TET-mediated DNA hydroxymethylation is negatively influenced by the PARP-dependent PARylation

Background Poly(ADP-ribosyl)ation (PARylation), a posttranslational modification introduced by PARP-1 and PARP-2, has first been implicated in DNA demethylation due to its role in base excision repair. Recent evidence indicates a direct influence of PARP-dependent PARylation on TET enzymes which catalyse hydroxymethylation of DNA—the first step in DNA demethylation. However, the exact nature of influence that PARylation exerts on TET activity is still ambiguous. In our recent study, we have observed a negative influence of PARP-1 on local TET-mediated DNA demethylation of a single gene and in this study, we further explore PARP–TET interplay. Results Expanding on our previous work, we show that both TET1 and TET2 can be in vitro PARylated by PARP-1 and PARP-2 enzymes and that TET1 PARylation negatively affects the TET1 catalytic activity in vitro. Furthermore, we show that PARylation inhibits TET-mediated DNA demethylation at the global genome level in cellulo. Conclusions According to our findings, PARP inhibition can positively influence TET activity and therefore affect global levels of DNA methylation and hydroxymethylation. This gives a strong rationale for future examination of PARP inhibitors' potential use in the therapy of cancers characterised by loss of 5-hydroxymethylcytosine

EpiCRISPR targeted methylation of Arx gene initiates transient switch of mouse pancreatic alpha to insulin-producing cells

Introduction: Beta cell dysfunction by loss of beta cell identity, dedifferentiation, and the presence of polyhormonal cells are main characteristics of diabetes. The straightforward strategy for curing diabetes implies reestablishment of pancreatic beta cell function by beta cell replacement therapy. Aristaless-related homeobox (Arx) gene encodes protein which plays an important role in the development of pancreatic alpha cells and is a main target for changing alpha cell identity. Results: In this study we used CRISPR/dCas9-based epigenetic tools for targeted hypermethylation of Arx gene promoter and its subsequent suppression in mouse pancreatic αTC1-6 cell line. Bisulfite sequencing and methylation profiling revealed that the dCas9-Dnmt3a3L-KRAB single chain fusion constructs (EpiCRISPR) was the most efficient. Epigenetic silencing of Arx expression was accompanied by an increase in transcription of the insulin gene (Ins2) mRNA on 5th and 7th post-transfection day, quantified by both RT-qPCR and RNA-seq. Insulin production and secretion was determined by immunocytochemistry and ELISA assay, respectively. Eventually, we were able to induce switch of approximately 1% of transiently transfected cells which were able to produce 35% more insulin than Mock transfected alpha cells. Conclusion: In conclusion, we successfully triggered a direct, transient switch of pancreatic alpha to insulin-producing cells opening a future research on promising therapeutic avenue for diabetes management. 1 Introductio

Relationship between serum tumor necrosis factor receptor-2 concentration and periodontal destruction in patients with type 2 diabetes: Cross-sectional study

Introduction: The role of tumor necrosis factor-α (TNFα) is well documented in pathogenesis of chronic periodontitis (CP) and type 2 diabetes (T2D). Considering short half-life of TNFα, tumor necrosis factor receptor-2 (TNFR2) is used as prosperous surrogate marker of TNFα activity. Objective The aim was to detect TNFR2 serum concentration and correlate it with periodontal destruction in patients with diagnosed T2D and nondiabetics. Methods The study included 85 patients divided into three groups: T2D + CP (group T2D, n = 34); nondiabetics + CP (Group PD, n = 27); and healthy controls (group HC, n = 24). T2D was diagnosed according to WHO criteria (2013) and periodontitis was diagnosed using International Workshop for a Classification of Periodontal Diseases and Conditions criteria (1999). TNFR2 level was measured by enzyme-linked immunosorbent assay (ELISA). Results There was no difference in TNFR2 level among the groups (Kruskal-Wallis, p = 0.482). Significant correlation (Pearson's correlation coefficient) was observed between clinical attachment loss (CAL) and TNFR2 concentration in PD group (rp = -0.460, p = 0.016). In T2D group, correlations were observed between TNFR2 concentration and CaL (rp = 0.363, p = 0.005) and periodontal inflamed surface area (PISA) (rp = 0.345, p = 0.046) and periodontalepithelial surface area (PESA) (rp = 0.578, p = 0.000). Conclusion Higher concentration of TNFR2 was associated with higher CAL, PESA, and PISA scores in T2D group. Contrary to that, nondiabetics with higher values of CAL exhibited lower concentration of TNFR2, presenting potential protective effect on periodontal destruction. These results imply that diabetes may alter TNFR2 secretion originated from periodontium.Uvod: Uloga faktora nekroze tumora-alfa (TNFα) dokazana je u patogenezi hronične parodontopatije (HP) i dijabetesa melitusa tipa 2 (DM tip 2). S obzirom na to da je poluživot TNFα veoma kratak, receptor 2 faktora nekroze tumora (TNFR2) koristi se kao marker aktivnosti TNFα. Cilj rada Cilj ovog rada je određivanje koncentracije TNFR2 u serumu i koreliranje sa parametrima destrukcije parodoncijuma kod zdravih i ispitanika sa dijagnostikovanim DM tip 2. Metode rada U studiju je uključeno 85 pacijenata podeljenih u tri grupe: DM tip 2 + HP (DM grupa, n = 34), zdravi ispitanici + HP (PD grupa, n = 27) i zdrave kontrole (ZK grupa, n = 24). Dijagnoza DM tip 2 postavljena je na osnovu kriterijuma SZO (2013), dok je dijagnoza HP postavljena na osnovu kriterijuma Internacionalne radionice za klasifikaciju stanja i oboljenja parodoncijuma (1999). Koncentracija TNFR2 merena je ELISA metodom. Rezultati Koncentracija serumskog TNFR2 nije se razlikovala među grupama (Kraskal-Volis, p = 0,482). Postoji značajna korelacija (Pirson) između nivoa pripojnog epitela (NPE) i koncentracije TNFR2 u PD grupi (rp = -0,460, p = 0,016). U DM tip 2 grupi, statistički značajna korelacija uočena je između koncentracije TNFR2 i NPE (rp = 0,363, p = 0,005), kao i parametara uticaja inflamacije iz parodoncijuma na sistemsko zdravlje - PISA (rp = 0,345, p = 0,046) i PESA (rp = 0,578, p = 0,000). Zaključak Kod pacijenata sa dijabetesom veće koncentracije TNFR2 odgovaraju većim vrednostima NPE, PESA i PISA. Nasuprot tome, kod sistemski zdravih ispitanika sa HP veće vrednosti NPE su povezane sa manjim koncentracijama TNFR2, što bi moglo govoriti o potencijalnoj zaštitnoj ulozi ovog citokina na destrukciju parodoncijuma. Rezultati govore da dijabetes može uticati na sekreciju TNFR2 iz parodoncijuma