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1.
Metabolomics ; 17(3): 32, 2021 03 11.
Artículo en Inglés | MEDLINE | ID: mdl-33704614

RESUMEN

INTRODUCTION: Prostate cancer is a multifactorial disease whose aetiology is still not fully understood. Metabolomics, by measuring several hundred metabolites simultaneously, could enhance knowledge on the metabolic changes involved and the potential impact of external factors. OBJECTIVES: The aim of the present study was to investigate whether pre-diagnostic plasma metabolomic profiles were associated with the risk of developing a prostate cancer within the following decade. METHODS: A prospective nested case-control study was set up among the 5141 men participant of the SU.VI.MAX cohort, including 171 prostate cancer cases, diagnosed between 1994 and 2007, and 171 matched controls. Nuclear magnetic resonance (NMR) metabolomic profiles were established from baseline plasma samples using NOESY1D and CPMG sequences. Multivariable conditional logistic regression models were computed for each individual NMR signal and for metabolomic patterns derived using principal component analysis. RESULTS: Men with higher fasting plasma levels of valine (odds ratio (OR) = 1.37 [1.07-1.76], p = .01), glutamine (OR = 1.30 [1.00-1.70], p = .047), creatine (OR = 1.37 [1.04-1.80], p = .02), albumin lysyl (OR = 1.48 [1.12-1.95], p = .006 and OR = 1.51 [1.13-2.02], p = .005), tyrosine (OR = 1.40 [1.06-1.85], p = .02), phenylalanine (OR = 1.39 [1.08-1.79], p = .01), histidine (OR = 1.46 [1.12-1.88], p = .004), 3-methylhistidine (OR = 1.37 [1.05-1.80], p = .02) and lower plasma level of urea (OR = .70 [.54-.92], p = .009) had a higher risk of developing a prostate cancer during the 13 years of follow-up. CONCLUSIONS: This exploratory study highlighted associations between baseline plasma metabolomic profiles and long-term risk of developing prostate cancer. If replicated in independent cohort studies, such signatures may improve the identification of men at risk for prostate cancer well before diagnosis and the understanding of this disease.


Asunto(s)
Espectroscopía de Resonancia Magnética/métodos , Metabolómica/métodos , Neoplasias de la Próstata/diagnóstico , Adulto , Biomarcadores de Tumor , Estudios de Casos y Controles , Humanos , Modelos Logísticos , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Estudios Prospectivos
2.
Br J Nutr ; 126(7): 982-992, 2021 10 14.
Artículo en Inglés | MEDLINE | ID: mdl-33298217

RESUMEN

Host-microbial co-metabolism products are being increasingly recognised to play important roles in physiological processes. However, studies undertaking a comprehensive approach to consider host-microbial metabolic relationships remain scarce. Metabolomic analysis yielding detailed information regarding metabolites found in a given biological compartment holds promise for such an approach. This work aimed to explore the associations between host plasma metabolomic signatures and gut microbiota composition in healthy adults of the Milieu Intérieur study. For 846 subjects, gut microbiota composition was profiled through sequencing of the 16S rRNA gene in stools. Metabolomic signatures were generated through proton NMR analysis of plasma. The associations between metabolomic variables and α- and ß-diversity indexes and relative taxa abundances were tested using multi-adjusted partial Spearman correlations, permutational ANOVA and multivariate associations with linear models, respectively. A multiple testing correction was applied (Benjamini-Hochberg, 10 % false discovery rate). Microbial richness was negatively associated with lipid-related signals and positively associated with amino acids, choline, creatinine, glucose and citrate (-0·133 ≤ Spearman's ρ ≤ 0·126). Specific associations between metabolomic signals and abundances of taxa were detected (twenty-five at the genus level and nineteen at the species level): notably, numerous associations were observed for creatinine (positively associated with eleven species and negatively associated with Faecalibacterium prausnitzii). This large-scale population-based study highlights metabolites associated with gut microbial features and provides new insights into the understanding of complex host-gut microbiota metabolic relationships. In particular, our results support the implication of a 'gut-kidney axis'. More studies providing a detailed exploration of these complex interactions and their implications for host health are needed.


Asunto(s)
Microbioma Gastrointestinal , Metaboloma , Adulto , Creatinina , Heces , Humanos , Metabolómica , Plasma/química , ARN Ribosómico 16S/genética
3.
J Pept Sci ; 27(11): e3357, 2021 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-34151482

RESUMEN

The p28 peptide derived from Pseudomonas aeruginosa azurin shows an anticancer activity after binding to p53 protein and is currently in Phase I of clinical trials. We have studied its structure in water and in a biomimetic media and show that the peptide is unstructured in water but when studied in a biomimetic medium assumes a structure very similar to the one observed in azurin, suggesting a high propensity of this peptide to maintain this secondary structure. Analysis of p28 sequences from different bacterial species indicates conservation of the secondary structure despite amino acid replacement in different positions, suggesting that others, similar peptides could be tested for binding to p53.


Asunto(s)
Antineoplásicos , Azurina , Antineoplásicos/farmacología , Biomimética , Fragmentos de Péptidos , Péptidos , Pseudomonas aeruginosa
4.
J Pept Sci ; 26(9): e3271, 2020 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-32585759

RESUMEN

Antimicrobial peptides (AMPs) appear as chemical compounds of increasing interest for their role in killing bacteria and, more recently, for their ability to bind endotoxin (lipopolysaccharide, LPS) that is released during bacterial infection and that may lead to septic shock. This dual role in the mechanism of action can further be enhanced in a synergistic way when two or more AMPs are combined together. Not all AMPs are able to bind LPS, suggesting that several modes of binding to the bacterial surface may exist. Here we analyze a natural AMP, crabrolin, and two mutated forms, one with increased positive charge (Crabrolin Plus) and the other with null charge (Crabrolin Minus), and compare their binding abilities to LPS. While Crabrolin WT as well Crabrolin Minus do not show binding to LPS, the mutated Crabrolin Plus exhibits binding and forms a well defined structure in the presence of LPS. The results strengthen the importance of positive charges for the binding to LPS and suggest the mutated form with increased positive charge as a promising candidate for antimicrobial and antiseptic activity.


Asunto(s)
Péptidos Catiónicos Antimicrobianos/farmacología , Lipopolisacáridos/metabolismo , Mutación , Venenos de Avispas/farmacología , Péptidos Catiónicos Antimicrobianos/química , Escherichia coli/efectos de los fármacos , Escherichia coli/metabolismo , Espectroscopía de Resonancia Magnética , Pruebas de Sensibilidad Microbiana , Modelos Moleculares , Unión Proteica , Conformación Proteica , Venenos de Avispas/química , Venenos de Avispas/genética
5.
Crit Care ; 23(1): 169, 2019 05 14.
Artículo en Inglés | MEDLINE | ID: mdl-31088568

RESUMEN

BACKGROUND: Septic shock is the most severe phase of sepsis and is associated with high rates of mortality. However, early stage prediction of septic shock outcomes remains difficult. Metabolomic techniques have emerged as a promising tool for improving prognosis. METHODS: Orthogonal projections to latent structures-discriminant analysis (OPLS-DA) models separating the serum metabolomes of survivors from those of non-survivors were established with samples obtained at the intensive care unit (ICU) admission (H0) and 24 h later (H24). For 51 patients with available H0 and H24 samples, multi-level modeling was performed to provide insight into different metabolic evolutions that occurred between H0 and H24 in the surviving and non-surviving patients. Relative quantification and receiver operational characteristic curves (ROC) were applied to estimate the predictability of key discriminatory metabolites for septic shock mortality. RESULTS: Metabolites that were involved in energy supply and protein breakdown were primarily responsible for differentiating survivors from non-survivors. This was not only seen in the H0 and H24 discriminatory models, but also in the H0-H24 paired models. Reanalysis of extra H0-H24 paired samples in the established multi-level model demonstrated good performance of the model for the classification of samplings. According to the ROC results, nine discriminatory metabolites defined consistently from the unpaired model and the H0-H24 time-trend change (ΔH24-H0) show good prediction of mortality. These results suggest that NMR-based metabolomic analysis is useful for a better overall assessment of septic shock patients. CONCLUSIONS: Dysregulation of the metabolites identified by this study is associated with poor outcomes for septic shock. Evaluation of these compounds during the first 24 h after ICU admission in the septic shock patient may be helpful for estimating the severity of cases and for predicting outcomes. TRIAL REGISTRATION: All human serum samples were collected and stored, provided by the "center of biologic resources for liver disease", in Jean Verdier Hospital, Bondy, France (BB-0033-00027).


Asunto(s)
Espectroscopía de Resonancia Magnética/métodos , Metabolómica/estadística & datos numéricos , Choque Séptico/metabolismo , Sobrevivientes/estadística & datos numéricos , Adulto , Anciano , Análisis Discriminante , Femenino , Francia , Humanos , Espectroscopía de Resonancia Magnética/estadística & datos numéricos , Masculino , Metabolómica/métodos , Persona de Mediana Edad , Análisis Multivariante , Pronóstico , Choque Séptico/fisiopatología , Análisis de Supervivencia
6.
Bioessays ; 38(6): 498-507, 2016 06.
Artículo en Inglés | MEDLINE | ID: mdl-27125471

RESUMEN

We propose that interaction rules derived from polyamine exchange in connected cells may explain the spatio-temporal organization of gap junctions observed during tissue regeneration and tumorigenesis. We also hypothesize that polyamine exchange can be considered as signal that allows cells to sense the proliferation status of their neighbors. Polyamines (putrescine, spermidine, and spermine) are indeed small aliphatic polycations that serve as fuels to sustain elevated proliferation rates of the order observed in cancer cells. Based on recent reports, we consider here that polyamines can be exchanged through gap junction channels between mammalian cells. Such intercellular exchange of polyamines has critical consequences on the local control of growth. In line with this hypothesis, the complex protein network that keeps polyamine levels finely tuned in mammalian cells can translate polyamine efflux or influx into integrated signals controlling transcription, translation, and cell communications.


Asunto(s)
Proliferación Celular/fisiología , Uniones Comunicantes/metabolismo , Poliaminas , Transducción de Señal , Animales , Humanos , Neoplasias/fisiopatología , Regeneración , Cicatrización de Heridas
7.
J Proteome Res ; 15(5): 1446-54, 2016 05 06.
Artículo en Inglés | MEDLINE | ID: mdl-27015127

RESUMEN

Radiofrequency ablation (RFA) is commonly performed as a curative approach in patients with hepatocellular carcinoma (HCC); however, the risk of tumor recurrence is difficult to predict due to a lack of reliable clinical and biological markers, and identification of new biomarkers poses a major challenge for improving prognoses. Metabolomics is a promising technique that may lead to the identification and characterization of new disease fingerprints. The objective of the present study was to explore, preoperatively and at various time points post-RFA, the metabolic profile of serum samples from HCC patients to identify factors associated with treatment response and recurrence. Sequential sera obtained before and after RFA procedures for 120 patients with HCC due to cirrhosis were investigated using nuclear magnetic resonance metabolomics. A multilevel orthogonal projection to latent structure analysis was used to discriminate intraindividual metabolic changes in response to RFA treatment. Recurrence-free survival differed depending on the underlying cause of cirrhosis. The statistical model showed significant differences depending on whether the liver disease had a viral or nonviral etiology before RFA intervention (explained variance of R(2)Y = 0.89 and predictability of Q(2)Y = 0.34). These profiles were also associated with specific and distinct metabolic responses after RFA.


Asunto(s)
Biomarcadores de Tumor/sangre , Carcinoma Hepatocelular/etiología , Carcinoma Hepatocelular/cirugía , Ablación por Catéter , Neoplasias Hepáticas/etiología , Neoplasias Hepáticas/cirugía , Metabolómica/métodos , Suero/metabolismo , Carcinoma Hepatocelular/mortalidad , Carcinoma Hepatocelular/patología , Supervivencia sin Enfermedad , Humanos , Cirrosis Hepática/etiología , Cirrosis Hepática/mortalidad , Cirrosis Hepática/virología , Neoplasias Hepáticas/mortalidad , Neoplasias Hepáticas/patología , Periodo Posoperatorio , Periodo Preoperatorio , Recurrencia , Suero/química , Factores de Tiempo , Resultado del Tratamiento , Virosis/complicaciones
8.
Anal Bioanal Chem ; 408(27): 7641-7649, 2016 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-27614981

RESUMEN

Septic shock is the most severe form of sepsis, which is still one of the leading causes of death in the intensive care unit (ICU). Even though early prognosis and diagnosis are known to be indispensable for reaching an optimistic outcome, pathogenic complexities and the lack of specific treatment make it difficult to predict the outcome individually. In the present study, serum samples from surviving and non-surviving septic shock patients were drawn before clinical intervention at admission. Metabolic profiles of all the samples were analyzed by liquid chromatography-mass spectrometry (LC-MS)-based metabolomics. One thousand four hundred nineteen peaks in positive mode and 1878 peaks in negative mode were retained with their relative standard deviation (RSD) below 30 %, in which 187 metabolites were initially identified by retention time and database in the light of the exact molecular mass. Differences between samples from the survivors and the non-survivors were investigated using multivariate and univariate analysis. Finally, 43 significantly varied metabolites were found in the comparison between survivors and non-survivors. Concretely, metabolites in the tricarboxylic acid (TCA) cycle, amino acids, and several energy metabolism-related metabolites were up-regulated in the non-survivors, whereas those in the urea cycle and fatty acids were generally down-regulated. Metabolites such as lysine, alanine, and methionine did not present significant changes in the comparison. Six metabolites were further defined as primary discriminators differentiating the survivors from the non-survivors at the early stage of septic shock. Our findings reveal that LC-MS-based metabolomics is a useful tool for studying septic shock. Graphical abstract ᅟ.


Asunto(s)
Cromatografía Liquida/métodos , Espectrometría de Masas/métodos , Metaboloma , Metabolómica/métodos , Choque Séptico/sangre , Choque Séptico/diagnóstico , Anciano , Aminoácidos/sangre , Análisis de Varianza , Biomarcadores/sangre , Ácidos Grasos/sangre , Femenino , Humanos , Unidades de Cuidados Intensivos , Límite de Detección , Masculino , Metabolómica/instrumentación , Persona de Mediana Edad , Análisis de Componente Principal , Pronóstico , Reproducibilidad de los Resultados , Choque Séptico/mortalidad , Choque Séptico/patología , Análisis de Supervivencia , Sobrevivientes/estadística & datos numéricos , Resultado del Tratamiento , Ácidos Tricarboxílicos/sangre
9.
Biochemistry ; 54(23): 3660-9, 2015 Jun 16.
Artículo en Inglés | MEDLINE | ID: mdl-26016807

RESUMEN

NFL-TBS.40-63 is a 24 amino acid peptide corresponding to the tubulin-binding site located on the light neurofilament subunit, which selectively enters glioblastoma cells, where it disrupts their microtubule network and inhibits their proliferation. We investigated its structural variability and binding modes on a tubulin heterodimer using a combination of NMR experiments, docking, and molecular dynamics (MD) simulations. Our results show that, while lacking a stable structure, the peptide preferentially binds on a specific single site located near the ß-tubulin C-terminal end, thus giving us precious hints regarding the mechanism of action of the NFL-TBS.40-63 peptide's antimitotic activity at the molecular level.


Asunto(s)
Modelos Moleculares , Proteínas de Neurofilamentos/química , Fragmentos de Péptidos/química , Tubulina (Proteína)/química , Sitios de Unión , Humanos , Ligandos , Simulación del Acoplamiento Molecular , Simulación de Dinámica Molecular , Proteínas de Neurofilamentos/metabolismo , Resonancia Magnética Nuclear Biomolecular , Fragmentos de Péptidos/metabolismo , Conformación Proteica , Pliegue de Proteína , Dominios y Motivos de Interacción de Proteínas , Estabilidad Proteica , Estructura Secundaria de Proteína , Solubilidad , Tubulina (Proteína)/metabolismo
10.
J Biol Chem ; 288(34): 24910-22, 2013 Aug 23.
Artículo en Inglés | MEDLINE | ID: mdl-23831686

RESUMEN

Microtubules are highly dynamic αß-tubulin polymers. In vitro and in living cells, microtubules are most often cold- and nocodazole-sensitive. When present, the MAP6/STOP family of proteins protects microtubules from cold- and nocodazole-induced depolymerization but the molecular and structure determinants by which these proteins stabilize microtubules remain under debate. We show here that a short protein fragment from MAP6-N, which encompasses its Mn1 and Mn2 modules (MAP6(90-177)), recapitulates the function of the full-length MAP6-N protein toward microtubules, i.e. its ability to stabilize microtubules in vitro and in cultured cells in ice-cold conditions or in the presence of nocodazole. We further show for the first time, using biochemical assays and NMR spectroscopy, that these effects result from the binding of MAP6(90-177) to microtubules with a 1:1 MAP6(90-177):tubulin heterodimer stoichiometry. NMR data demonstrate that the binding of MAP6(90-177) to microtubules involve its two Mn modules but that a single one is also able to interact with microtubules in a closely similar manner. This suggests that the Mn modules represent each a full microtubule binding domain and that MAP6 proteins may stabilize microtubules by bridging tubulin heterodimers from adjacent protofilaments or within a protofilament. Finally, we demonstrate that Ca(2+)-calmodulin competes with microtubules for MAP6(90-177) binding and that the binding mode of MAP6(90-177) to microtubules and Ca(2+)-calmodulin involves a common stretch of amino acid residues on the MAP6(90-177) side. This result accounts for the regulation of microtubule stability in cold condition by Ca(2+)-calmodulin.


Asunto(s)
Calmodulina/química , Proteínas Asociadas a Microtúbulos/química , Microtúbulos/química , Tubulina (Proteína)/química , Animales , Calmodulina/genética , Calmodulina/metabolismo , Células HeLa , Humanos , Espectroscopía de Resonancia Magnética , Ratones , Proteínas Asociadas a Microtúbulos/genética , Proteínas Asociadas a Microtúbulos/metabolismo , Microtúbulos/genética , Microtúbulos/metabolismo , Multimerización de Proteína/fisiología , Estructura Terciaria de Proteína , Ratas , Tubulina (Proteína)/genética , Tubulina (Proteína)/metabolismo
11.
J Biol Chem ; 287(4): 2446-58, 2012 Jan 20.
Artículo en Inglés | MEDLINE | ID: mdl-22147700

RESUMEN

The massive uptake of compatible osmolytes such as betaine, taurine, and myo-inositol is a protective response shared by all eukaryotes exposed to hypertonic stress. Their accumulation results mostly from the expression of specific transporters triggered by the transcriptional factor NFAT5/TonEBP. This allows the recovery of the cell volume without increasing intracellular ionic strength. In this study we consider the assembly and dissociation of mRNA stress granules (SGs) in hypertonic-stressed cells and the role of compatible osmolytes. In agreement with in vitro results obtained on isolated mRNAs, both macromolecular crowding and a high ionic strength favor the assembly of SGs in normal rat kidney epithelial cells. However, after hours of constant hypertonicity, the slow accumulation in the cytoplasm of compatible osmolytes via specific transporters both reduces macromolecular crowding and ionic strength, thus leading to the progressive dissociation of SGs. In line with this, when cells are exposed to hypertonicity to accumulate a large amount of compatible osmolytes, the formation of SGs is severely impaired, and cells increase their chances of survival to another hypertonic episode. Altogether, these results indicate that the impact of compatible osmolytes on the mRNA-associated machineries and especially that associated with SGs may play an important role in cell resistance and adaption to hyperosmolarity in many tissues like kidney and liver.


Asunto(s)
Gránulos Citoplasmáticos/metabolismo , Riñón/metabolismo , Hígado/metabolismo , ARN Mensajero/metabolismo , Animales , Línea Celular , Gránulos Citoplasmáticos/genética , Presión Osmótica/fisiología , ARN Mensajero/genética , Ratas , Ovinos , Factores de Transcripción/genética , Factores de Transcripción/metabolismo
12.
Membranes (Basel) ; 13(3)2023 Mar 22.
Artículo en Inglés | MEDLINE | ID: mdl-36984752

RESUMEN

(1) Background: antimicrobial resistance is becoming a dramatic problem for public health, and the design of new antimicrobial agents is an active research area. (2) Methods: based on our previous work, we designed an improved version of the crabrolin peptide and characterized its functional and structural properties with a wide range of techniques. (3) Results: the newly designed peptide, crabrolin21, is much more active than the previous ones and shows specific selectivity towards bacterial cells. (4) Conclusions: crabrolin21 shows interesting properties and deserves further studies.

13.
Biochemistry ; 51(21): 4331-42, 2012 May 29.
Artículo en Inglés | MEDLINE | ID: mdl-22558917

RESUMEN

Connexins are structurally related transmembrane proteins that assemble to form gap junction channels involved in the mediation of intercellular communication. It has been shown that the intracellular tail of connexin43 (Cx43) interacts with tubulin and microtubules with putative impacts on its own intracellular trafficking, its activity in channel communication, and its interference with specific growth factor signal transduction cascades. We demonstrate here that the microtubule binding of Cx43 is mainly driven by a short region of 26 amino acid residues located within the intracellular tail of Cx43. The nuclear magnetic resonance structural analysis of a peptide (K26D) corresponding to this region shows that this peptide is unstructured when free in solution and adopts a helix conformation upon binding with tubulin. In addition, the resulting K26D-tubulin molecular complex defines a new structural organization that could be shared by other microtubule partners. Interestingly, the K26D-tubulin interaction is prevented by the phosphorylation of K26D at a src kinase specific site. Altogether, the results elucidate the mechanism of the interaction of Cx43 with the microtubule cytoskeleton and propose a pathway for understanding the microtubule-dependent regulation of Cx43 gap junctional communications and the involvement of Cx43 in TGF-ß signal transduction.


Asunto(s)
Conexina 43/química , Conexina 43/metabolismo , Microtúbulos/metabolismo , Tubulina (Proteína)/metabolismo , Secuencia de Aminoácidos , Animales , Comunicación Celular , Conexina 43/genética , Cristalografía por Rayos X , Uniones Comunicantes/metabolismo , Humanos , Técnicas In Vitro , Modelos Moleculares , Datos de Secuencia Molecular , Resonancia Magnética Nuclear Biomolecular , Fragmentos de Péptidos/química , Fragmentos de Péptidos/genética , Fragmentos de Péptidos/metabolismo , Fosforilación , Conformación Proteica , Dominios y Motivos de Interacción de Proteínas , Ovinos
14.
Biochemistry ; 51(44): 8919-30, 2012 Nov 06.
Artículo en Inglés | MEDLINE | ID: mdl-23046344

RESUMEN

Being able to differentiate local fluctuations from global folding-unfolding dynamics of a protein is of major interest for improving our understanding of structure-function determinants. The maltose binding protein (MBP), a protein that belongs to the maltose transport system, has a structure composed of two globular domains separated by a rigid-body "hinge bending". Here we determined, by using hydrogen exchange (HX) nuclear magnetic resonance experiments, the apparent stabilization free energies of 101 residues of MBP bound to ß-cyclodextrin (MBP-ßCD) under native conditions. We observed that the last helix of MBP (helix α14) has a lower protection factor than the rest of the protein. Further, HX experiments were performed using guanidine hydrochloride under subdenaturing conditions to discriminate between local fluctuations and global unfolding events and to determine the MBP-ßCD energy landscape. The results show that helix α4 and a part of helices α5 and α6 are clearly grouped into a subdenaturing folding unit and represent a partially folded intermediate under native conditions. In addition, we observed that amide protons located in the hinge between the two globular domains share similar ΔG(gu)(app) and m values and should unfold simultaneously. These observations provide new points of view for improving our understanding of the thermodynamic stability and the mechanisms that drive folding-unfolding dynamics of proteins.


Asunto(s)
Proteínas de Unión a Maltosa/química , Pliegue de Proteína , Desplegamiento Proteico , Hidrógeno/metabolismo , Espectroscopía de Resonancia Magnética , Estructura Secundaria de Proteína , Termodinámica
15.
J Biol Chem ; 286(4): 3065-78, 2011 Jan 28.
Artículo en Inglés | MEDLINE | ID: mdl-21062741

RESUMEN

The C-terminal region of tubulin is involved in multiple aspects of the regulation of microtubule assembly. To elucidate the molecular mechanisms of this regulation, we study here, using different approaches, the interaction of Tau, spermine, and calcium, three representative partners of the tubulin C-terminal region, with a peptide composed of the last 42 residues of α1a-tubulin. The results show that their binding involves overlapping amino acid stretches in the C-terminal tubulin region: amino acid residues 421-441 for Tau, 430-432 and 444-451 for spermine, and 421-443 for calcium. Isothermal titration calorimetry, NMR, and cosedimentation experiments show that Tau and spermine have similar micromolar binding affinities, whereas their binding stoichiometry differs (C-terminal tubulin peptide/spermine stoichiometry 1:2, and C-terminal tubulin peptide/Tau stoichiometry 8:1). Interestingly, calcium, known as a negative regulator of microtubule assembly, can compete with the binding of Tau and spermine with the C-terminal domain of tubulin and with the positive effect of these two partners on microtubule assembly in vitro. This observation opens up the possibility that calcium may participate in the regulation of microtubule assembly in vivo through direct (still unknown) or indirect mechanism (displacement of microtubule partners). The functional importance of this part of tubulin was also underlined by the observation that an α-tubulin mutant deleted from the last 23 amino acid residues does not incorporate properly into the microtubule network of HeLa cells. Together, these results provide a structural basis for a better understanding of the complex interactions and putative competition of tubulin cationic partners with the C-terminal region of tubulin.


Asunto(s)
Calcio/metabolismo , Espermidina/metabolismo , Tubulina (Proteína)/metabolismo , Proteínas tau/metabolismo , Calcio/química , Cationes/química , Cationes/metabolismo , Células HeLa , Humanos , Microtúbulos/química , Microtúbulos/genética , Microtúbulos/metabolismo , Resonancia Magnética Nuclear Biomolecular , Unión Proteica , Estructura Terciaria de Proteína , Espermidina/química , Tubulina (Proteína)/química , Tubulina (Proteína)/genética , Proteínas tau/química , Proteínas tau/genética
16.
Metabolites ; 12(11)2022 Nov 08.
Artículo en Inglés | MEDLINE | ID: mdl-36355164

RESUMEN

Metabolic dysfunction-associated fatty liver disease (MAFLD) is a complex disorder that is implicated in dysregulations in multiple biological pathways, orchestrated by interactions between genetic predisposition, metabolic syndromes and environmental factors. The limited knowledge of its pathogenesis is one of the bottlenecks in the development of prognostic and therapeutic options for MAFLD. Moreover, the extent to which metabolic pathways are altered due to ongoing hepatic steatosis, inflammation and fibrosis and subsequent liver damage remains unclear. To uncover potential MAFLD pathogenesis in humans, we employed an untargeted nuclear magnetic resonance (NMR) spectroscopy- and high-resolution mass spectrometry (HRMS)-based multiplatform approach combined with a computational multiblock omics framework to characterize the plasma metabolomes and lipidomes of obese patients without (n = 19) or with liver biopsy confirmed MAFLD (n = 63). Metabolite features associated with MAFLD were identified using a metabolome-wide association study pipeline that tested for the relationships between feature responses and MAFLD. A metabolic pathway enrichment analysis revealed 16 pathways associated with MAFLD and highlighted pathway changes, including amino acid metabolism, bile acid metabolism, carnitine shuttle, fatty acid metabolism, glycerophospholipid metabolism, arachidonic acid metabolism and steroid metabolism. These results suggested that there were alterations in energy metabolism, specifically amino acid and lipid metabolism, and pointed to the pathways being implicated in alerted liver function, mitochondrial dysfunctions and immune system disorders, which have previously been linked to MAFLD in human and animal studies. Together, this study revealed specific metabolic alterations associated with MAFLD and supported the idea that MAFLD is fundamentally a metabolism-related disorder, thereby providing new perspectives for diagnostic and therapeutic strategies.

17.
Biophys J ; 101(1): 205-16, 2011 Jul 06.
Artículo en Inglés | MEDLINE | ID: mdl-21723831

RESUMEN

Microtubules (MTs) are cylindrical cytoskeleton polymers composed of α-ß tubulin heterodimers whose dynamic properties are essential to fulfill their numerous cellular functions. In response to spatial confinement, dynamic MTs, even in the absence of protein partners, were shown to self-organize into higher order structures (spindle or striped structures) which lead to interesting dynamical properties (MT oscillations). In this study, we considered the assembly and sensitivity of dynamic MTs when in bundles. To perform this study, spermine, a natural tetravalent polyamine present at high concentrations in all eukaryote cells, was used to trigger MT bundling while preserving MT dynamics. Interestingly, we first show that, near physiological ionic strengths, spermine promotes the bundling of MTs whereas it does not lead to aggregation of free tubulin, which would have been detrimental to MT polymerization. Experimental and theoretical results also indicate that, to obtain a high rate of bundle assembly, bundling should take place at the beginning of assembly when rapid rotational movements of short and newly nucleated MTs are still possible. On the other hand, the bundling process is significantly slowed down for long MTs. Finally, we found that short MT bundles exhibit a higher sensitivity to cold exposure than do isolated MTs. To account for this phenomenon, we suggest that a collective behavior takes place within MT bundles because an MT entering into a phase of shortening could increase the probability of the other MTs in the same bundle to enter into shortening phase due to their close proximity. We then elaborate on some putative applications of our findings to in vivo conditions including neurons.


Asunto(s)
Microtúbulos/efectos de los fármacos , Microtúbulos/metabolismo , Espermina/farmacología , Animales , Frío , Difusión/efectos de los fármacos , Cinética , Concentración Osmolar , Estructura Cuaternaria de Proteína , Ovinos , Tubulina (Proteína)/química
18.
Am J Physiol Cell Physiol ; 301(3): C705-16, 2011 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-21677260

RESUMEN

Upon hypertonic stress most often resulting from high salinity, cells need to balance their osmotic pressure by accumulating neutral osmolytes called compatible osmolytes like betaine, myo-inositol, and taurine. However, the massive uptake of compatible osmolytes is a slow process compared with other defense mechanisms related to oxidative or heat stress. This is especially critical for cycling cells as they have to double their volume while keeping a hospitable intracellular environment for the molecular machineries. Here we propose that clustered cells can accelerate the supply of compatible osmolytes to cycling cells via the transit, mediated by gap junctions, of compatible osmolytes from arrested to cycling cells. Both experimental results in epithelial normal rat kidney cells and theoretical estimations show that gap junctions indeed play a key role in cell adaptation to chronic hypertonicity. These results can provide basis for a better understanding of the functions of gap junctions in osmoregulation not only for the kidney but also for many other epithelia. In addition to this, we suggest that cancer cells that do not communicate via gap junctions poorly cope with hypertonic environments thus explaining the rare occurrence of cancer coming from the kidney medulla.


Asunto(s)
Adaptación Fisiológica/fisiología , Células Epiteliales/fisiología , Uniones Comunicantes/fisiología , Riñón/fisiología , Estrés Fisiológico/fisiología , Equilibrio Hidroelectrolítico/fisiología , Adaptación Fisiológica/efectos de los fármacos , Animales , Betaína/metabolismo , Betaína/farmacología , Comunicación Celular/fisiología , Recuento de Células , Línea Celular , Proliferación Celular/efectos de los fármacos , Conexina 43/genética , Conexina 43/metabolismo , Citoesqueleto/metabolismo , Citoesqueleto/patología , Células Epiteliales/citología , Células Epiteliales/efectos de los fármacos , Células Epiteliales/patología , Uniones Comunicantes/efectos de los fármacos , Uniones Comunicantes/patología , Ácido Glicirretínico/farmacología , Células HeLa , Humanos , Soluciones Hipertónicas , Inositol/metabolismo , Inositol/farmacología , Riñón/citología , Microtúbulos/efectos de los fármacos , Microtúbulos/metabolismo , Microtúbulos/patología , Nocodazol/farmacología , Ácidos Oléicos/farmacología , ARN Interferente Pequeño/genética , Ratas , Solución Salina Hipertónica , Fibras de Estrés/metabolismo , Fibras de Estrés/patología , Estrés Fisiológico/efectos de los fármacos , Equilibrio Hidroelectrolítico/efectos de los fármacos , Cicatrización de Heridas/efectos de los fármacos , Cicatrización de Heridas/fisiología
19.
Biochem J ; 430(1): 151-9, 2010 Aug 15.
Artículo en Inglés | MEDLINE | ID: mdl-20524932

RESUMEN

Owing to preferential electrostatic adsorption of multivalent cations on highly anionic surfaces, natural multivalent polyamines and especially quadrivalent spermine can be considered as potential regulators of the complex dynamical properties of anionic MTs (microtubules). Indeed, the C-terminal tails of tubulin display many negative residues in a row which should enable the formation of a correlated liquid-like phase of multivalent counterions on its surface. Although it is known that polyamine counterions promote MT assembly in vitro, little is known about the relevance of this interaction in vivo. In the present study, we have explored the relationship between polyamine levels and MT assembly in HeLa and epithelial NRK (normal rat kidney) cells using DFMO (alpha-difluoromethylornithine), an irreversible inhibitor of ornithine decarboxylase, and APCHA [N-(3-aminopropyl)-N-cyclohexylamine], a spermine synthase inhibitor. Under conditions of intracellular polyamine depletion, the MT network is clearly disrupted and the MT mass decreases. Addition of spermine to polyamine-depleted cells reverses this phenotype and rapidly promotes the extensions of the MT network. Finally, we show that polyamine levels modulate the coating of MTs with MAP4 (MT-associated protein 4), an MT-stabilizing protein, and the spatial distribution of EB1 (end-binding protein 1), an MT plus-end-binding protein. In addition, polyamines favour the formation of gap junctions in NRK cells, a process which requires MT extensions at the cell periphery. The present study provides a basis for a better understanding of the role played by polyamines in MT assembly and establishes polyamine metabolism as a potential cellular target for modulating MT functions.


Asunto(s)
Microtúbulos/fisiología , Poliaminas/metabolismo , Animales , Comunicación Celular , Línea Celular , Células Epiteliales/fisiología , Células Epiteliales/ultraestructura , Uniones Comunicantes/fisiología , Humanos , Proteínas Asociadas a Microtúbulos/metabolismo , Microtúbulos/ultraestructura , Ratas , Ovinos , Tubulina (Proteína)/fisiología
20.
Cancers (Basel) ; 13(13)2021 Jun 23.
Artículo en Inglés | MEDLINE | ID: mdl-34201735

RESUMEN

BACKGROUND: The prevention and early screening of PCa is highly dependent on the identification of new biomarkers. In this study, we investigated whether plasma metabolic profiles from healthy males provide novel early biomarkers associated with future risk of PCa. METHODS: Using the Supplémentation en Vitamines et Minéraux Antioxydants (SU.VI.MAX) cohort, we identified plasma samples collected from 146 PCa cases up to 13 years prior to diagnosis and 272 matched controls. Plasma metabolic profiles were characterized using ultra-high-performance liquid chromatography-high resolution mass spectrometry (UHPLC-HRMS). RESULTS: Orthogonal partial least squares discriminant analysis (OPLS-DA) discriminated PCa cases from controls, with a median area under the receiver operating characteristic curve (AU-ROC) of 0.92 using a 1000-time repeated random sub-sampling validation. Sparse Partial Least Squares Discriminant Analysis (sPLS-DA) identified the top 10 most important metabolites (p < 0.001) discriminating PCa cases from controls. Among them, phosphate, ethyl oleate, eicosadienoic acid were higher in individuals that developed PCa than in the controls during the follow-up. In contrast, 2-hydroxyadenine, sphinganine, L-glutamic acid, serotonin, 7-keto cholesterol, tiglyl carnitine, and sphingosine were lower. CONCLUSION: Our results support the dysregulation of amino acids and sphingolipid metabolism during the development of PCa. After validation in an independent cohort, these signatures may promote the development of new prevention and screening strategies to identify males at future risk of PCa.

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