RESUMEN
Diabetic retinopathy (DR) is one of the main causes of vision loss in middle-aged economically active people. Modifiable (i.e., hyperglycaemia, hypertension, hyperlipidaemia, obesity, and cigarette smoke) and non-modifiable factors (i.e., duration of diabetes, puberty, pregnancy and genetic susceptibility) are involved in the development of DR. Epigenetic mechanisms, modulating the oxidative stress, inflammation, apoptosis, and aging, could influence the course of DR. Herein, we conducted a systematic review of observational studies investigating how epigenetics affects type 2 diabetes retinopathy (T2DR). A total of 23 epidemiological studies were included: 14 studies focused on miRNA, 4 studies on lnc-RNA, one study on both miRNA and lnc-RNA, and 4 studies on global or gene-specific DNA methylation. A direct relation between the dysregulation of miR-21, miR-93, and miR-221 and FPG, HbA1c, and HOMA-IR was identified. A panel of three miRNAs (hsa-let-7a-5p, hsa-miR-novel-chr5_15976, and hsa-miR-28-3p) demonstrated a good sensitivity and specificity for predicting T2DR. Little evidence is available regarding the possible role of the long non-coding MALAT1 dysregulation and MTHFR gene promoter hypermethylation. Despite these initial, encouraging findings potentially suggesting a role of epigenetics in T2DR, the use in clinical practice for the diagnosis and staging of this complication encounters several difficulties and further targeted investigations are still necessary.
Asunto(s)
Metilación de ADN , Diabetes Mellitus Tipo 2/metabolismo , Retinopatía Diabética/metabolismo , Epigénesis Genética , Metilenotetrahidrofolato Reductasa (NADPH2)/biosíntesis , MicroARNs/biosíntesis , Regiones Promotoras Genéticas , ARN Largo no Codificante/biosíntesis , Diabetes Mellitus Tipo 2/genética , Diabetes Mellitus Tipo 2/patología , Retinopatía Diabética/genética , Retinopatía Diabética/patología , Humanos , Metilenotetrahidrofolato Reductasa (NADPH2)/genética , MicroARNs/genética , ARN Largo no Codificante/genéticaRESUMEN
One of the risk factors for vascular obstetric complications, such as intrauterine growth restriction (IUGR), is inherited thrombophilias. Nevertheless, routine screening for thrombophilias is not endorsed in pregnant women due to their low prevalence and conflicting results of published studies regarding the usefulness of screening in these patients. The cause of IUGR remains unknown in almost 1 quarter of cases. There are no published studies evaluating the association of inherited thrombophilias and IUGR in patients with IUGR of unknown origin. Understanding and preventing IUGR is an important public health concern, as IUGR has been associated with fetal mortality and neonatal morbidity, as well as adverse long-standing consequences. This study aimed to evaluate the prevalence of inherited thrombophilias in IUGR of unknown cause and to test the association between the inherited thrombophilias and IUGR of unknown cause.This study included 33 cases of IUGR of unknown cause tested for inherited thrombophilias and 66 controls individually matched for age, ethnicity, and smoking status.Patients with plasminogen activator inhibitor 1 (PAI-1) and methylenetetrahydrofolate reductase (MTHFR) had significantly higher odds for IUGR of unknown cause (Pâ<â.001 and Pâ=â.002, respectively) with OR 13.546 (CI 95% 3.79-48.37) and 8.139 (CI 95% 2.20-30.10), respectively. A positive association between other inherited thrombophilias (homozygous 20210 prothrombin gene mutation and homozygous factor V Leiden) and IUGR of unknown cause was also found, Pâ=â.096, OR 6.106 (CI 95% 0.72-51.30), although it was not statistically significant (Pâ=â.096, ORâ=â6.106, CI 95% 0.72-51.30).Our results indicate that PAI-1 and MTHFR thrombophilias represent risk factors for IUGR of otherwise unidentified cause.
Asunto(s)
Retardo del Crecimiento Fetal/etiología , Metilenotetrahidrofolato Reductasa (NADPH2)/biosíntesis , Inhibidor 1 de Activador Plasminogénico/biosíntesis , Trombofilia/complicaciones , Trombofilia/genética , Adulto , Índice de Masa Corporal , Estudios de Casos y Controles , Femenino , Humanos , Embarazo , Estudios RetrospectivosRESUMEN
Purpose: Hyperhomocysteinemia (Hhcy) is implicated in certain retinal neurovascular diseases, although whether it is causative remains uncertain. In isolated ganglion cells (GCs), mild Hhcy induces profound death, whereas retinal phenotypes in Hhcy mice caused by mutations in remethylation (methylene tetrahydrofolatereductase [Mthfr+/-]) or transsulfuration pathways (cystathionine ß-synthase [Cbs+/-]) demonstrate mild GC loss and mild vasculopathy. The current work investigated compensation in vivo of one pathway for the other, and, because the transsulfuration pathway yields cysteine necessary for formation of glutathione (GSH), taurine, and hydrogen sulfide (H2S), they were analyzed also. Methods: Retinas isolated from wild-type (WT), Mthfr+/-, and Cbs+/- mice (12 and 22 weeks) were analyzed for methylene tetrahydrofolate reductase (MTHFR), cystathionine-ß-synthase (CBS), and cystathionase (CTH) RNA/protein levels. Retinas were evaluated for levels of reduced:oxidized GSH (GSH:GSSG), Slc7a11 (xCT), taurine, taurine transporter (TAUT), and H2S. Results: Aside from decreased CBS RNA/protein levels in Cbs+/- retinas, there were minimal alterations in remethylation/transsulfuration pathways in the two mutant mice strains. Glutathione and taurine levels in Mthfr+/- and Cbs+/- retinas were similar to WT, which may be due to robust levels of xCT and TAUT in mutant retinas. Interestingly, levels of H2S were markedly increased in retinas of Mthfr+/- and Cbs+/- mice compared with WT. Conclusions: Ganglion cell loss and vasculopathy observed in Mthfr+/- and Cbs+/- mouse retinas may be milder than expected, not because of compensatory increases of enzymes in remethylation/transsulfuration pathways, but because downstream transsulfuration pathway products GSH, taurine, and H2S are maintained at robust levels. Elevation of H2S is particularly intriguing owing to neuroprotective properties reported for this gasotransmitter.
Asunto(s)
Regulación de la Expresión Génica , Glutatión/metabolismo , Sulfuro de Hidrógeno/metabolismo , Hiperhomocisteinemia/genética , Metilenotetrahidrofolato Reductasa (NADPH2)/genética , Células Ganglionares de la Retina/metabolismo , Taurina/metabolismo , Animales , Modelos Animales de Enfermedad , Hiperhomocisteinemia/complicaciones , Hiperhomocisteinemia/metabolismo , Metilenotetrahidrofolato Reductasa (NADPH2)/biosíntesis , Ratones , Ratones Endogámicos C57BL , Ratones Mutantes , ARN/genética , Reacción en Cadena en Tiempo Real de la Polimerasa , Retina/metabolismo , Retina/patología , Enfermedades de la Retina/etiología , Enfermedades de la Retina/genética , Enfermedades de la Retina/metabolismo , Células Ganglionares de la Retina/patologíaRESUMEN
Breast cancer (BC) is the leading cause of cancer-related death among women in 2014. Methylenetetrahydrofolate reductase (MTHFR), methionine synthase (MTR), and MTR reductase (MTRR) are enzymes that play an important role in folate metabolism. The single nucleotide polymorphisms, MTHFR C677T, A1298C, MTR A2756G, and MTRR A66G, alter plasmatic folate and homocysteine concentrations, causing problems during the repairment, synthesis, and methylation of the genetic material. Therefore, it is essential to know how BC risk is associated with histopathological and immunohistochemical characteristics, genotype polymorphisms, and gene expression in a high altitude Ecuadorian mestizo population. DNA was extracted from 195 healthy and 114 affected women. Genotypes were determined by restriction enzymes and genomic sequencing. mRNA was extracted from 26 glandular breast tissue samples, both from cancerous tissue and healthy tissue adjacent to the tumor. Relative gene expression was determined with the comparative Livak method (2(-ΔΔCT)). We found significant association between the rs1801133 (A222V) genotypes and an increased risk of BC development: C/T (odds ratio [OR] = 1.8; 95 % confidence interval [CI] = 1.1-3.2; P = 0.039), T/T (OR = 2.9; 95 % CI = 1.2-7.2; P = 0.025), and C/T + T/T (OR = 1.9; 95 % CI = 1.1-3.3; P = 0.019). Regarding relative gene expression, we found significant mRNA subexpression between the combined genotypes C/T + T/T (rs1801133) and triple negative breast cancer (TNBC) (P = 0.034). In brief, the MTHFR gene and its protein could act as potential predictive biomarkers of BC, especially TNBC among the high altitude Ecuadorian mestizo population.
Asunto(s)
Biomarcadores de Tumor/biosíntesis , Neoplasias de la Mama/genética , Ácido Fólico/metabolismo , Estudios de Asociación Genética , Metilenotetrahidrofolato Reductasa (NADPH2)/genética , Adulto , Anciano , Altitud , Biomarcadores de Tumor/genética , Neoplasias de la Mama/metabolismo , Neoplasias de la Mama/patología , Ecuador , Femenino , Ácido Fólico/genética , Regulación Neoplásica de la Expresión Génica , Predisposición Genética a la Enfermedad , Genotipo , Humanos , Metilenotetrahidrofolato Reductasa (NADPH2)/biosíntesis , Persona de Mediana Edad , Polimorfismo de Nucleótido Simple , ARN Mensajero/biosíntesis , Factores de RiesgoRESUMEN
PURPOSE: Methylenetetrahydrofolate reductase (Mthfr) is a key enzyme in homocysteine-methionine metabolism. We investigated Mthfr expression in retina and asked whether mild hyperhomocysteinemia, due to Mthfr deficiency, alters retinal neurovascular structure and function. METHODS: Expression of Mthfr was investigated at the gene and protein level using quantitative (q) RT-PCR, in situ hybridization, immunoblotting, and immunohistochemistry (IHC). The Mthfr+/+ and Mthfr+/- mice were subjected to comprehensive evaluation using ERG, funduscopy, fluorescein angiography (FA), spectral-domain optical coherence tomography (SD-OCT), HPLC, and morphometric and IHC analysis of glial fibrillary acidic protein (GFAP) at 8 to 24 weeks. RESULTS: Gene and protein analyses disclosed widespread retinal expression of Mthfr. Electroretinography (ERG) revealed a significant decrease in positive scotopic threshold response in retinas of Mthfr+/- mice at 24 weeks. Fundus examination in mice from both groups was normal; FA revealed areas of focal vascular leakage in 20% of Mthfr+/- mice at 12 to 16 weeks and 60% by 24 weeks. The SD-OCT revealed a significant decrease in nerve fiber layer (NFL) thickness at 24 weeks in Mthfr+/- compared to Mthfr+/+ mice. There was a 2-fold elevation in retinal hcy at 24 weeks in Mthfr+/- mice by HPLC and IHC. Morphometric analysis revealed an approximately 20% reduction in cells in the ganglion cell layer of Mthfr+/- mice at 24 weeks. The IHC indicated significantly increased GFAP labeling suggestive of Müller cell activation. CONCLUSIONS: Mildly hyperhomocysteinemic Mthfr+/- mice demonstrate reduced ganglion cell function, thinner NFL, and mild vasculopathy by 24 weeks. The retinal phenotype is similar to that of hyperhomocysteinemic mice with deficiency of cystathionine-ß-synthase (Cbs) reported earlier. The data support the hypothesis that hyperhomocysteinemia may be causative in certain retinal neurovasculopathies.
Asunto(s)
ADN/genética , Regulación de la Expresión Génica , Homocistinuria/patología , Hiperhomocisteinemia/patología , Metilenotetrahidrofolato Reductasa (NADPH2)/deficiencia , Metilenotetrahidrofolato Reductasa (NADPH2)/genética , Espasticidad Muscular/patología , Células Ganglionares de la Retina/patología , Animales , Modelos Animales de Enfermedad , Electrorretinografía , Angiografía con Fluoresceína , Fondo de Ojo , Homocistinuria/genética , Homocistinuria/metabolismo , Hiperhomocisteinemia/genética , Hiperhomocisteinemia/metabolismo , Immunoblotting , Inmunohistoquímica , Metilenotetrahidrofolato Reductasa (NADPH2)/biosíntesis , Metilenotetrahidrofolato Reductasa (NADPH2)/metabolismo , Ratones , Ratones Transgénicos , Espasticidad Muscular/genética , Espasticidad Muscular/metabolismo , Trastornos Psicóticos/genética , Trastornos Psicóticos/metabolismo , Trastornos Psicóticos/patología , Reacción en Cadena en Tiempo Real de la Polimerasa , Tomografía de Coherencia ÓpticaRESUMEN
AIM: We used a panel of 17 non-small-cell lung cancer cell lines to investigate whether the presence of polymorphisms in the RRM1, ERCC1, ABCB1 and MTHFR genes and alterations in their mRNA expression can affect the in vitro chemosensitivity to cisplatin and gemcitabine. MATERIALS & METHODS: Polymorphisms in these genes were evaluated by direct sequencing. mRNA expression levels were assessed by realtime PCR. In vitro chemosensitivity to cisplatin and gemcitabine was expressed as IC50 values, using the MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) assay. RESULTS: There was a significant, positive correlation between RRM1 mRNA expression and IC50 values for gemcitabine (r = 0.6533, p = 0.0045), and there was a significant, negative correlation between ABCB1 mRNA expression and IC50 values for cisplatin (r = -0.5459, p = 0.0287). When examining the association between the polymorphisms and IC50, we found that only the MTHFR 1298A>C polymorphism showed a tendency to be more chemosensitive to gemcitabine (p = 0.0440). CONCLUSION: These in vitro results suggest that mRNA expression levels of the RRM1 and ABCB1 genes may be useful indicators of chemosensitivity to gemcitabine and cisplatin, respectively. The MTHFR 1298A>C polymorphism was associated with gemcitabine chemosensitivity, which require further functional analysis with co-expressed genes and should be explored in prospective clinical studies to determine its potential clinical application as a predictive biomarker. Original submitted 11 February 2014; Revision submitted 3 November 2014.
Asunto(s)
Carcinoma de Pulmón de Células no Pequeñas/genética , Proteínas de Unión al ADN/biosíntesis , Resistencia a Antineoplásicos/genética , Endonucleasas/biosíntesis , Metilenotetrahidrofolato Reductasa (NADPH2)/biosíntesis , Proteínas Supresoras de Tumor/biosíntesis , Subfamilia B de Transportador de Casetes de Unión a ATP/biosíntesis , Subfamilia B de Transportador de Casetes de Unión a ATP/genética , Protocolos de Quimioterapia Combinada Antineoplásica/administración & dosificación , Carcinoma de Pulmón de Células no Pequeñas/patología , Línea Celular Tumoral , Cisplatino/administración & dosificación , Proteínas de Unión al ADN/genética , Desoxicitidina/administración & dosificación , Desoxicitidina/análogos & derivados , Endonucleasas/genética , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Estudios de Asociación Genética , Humanos , Metilenotetrahidrofolato Reductasa (NADPH2)/genética , Polimorfismo de Nucleótido Simple , ARN Mensajero/biosíntesis , Ribonucleósido Difosfato Reductasa , Proteínas Supresoras de Tumor/genética , GemcitabinaRESUMEN
Hyperhomocysteinemia (HHcy) is prevalent in patients with hypertension and is an independent risk factor for aortic pathologies. HHcy is known to cause an imbalance between matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs), leading to the accumulation of collagen in the aorta and resulting in stiffness and development of hypertension. Although the exact mechanism of extracellular matrix (ECM) remodeling is unclear, emerging evidence implicates epigenetic regulation involving DNA methylation. Our purpose was to investigate whether 5-aza-2'-deoxycytidine (Aza), a DNA methyltransferase (DNMT1) inhibitor, reduces high blood pressure (BP) by regulating aortic ECM remodeling in HHcy. Wild-type and cystathionine ß-synthase (CBS)(+/-) HHcy mice were treated with Aza (0.5 mg/kg body weight). In HHcy mice, Aza treatment normalized the plasma homocysteine (Hcy) level and BP. Thoracic and abdominal aorta ultrasound revealed a reduction in the resistive index and wall-to-lumen ratio. Vascular response to phenylephrine, acetylcholine, and sodium nitroprusside improved after Aza in HHcy mice. Histology showed a marked reduction in collagen deposition in the aorta. Aza treatment decreased the expression of DNMT1, MMP9, TIMP1, and S-adenosyl homocysteine hydrolase (SAHH) and upregulated methylene tetrahydrofolate reductase (MTHFR). We conclude that reduction of DNA methylation by Aza in HHcy reduces adverse aortic remodeling to mitigate hypertension.
Asunto(s)
Aorta/fisiopatología , Azacitidina/análogos & derivados , Metilación de ADN , Epigénesis Genética/fisiología , Hiperhomocisteinemia/genética , Hipertensión/prevención & control , Resistencia Vascular/efectos de los fármacos , Acetilcolina/farmacología , Adenosilhomocisteinasa/biosíntesis , Adenosilhomocisteinasa/genética , Animales , Aorta/química , Aorta/diagnóstico por imagen , Aorta/efectos de los fármacos , Azacitidina/farmacología , Colágeno/metabolismo , ADN (Citosina-5-)-Metiltransferasa 1 , ADN (Citosina-5-)-Metiltransferasas/antagonistas & inhibidores , ADN (Citosina-5-)-Metiltransferasas/biosíntesis , ADN (Citosina-5-)-Metiltransferasas/genética , Metilación de ADN/efectos de los fármacos , Decitabina , Endotelio Vascular/fisiopatología , Epigénesis Genética/genética , Proteínas de la Matriz Extracelular/metabolismo , Regulación Enzimológica de la Expresión Génica/efectos de los fármacos , Homocistinuria/complicaciones , Homocistinuria/tratamiento farmacológico , Homocistinuria/genética , Hiperhomocisteinemia/complicaciones , Hiperhomocisteinemia/fisiopatología , Hipertensión/etiología , Hipertensión/genética , Masculino , Metaloproteinasa 9 de la Matriz/biosíntesis , Metaloproteinasa 9 de la Matriz/genética , Metilenotetrahidrofolato Reductasa (NADPH2)/biosíntesis , Metilenotetrahidrofolato Reductasa (NADPH2)/genética , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Nitroprusiato/farmacología , Fenilefrina/farmacología , Inhibidor Tisular de Metaloproteinasa-1/biosíntesis , Inhibidor Tisular de Metaloproteinasa-1/genética , Ultrasonografía , Resistencia Vascular/genéticaRESUMEN
OBJECTIVE: To evaluate the role of key enzymes in the methionine-homocysteine metabolism (MHM) in the physiopathology of preeclampsia (PE). METHODS: Plasma and placenta from pregnant women (32 controls and 16 PE patients) were analyzed after informed consent. Protein was quantified by western blot. RNA was obtained with RNA purification kit and was quantified by reverse transcritase followed by real-time PCR (RT-qPCR). Identification of the C677T and A1298C methylenetetrahydrofolate reductase (MTHFR) single-nucleotide polymorphisms (SNPs) and A2756G methionine synthase (MTR) SNP was performed using PCR followed by a high-resolution melting (HRM) analysis. S-adenosyl methionine (SAM) and S-adenosyl homocysteine (SAH) were measured in plasma using high-performance liquid chromatography-tandem mass spectrometry (HPLC/MS/MS). The SNP association analysis was carried out using Fisher's exact test. Statistical analysis was performed using a Mann-Whitney test. RESULTS: RNA expression of MTHFR and MTR was significantly higher in patients with PE as compared with controls. Protein, SAM, and SAH levels showed no significant difference between preeclamptic patients and controls. No statistical differences between controls and PE patients were observed with the different SNPs studied. CONCLUSION: The RNA expression of MTHFR and MTR is elevated in placentas of PE patients, highlighting a potential compensation mechanism of the methionine-homocysteine metabolism in the physiopathology of this disease.
Asunto(s)
5-Metiltetrahidrofolato-Homocisteína S-Metiltransferasa/genética , Homocisteína/sangre , Metionina/sangre , Metilenotetrahidrofolato Reductasa (NADPH2)/genética , Preeclampsia/enzimología , 5-Metiltetrahidrofolato-Homocisteína S-Metiltransferasa/biosíntesis , Adulto , Femenino , Regulación de la Expresión Génica , Humanos , Metilenotetrahidrofolato Reductasa (NADPH2)/biosíntesis , Polimorfismo de Nucleótido Simple , Preeclampsia/sangre , Embarazo , ARN/genética , S-Adenosilhomocisteína/sangre , S-Adenosilmetionina/sangreRESUMEN
Breast cancer (BC) is a complex disease influenced by environmental and genetic factors. The disease has important genetic and environmental components, most of them are still unknown. An important role of gene polymorphisms related to the risk of developing BC has been reported. However, the results have been controversial. We investigated the association of TSER, MTHFR C677T, p53 codon 72 and MDR1 C3435T gene polymorphisms with breast carcinoma in women from Canary Islands (Spain). Blood samples collected from 135 patients with BC and 304 healthy controls all of them Caucasian, were analyzed through polymerase chain reaction-restriction fragment length polymorphism. Subsequently, a structured questionnaire including patient history and risk factors in relation to BC development was filled out. Allelic frequencies of these genetic variations were: TSER, (2) 0.55 and (3) 0.45 in cases, 0.49 and 0.51 respectively in controls (P=0.240); MTHFR C677T, (C) 0.63 and (T) 0.37 in cases, 0.60 and 0.40 respectively in controls (P=0.568); p53 Arg72Pro, (Arg) 0.74 and (Pro) 0.26 in cases and controls (P=0.910); MDR1 C3435T, (C) 0.52 and (T) 0.48 in cases, 0.55 and 0.45 respectively in controls (P=0.523). We did not observe any gene polymorphism as a risk factor to develop BC. A statistical association was observed between p53 codon 72 polymorphism and family history of breast cancer in both groups, as well as between MDR1 C3435T and smoking habits in cases (P<0.05). Gene polymorphisms vary by regions. The present study contributes to the characterization of the genetic pattern of the Canary population.
Asunto(s)
Miembro 1 de la Subfamilia B de Casetes de Unión a ATP/genética , Neoplasias de la Mama/genética , Metilenotetrahidrofolato Reductasa (NADPH2)/genética , Polimorfismo Genético , Timidilato Sintasa/genética , Proteína p53 Supresora de Tumor/genética , Subfamilia B de Transportador de Casetes de Unión a ATP , Miembro 1 de la Subfamilia B de Casetes de Unión a ATP/biosíntesis , Adulto , Anciano , Estudios de Casos y Controles , Codón , Femenino , Frecuencia de los Genes , Humanos , Metilenotetrahidrofolato Reductasa (NADPH2)/biosíntesis , Persona de Mediana Edad , Factores de Riesgo , Timidilato Sintasa/biosíntesis , Proteína p53 Supresora de Tumor/biosíntesisRESUMEN
There is limited available information on the effects of arsenic on enzymes participating in the folate cycle. Therefore, our aim was to evaluate the effects of sodium arsenite on the protein levels of methylenetetrahydrofolate reductase (MTHFR) and dihydrofolate reductase (DHFR) and its further relationship with the expression MT1/2 and c-myc in MCF-7 cells. Arsenite treatment (0-10 microM) for 4 h decreased MTHFR levels in a concentration-dependent fashion without significant effects on DHFR. The effects on MTHFR were observed at arsenite concentrations not significantly affecting cell viability. We also observed an increase in S-phase recruitment at all concentrations probed. Lower concentrations (<5 microM) induced cell proliferation, showing a high proportion of BrdU-stained cells, indicating a higher DNA synthesis rate. However, higher concentrations (> or =5 microM) or longer treatment periods induced apoptosis. Arsenite also induced dose-dependent increases in MT1/2 and c-Myc protein levels. The levels of MTHFR were inversely correlated to MT1/2 and c-Myc overexpression and increased S-phase recruitment. Our findings indicate that breast epithelial cells are responsive to arsenite and suggest that exposure may pose a risk for breast cancer. The reductions in MTHFR protein levels contribute to understand the mechanisms underlying the induction of genes influencing growth regulation, such as c-myc and MT1/2. However, further research is needed to ascertain if the effects here reported following short-time and high-dose exposure are relevant for human populations chronically exposed to low arsenic concentrations.
Asunto(s)
Arsenitos/toxicidad , Ciclo Celular/efectos de los fármacos , Metalotioneína/biosíntesis , Metilenotetrahidrofolato Reductasa (NADPH2)/biosíntesis , Proteínas Proto-Oncogénicas c-myc/biosíntesis , Compuestos de Sodio/toxicidad , Antimetabolitos , Western Blotting , Bromodesoxiuridina , Línea Celular Tumoral , Supervivencia Celular/efectos de los fármacos , Femenino , Citometría de Flujo , Expresión Génica/efectos de los fármacos , Humanos , Fase S/efectos de los fármacosRESUMEN
Methylenetetrahydrofolate reductase (MTHFR), an enzyme in folate and homocysteine metabolism, influences many cellular processes including methionine and nucleotide synthesis, methylation reactions, and maintenance of homocysteine at nontoxic levels. Mild deficiency of MTHFR is common in many populations and modifies risk for several complex traits including vascular disease, birth defects, and cancer. We recently demonstrated that MTHFR can be up-regulated by NF-kappaB, an important mediator of cell survival that is activated by endoplasmic reticulum (ER) stress. This observation, coupled with the reports that homocysteine can induce ER stress, prompted us to examine the possible regulation of MTHFR by ER stress. We found that several well characterized stress inducers (tunicamycin, thapsigargin, and A23187) as well as homocysteine could increase Mthfr mRNA and protein in Neuro-2a cells. The induction of MTHFR was also observed after overexpression of inositol-requiring enzyme-1 (IRE1) and was inhibited by a dominant-negative mutant of IRE1. Because IRE1 triggers c-Jun signaling, we examined the possible involvement of c-Jun in up-regulation of MTHFR. Transfection of c-Jun and two activators of c-Jun (LiCl and sodium valproate) increased MTHFR expression, whereas a reported inhibitor of c-Jun (SP600125) and a dominant-negative derivative of c-Jun N-terminal kinase-1 reduced MTHFR activation. We conclude that ER stress increases MTHFR expression and that IRE1 and c-Jun mediate this activation. These findings provide a novel mechanism by which the ER can regulate homeostasis and allude to an important role for MTHFR in cell survival.
Asunto(s)
Retículo Endoplásmico/metabolismo , Endorribonucleasas/genética , Regulación Enzimológica de la Expresión Génica , Proteínas de la Membrana/genética , Metilenotetrahidrofolato Reductasa (NADPH2)/biosíntesis , FN-kappa B/metabolismo , Proteínas Serina-Treonina Quinasas/genética , Animales , Línea Celular , Línea Celular Tumoral , Inhibidores Enzimáticos/farmacología , Homocisteína/metabolismo , Humanos , Metilenotetrahidrofolato Reductasa (NADPH2)/genética , Ratones , Proteína Quinasa 8 Activada por Mitógenos/metabolismo , Proteínas Proto-Oncogénicas c-jun/metabolismo , ARN Mensajero/metabolismoRESUMEN
OBJECTIVE: To evaluate potential modifiers of the palatal phenotype in individuals with the 22q11.2 deletion syndrome. DESIGN: Data from 356 subjects enrolled in a study of the 22q11.2 deletion syndrome were used to evaluate potential modifiers of the palatal phenotype. Specifically, subjects with and without velopharyngeal inadequacy and/or structural malformations of the palate were compared with respect to gender, race, and genotype for variants of seven genes that may influence palatal development. METHODS: The chi-square test or Fisher exact test was used to evaluate the association between palatal phenotype and each potential modifier. Odds ratios and their associated 95% confidence intervals were used to measure the magnitude of the association between palatal phenotype, subject gender and race, and each of the bi-allelic variants. RESULTS: The palatal phenotype observed in individuals with the 22q11.2 deletion syndrome was significantly associated with both gender and race. In addition, there was tentative evidence that the palatal phenotype may be influenced by variation within the gene that encodes methionine synthase. CONCLUSIONS: Variation in the palatal phenotype observed between individuals with the 22q11.2 deletion syndrome may be related to personal characteristics such as gender and race as well as variation within genes that reside outside of the 22q11.2 region.
Asunto(s)
Deleción Cromosómica , Trastornos de los Cromosomas/genética , Cromosomas Humanos Par 22/genética , Fisura del Paladar/complicaciones , Paladar Duro/anomalías , Insuficiencia Velofaríngea/genética , 5-Metiltetrahidrofolato-Homocisteína S-Metiltransferasa/biosíntesis , Distribución de Chi-Cuadrado , Niño , Trastornos de los Cromosomas/enzimología , Cistationina betasintasa/biosíntesis , Etnicidad , Femenino , Ferredoxina-NADP Reductasa/biosíntesis , Humanos , Masculino , Metilenotetrahidrofolato Reductasa (NADPH2)/biosíntesis , Fenotipo , Polimorfismo de Nucleótido Simple , Factores Sexuales , Síndrome , Insuficiencia Velofaríngea/etiologíaRESUMEN
We investigated the influence of hypothyroidism on homocysteine metabolism in rats, focusing on a hypothetical deficient synthesis of FAD by riboflavin kinases. Animals were allocated in control group (n = 7), thyroidectomized rats (n = 6), rats with diet deficient in vitamin B2, B9, B12, choline and methionine (n = 7), thyroidectomized rats with deficient diet (n = 9). Homocysteine was decreased in operated rats (2.6 +/- 1.01 vs. 4.05 +/- 1.0 mumol/L, P = 0.02) and increased in deficient diet rats (29.56 +/- 4.52 vs. 4.05 +/- 1.0 micromol/L, P = 0.001), when compared to control group. Erythrocyte-Glutathione-Reductase-Activation-Coefficient (index of FAD deficiency) was increased in thyroidectomized or deficient diet rats (P = 0.004 for both). Methylenetetrahydrofolate-reductase and methionine-synthase activities were decreased in thyroidectomized rats but not in those subjected to deficient diet. Cystathionine-beta-synthase was increased only in operated rats. Taken together, these results showed a defective re-methylation in surgical hypothyroidism, which was due in part to a defective synthesis of vitamin B2 coenzymes. This defective pathway was overcompensated by the increased Cystathionine-beta-synthase activity.