SRA-Domain Proteins Required for DRM2-Mediated De Novo DNA Methylation

De novo DNA methylation and the maintenance of DNA methylation in asymmetrical sequence contexts is catalyzed by homologous proteins in plants (DRM2) and animals (DNMT3a/b). In plants, targeting of DRM2 depends on small interfering RNAs (siRNAs), although the molecular details are still unclear. Here, we show that two SRA-domain proteins (SUVH9 and SUVH2) are also essential for DRM2-mediated de novo and maintenance DNA methylation in Arabidopsis thaliana. At some loci, SUVH9 and SUVH2 act redundantly, while at other loci only SUVH2 is required, and this locus specificity correlates with the differing DNA-binding affinity of the SRA domains within SUVH9 and SUVH2. Specifically, SUVH9 preferentially binds methylated asymmetric sites, while SUVH2 preferentially binds methylated CG sites. The suvh9 and suvh2 mutations do not eliminate siRNAs, suggesting a role for SUVH9 and SUVH2 late in the RNA-directed DNA methylation pathway. With these new results, it is clear that SRA-domain proteins are involved in each of the three pathways leading to DNA methylation in Arabidopsis

Everted saphenous vein graft for long anterior urethral strictures in men with tobacco-exposed oral mucosa: A prospective nonrandomized study

Introduction: Oral mucosal graft (OMG) is the gold standard for urethral substitution but has poor results in long anterior urethral strictures and chronic tobacco-exposed oral mucosa. Saphenous vein has been recently described for long-segment anterior urethral stricture with successful initial results. Our objective was to compare the early outcomes of everted saphenous vein graft (eSVG) substitution urethroplasty in patients with tobacco-exposed oral mucosa and OMG urethroplasty in patients with nontobacco-exposed oral mucosa for long anterior urethral strictures. Materials and Methods: 30 patients with long anterior urethral strictures underwent substitution urethroplasty using Dorsolateral onlay approach. Fifteen patients with healthy oral mucosa underwent OMG urethroplasty (Group 1) and 15 patients who had unhealthy oral mucosa due to chronic tobacco exposure underwent eSVG urethroplasty (Group 2). Outcomes were assessed with the International Prostate Symptom Score (IPSS); uroflowmetry; donor and recipient site complications at 1, 3, and 6 months; and symptomatic assessment thereafter. Retrograde urethrogram was done at 3 months in both the groups. Successful urethroplasty was defined as satisfactory voiding (Qmax>15 ml/s) and no need for endoscopic dilatation/direct vision internal urethrotomy in follow-up. Results: Mean stricture and harvested graft length were 10.8 cm and 12.33 cm in Group 1, while in Group 2 were 13.6 cm and 15.73 cm, respectively. Nine of 13 patients in Group 1 (69.2%) and 11 of 14 in Group 2 (78.5%) with a minimum follow-up till 18 months had successful outcome at an average follow-up of 23.13 months. Donor and recipient site complications were comparable in both the groups. At 18 months, mean IPSS and Qmax in successful patients were 7.9 and 25.6 ml/s in Group 1, while in Group 2 were 8.0 and 22.6 ml/s. Conclusions: Outcomes of great saphenous vein graft urethroplasty are comparable to OMG, and it is an acceptable option in long-segment anterior urethral stricture patients with chronic tobacco-exposed oral mucosa

SRA-domain proteins required for DRM2-mediated de novo DNA methylation.

De novo DNA methylation and the maintenance of DNA methylation in asymmetrical sequence contexts is catalyzed by homologous proteins in plants (DRM2) and animals (DNMT3a/b). In plants, targeting of DRM2 depends on small interfering RNAs (siRNAs), although the molecular details are still unclear. Here, we show that two SRA-domain proteins (SUVH9 and SUVH2) are also essential for DRM2-mediated de novo and maintenance DNA methylation in Arabidopsis thaliana. At some loci, SUVH9 and SUVH2 act redundantly, while at other loci only SUVH2 is required, and this locus specificity correlates with the differing DNA-binding affinity of the SRA domains within SUVH9 and SUVH2. Specifically, SUVH9 preferentially binds methylated asymmetric sites, while SUVH2 preferentially binds methylated CG sites. The suvh9 and suvh2 mutations do not eliminate siRNAs, suggesting a role for SUVH9 and SUVH2 late in the RNA-directed DNA methylation pathway. With these new results, it is clear that SRA-domain proteins are involved in each of the three pathways leading to DNA methylation in Arabidopsis