs in less than 15 min.


Assuntos
Eletroforese em Microchip , Ubiquitina , Enzimas Desubiquitinantes/metabolismo , Eletroforese Capilar , Humanos , Proteoma , Ubiquitina/metabolismo
7.
Anal Chem ; 93(41): 13791-13799, 2021 10 19.
Artigo em Inglês | MEDLINE | ID: mdl-34606255

RESUMO

Parallel reaction monitoring (PRM) has emerged as a popular approach for targeted protein quantification. With high ion utilization efficiency and first-in-class acquisition speed, the timsTOF Pro provides a powerful platform for PRM analysis. However, sporadic chromatographic drift in peptide retention time represents a fundamental limitation for the reproducible multiplexing of targets across PRM acquisitions. Here, we present PRM-LIVE, an extensible, Python-based acquisition engine for the timsTOF Pro, which dynamically adjusts detection windows for reproducible target scheduling. In this initial implementation, we used iRT peptides as retention time standards and demonstrated reproducible detection and quantification of 1857 tryptic peptides from the cell lysate in a 60 min PRM-LIVE acquisition. As an application in functional proteomics, we use PRM-LIVE in an activity-based protein profiling platform to assess binding selectivity of small-molecule inhibitors against 220 endogenous human kinases.


Assuntos
Espectrometria de Mobilidade Iônica , Proteômica , Humanos , Espectrometria de Massas , Peptídeos , Proteínas
8.
PLoS Genet ; 14(9): e1007665, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-30248094

RESUMO

Heme-iron recycling from senescent red blood cells (erythrophagocytosis) accounts for the majority of total body iron in humans. Studies in cultured cells have ascribed a role for HRG1/SLC48A1 in heme-iron transport but the in vivo function of this heme transporter is unclear. Here we present genetic evidence in a zebrafish model that Hrg1 is essential for macrophage-mediated heme-iron recycling during erythrophagocytosis in the kidney. Furthermore, we show that zebrafish Hrg1a and its paralog Hrg1b are functional heme transporters, and genetic ablation of both transporters in double knockout (DKO) animals shows lower iron accumulation concomitant with higher amounts of heme sequestered in kidney macrophages. RNA-seq analyses of DKO kidney revealed large-scale perturbation in genes related to heme, iron metabolism and immune functions. Taken together, our results establish the kidney as the major organ for erythrophagocytosis and identify Hrg1 as an important regulator of heme-iron recycling by macrophages in the adult zebrafish.


Assuntos
Citofagocitose/fisiologia , Eritrócitos/fisiologia , Rim Cefálico/metabolismo , Hemeproteínas/metabolismo , Proteínas Carreadoras de Solutos/fisiologia , Proteínas de Peixe-Zebra/fisiologia , Peixe-Zebra/fisiologia , Animais , Animais Geneticamente Modificados , Feminino , Técnicas de Inativação de Genes , Hematopoese/fisiologia , Heme/metabolismo , Hemeproteínas/genética , Ferro/metabolismo , Macrófagos/metabolismo , Masculino , Modelos Animais , Proteínas Carreadoras de Solutos/genética , Proteínas de Peixe-Zebra/genética
9.
Proc Natl Acad Sci U S A ; 115(49): 12513-12518, 2018 12 04.
Artigo em Inglês | MEDLINE | ID: mdl-30455312

RESUMO

Concerns about malaria parasite resistance to treatment with artemisinin drugs (ARTs) have grown with findings of prolonged parasite clearance t1/2s (>5 h) and their association with mutations in Plasmodium falciparum Kelch-propeller protein K13. Here, we describe a P. falciparum laboratory cross of K13 C580Y mutant with C580 wild-type parasites to investigate ART response phenotypes in vitro and in vivo. After genotyping >400 isolated progeny, we evaluated 20 recombinants in vitro: IC50 measurements of dihydroartemisinin were at similar low nanomolar levels for C580Y- and C580-type progeny (mean ratio, 1.00; 95% CI, 0.62-1.61), whereas, in a ring-stage survival assay, the C580Y-type progeny had 19.6-fold (95% CI, 9.76-39.2) higher average counts. In splenectomized Aotus monkeys treated with three daily doses of i.v. artesunate, t1/2 calculations by three different methods yielded mean differences of 0.01 h (95% CI, -3.66 to 3.67), 0.80 h (95% CI, -0.92 to 2.53), and 2.07 h (95% CI, 0.77-3.36) between C580Y and C580 infections. Incidences of recrudescence were 57% in C580Y (4 of 7) versus 70% in C580 (7 of 10) infections (-13% difference; 95% CI, -58% to 35%). Allelic substitution of C580 in a C580Y-containing progeny clone (76H10) yielded a transformant (76H10C580Rev) that, in an infected monkey, recrudesced regularly 13 times over 500 d. Frequent recrudescences of ART-treated P. falciparum infections occur with or without K13 mutations and emphasize the need for improved partner drugs to effectively eliminate the parasites that persist through the ART component of combination therapy.


Assuntos
Antimaláricos/farmacologia , Artemisininas/farmacologia , Malária Falciparum/parasitologia , Plasmodium falciparum/efeitos dos fármacos , Animais , Aotidae , Cruzamentos Genéticos , Resistência a Medicamentos , Regulação da Expressão Gênica , Mutação , Proteínas de Protozoários/genética , Proteínas de Protozoários/metabolismo
10.
Mol Cell Proteomics ; 17(12): 2534-2545, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30385480

RESUMO

In bottom-up proteomics, peptides are separated by liquid chromatography with elution peak widths in the range of seconds, whereas mass spectra are acquired in about 100 microseconds with time-of-flight (TOF) instruments. This allows adding ion mobility as a third dimension of separation. Among several formats, trapped ion mobility spectrometry (TIMS) is attractive because of its small size, low voltage requirements and high efficiency of ion utilization. We have recently demonstrated a scan mode termed parallel accumulation - serial fragmentation (PASEF), which multiplies the sequencing speed without any loss in sensitivity (Meier et al., PMID: 26538118). Here we introduce the timsTOF Pro instrument, which optimally implements online PASEF. It features an orthogonal ion path into the ion mobility device, limiting the amount of debris entering the instrument and making it very robust in daily operation. We investigate different precursor selection schemes for shotgun proteomics to optimally allocate in excess of 100 fragmentation events per second. More than 600,000 fragmentation spectra in standard 120 min LC runs are achievable, which can be used for near exhaustive precursor selection in complex mixtures or accumulating the signal of weak precursors. In 120 min single runs of HeLa digest, MaxQuant identified more than 6,000 proteins without matching to a library and with high quantitative reproducibility (R > 0.97). Online PASEF achieves a remarkable sensitivity with more than 2,500 proteins identified in 30 min runs of only 10 ng HeLa digest. We also show that highly reproducible collisional cross sections can be acquired on a large scale (R > 0.99). PASEF on the timsTOF Pro is a valuable addition to the technological toolbox in proteomics, with a number of unique operating modes that are only beginning to be explored.


Assuntos
Espectrometria de Mobilidade Iônica/métodos , Peptídeos/análise , Proteoma/análise , Proteômica/instrumentação , Proteômica/métodos , Espectrometria de Massas em Tandem/métodos , Algoritmos , Cromatografia Líquida , Confiabilidade dos Dados , Escherichia coli , Proteínas de Escherichia coli/análise , Células HeLa , Humanos , Íons/análise , Reprodutibilidade dos Testes
11.
PLoS Genet ; 11(5): e1005221, 2015 May.
Artigo em Inglês | MEDLINE | ID: mdl-25978409

RESUMO

Bone morphogenetic proteins (BMPs) belong to the transforming growth factor ß (TGFß) superfamily of secreted molecules. BMPs play essential roles in multiple developmental and homeostatic processes in metazoans. Malfunction of the BMP pathway can cause a variety of diseases in humans, including cancer, skeletal disorders and cardiovascular diseases. Identification of factors that ensure proper spatiotemporal control of BMP signaling is critical for understanding how this pathway is regulated. We have used a unique and sensitive genetic screen to identify the plasma membrane-localized tetraspanin TSP-21 as a key new factor in the C. elegans BMP-like "Sma/Mab" signaling pathway that controls body size and postembryonic M lineage development. We showed that TSP-21 acts in the signal-receiving cells and genetically functions at the ligand-receptor level. We further showed that TSP-21 can associate with itself and with two additional tetraspanins, TSP-12 and TSP-14, which also promote Sma/Mab signaling. TSP-12 and TSP-14 can also associate with SMA-6, the type I receptor of the Sma/Mab pathway. Finally, we found that glycosphingolipids, major components of the tetraspanin-enriched microdomains, are required for Sma/Mab signaling. Our findings suggest that the tetraspanin-enriched membrane microdomains are important for proper BMP signaling. As tetraspanins have emerged as diagnostic and prognostic markers for tumor progression, and TSP-21, TSP-12 and TSP-14 are all conserved in humans, we speculate that abnormal BMP signaling due to altered expression or function of certain tetraspanins may be a contributing factor to cancer development.


Assuntos
Proteínas Morfogenéticas Ósseas/metabolismo , Proteínas de Caenorhabditis elegans/metabolismo , Glicoesfingolipídeos/farmacologia , Transdução de Sinais , Tetraspaninas/metabolismo , Sequência de Aminoácidos , Animais , Proteínas Morfogenéticas Ósseas/genética , Caenorhabditis elegans/genética , Proteínas de Caenorhabditis elegans/antagonistas & inibidores , Proteínas de Caenorhabditis elegans/genética , Regulação da Expressão Gênica , Genes Reporter , Marcadores Genéticos , Dados de Sequência Molecular , Mutação , Fenótipo , Sensibilidade e Especificidade , Análise de Sequência de DNA , Tetraspaninas/genética , Fatores de Transcrição/antagonistas & inibidores , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Fator de Crescimento Transformador beta/genética , Fator de Crescimento Transformador beta/metabolismo
12.
Dev Biol ; 416(2): 300-11, 2016 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-27341757

RESUMO

Spatial polarity cues in animals are used repeatedly during development for many processes, including cell fate determination, cell migration, and axon guidance. In Caenorhabditis elegans, the body wall muscle extends the length of the animal in four distinct quadrants and generates an UNC-129/TGF-ß-related signal that is much higher in the dorsal two muscle quadrants compared to their ventral counterparts. This pattern of unc-129 expression requires the activity of the proposed transcriptional repressor UNC-130/FOXD whose body wall muscle activity is restricted to the ventral two body wall muscle quadrants. To understand how these dorsal-ventral differences in UNC-130 activity are established and maintained, we have analyzed the regulation of unc-130 expression and the distribution of UNC-130 protein. We have identified widespread, cis-acting elements in the unc-130 promoter that function to positively regulate ventral body wall muscle expression and negatively regulate dorsal body wall muscle expression. We have defined the temporal distribution of UNC-130 protein in body wall muscle cells during embryogenesis, demonstrated that this pattern is required to establish the dorsal-ventral polarity of UNC-129/TGF-ß, and shown that UNC-130 is not required post-embryonically to maintain the asymmetry of body wall muscle unc-129 expression. Finally, we have tested the impact of the depletion of a variety of transcription factors, repressors, and signaling molecules to identify additional regulators of body wall muscle UNC-130 polarity. Our results confirm and extend earlier studies to clarify the mechanisms by which UNC-130 is controlled and affects the pattern of unc-129 expression in body wall muscle. These results further our understanding of the transcriptional logic behind the generation of polarity cues involving this poorly understood subclass of Forkhead factors.


Assuntos
Padronização Corporal/genética , Proteínas de Caenorhabditis elegans/genética , Caenorhabditis elegans/embriologia , Regulação da Expressão Gênica no Desenvolvimento , Mesoderma/embriologia , Fatores de Transcrição/genética , Animais , Animais Geneticamente Modificados , Caenorhabditis elegans/genética , Caenorhabditis elegans/crescimento & desenvolvimento , Proteínas de Caenorhabditis elegans/biossíntese , Movimento Celular , DNA de Helmintos/genética , Fatores de Transcrição Forkhead/genética , Genes Reporter , Larva , Proteínas Luminescentes/análise , Proteínas Luminescentes/genética , Mesoderma/fisiologia , Músculos/embriologia , Mutação , Interferência de RNA , Proteínas Recombinantes de Fusão/metabolismo , Elementos Reguladores de Transcrição , Fatores de Transcrição/biossíntese , Fator de Crescimento Transformador beta/biossíntese , Fator de Crescimento Transformador beta/genética , Fator de Crescimento Transformador beta/metabolismo
13.
Dev Biol ; 412(2): 191-207, 2016 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-26953187

RESUMO

The development of the single cell layer skin or hypodermis of Caenorhabditis elegans is an excellent model for understanding cell fate specification and differentiation. Early in C. elegans embryogenesis, six rows of hypodermal cells adopt dorsal, lateral or ventral fates that go on to display distinct behaviors during larval life. Several transcription factors are known that function in specifying these major hypodermal cell fates, but our knowledge of the specification of these cell types is sparse, particularly in the case of the ventral hypodermal cells, which become Vulval Precursor Cells and form the vulval opening in response to extracellular signals. Previously, the gene pvl-4 was identified in a screen for mutants with defects in vulval development. We found by whole genome sequencing that pvl-4 is the Paired-box gene pax-3, which encodes the sole PAX-3 transcription factor homolog in C. elegans. pax-3 mutants show embryonic and larval lethality, and body morphology abnormalities indicative of hypodermal cell defects. We report that pax-3 is expressed in ventral P cells and their descendants during embryogenesis and early larval stages, and that in pax-3 reduction-of-function animals the ventral P cells undergo a cell fate transformation and express several markers of the lateral seam cell fate. Furthermore, forced expression of pax-3 in the lateral hypodermal cells causes them to lose expression of seam cell markers. We propose that pax-3 functions in the ventral hypodermal cells to prevent these cells from adopting the lateral seam cell fate. pax-3 represents the first gene required for specification solely of the ventral hypodermal fate in C. elegans providing insights into cell type diversification.


Assuntos
Proteínas de Caenorhabditis elegans/metabolismo , Caenorhabditis elegans/metabolismo , Epiderme/metabolismo , Fatores de Transcrição Box Pareados/metabolismo , Animais , Animais Geneticamente Modificados , Caenorhabditis elegans/embriologia , Caenorhabditis elegans/genética , Proteínas de Caenorhabditis elegans/genética , Linhagem da Célula/genética , Embrião não Mamífero/citologia , Embrião não Mamífero/embriologia , Embrião não Mamífero/metabolismo , Células Epidérmicas , Epiderme/embriologia , Feminino , Larva/citologia , Larva/genética , Larva/metabolismo , Proteínas Luminescentes/genética , Proteínas Luminescentes/metabolismo , Microscopia de Fluorescência , Mutação , Fatores de Transcrição Box Pareados/genética , Interferência de RNA , Vulva/citologia , Vulva/embriologia , Vulva/metabolismo
14.
Chemphyschem ; 17(5): 665-9, 2016 Mar 03.
Artigo em Inglês | MEDLINE | ID: mdl-26752223

RESUMO

The emissive properties of thiol-capped CdSe nanocrystals (NCs) with intrinsic dual emission are investigated through temperature-dependent photoluminescence (PL) measurements. We demonstrate the influence of thiols on the relative PL intensities of the core and surface emissive states, as well as on the observed Stokes shifts. A redshift of both the core and surface PL in comparison with phosphonate-capped NCs is consistent with recent work exploring the effect of thiols as excitonic hole-delocalizing ligands. This observation is consistent with prior reports suggesting that surface excitons originate from electrons bound to cadmium trap states.

15.
J Biol Chem ; 289(23): 16072-84, 2014 Jun 06.
Artigo em Inglês | MEDLINE | ID: mdl-24782314

RESUMO

Cell cycle progression requires a series of highly coordinated events that ultimately lead to faithful segregation of chromosomes. Aurora B is an essential mitotic kinase, which is involved in regulation of microtubule-kinetochore attachments and cytokinesis. Inhibition of Aurora B results in stabilization of p53 and induction of p53-target genes such as p21 to inhibit proliferation. We have previously demonstrated that induction of p21 by p53 after inhibition of Aurora B is dependent on the p38 MAPK, which promotes transcriptional elongation of p21 by RNA Pol II. In this study, we show that a subset of p53-target genes are induced in a p38-dependent manner upon inhibition of Aurora B. We also demonstrate that inhibition of Aurora B results in down-regulation of E2F-mediated transcription and that the cell cycle arrest after Aurora B inhibition depends on p53 and pRB tumor suppressor pathways. In addition, we report that activation of p21 after inhibition of Aurora B is correlated with increased chromosome missegregation and aneuploidy but not with binucleation or tetraploidy. We provide evidence that p21 is activated in aneuploid cells by reactive oxygen species (ROS) and p38 MAPK. Finally, we demonstrate that certain drugs that act on aneuploid cells synergize with inhibitors of Aurora B to inhibit colony formation and oncogenic transformation. These findings provide an important link between aneuploidy and the stress pathways activated by Aurora B inhibition and also support the use of Aurora B inhibitors in combination therapy for treatment of cancer.


Assuntos
Aneuploidia , Aurora Quinase B/efeitos dos fármacos , Ciclo Celular , Inibidor de Quinase Dependente de Ciclina p21/biossíntese , Espécies Reativas de Oxigênio/metabolismo , Linhagem Celular , Citometria de Fluxo , Humanos , Hibridização in Situ Fluorescente , Inibidores de Proteínas Quinases/farmacologia , Transdução de Sinais , Proteínas Quinases p38 Ativadas por Mitógeno/metabolismo
16.
Mol Carcinog ; 54(8): 585-97, 2015 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-24375802

RESUMO

Deacetylase inhibitors (DACi) are a new class of drugs with a broad spectrum of mechanisms that favor their application in cancer therapy. Currently, the exact mechanisms and cellular effects of DACi have not been fully elucidated. In addition to their effects on histone acetylation, DACi can interfere with gene expression via miRNA pathways. Treatment with panobinostat (LBH589), a novel potent DACi, led to the highly aberrant modulation of several miRNAs in hepatocellular carcinoma (HCC) cell lines as shown by miRNA array analysis. Among them, hsa-miR-19a, hsa-miR-19b1 and the corresponding precursors were down-regulated by panobinostat in TP53(-/-) Hep3B and TP53(+/+) HepG2 cell lines; hsa-miR30a-5p mature form only was suppressed in both HCC cell lines, as confirmed by further RT-qPCR analysis. In HCC cell lines, panobinostat caused the upregulation of the predicted miRNA targets APAF1 and Beclin1 protein levels. Transfection with oligonucleotides mimicking these miRNAs led to an increase in the viability rate of both cell lines as analyzed by impedance-based real-time cell analysis. In addition, transfecting miRNA mimicking oligonucleotides resulted in the decrease of APAF1, Beclin1 and PAK6 at the protein level, proving the regulating influence of the investigated miRNAs on gene final products. The overexpression of the above mentioned oncomiRs in Hep3B and HepG2 cell lines leads to cell proliferation and downregulation of cell death associated proteins. In our model, panobinostat exerts its anti-cancer effect by suppressing these miRNAs and restoring the expression of their corresponding tumor suppressor targets.


Assuntos
Carcinoma Hepatocelular/genética , Inibidores de Histona Desacetilases/farmacologia , Ácidos Hidroxâmicos/farmacologia , Indóis/farmacologia , Neoplasias Hepáticas/genética , MicroRNAs/genética , Proteínas Reguladoras de Apoptose/genética , Proteínas Reguladoras de Apoptose/metabolismo , Fator Apoptótico 1 Ativador de Proteases/genética , Fator Apoptótico 1 Ativador de Proteases/metabolismo , Proteína Beclina-1 , Carcinoma Hepatocelular/metabolismo , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Células Hep G2 , Humanos , Neoplasias Hepáticas/metabolismo , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Panobinostat , Quinases Ativadas por p21/genética , Quinases Ativadas por p21/metabolismo
17.
Phys Chem Chem Phys ; 17(29): 18882-94, 2015 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-26130059

RESUMO

The intricate chemistry occurring at the surface of semiconductor nanocrystals is crucial to tailoring their optical properties to a myriad of applications. This perspective aims to re-evaluate long held ideas in semiconductor nanocrystal surface science in the light of a body of new and rich research. We start by reviewing recent developments in ligand chemistry, followed by a discussion of spectroscopic and computational approaches used for advancing the poorly-understood electronic structure of the surface. With the insights gained, we show how the surface impacts emissive behaviour and we summarize strategies to increase fluorescent quantum yield. This discussion is followed by a review of experimental approaches for quantitative analysis of the surface chemistry at concentrations relevant to spectroscopic measurements. We end by highlighting some new directions in ligand chemistry, namely all-inorganically passivated semiconductor nanocrystals and new applications of surface emission.

18.
Proc Natl Acad Sci U S A ; 109(43): 17669-74, 2012 Oct 23.
Artigo em Inglês | MEDLINE | ID: mdl-22988095

RESUMO

O-GlcNAcylation is an abundant posttranslational modification in the brain implicated in human neurodegenerative diseases. We have exploited viable null alleles of the enzymes of O-GlcNAc cycling to examine the role of O-GlcNAcylation in well-characterized Caenorhabditis elegans models of neurodegenerative proteotoxicity. O-GlcNAc cycling dramatically modulated the severity of the phenotype in transgenic models of tauopathy, amyloid ß-peptide, and polyglutamine expansion. Intriguingly, loss of function of O-GlcNAc transferase alleviated, whereas loss of O-GlcNAcase enhanced, the phenotype of multiple neurodegenerative disease models. The O-GlcNAc cycling mutants act in part by altering DAF-16-dependent transcription and modulating the protein degradation machinery. These findings suggest that O-GlcNAc levels may directly influence neurodegenerative disease progression, thus making the enzymes of O-GlcNAc cycling attractive targets for neurodegenerative disease therapies.


Assuntos
Acetilglucosamina/metabolismo , Caenorhabditis elegans/metabolismo , Modelos Animais de Doenças , Mutação , Doenças Neurodegenerativas/patologia , Alelos , Animais , Caenorhabditis elegans/genética , Humanos , Doenças Neurodegenerativas/metabolismo , Proteólise
19.
Hippocampus ; 24(1): 32-43, 2014 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-23996525

RESUMO

The slow afterhyperpolarizing current (sIAHP ) is a calcium-dependent potassium current that underlies the late phase of spike frequency adaptation in hippocampal and neocortical neurons. sIAHP is a well-known target of modulation by several neurotransmitters acting via the cyclic AMP (cAMP) and protein kinase A (PKA)-dependent pathway. The neuropeptide pituitary adenylate cyclase activating peptide (PACAP) and its receptors are present in the hippocampal formation. In this study we have investigated the effect of PACAP on the sIAHP and the signal transduction pathway used to modulate intrinsic excitability of hippocampal pyramidal neurons. We show that PACAP inhibits the sIAHP , resulting in a decrease of spike frequency adaptation, in rat CA1 pyramidal cells. The suppression of sIAHP by PACAP is mediated by PAC1 and VPAC1 receptors. Inhibition of PKA reduced the effect of PACAP on sIAHP, suggesting that PACAP exerts part of its inhibitory effect on sIAHP by increasing cAMP and activating PKA. The suppression of sIAHP by PACAP was also strongly hindered by the inhibition of p38 MAP kinase (p38 MAPK). Concomitant inhibition of PKA and p38 MAPK indicates that these two kinases act in a sequential manner in the same pathway leading to the suppression of sIAHP. Conversely, protein kinase C is not part of the signal transduction pathway used by PACAP to inhibit sIAHP in CA1 neurons. Our results show that PACAP enhances the excitability of CA1 pyramidal neurons by inhibiting the sIAHP through the activation of multiple signaling pathways, most prominently cAMP/PKA and p38 MAPK. Our findings disclose a novel modulatory action of p38 MAPK on intrinsic excitability and the sIAHP, underscoring the role of this current as a neuromodulatory hub regulated by multiple protein kinases in cortical neurons.


Assuntos
Região CA1 Hipocampal/fisiologia , Sistema de Sinalização das MAP Quinases/fisiologia , Polipeptídeo Hipofisário Ativador de Adenilato Ciclase/metabolismo , Células Piramidais/fisiologia , Animais , Região CA1 Hipocampal/efeitos dos fármacos , Masculino , Técnicas de Patch-Clamp , Polipeptídeo Hipofisário Ativador de Adenilato Ciclase/farmacologia , Células Piramidais/efeitos dos fármacos , Ratos , Ratos Sprague-Dawley
20.
Int J Cancer ; 134(1): 32-42, 2014 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-23784932

RESUMO

Ovarian cancer is typically accompanied by the occurrence of malignant ascites containing large number of macrophages. It has been suggested that these tumor-associated macrophages (TAMs) are skewed to alternative polarization (M2) and thereby play an essential role in therapy resistance and metastatic spread. In our study, we have investigated the nature, regulation and clinical correlations of TAM polarization in serous ovarian cancer. Macrophage polarization markers on TAMs and ascites cytokine levels were analyzed for 30 patients and associated with relapse-free survival (RFS) in a prospective study with 20 evaluable patients. Surface expression of the M2 marker CD163 on TAMs was inversely associated with RFS (p < 0.01). However, global gene expression profiles determined for 17 of these patients revealed a mixed-polarization phenotype unrelated to the M1/M2 classification. CD163 surface expression also correlated with the ascites levels of IL-6 and IL-10 (p < 0.05), both cytokines induced CD163 expression, and their ascites levels showed a clear inverse association with RFS (p < 0.01). These findings define a subgroup of patients with high CD163 expression, high IL-6 and/or IL-10 levels and poor clinical outcome.


Assuntos
Ascite/imunologia , Cistadenocarcinoma Seroso/imunologia , Macrófagos/imunologia , Neoplasias Ovarianas/imunologia , Antígenos CD/biossíntese , Antígenos CD/imunologia , Antígenos de Diferenciação Mielomonocítica/biossíntese , Antígenos de Diferenciação Mielomonocítica/imunologia , Polaridade Celular , Cistadenocarcinoma Seroso/metabolismo , Cistadenocarcinoma Seroso/patologia , Citocinas/biossíntese , Citocinas/imunologia , Intervalo Livre de Doença , Ensaio de Imunoadsorção Enzimática , Feminino , Citometria de Fluxo , Humanos , Estimativa de Kaplan-Meier , Macrófagos/metabolismo , Macrófagos/patologia , Recidiva Local de Neoplasia/imunologia , Recidiva Local de Neoplasia/metabolismo , Recidiva Local de Neoplasia/patologia , Análise de Sequência com Séries de Oligonucleotídeos , Neoplasias Ovarianas/metabolismo , Neoplasias Ovarianas/patologia , Fenótipo , Receptores de Superfície Celular/biossíntese , Receptores de Superfície Celular/imunologia , Transcriptoma
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA