DNA damage signatures in peripheral blood cells as biomarkers in prodromal huntington disease.

Easily accessible biomarkers in Huntington disease (HD) are actively searched. We investigated telomere length and DNA double-strand breaks (histone variant pγ-H2AX) as predictive disease biomarkers in peripheral blood mononuclear cells (PBMC) from 25 premanifest subjects, 58 HD patients with similar CAG expansion in the huntingtin gene (HTT), and 44 healthy controls (HC). PBMC from the pre-HD and HD groups showed shorter telomeres (p < 0.0001) and a significant increase of pγ-H2AX compared to the controls (p < 0.0001). The levels of pγ-H2AX correlated robustly with the presence of the mutated gene in pre-HD and HD. The availability of a potentially reversible biomarker (pγ-H2AX) in the premanifest stage of HD, negligible in HC, provides a novel tool to monitor premanifest subjects and find patient-specific drugs. Ann Neurol 2018;00:1-6 ANN NEUROL 2019;85:296-301.

A distinct group of CpG islands shows differential DNA methylation between replicas of the same cell line in vitro.

BACKGROUND: CpG dinucleotide-rich genomic DNA regions, known as CpG islands (CGIs), can be methylated at their cytosine residues as an epigenetic mark that is stably inherited during cell mitosis. Differentially methylated regions (DMRs) are genomic regions showing different degrees of DNA methylation in multiple samples. In this study, we focused our attention on CGIs showing different DNA methylation between two culture replicas of the same cell line. RESULTS: We used methylation data of 35 cell lines from the Encyclopedia of DNA Elements (ENCODE) consortium to identify CpG islands that were differentially methylated between replicas of the same cell line and denoted them Inter Replicas Differentially Methylated CpG islands (IRDM-CGIs). We identified a group of IRDM-CGIs that was consistently shared by different cell lines, and denoted it common IRDM-CGIs. X chromosome CGIs were overrepresented among common IRDM-CGIs. Autosomal IRDM-CGIs were preferentially located in gene bodies and intergenic regions had a lower G + C content, a smaller mean length, and a reduced CpG percentage. Functional analysis of the genes associated with autosomal IRDM-CGIs showed that many of them are involved in DNA binding and development. CONCLUSIONS: Our results show that several specific functional and structural features characterize common IRDM-CGIs. They may represent a specific subset of CGIs that are more prone to being differentially methylated for their intrinsic characteristics.

Can telomere shortening in human peripheral blood leukocytes serve as a disease biomarker of Friedreich's ataxia?

Enhanced oxidative stress and inflammation contribute to telomere erosion. Friedreich's ataxia is a neurodegenerative disorder caused by a reduction in frataxin expression that results in mitochondrial dysfunction and oxidative damage. Furthermore, frataxin deficiency induces a strong activation of inflammatory genes and neuronal death. We investigated telomere length (TL) in peripheral blood leukocytes of 37 patients with Friedreich's ataxia and 36 controls. We noted a significant telomere shortening in patients with Friedreich's ataxia compared to healthy controls (p=0.03). We also found a correlation between TL and disease duration (p=0.001). Our observations lead to the hypothesis that the TL of human peripheral blood leukocytes may serve as a biomarker of Friedreich's ataxia that could be used as an outcome measure in clinical trials.

Predictors of survival in a Huntington's disease population from southern Italy.

BACKGROUND: The primary aim of the present study was to determine the survival rates and identify predictors of disease duration in a cohort of Huntington's disease (HD) patients from Southern Italy. METHODS: All medical records of HD patients followed between 1977 and 2008 at the Department of Neurological Sciences of Federico II University in Naples were retrospectively reviewed and 135 patients were enrolled in the analysis. At the time of data collection, 41 patients were deceased (19 males and 22 females) with a mean ± SD age at death of 56.6 ± 14.9 years (range 18-83). RESULTS: The median survival time was 20 years (95% CI: 18.3-21.7). Cox regression analysis showed that the number of CAG in the expanded allele (HR 1.09 for 1 point triplet increase, p=0.002) and age of onset (HR 1.05 for 1 point year increase, p=0.002) were independent and significant predictors of lower survival rates. CONCLUSIONS: We believe that these findings are important for a better understanding of the natural history of the disease and may be relevant in designing future therapeutic trials.

Shorter telomeres in patients with cerebral autosomal dominant arteriopathy and leukoencephalopathy (CADASIL).

CADASIL is a hereditary systemic vasculopathy which affects mainly small cerebral arteries and is caused by mutations in the Notch3 gene. Misfolding of Notch3 is linked to endoplasmic reticulum stress and increased reactive oxygen species, which may result in dysfunction of endothelial cells, inflammation and ischemia. Oxidative stress and inflammation may induce a rapid telomere shortening in peripheral blood leukocytes (PBLs). The aim of this study was to assess the telomere length in PBLs from 29 patients with a genetic diagnosis of CADASIL by using a modified quantitative real-time polymerase chain reaction based assay. PBL telomere length was significantly shorter in CADASIL patients (T/S ratio = 0.17, 95% CI, 0.14-0.20) than in the controls (T/S ratio = 0.31, 95% CI, 0.27-0.35, t-test p < 0.001). Moreover, patients with functional dependence displayed shorter telomeres than those with functional independence (p = 0.039). Our data provide the first evidence that PBL telomere length is shortened in CADASIL disease, and this may be a systemic oxidative stress indicator in CADASIL patients, providing a possible biomarker of disease progression and for future therapeutic strategies.

PPAR-gamma agonist Azelaoyl PAF increases frataxin protein and mRNA expression: new implications for the Friedreich's ataxia therapy.

Friedreich's ataxia is a neurodegenerative disease due to frataxin deficiency, and thus, drugs increasing the frataxin amount are excellent candidates for therapy. By screening Gene Expression Omnibus profiles, we identified records showing a frataxin response to the peroxisome proliferator-activated receptors gamma (PPAR-gamma) agonist rosiglitazone. We decided to investigate the effect of the PPAR-gamma agonist Azelaoyl PAF on the frataxin protein and mRNA expression profile. We treated human neuroblastoma cells SKNBE and primary fibroblasts from skin biopsies from Friedreich's ataxia (FRDA) patients and healthy controls with the PPAR-gamma agonist Azelaoyl PAF. We show in this paper for the first time that Azelaoyl PAF significantly increases the intracellular frataxin levels by twofold in the neuroblastoma cell line SKNBE and fibroblasts from FRDA patients and that Azelaoyl PAF increases frataxin protein through a transcriptional mechanism. PPAR-gamma agonist Azelaoyl PAF increases both messenger RNA and protein levels of frataxin. We hypothesize that PPAR-gamma agonists could play a role in the treatment of FRDA, and our results offer the logical bases to further investigate the usefulness of this group of agents for the treatment of the FRDA.

Recombinant human erythropoietin increases frataxin protein expression without increasing mRNA expression.

Friedreich's ataxia is an autosomal recessive neurodegenerative disease that is due to the loss of function of the frataxin protein. The molecular basis of this disease is still a matter of debate and treatments have so far focused on managing symptoms. Drugs that can increase the amount of frataxin protein offer a possible therapy for the disease. One such drug is recombinant human erythropoietin (rhu-EPO). Here, we report the effects of rhu-EPO on frataxin mRNA and protein in primary fibroblast cell cultures derived from Friedreich's ataxia patients. We observed a slight but significant increase in the amount of frataxin protein. Interestingly, we did not observe any increase in the messenger RNA expression at any of the times and doses tested, suggesting that the regulatory effects of rhu-EPO on the frataxin protein was at the post-translational level. These findings could help the evaluation of the treatment with erythropoietin as a potential therapeutic agent for Friedreich's ataxia.

Pro12Ala polymorphism of the PPARgamma2 locus modulates the relationship between energy intake and body weight in type 2 diabetic patients.

OBJECTIVE: We explore the relationship among BMI, habitual diet, and the Pro12Ala polymorphism in the peroxisome proliferator-activated receptor (PPAR)gamma2. RESEARCH DESIGN AND METHODS: The Pro12Ala variant was characterized in 343 unrelated type 2 diabetic patients who were consecutively seen at the outpatient clinic of a health district of the province of Naples. Anthropometric and laboratory parameters were measured; habitual diet was assessed by a validated semiquantitative food frequency questionnaire. RESULTS: The overall frequency of Ala12 was 12% (n = 42). BMI was significantly higher in Ala carriers than non-Ala carriers, whereas total daily energy intake or macronutrient composition of the diet were similar in the two groups. For further analysis, participants were stratified according to genotype and sex-specific quartiles of energy intake. BMI increased in both genotype groups with increasing energy intake (P < 0.03). BMI was similar in Ala carriers and non-Ala carriers (30.0 vs. 30.1 kg/m2, P > 0.10) in the lower quartile of energy intake but significantly higher in Ala carriers in the upper quartile (36.0 vs. 32.1 kg/m2, P < 0.001). Average daily energy intake and diet composition were comparable within each quartile for carriers or noncarriers of the Ala allele. Relative to the noncarriers, Ala carriers had a significantly lower energy intake per kilogram body weight, thus suggesting that the Ala allele is associated with a higher food efficiency. The confounding role of medications, glucose control, and physical exercise was ruled out. CONCLUSIONS: This study provides evidence of a differential susceptibility to fat accumulation, and, hence, weight gain, in response to habitual high energy intake for Ala carriers compared with Pro/Pro homozygotes.

Mitochondrial AKAP121 links cAMP and src signaling to oxidative metabolism.

AKAP121 focuses distinct signaling events from membrane to mitochondria by binding and targeting cAMP-dependent protein kinase (PKA), protein tyrosine phosphatase (PTPD1), and mRNA. We find that AKAP121 also targets src tyrosine kinase to mitochondria via PTPD1. AKAP121 increased src-dependent phosphorylation of mitochondrial substrates and enhanced the activity of cytochrome c oxidase, a component of the mitochondrial respiratory chain. Mitochondrial membrane potential and ATP oxidative synthesis were enhanced by AKAP121 in an src- and PKA-dependent manner. Finally, siRNA-mediated silencing of endogenous AKAP121 drastically impaired synthesis and accumulation of mitochondrial ATP. These findings indicate that AKAP121, through its role in enhancing cAMP and tyrosine kinase signaling to distal organelles, is an important regulator in mitochondrial metabolism.

Cerebellar vermis aplasia: patient report and exclusion of the candidate genes EN2 and ZIC1.

Cerebellar vermis aplasia (ACV, OMIM 117360) is a rare malformation of the cerebellum, with only few familial patients reported so far. Main clinical features of this rare disorder include floppiness and delayed milestones in early infancy, preceding mild cerebellar ataxia, non-progressive clinical course, normal or slightly delayed intelligence, and occasional nystagmus. Neuroimaging reveals selective involvement of the cerebellum, which is prominent in the vermis. Because of the large preponderance of female patients, X-linked dominant transmission was suggested by [Fenichel and Phillips (1989); Arch Neurol 46:582-583], and subsequent reports only concern female patients. Only one family with male-to-male transmission presenting with a generalized atrophy of the cerebellum rather than a more localized vermis aplasia has been reported so far. We report on a family in which father and son are affected by a mild form of ACV, thus confirming an autosomal mode of inheritance of the disease. Our patients showed a progressive improvement of their motor abilities, neurological examination of the father being actually normal except for a mild mental retardation. We also evaluated the potential role of two candidate genes, EN2 and ZIC1, responsible for abnormal cerebellar development in murine knock-out models. However, molecular analysis failed to reveal any causative mutation in the coding sequence of the two genes in our patients. The understanding of the genetic basis of autosomal dominant ACV would allow a better classification of isolate cerebellar malformations and might permit to understand cell differentiation and migration in the developing central nervous system.

Reduced striatal [123 I]FP-CIT binding in SCA2 patients without parkinsonism.

Degeneration of substantia nigra has been described in spinocerebellar ataxia type 2 (SCA2). In this study, dopamine transporter (DAT) density with [123 I]FP-CIT SPECT was studied in six SCA2 patients with no parkinsonian signs, six Parkinson's disease (PD) patients, and six controls. Marked striatal DAT loss was found in both SCA2 and PD patients. However, a more severe reduction in the caudate and a higher putamen to caudate ratio distinguished SCA2 from PD patients, suggesting a more uniform nigrostriatal impairment in SCA2. Striatal DAT density of SCA2 patients correlated with the severity of cerebellar ataxia.