Background: DNA methylation has been implicated in the pathogenesis of allergy and atopy. This study aimed to identify whether DNA methylation also plays an important role in the pathogenesis of nasal polyps (NP). Methodology: NP tissues were obtained from 32 patients with chronic rhinosinusitis with bilateral NP. Biopsies of inferior turbinate mucosa (ITM) were taken from 18 patients who underwent rhinoseptoplasty (control group). The methylated genes, which were detected by DNA methylation microarray, were validated by methylation-specific polymerase chain reaction, bisulphite sequencing, real-time polymerase chain reaction and immunohistochemistry. Results: DNA methylation microarray identified 8,008 CpG islands in 2,848 genes. One hundred and ninety-eight genes were found to have a methylated signal in the promoter region in NP samples compared with ITM samples. The four top genes that changed, COL18A1, EP300, GNAS and SMURF1, were selected for further study. The methylation frequency of COL18A1 was significantly higher in NP samples than in ITM samples. Conclusions: DNA methylation might play an important role in the pathogenesis of NP. Promoter methylation of COL18A1 was found to be significantly increased in NP tissues, further studies are necessary to confirm the significance of these epigenetic factors in the mechanisms underlying the development or persistence of NP.

ABSTRACT. Tomato yellow leaf curl virus is one of the main diseases affecting tomato production worldwide. Previous studies have shown that Ty-2 is an important resistance gene located between molecular markers C2_At2g28250 (82.3 cM) and T0302 (89.0 cM), and exhibits strong resistance to tomato yellow leaf curl virus in Asia. In this study, Ty-2 candidate genes were subjected to bioinformatic analysis for the sequenced tomato genome. We identified 69 genes between molecular markers C2_At2g28250 and T0302, 22 of which were disease-related resistant genes, including nucleotide binding site-leucine-rich repeat disease resistance genes, protease genes (protein kinase, kinase receptor, and protein isomerase), cytochromes, and transcription factors. Expressed sequence tag analysis revealed that 77.3% (17/22) of candidate disease-resistance genes were expressed, involving 143 expressed sequence tags. Based on full-length cDNA sequence analysis, 7 candidate genes were found, 4 of which were involved in tomato responses to pathogens. Microarray ex-Y.F. Liu et al. 7948©FUNPEC-RP www.funpecrp.com.br Genetics and Molecular Research 14 (3): 7947-7956 (2015) pression analysis also showed that most candidate genes were involved in the tomato responses to multiple pathogens, including fungi, viruses, and bacteria. RNA-seq expression analysis revealed that all candidate genes participated in tomato growth and development.