title: DNA methylation and mRNA expression of HLA-DQA1 alleles in type 1 diabetes mellitus.
abstract: Type 1 diabetes (T1D) belongs among polygenic multifactorial autoimmune diseases. The highest risk is associated with human leucocyte antigen (HLA) class II genes, including HLA-DQA1 gene. Our aim was to investigate DNA methylation of HLA-DQA1 promoter alleles (QAP) and correlate methylation status with individual HLA-DQA1 allele expression of patients with T1D and healthy controls. DNA methylation is one of the epigenetic modifications that regulate gene expression and is known to be shaped by the environment.Sixty one patients with T1D and 39 healthy controls were involved in this study. Isolated DNA was treated with sodium bisulphite and HLA-DQA1 promoter sequence was amplified using nested PCR. After sequencing, DNA methylation of HLA-DQA1 promoter alleles was analysed. Individual mRNA HLA-DQA1 relative allele expression was assessed using two different endogenous controls (PPIA, DRA). We have found statistically significant differences in HLA-DQA1 allele 02:01 expression (PPIA normalization, Pcorr = 0·041; DRA normalization, Pcorr = 0·052) between healthy controls and patients with T1D. The complete methylation profile of the HLA-DQA1 promoter was gained with the most methylated allele DQA1*02:01 and the least methylated DQA1*05:01 in both studied groups. Methylation profile observed in patients with T1D and healthy controls was similar, and no correlation between HLA-DQA1 allele expression and DNA methylation was found. Although we have not proved significant methylation differences between the two groups, detailed DNA methylation status and its correlation with expression of each HLA-DQA1 allele in patients with T1D have been described for the first time.
authors: Department of General Biology and Genetics, Third Faculty of Medicine, Charles University in Prague, Prague, Czech Republic.
authors: Pavel
authors: P
authors: Cepek
authors: Department of General Biology and Genetics, Third Faculty of Medicine, Charles University in Prague, Prague, Czech Republic.
authors: Marta
authors: M
authors: Zajacova
authors: Department of General Biology and Genetics, Third Faculty of Medicine, Charles University in Prague, Prague, Czech Republic.
authors: Anna
authors: A
authors: Kotrbova-Kozak
authors: University Hospital Kralovske Vinohrady, Prague, Czech Republic.
authors: Elena
authors: E
authors: Silhova
authors: Department of General Biology and Genetics, Third Faculty of Medicine, Charles University in Prague, Prague, Czech Republic.
authors: Marie
authors: M
authors: Cerna
mesh_terms: D000328:Adult; D000368:Aged; D019175:DNA Methylation; D003922:Diabetes Mellitus, Type 1 / Q000235:genetics*; D005260:Female; D005787:Gene Frequency; D020022:Genetic Predisposition to Disease; D005838:Genotype; D059848:HLA-DQ alpha-Chains / Q000235:genetics*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011401:Promoter Regions, Genetic / Q000235:genetics*; D012333:RNA, Messenger / Q000032:analysis*; D055815:Young Adult
chemical_list: D059848:HLA-DQ alpha-Chains; C069050:HLA-DQA1 antigen; D012333:RNA, Messenger
keywords: DNA methylation; HLA class II genes; HLA-DQA1 promoter (QAP); mRNA expression; type 1 diabetes mellitus