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1.
Eur J Neurosci ; 2024 Aug 28.
Artículo en Inglés | MEDLINE | ID: mdl-39205434

RESUMEN

While it is generally known that metabolic disorders and circadian dysfunction are intertwined, how the two systems affect each other is not well understood, nor are the genetic factors that might exacerbate this pathological interaction. Blood chemistry is profoundly changed in metabolic disorders, and we have previously shown that serum factors change cellular clock properties. To investigate if circulating factors altered in metabolic disorders have circadian modifying effects, and whether these effects are of genetic origin, we measured circadian rhythms in U2OS cell in the presence of serum collected from diabetic, obese or control subjects. We observed that circadian period lengthening in U2OS cells was associated with serum chemistry that is characteristic of insulin resistance. Characterizing the genetic variants that altered circadian period length by genome-wide association analysis, we found that one of the top variants mapped to the E3 ubiquitin ligase MARCH1 involved in insulin sensitivity. Confirming our data, the serum circadian modifying variants were also enriched in type 2 diabetes and chronotype variants identified in the UK Biobank cohort. Finally, to identify serum factors that might be involved in period lengthening, we performed detailed metabolomics and found that the circadian modifying variants are particularly associated with branched chain amino acids, whose levels are known to correlate with diabetes and insulin resistance. Overall, our multi-omics data showed comprehensively that systemic factors serve as a path through which metabolic disorders influence circadian system, and these can be examined in human populations directly by simple cellular assays in common cultured cells.

2.
Cell ; 139(7): 1327-41, 2009 Dec 24.
Artículo en Inglés | MEDLINE | ID: mdl-20064378

RESUMEN

p53 is a tumor suppressor protein whose function is frequently lost in cancers through missense mutations within the Tp53 gene. This results in the expression of point-mutated p53 proteins that have both lost wild-type tumor suppressor activity and show gain of functions that contribute to transformation and metastasis. Here, we show that mutant p53 expression can promote invasion, loss of directionality of migration, and metastatic behavior. These activities of p53 reflect enhanced integrin and epidermal growth factor receptor (EGFR) trafficking, which depends on Rab-coupling protein (RCP) and results in constitutive activation of EGFR/integrin signaling. We provide evidence that mutant p53 promotes cell invasion via the inhibition of TAp63, and simultaneous loss of p53 and TAp63 recapitulates the phenotype of mutant p53 in cells. These findings open the possibility that blocking alpha5/beta1-integrin and/or the EGF receptor will have therapeutic benefit in mutant p53-expressing cancers.


Asunto(s)
Movimiento Celular , Integrina alfa5beta1/metabolismo , Metástasis de la Neoplasia , Proteína p53 Supresora de Tumor/metabolismo , Proteínas Adaptadoras Transductoras de Señales/metabolismo , Línea Celular Tumoral , Receptores ErbB/metabolismo , Humanos , Proteínas de la Membrana/metabolismo , Mutación , Seudópodos/metabolismo , Proteína p53 Supresora de Tumor/genética
3.
Genes Dev ; 30(16): 1895-907, 2016 08 15.
Artículo en Inglés | MEDLINE | ID: mdl-27601530

RESUMEN

The discovery of transcription factors (TFs) controlling pathways in health and disease is of paramount interest. We designed a widely applicable method, dubbed barcorded synthetic tandem repeat promoter screening (BC-STAR-PROM), to identify signal-activated TFs without any a priori knowledge about their properties. The BC-STAR-PROM library consists of ∼3000 luciferase expression vectors, each harboring a promoter (composed of six tandem repeats of synthetic random DNA) and an associated barcode of 20 base pairs (bp) within the 3' untranslated mRNA region. Together, the promoter sequences encompass >400,000 bp of random DNA, a sequence complexity sufficient to capture most TFs. Cells transfected with the library are exposed to a signal, and the mRNAs that it encodes are counted by next-generation sequencing of the barcodes. This allows the simultaneous activity tracking of each of the ∼3000 synthetic promoters in a single experiment. Here we establish proof of concept for BC-STAR-PROM by applying it to the identification of TFs induced by drugs affecting actin and tubulin cytoskeleton dynamics. BC-STAR-PROM revealed that serum response factor (SRF) is the only immediate early TF induced by both actin polymerization and microtubule depolymerization. Such changes in cytoskeleton dynamics are known to occur during the cell division cycle, and real-time bioluminescence microscopy indeed revealed cell-autonomous SRF-myocardin-related TF (MRTF) activity bouts in proliferating cells.


Asunto(s)
Estudios de Asociación Genética/métodos , Regiones Promotoras Genéticas/genética , Secuencias Repetidas en Tándem/genética , Factores de Transcripción/genética , Animales , Antineoplásicos/farmacología , Línea Celular , Citoesqueleto/efectos de los fármacos , Depsipéptidos/farmacología , Técnicas de Silenciamiento del Gen , Genes Sintéticos , Técnicas Genéticas/normas , Humanos , Ratones , Factor de Respuesta Sérica/genética , Transducción de Señal , Vinblastina/farmacología
4.
Nucleic Acids Res ; 41(16): 7783-92, 2013 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-23814182

RESUMEN

The initiation factor 4E (eIF4E) is implicated in most of the crucial steps of the mRNA life cycle and is recognized as a pivotal protein in gene regulation. Many of these roles are mediated by its interaction with specific proteins generally known as eIF4E-interacting partners (4E-IPs), such as eIF4G and 4E-BP. To screen for new 4E-IPs, we developed a novel approach based on structural, in silico and biochemical analyses. We identified the protein Angel1, a member of the CCR4 deadenylase family. Immunoprecipitation experiments provided evidence that Angel1 is able to interact in vitro and in vivo with eIF4E. Point mutation variants of Angel1 demonstrated that the interaction of Angel1 with eIF4E is mediated through a consensus eIF4E-binding motif. Immunofluorescence and cell fractionation experiments showed that Angel1 is confined to the endoplasmic reticulum and Golgi apparatus, where it partially co-localizes with eIF4E and eIF4G, but not with 4E-BP. Furthermore, manipulating Angel1 levels in living cells had no effect on global translation rates, suggesting that the protein has a more specific function. Taken together, our results illustrate that we developed a powerful method for identifying new eIF4E partners and open new perspectives for understanding eIF4E-specific regulation.


Asunto(s)
Proteínas Portadoras/metabolismo , Factor 4E Eucariótico de Iniciación/metabolismo , Animales , Proteínas Portadoras/química , Proteínas Portadoras/clasificación , Citoplasma/química , Retículo Endoplásmico/química , Factor 4E Eucariótico de Iniciación/análisis , Aparato de Golgi/química , Células HeLa , Humanos , Ratones , Dominios y Motivos de Interacción de Proteínas , Ribonucleasas/clasificación
5.
Nucleic Acids Res ; 39(8): 3496-503, 2011 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-21183464

RESUMEN

eIF4E binding protein (4E-BP) inhibits translation of capped mRNA by binding to the initiation factor eIF4E and is known to be mostly or completely unstructured in both free and bound states. Using small angle X-ray scattering (SAXS), we report here the analysis of 4E-BP structure in solution, which reveals that while 4E-BP is intrinsically disordered in the free state, it undergoes a dramatic compaction in the bound state. Our results demonstrate that 4E-BP and eIF4E form a 'fuzzy complex', challenging current visions of eIF4E/4E-BP complex regulation.


Asunto(s)
Factor 4E Eucariótico de Iniciación/química , Factores Eucarióticos de Iniciación/química , Factor 4E Eucariótico de Iniciación/metabolismo , Factores Eucarióticos de Iniciación/metabolismo , Modelos Moleculares , Unión Proteica , Dispersión del Ángulo Pequeño , Análisis de Secuencia de Proteína , Difracción de Rayos X
6.
CPT Pharmacometrics Syst Pharmacol ; 12(12): 1872-1883, 2023 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-37794718

RESUMEN

When used in real-world conditions, substantial interindividual variations in direct oral anticoagulant (DOAC) plasma concentrations are observed for a given dose, leading to a risk of over- or under-exposure and clinically significant adverse events. Physiologically-based pharmacokinetic (PBPK) models could help physicians to tailor DOAC prescriptions in vulnerable patient populations, such as those in the hospital setting. The present study aims to validate prospectively PBPK models for rivaroxaban and apixaban in a large cohort of elderly, polymorbid, and hospitalized patients. In using a model of geriatric population integrating appropriate physiological parameters into models first optimized with healthy volunteer data, observed plasma concentration collected in hospitalized patients on apixaban (n = 100) and rivaroxaban (n = 100) were adequately predicted (ratio predicted/observed area under the concentration curve for a dosing interval [AUCtau ] = 0.97 [0.96-0.99] geometric mean, 90% confidence interval, ratio predicted/observed AUCtau = 1.03 [1.02-1.05]) for apixaban and rivaroxaban, respectively. Validation of the present PBPK models for rivaroxaban and apixaban in in-patients represent an additional step toward the feasibility of bedside use.


Asunto(s)
Pirazoles , Rivaroxabán , Humanos , Anciano , Rivaroxabán/farmacocinética , Pirazoles/farmacocinética , Piridonas/farmacocinética , Administración Oral , Anticoagulantes
7.
CPT Pharmacometrics Syst Pharmacol ; 12(10): 1541-1552, 2023 10.
Artículo en Inglés | MEDLINE | ID: mdl-37723920

RESUMEN

This study aimed to characterize apixaban pharmacokinetics (PKs) and its variability in a real-world clinical setting of hospitalized patients using a population PK (PopPK) approach. Model-based simulations helped to identify factors that affect apixaban exposure and their clinical significance. A classic stepwise strategy was applied to determine the best PopPK model for describing typical apixaban PKs in hospitalized patients from the OptimAT study (n = 100) and evaluating the associated variability and influencing factors. Apixaban exposure under specific conditions was assessed using the final model. A two-compartment model with first-order absorption and elimination best described the data. The developed PopPK model revealed a major role of renal function and a minor role of P-glycoprotein phenotypic (P-gp) activity in explaining apixaban variability. The final model indicated that a patient with stage 4 chronic kidney disease (creatinine clearance [CLcr] = 15-29 mL/min) would have a 45% higher drug exposure than a patient with normal renal function (CLcr >90 mL/min), with a further 12% increase if the patient was also a poor metabolizer of P-gp. A high interindividual variability in apixaban PKs was observed in a real-life setting, which was partially explained by renal function and by P-gp phenotypic activity. Target apixaban concentrations are reached under standard dosage regimens, but overexposure can rapidly occur in the presence of cumulative factors warranting the development of a predictive tool for tailoring apixaban exposure and its clinical utility in at-risk patients.


Asunto(s)
Modelos Biológicos , Piridonas , Humanos , Piridonas/farmacocinética , Pirazoles/farmacocinética , Área Bajo la Curva
8.
PLoS One ; 18(4): e0281585, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-37018188

RESUMEN

BACKGROUND: Despite the widespread use of glucocorticoids in inflammatory and autoimmune disorders, there is uncertainty about the safe cessation of long-term systemic treatment, as data from prospective trials are largely missing. Due to potential disease relapse or glucocorticoid-induced hypocortisolism, the drug is often tapered to sub-physiological doses rather than stopped when the underlying disease is clinically stable, increasing the cumulative drug exposure. Conversely, the duration of exposure to glucocorticoids should be minimized to lower the risk of side effects. METHODS: We designed a multicenter, randomized, triple-blinded, placebo-controlled trial to test the clinical noninferiority of abrupt glucocorticoid stop compared to tapering after ≥28 treatment days with ≥420 mg cumulative and ≥7.5 mg mean daily prednisone-equivalent dose. 573 adult patients treated systemically for various disorders will be included after their underlying disease has been stabilized. Prednisone in tapering doses or matching placebo is administered over 4 weeks. A 250 mg ACTH-test, the result of which will be revealed a posteriori, is performed at study inclusion; all patients are instructed on glucocorticoid stress cover dosing. Follow-up is for 6 months. The composite primary outcome measure is time to hospitalization, death, initiation of unplanned systemic glucocorticoid therapy, or adrenal crisis. Secondary outcomes include the individual components of the primary outcome, cumulative glucocorticoid doses, signs and symptoms of hypocortisolism, and the performance of the ACTH test in predicting the clinical outcome. Cox proportional hazard, linear, and logistic regression models will be used for statistical analysis. CONCLUSION: This trial aims to demonstrate the clinical noninferiority and safety of abrupt treatment cessation after ≥28 days of systemic glucocorticoid therapy in patients with stabilized underlying disease. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT03153527; EUDRA-CT: 2020-005601-48 https://clinicaltrials.gov/ct2/show/NCT03153527?term=NCT03153527&draw=2&rank=1.


Asunto(s)
Insuficiencia Suprarrenal , Glucocorticoides , Adulto , Humanos , Insuficiencia Suprarrenal/inducido químicamente , Hormona Adrenocorticotrópica , Glucocorticoides/efectos adversos , Glucocorticoides/uso terapéutico , Estudios Multicéntricos como Asunto , Recurrencia Local de Neoplasia/tratamiento farmacológico , Prednisona/efectos adversos , Prednisona/uso terapéutico , Estudios Prospectivos , Ensayos Clínicos Controlados Aleatorios como Asunto , Privación de Tratamiento
9.
Clin Transl Sci ; 15(7): 1796-1804, 2022 07.
Artículo en Inglés | MEDLINE | ID: mdl-35706350

RESUMEN

During the latest pandemic, the RECOVERY study showed the benefits of dexamethasone (DEX) use in COVID-19 patients. Obesity has been proven to be an independent risk factor for severe forms of infection, but little information is available in the literature regarding DEX dose adjustment according to body weight. We conducted a prospective, observational, exploratory study at Geneva University Hospitals to assess the impact of weight on DEX pharmacokinetics (PK) in normal-weight versus obese COVID-19 hospitalized patients. Two groups of patients were enrolled: normal-weight and obese (body mass index [BMI] 18.5-25 and >30 kg/m2 , respectively). All patients received the standard of care therapy of 6 mg DEX orally. Blood samples were collected, and DEX concentrations were measured. The mean DEX AUC0-8 and Cmax were lower in the obese compared to the normal-weight group (572.02 ± 258.96 vs. 926.92 ± 552.12 ng h/ml and 138.67 ± 68.03 vs. 203.44 ± 126.30 ng/ml, respectively). A decrease in DEX AUC0-8 of 4% per additional BMI unit was observed, defining a significant relationship between weight and DEX AUC0-8 (p = 0.004, 95% CI 2-7%). In women, irrespective of the BMI, DEX AUC0-8 increased by 214% in comparison to men (p < 0.001, 95% CI 154-298%). Similarly, the mean Cmax increased by 205% in women (p < 0.001, 95% CI 141-297%). Conversely, no significant difference between the obese and normal-weight groups was observed for exploratory treatment outcomes, such as the length of hospitalization. BMI, weight, and gender significantly affected DEX AUC. We conclude that dose adjustment would be needed if the aim is to achieve the same exposures in normal-weight and obese patients.


Asunto(s)
Tratamiento Farmacológico de COVID-19 , Índice de Masa Corporal , Dexametasona/efectos adversos , Femenino , Humanos , Masculino , Obesidad/complicaciones , Estudios Prospectivos
10.
J Pers Med ; 12(4)2022 Mar 24.
Artículo en Inglés | MEDLINE | ID: mdl-35455642

RESUMEN

Apixaban and rivaroxaban are the two most prescribed direct factor Xa inhibitors. With the increased use of DOACs in real-world settings, safety and efficacy concerns have emerged, particularly regarding their concomitant use with other drugs. Increasing evidence highlights drug−drug interactions with CYP3A/P-gp modulators leading to adverse events. However, current recommendations for dose adjustment do not consider CYP3A/P-gp genotype and phenotype. We aimed to determine their impact on apixaban and rivaroxaban blood exposure. Three-hundred hospitalized patients were included. CYP3A and P-gp phenotypic activities were assessed by the metabolic ratio of midazolam and AUC0−6h of fexofenadine, respectively. Relevant CYP3A and ABCB1 genetic polymorphisms were also tested. Capillary blood samples collected at four time-points after apixaban or rivaroxaban administration allowed the calculation of pharmacokinetic parameters. According to the developed multivariable linear regression models, P-gp activity (p < 0.001) and creatinine clearance (CrCl) (p = 0.01) significantly affected apixaban AUC0−6h. P-gp activity (p < 0.001) also significantly impacted rivaroxaban AUC0−6h. The phenotypic switch (from normal to poor metabolizer) of P-gp led to an increase of apixaban and rivaroxaban AUC0−6h by 16% and 25%, respectively, equivalent to a decrease of 38 mL/min in CrCl according to the apixaban model. CYP3A phenotype and tested SNPs of CYP3A/P-gp had no significant impact. In conclusion, P-gp phenotypic activity, rather than known CYP3A/P-gp polymorphisms, could be relevant for dose adjustment.

11.
Clin Pharmacol Ther ; 111(6): 1268-1277, 2022 06.
Artículo en Inglés | MEDLINE | ID: mdl-35262906

RESUMEN

Precision dosing strategies require accounting for between-patient variability in pharmacokinetics together with subsequent pharmacodynamic differences. Liquid biopsy is a valuable new approach to diagnose disease prior to the appearance of clinical signs and symptoms, potentially circumventing invasive tissue biopsies. However, the possibility of quantitative grading of biomarkers, as opposed to simply confirming their presence or absence, is relatively new. In this study, we aimed to verify expression measurements of cytochrome P450 (CYP) enzymes and the transporter P-glycoprotein (P-gp) in liquid biopsy against genotype and activity phenotype (assessed by the Geneva cocktail approach) in 30 acutely ill patients with cardiovascular disease in a hospital setting. After accounting for exosomal shedding, expression in liquid biopsy correlated with activity phenotype for CYP1A2, CYP2B6, CYP2C9, CYP3A, and P-gp (r = 0.44-0.70, P ≤ 0.05). Although genotype offered a degree of stratification, large variability (coefficient of variation (CV)) in activity (up to 157%) and expression in liquid biopsy (up to 117%) was observed within each genotype, indicating a mismatch between genotype and phenotype. Further, exosome screening revealed expression of 497 targets relevant to drug metabolism and disposition (159 enzymes and 336 transporters), as well as 20 molecular drug targets. Although there were no functional data available to correlate against these large-scale measurements, assessment of disease perturbation from healthy baseline was possible. Verification of liquid biopsy against activity phenotype is important to further individualize modeling approaches that aspire to achieve precision dosing from the start of drug treatment without the need for multiple rounds of dose optimization.


Asunto(s)
Enfermedades Cardiovasculares , Citocromo P-450 CYP3A , Subfamilia B de Transportador de Casetes de Unión a ATP , Biomarcadores , Enfermedades Cardiovasculares/diagnóstico , Enfermedades Cardiovasculares/tratamiento farmacológico , Enfermedades Cardiovasculares/genética , Citocromo P-450 CYP2C19/genética , Citocromo P-450 CYP2C9/genética , Citocromo P-450 CYP3A/metabolismo , Sistema Enzimático del Citocromo P-450/genética , Sistema Enzimático del Citocromo P-450/metabolismo , Humanos , Biopsia Líquida , Proteínas de Transporte de Membrana
12.
Acta Physiol (Oxf) ; 232(1): e13610, 2021 05.
Artículo en Inglés | MEDLINE | ID: mdl-33351229

RESUMEN

AIM: The worldwide increase in obesity and type 2 diabetes (T2D) represents a major health challenge. Chronically altered lipids induced by obesity further promote the development of T2D, and the accumulation of toxic lipid metabolites in serum and peripheral organs may contribute to the diabetic phenotype. METHODS: To better understand the complex metabolic pattern of lean and obese T2D and non-T2D individuals, we analysed the lipid profile of human serum, skeletal muscle and visceral adipose tissue of two cohorts by systematic mass spectrometry-based lipid analysis. RESULTS: Lipid homeostasis was strongly altered in a disease- and tissue-specific manner, allowing us to define T2D signatures associated with obesity from those that were obesity independent. Lipid changes encompassed lyso-, diacyl- and ether-phospholipids. Moreover, strong changes in sphingolipids included cytotoxic 1-deoxyceramide accumulation in a disease-specific manner in serum and visceral adipose tissue. The high amounts of non-canonical 1-deoxyceramide present in human adipose tissue most likely come from cell-autonomous synthesis because 1-deoxyceramide production increased upon differentiation to adipocytes in mouse cell culture experiments. CONCLUSION: Taken together, the observed lipidome changes in obesity and T2D will facilitate the identification of T2D patient subgroups and represent an important step towards personalized medicine in diabetes.


Asunto(s)
Diabetes Mellitus Tipo 2 , Esfingolípidos , Tejido Adiposo/fisiología , Animales , Éter , Humanos , Lípidos/química , Ratones , Obesidad
13.
Nat Commun ; 12(1): 2113, 2021 04 09.
Artículo en Inglés | MEDLINE | ID: mdl-33837202

RESUMEN

The accumulation of adenosine is strongly correlated with the need for sleep and the detection of sleep pressure is antagonised by caffeine. Caffeine also affects the circadian timing system directly and independently of sleep physiology, but how caffeine mediates these effects upon the circadian clock is unclear. Here we identify an adenosine-based regulatory mechanism that allows sleep and circadian processes to interact for the optimisation of sleep/wake timing in mice. Adenosine encodes sleep history and this signal modulates circadian entrainment by light. Pharmacological and genetic approaches demonstrate that adenosine acts upon the circadian clockwork via adenosine A1/A2A receptor signalling through the activation of the Ca2+ -ERK-AP-1 and CREB/CRTC1-CRE pathways to regulate the clock genes Per1 and Per2. We show that these signalling pathways converge upon and inhibit the same pathways activated by light. Thus, circadian entrainment by light is systematically modulated on a daily basis by sleep history. These findings contribute to our understanding of how adenosine integrates signalling from both light and sleep to regulate circadian timing in mice.


Asunto(s)
Adenosina/metabolismo , Trastornos Cronobiológicos/fisiopatología , Relojes Circadianos/efectos de los fármacos , Sueño/fisiología , Animales , Encéfalo/patología , Cafeína/farmacología , Línea Celular Tumoral , Trastornos Cronobiológicos/tratamiento farmacológico , Trastornos Cronobiológicos/etiología , Trastornos Cronobiológicos/patología , Relojes Circadianos/fisiología , Ritmo Circadiano/efectos de los fármacos , Ritmo Circadiano/fisiología , Modelos Animales de Enfermedad , Humanos , Luz , Masculino , Ratones , Ratones Transgénicos , Proteínas Circadianas Period/genética , Proteínas Circadianas Period/metabolismo , Fotoperiodo , Quinazolinas/administración & dosificación , Receptor de Adenosina A1/metabolismo , Receptor de Adenosina A2A/metabolismo , Transducción de Señal/efectos de los fármacos , Transducción de Señal/fisiología , Transducción de Señal/efectos de la radiación , Sueño/efectos de los fármacos , Privación de Sueño/complicaciones , Triazoles/administración & dosificación
14.
Artículo en Inglés | MEDLINE | ID: mdl-26683231

RESUMEN

In mammals, including humans, nearly all physiological processes are subject to daily oscillations that are governed by a circadian timing system with a complex hierarchical structure. The central pacemaker, residing in the suprachiasmatic nucleus (SCN) of the ventral hypothalamus, is synchronized daily by photic cues transmitted from the retina to SCN neurons via the retinohypothalamic tract. In turn, the SCN must establish phase coherence between self-sustained and cell-autonomous oscillators present in most peripheral cell types. The synchronization signals (Zeitgebers) can be controlled more or less directly by the SCN. In mice and rats, feeding-fasting rhythms, which are driven by the SCN through rest-activity cycles, are the most potent Zeitgebers for the circadian oscillators of peripheral organs. Signaling through the glucocorticoid receptor and the serum response factor also participate in the phase entrainment of peripheral clocks, and these two pathways are controlled by the SCN independently of feeding-fasting rhythms. Body temperature rhythms, governed by the SCN directly and indirectly through rest-activity cycles, are perhaps the most surprising cues for peripheral oscillators. Although the molecular makeup of circadian oscillators is nearly identical in all cells, these oscillators are used for different purposes in the SCN and in peripheral organs.


Asunto(s)
Actinas/metabolismo , Temperatura Corporal/fisiología , Relojes Circadianos/fisiología , Ritmo Circadiano/fisiología , Glucocorticoides/metabolismo , Receptores de Glucocorticoides/metabolismo , Retina/fisiología , Núcleo Supraquiasmático/fisiología , Animales , Relojes Biológicos , Señales (Psicología) , Ayuno/fisiología , Conducta Alimentaria/fisiología , Humanos , Mamíferos , Ratones , Ratas , Transducción de Señal
15.
Front Genet ; 5: 117, 2014.
Artículo en Inglés | MEDLINE | ID: mdl-24834072

RESUMEN

Fertilization of sea urchin eggs involves an increase in protein synthesis associated with a decrease in the amount of the translation initiation inhibitor 4E-BP. A highly simple reaction model for the regulation of protein synthesis was built and was used to simulate the physiological changes in the total 4E-BP amount observed during time after fertilization. Our study evidenced that two changes occurring at fertilization are necessary to fit with experimental data. The first change was an 8-fold increase in the dissociation parameter (koff1) of the eIF4E:4E-BP complex. The second was an important 32.5-fold activation of the degradation mechanism of the protein 4E-BP. Additionally, the changes in both processes should occur in 5 min time interval post-fertilization. To validate the model, we checked that the kinetic of the predicted 4.2-fold increase of eIF4E:eIF4G complex concentration at fertilization matched the increase of protein synthesis experimentally observed after fertilization (6.6-fold, SD = 2.3, n = 8). The minimal model was also used to simulate changes observed after fertilization in the presence of rapamycin, a FRAP/mTOR inhibitor. The model showed that the eIF4E:4E-BP complex destabilization was impacted and surprisingly, that the mechanism of 4E-BP degradation was also strongly affected, therefore suggesting that both processes are controlled by the protein kinase FRAP/mTOR.

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