Myocyte enhancer factor 2A delays vascular endothelial cell senescence by activating the PI3K/p-Akt/SIRT1 pathway.

Myocyte enhancer factor 2A (MEF2A) dysfunction is closely related to the occurrence of senile diseases such as cardiocerebrovascular diseases, but the underlying molecular mechanism is unclear. Here, we studied the effects of MEF2A on the senescent phenotype of vascular endothelial cells (VEC) and downstream signaling pathway, and the association between plasma MEF2A levels and coronary artery disease (CAD). Results showed that MEF2A silencing promoted cell senescence and down-regulated PI3K/p-AKT/Sirtuin 1 (SIRT1) expression. MEF2A overexpression delayed cell senescence and up-regulated PI3K/p-AKT/SIRT1. Hydrogen peroxide (H2O2) treatment induced cellular senescence and down-regulated the expression of MEF2A and PI3K/p-AKT/SIRT1. MEF2A overexpression inhibited cellular senescence and the down-regulation of PI3K/p-AKT/SIRT1 induced by H2O2. Further study revealed that MEF2A directly up-regulated the expression of PIK3CA and PIK3CG through MEF2 binding sites in the promoter region. Pearson correlation and logistic regression analysis showed that the plasma level of MEF2A was negatively correlated with CAD, and with age in the controls. These results suggested that MEF2A can directly up-regulate PI3K gene expression, and one of the molecular mechanisms of delaying effect of MEF2A on VEC cell senescence was SIRT1-expression activation through the PI3K/p-Akt pathway. Moreover, the plasma MEF2A levels may be a potential biomarker for CAD risk prediction.

Phase 2 study of panobinostat with or without rituximab in relapsed diffuse large B-cell lymphoma.

The majority of diffuse large B-cell lymphoma (DLBCL) tumors contain mutations in histone-modifying enzymes (HMEs), indicating a potential therapeutic benefit of histone deacetylase inhibitors (HDIs), and preclinical data suggest that HDIs augment the effect of rituximab. In this randomized phase 2 study, we evaluated the response rate and toxicity of panobinostat, a pan-HDI administered 30 mg orally 3 times weekly, with or without rituximab, in 40 patients with relapsed or refractory de novo (n = 27) or transformed (n = 13) DLBCL. Candidate genes and whole exomes were sequenced in relapse tumor biopsies to search for molecular correlates, and these data were used to quantify circulating tumor DNA (ctDNA) in serial plasma samples. Eleven of 40 patients (28%) responded to panobinostat (95% confidence interval [CI] 14.6-43.9) and rituximab did not increase responses. The median duration of response was 14.5 months (95% CI 9.4 to "not reached"). At time of data censoring, 6 of 11 patients had not progressed. Of the genes tested for mutations, only those in MEF2B were significantly associated with response. We detected ctDNA in at least 1 plasma sample from 96% of tested patients. A significant increase in ctDNA at day 15 relative to baseline was strongly associated with lack of response (sensitivity 71.4%, specificity 100%). We conclude that panobinostat induces very durable responses in some patients with relapsed DLBCL, and early responses can be predicted by mutations in MEF2B or a significant change in ctDNA level at 15 days after treatment initiation. This clinical trial was registered at www.ClinicalTrials.gov (#NCT01238692).

Epigenome-wide DNA methylation in hearing ability: new mechanisms for an old problem.

Epigenetic regulation of gene expression has been shown to change over time and may be associated with environmental exposures in common complex traits. Age-related hearing impairment is a complex disorder, known to be heritable, with heritability estimates of 57-70%. Epigenetic regulation might explain the observed difference in age of onset and magnitude of hearing impairment with age. Epigenetic epidemiology studies using unrelated samples can be limited in their ability to detect small effects, and recent epigenetic findings in twins underscore the power of this well matched study design. We investigated the association between venous blood DNA methylation epigenome-wide and hearing ability. Pure-tone audiometry (PTA) and Illumina HumanMethylation array data were obtained from female twin volunteers enrolled in the TwinsUK register. Two study groups were explored: first, an epigenome-wide association scan (EWAS) was performed in a discovery sample (n=115 subjects, age range: 47-83 years, Illumina 27 k array), then replication of the top ten associated probes from the discovery EWAS was attempted in a second unrelated sample (n=203, age range: 41-86 years, Illumina 450 k array). Finally, a set of monozygotic (MZ) twin pairs (n = 21 pairs) within the discovery sample (Illumina 27 k array) was investigated in more detail in an MZ discordance analysis. Hearing ability was strongly associated with DNA methylation levels in the promoter regions of several genes, including TCF25 (cg01161216, p = 6.6 × 10(-6)), FGFR1 (cg15791248, p = 5.7 × 10(-5) and POLE (cg18877514, p= 6.3 × 10(-5)). Replication of these results in a second sample confirmed the presence of differential methylation at TCF25 (p(replication)=6 × 10(-5)) and POLE (p(replication) =0.016). In the MZ discordance analysis, twins' intrapair difference in hearing ability correlated with DNA methylation differences at ACP6 (cg01377755, r= -0.75, p=1.2 × 10(-4)) and MEF2D (cg08156349, r= -0.75, p=1.4 × 10(-4)). Examination of gene expression in skin, suggests an influence of differential methylation on expression, which may account for the variation in hearing ability with age.

Reduced expression of the chaperone-mediated autophagy carrier hsc70 protein in lymphomonocytes of patients with Parkinson's disease.

Chaperone-mediated autophagy (CMA) impairment is recognized to play a pathogenetic role in Parkinson's disease (PD). A reduced expression of lysosomal-associated membrane protein (lamp) 2A and heat shock cognate (hsc) 70 protein, the two key regulators of CMA, has been reported in brains of PD patients. To verify the existence of a possible systemic CMA dysfunction in PD, in this study the expression of hsc70 and lamp2A was assessed in peripheral blood mononuclear cells (PBMC) of patients with sporadic PD and compared to healthy subjects. The expression of myocyte enhancer factor 2D (MEF2D), a transcriptional factor implicated in neuronal survival and specific substrate of CMA, was also evaluated. Protein and gene expression was assessed by Western blot and real-time PCR, respectively, in PBMC obtained from 53 sporadic PD patients and 53 healthy subjects. A significant reduction of hsc70 levels was observed in PBMC of PD patients, both under basal conditions and after autophagy induction obtained with serum deprivation. No difference emerged in lamp2A and MEF2D expression between patients and controls. No influence of the clinical characteristics of patients emerged on hsc70, lamp2A and MEF2D expression. These results, despite being not suggestive of the existence of a CMA impairment in PBMC of PD patients, identify a systemic hsc70 reduction in PD patients. Further studies on specific mechanisms and biological significance of such alteration are needed to corroborate this finding that could lead to the identification of a new trait biomarker for PD.