Although blood-brain barrier (BBB) integrity is maintained by the cross-talk of endothelial cells, junction proteins, and neurogliovascular network, the epigenetic mechanisms behind BBB permeability are largely unknown. We are reporting for the first time miR29b-mediated regulation of BBB, which is a novel mechanism underlying BBB integrity. We hypothesize that miR29b regulates BBB dysfunction by regulating DNMT3b, which consequently regulates the levels of metalloproteinases, that can eat up the membrane and junction proteins leading to leaky vasculature. In addition, 5 0 -azacytidine (5 0 -aza) was used to test its efficacy on BBB permeability. Blood-brain barrier disruption model was created by using homocysteine, and in the models miR29b was identified to be most affected, by using microRNA RT 2 -qPCR array. MiR29b mimics and inhibitors also confirmed that miR29b regulates the levels DNMT3b and MMP9. In hyperhomocysteinemic cystathionine-b-synthase deficient (CBS þ / À ) mice with high brain vessel permeability, miR29b levels were also high as compared with wild-type (WT) mice. Interestingly, 5 0 -aza improved BBB permeability by decreasing the expression of miR29b. In conclusion, our data suggested miR29b-mediated regulation of BBB dysfunction through DNMT3b and MMP9. It also potentiates the use of microRNAs as candidates for future epigenetic therapies in the improvement of BBB integrity.

DNA topoisomerase 3B (TOP3B) is unique among all mammalian topoisomerases for its dual activities that resolve both DNA and RNA topological entanglements to facilitate transcription and translation. However, the mechanism by which TOP3B activity is regulated is still elusive. Here, we have identified arginine methylation as an important post-translational modification (PTM) for TOP3B activity. Protein arginine methyltransferase (PRMT) 1, PRMT3 and PRMT6 all methylate TOP3B in vitro at its C-terminal arginine (R) and glycine (G)-rich motif. Site-directed mutagenesis analysis identified R833 and R835 as the major methylation sites. Using a methylation-specific antibody, we confirmed that TOP3B is methylated in cells and that mutation of R833 and R835 to lysine (K) significantly reduces TOP3B methylation. The methylation-deficient TOP3B (R833/835K) is less active in resolving negatively supercoiled DNA, which consequently lead to accumulation of co-transcriptionally formed R-loops in vitro and in cells. Additionally, the methylation-deficient TOP3B (R833/835K) shows reduced stress granule localization, indicating that methylation is critical for TOP3B function in translation regulation. Mechanistically, we found that R833/835 methylation is partially involved in the interaction of TOP3B with its auxiliary factor, the Tudor domain-containing protein 3 (TDRD3). Together, our findings provide the first evidence for the regulation of TOP3B activity by PTM.

In this paper, we report the dose-dependent antioxidant activity and DNA protective effects of zingerone. At 500 μg/mL, the DPPH radical scavenging activity of zingerone and ascorbic acid as a standard was found to be 86.7 and 94.2 % respectively. At the same concentration, zingerone also showed significant reducing power (absorbance 0.471) compared to that of ascorbic acid (absorbance 0.394). The in vitro toxicity of stannous chloride (SnCl2) was evaluated using genomic and plasmid DNA. SnCl2-induced degradation of genomic DNA was found to occur at a concentration of 0.8 mM onwards with complete degradation at 1.02 mM and above. In the case of plasmid DNA, conversion of supercoiled DNA into the open circular form indicative of DNA nicking activity was observed at a concentration of 0.2 mM onwards; complete conversion was observed at a concentration of 1.02 mM and above. Zingerone was found to confer protection against SnCl2-induced oxidative damage to genomic and plasmid DNA at concentrations of 500 and 750 μg/mL onwards, respectively. This protective effect was further confirmed in the presence of UV/H2O2-a known reactive oxygen species (ROS) generating system-wherein protection by zingerone against ROS-mediated DNA damage was observed at a concentration of 250 μg/mL onwards in a dose-dependent manner. This study clearly indicated the in vitro DNA protective property of zingerone against SnCl2-induced, ROS-mediated DNA damage.

Hyperhomocysteinemia (HHcy) is prevalent in patients with chronic kidney disease (CKD) and end-stage renal disease (ESRD). Emerging studies suggest that epigenetic mechanisms contribute to the development and progression of fibrosis in CKD. HHcy and its intermediates are known to alter the DNA methylation pattern, which is a critical regulator of epigenetic information. In this study, we hypothesized that HHcy causes renovascular remodeling by DNA hypermethylation, leading to glomerulosclerosis. We also evaluated whether the DNA methylation inhibitor, 5-aza-2'-deoxycytidine (5-Aza) could modulate extracellular matrix (ECM) metabolism and reduce renovascular fibrosis. C57BL/6J (wild-type) and cystathionine-β-synthase (CBS(+/-)) mice, treated without or with 5-Aza (0.5 mg/kg body weight, i.p.), were used. CBS(+/-) mice showed high plasma Hcy levels, hypertension, and significant glomerular and arteriolar injury. 5-Aza treatment normalized blood pressure and reversed renal injury. CBS(+/-) mice showed global hypermethylation and up-regulation of DNA methyltransferase-1 and -3a. Methylation-specific PCR showed an imbalance between matrix metalloproteinase (MMP)-9 and tissue inhibitor of metalloproteinase (TIMP)-1 and -2 and also increased collagen and galectin-3 expression. 5-Aza reduced abnormal DNA methylation and restored the MMP-9/TIMP-1, -2 balance. In conclusion, our data suggest that during HHcy, abnormal DNA methylation and an imbalance between MMP-9 and TIMP-1 and -2 lead to ECM remodeling and renal fibrosis.