Modulation of methylation in the FMR1 promoter region after long term treatment with L-carnitine and acetyl-L-carnitine

Maternal L-carnitine supplementation ameliorates renal underdevelopment and epigenetic changes in male mice offspring due to maternal smoking

OBJECTIVES

Epidemiological and animal studies showed that L-carnitine (LC) supplementation can ameliorate oxidative stress-induced tissues damage. We have previously shown that maternal cigarette smoke exposure (SE) can increase renal oxidative stress in newborn offspring with postnatal kidney underdevelopment and renal dysfunction in adulthood, which were normalised by LC administration in the SE dams during pregnancy. Exposure to an adverse intrauterine environment may lead to alteration in the epigenome, a mechanism by which adverse prenatal conditions increase the susceptibility to chronic disease later in life. The current study aimed to determine whether maternal SE induces epigenetic changes in the offspring's kidney are associated with renal underdevelopment, and the protective effect of maternal LC supplementation.

METHOD

Female Balb/c mice (7 weeks) were exposed to cigarette smoke (SE) or air (Sham) for 6 weeks prior to mating, during gestation and lactation. A subgroup of the SE dams received LC via drinking water (SE + LC, 1.5 mmol/L) throughout gestation and lactation. Male offspring were studied at postnatal day (P)1, P20, and 13 weeks.

RESULTS

Maternal SE altered the expression of renal development markers glial cell line-derived neurotrophic factor and fibroblast growth factor 2, which were associated with increased renal global DNA methylation and DNA methyltransferase 1 mRNA expression at birth. These disorders were reversed by maternal LC administration.

CONCLUSION

The effect of maternal SE on renal underdevelopment involves global epigenetic alterations from birth, which can be prevented by maternal LC supplementation.

Acetylcarnitine potentiates the anticarcinogenic effects of butyrate on SW480 colon cancer cells

Butyrate is a potent anticarcinogenic compound against colon cancer cells in vitro. However, its rapid metabolism is hypothesized to limit its anticancer benefits in colonic epithelial cells. Carnitine, a potent antioxidant, is essential to fatty acid oxidation. The aims of this study were to identify a colon cancer cell line capable of transporting carnitine. We evaluated the effect of carnitine and acetylcarnitine (ALCAR) on the response of colon carcinoma cells to butyrate. We explored the mechanisms underlying the anticarcinogenic benefit. SW480 cells were incubated with butyrate ± carnitine or ALCAR. Carnitine uptake was assessed using [3H]-carnitine. Apoptosis and cell viability were assessed using an ELISA kit and flow cytometry, respectively. Modulation of proteins implicated in carnitine transport, cell death and proliferation were assessed by western blotting. SW480 cells were found to transport carnitine primarily via the OCTN2 transporter. Butyrate induced SW480 cell death occurred at concentrations of 2 mM and higher. Cells treated with the combination of butyrate (3 mM) with ALCAR exhibited increased mortality. The addition of carnitine or ALCAR also increased butyrate-induced apoptosis. Butyrate increased levels of cyclin D1, p21 and PARP p86, but decreased Bcl-XL and survivin levels. Butyrate also downregulated dephospho-β-catenin and increased acetylated histone H4 levels. Butyrate and carnitine decreased survivin levels by ≥25%. ALCAR independently induced a 20% decrease in p21. These results demonstrate that butyrate and ALCAR are potentially beneficial anticarcinogenic nutrients that inhibit colon cancer cell survival in vitro. The combination of both agents may have superior anticarcinogenic properties than butyrate alone.

L-acetylcarnitine for treating fragile X syndrome

BACKGROUND

People with fragile X syndrome (FXS) have an intellectual dysfunction that can range from very mild to severe. Symptoms can include speech and language delays and behavioural difficulties such as aggression or self injurious behaviours, emotional lability, and anxiety-related problems (for example obsessive-compulsive symptoms and perseverative behaviours). In some cases, affected people may have an additional diagnosis of attention deficit hyperactivity disorder or an autism spectrum disorder.

OBJECTIVES

To review the efficacy and safety of L-acetylcarnitine in improving the psychological, intellectual, and social performance of people with FXS.

SEARCH METHODS

In May 2015 we searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, PsycINFO, Web of Science, and two other databases. We also searched three trials registers, four theses databases, and the reference lists of relevant studies and reviews.

SELECTION CRITERIA

Randomised controlled trials (RCTs) that assessed the efficacy of L-acetylcarnitine, at any dose, in people of any age diagnosed with FXS compared with placebo.

DATA COLLECTION AND ANALYSIS

For each trial, two review authors independently extracted data on the children included and interventions compared, and assessed the risk of bias of the studies across the following domains: randomisation sequence generation, allocation concealment, blinding (of participants, personnel, and outcome assessors), incomplete outcome data, selective outcome reporting, and other potential sources of bias.

MAIN RESULTS

We found only two RCTs that compared oral L-acetylcarnitine (LAC) with oral placebo in children with FXS. The studies included a total of 83 participants, all of them male, who were treated and followed for one year. The age of participants at the start of treatment ranged from 6 to 13 years, with a mean age of 9 years. Neither study provided information on randomisation, allocation concealment procedures, or blinding of outcome assessment, and we received no responses from the authors we emailed for clarification. We therefore rated studies as being at unclear risk of bias on these domains. We judged both studies to be at low risk of bias for blinding of participants and personnel, incomplete outcome data, and selective reporting, but to be at high risk of other bias, as at least one study was funded by a drug company, and in both studies people working for the company were part of the research team.We used the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach to rate the quality of the available evidence. Overall, the quality of the evidence was low due to the imprecision of results and high risk of other bias.Regarding the primary outcome of psychological and learning capabilities, both studies assessed the effect of interventions on children's verbal and non-verbal intellectual functioning using the Wechsler Intelligence Scale for Children - Revised. The authors did not provide detailed data on those results but said that they found no important differences between treatment and placebo.Both studies evaluated the impact of the treatment on hyperactive behaviour using the Conners' Abbreviated Parent-Teacher Questionnaire. In one study, teachers' assessments of the children found no clear evidence of a difference (mean difference (MD) 0.50, 95% confidence interval (CI) -5.08 to 6.08, n = 51; low-quality evidence). The other study stated that there were no differences between treated and untreated participants, but did not provide detailed data for inclusion in the meta-analysis.Parents' assessments favoured LAC in one study (MD -0.57, 95% CI -0.94 to -0.19, n = 17; low-quality evidence), but not in the other (MD -2.80, 95% CI -7.61 to 2.01, n = 51; low-quality evidence), though changes were not large enough to be considered clinically relevant.Regarding social skills, one study reported no clear evidence of a difference in Vineland Adaptive Behavior composite scores (MD 8.20, 95% CI -0.02 to 16.42, n = 51; low-quality evidence), yet results in the socialisation domain favoured LAC (MD 11.30, 95% CI 2.52 to 20.08, n = 51; low-quality evidence).Both studies assessed the safety of the active treatment and recorded no side effects. Neither of the included studies assessed the secondary outcome of caregiver burden.

AUTHORS' CONCLUSIONS

Low-quality evidence from two small trials showed that when compared to placebo, LAC may not improve intellectual functioning or hyperactive behaviour in children with FXS.

Molecular mechanisms of phase change in locusts

Phase change in locusts is an ideal model for studying the genetic architectures and regulatory mechanisms associated with phenotypic plasticity. The recent development of genomic and metabolomic tools and resources has furthered our understanding of the molecular basis of phase change in locusts. Thousands of phase-related genes and metabolites have been highlighted using large-scale expressed sequence tags, microarrays, high-throughput transcriptomic sequences, or metabolomic approaches. However, only several key factors, including genes, metabolites, and pathways, have a critical role in phase transition in locusts. For example, CSP (chemosensory protein) and takeout genes, the dopamine pathway, protein kinase A, and carnitines were found to be involved in the regulation of behavioral phase change and gram-negative bacteria-binding proteins in prophylaxical disease resistance of gregarious locusts. Epigenetic mechanisms including small noncoding RNAs and DNA methylation have been implicated. We review these new advances in the molecular basis of phase change in locusts and present some challenges that need to be addressed.

Methotrexate treatment of FraX fibroblasts results in FMR1 transcription but not in detectable FMR1 protein levels

Background

Fragile X syndrome is caused by the loss of FMRP expression due to methylation of the FMR1 promoter. Treatment of fragile X syndrome patients’ lymphoblastoid cells with 5-azadeoxycytidine results in demethylation of the promoter and reactivation of the gene. The aim of the study was to analyze if methotrexate, an agent which also reduces DNA methylation but with less toxicity than 5-azadeoxycytidine, has therapeutic potential in fragile X syndrome.

Methods

Fibroblasts of fragile X syndrome patients were treated with methotrexate in concentrations ranging from 1 to 4 μg/ml for up to 14 days. FMR1 and FMRP expression were analyzed by quantitative PCR and western blotting.

Results

FMR1 mRNA was detected and levels correlated positively with methotrexate concentrations and time of treatment, but western blotting did not show detectable FMRP levels.

Conclusions

We show that it is possible to reactivate FMR1 transcription in fibroblasts of fragile X syndrome patients by treatment with methotrexate. However, we were not able to show FMRP expression, possibly due to the reduced translation efficacy caused by the triplet repeat extension. Unless FMR1 reactivation is more effective in vivo our results indicate that methotrexate has no role in the treatment of fragile X syndrome.

Metabolomic analysis reveals that carnitines are key regulatory metabolites in phase transition of the locusts

Phenotypic plasticity occurs prevalently and plays a vital role in adaptive evolution. However, the underlying molecular mechanisms responsible for the expression of alternate phenotypes remain unknown. Here, a density-dependent phase polyphenism of Locusta migratoria was used as the study model to identify key signaling molecules regulating the expression of phenotypic plasticity. Metabolomic analysis, using high-performance liquid chromatography and gas chromatography-mass spectrometry, showed that solitarious and gregarious locusts have distinct metabolic profiles in hemolymph. A total of 319 metabolites, many of which are involved in lipid metabolism, differed significantly in concentration between the phases. In addition, the time course of changes in the metabolic profiles of locust hemolymph that accompany phase transition was analyzed. Carnitine and its acyl derivatives, which are involved in the lipid β-oxidation process, were identified as key differential metabolites that display robust correlation with the time courses of phase transition. RNAi silencing of two key enzymes from the carnitine system, carnitine acetyltransferase and palmitoyltransferase, resulted in a behavioral transition from the gregarious to solitarious phase and the corresponding changes of metabolic profiles. In contrast, the injection of exogenous acetylcarnitine promoted the acquisition of gregarious behavior in solitarious locusts. These results suggest that carnitines mediate locust phase transition possibly through modulating lipid metabolism and influencing the nervous system of the locusts.

Individualization of mycophenolate mofetil dose in renal transplant recipients

The immunosuppressive agent mycophenolate mofetil has been successfully used over the past 10 years to prevent acute allograft rejection after renal transplantation. It has mainly been administered as a fixed dose of mycophenolate mofetil 1000 mg b.i.d. The pharmacokinetics of mycophenolic acid, the active moiety of the prodrug mycophenolate mofetil, show large between-patient variability, and exposure to mycophenolic acid correlates with the risk for acute rejection. This suggests that already excellent clinical results can be further improved by mycophenolate mofetil dose individualization. This review discusses different arguments in favour of individualization of mycophenolate mofetil dose, as well as strategies for managing mycophenolate mofetil therapy individualization, including pharmacokinetic and pharmacodynamic monitoring and dose individualization based on pharmacogenetic information. It is expected that pharmacokinetic monitoring of mycophenolic acid will offer the most effective and feasible tool for mycophenolate mofetil dose individualization.

Therapeutics development for triplet repeat expansion diseases

The underlying genetic mutations for many inherited neurodegenerative disorders have been identified in recent years. One frequent type of mutation is trinucleotide repeat expansion. Depending on the location of the repeat expansion, the mutation might result in a loss of function of the disease gene, a toxic gain of function or both. Disease gene identification has led to the development of model systems for investigating disease mechanisms and evaluating treatments. Examination of experimental findings reveals similarities in disease mechanisms as well as possibilities for treatment.

Differential epigenetic modifications in the FMR1 gene of the fragile X syndrome after reactivating pharmacological treatments

The fragile X syndrome is caused by a >200 CGG repeat expansion within the FMR1 gene promoter, with consequent DNA hypermethylation and inactivation of its expression. To further clarify the mechanisms that suppress the activity of the mutant gene and the conditions that may permit its reactivation, we investigated the acetylation and methylation status of three different regions of the FMR1 gene (promoter, exon 1 and exon 16) of three fragile X cell lines, using a chromatin immunoprecipitation (ChIP) assay with antibodies against acetylated-H3/H4 histones and against dimethylated lysine residues K4 and K9 of histone H3 (H3-K4 and H3-K9). We then coupled the ChIP assay with real-time PCR, obtaining absolute quantification of immunoprecipitated chromatin. Basal levels of histone acetylation and H3-K4 methylation were much higher in transcriptionally active wild-type controls than in inactive fragile X cell lines. Treatment of fragile X cell lines with the DNA demethylating drug 5-aza-2-deoxycytidine (5-azadC), known to reactivate the FMR1 gene, induced a decrease of H3-K9 methylation, an increase of H3 and H4 acetylation and an increase of H3-K4 methylation. Treatment with acetyl-L-carnitine (ALC), a compound that reduces the in vitro expression of the FRAXA fragile site without affecting DNA methylation, caused an increase of H3 and H4 acetylation. However, H3-K4 methylation remained extremely low, in accordance with the observation that ALC alone does not reactivate the FMR1 gene. Our experiments indicate that H3-K4 methylation and DNA demethylation are the main epigenetic switches activating the expression of the FMR1 gene, with histone acetylation playing an ancillary role.

Understanding the biological underpinnings of fragile X syndrome

PURPOSE OF REVIEW

The purpose of this review is to present the latest findings on fragile X syndrome and to put them into perspective. Fragile X syndrome is a relatively common form of inherited mental retardation, caused by loss of function of the FMR1 gene on the long arm of the X chromosome. The molecular mechanisms underlying the syndrome are complex and continue to surprise researchers more than 12 years after the cloning of the gene.

RECENT FINDINGS

We will specifically discuss the various aspects of the clinical phenotype, reassessed with the employment of functional imaging and electrophysiological techniques. The unexpected finding of a pathologic phenotype in premutation carriers is highlighted, as it represents a new and distinct condition with a different presentation in males and females. The third section deals briefly with the various functions of the FMRP protein, an RNA-binding protein interacting with multiple RNA molecules as well as proteins. It is important to realize that FMRP is probably changing partners several times, depending on its localization, on posttranslational modifications and on the available interacting proteins. In the following section, we present in short recent discoveries on the defective neuronal circuits in the fragile X syndrome. Most of these new data were made available by the study of animal models, mostly the Fmr1 knockout mouse, but also Drosophila.

SUMMARY

We briefly discuss the alternative options for treating fragile X syndrome. Presently, a neuropharmacological approach acting on either critical receptors or aimed at reactivating the silenced FMR1 gene appears promising.