Decreased DNA methyltransferase 3A and 3B mRNA expression in peripheral blood mononuclear cells and increased plasma SAH concentration in adult patients with idiopathic thrombocytopenic purpura.
OBJECTIVE
DNA methylation is known to play an important role in gene transcription and alterations of methylation contribute to the development of certain disorders such as cancer and immunodeficiency. Recent years have found an increasing interest in the role of epigenetic modifications in the etiology of human autoimmune diseases, such as systemic lupus erythromatosus (SLE) and rheumatoid arthritis (RA). DNA methyltransferases (DNMTs) are involved in the epigenetic control of DNA methylation processes. S-adenosylmethionine (SAM) and S-adenosylhomocysteine (SAH), as the substrate and product of essential cellular methyltransferase reactions, have important indicator action of cellular methylation status. The aim of this study is to explore if DNA methylation plays a role in the pathogenesis of idiopathic thrombocytopenic purpura (ITP).


METHODS
DNMT1, DNMT3A, and DNMT3B mRNA expression in peripheral blood mononuclear cells (PBMCs) of adult ITP patients were analyzed by real-time quantitative polymerase chain reaction. Plasma SAM and SAH levels were assayed with reversed-phase high performance liquid chromatography (HPLC).


RESULTS
DNMT3A and DNMT3B mRNA expressions were significantly lower in ITP patients than in healthy controls (p < 0.001), while DNMT1 mRNA expression was not significantly different between the two groups (p = 0.774). Plasma SAH concentration was significantly elevated in ITP patients than in healthy controls (p < 0.05), while the plasma SAM and SAM/SAH were not significantly different between the two groups (p = 0.133, p = 0.624 respectively).


CONCLUSIONS
Our observations suggest that aberrant DNA methylation status reflected by increased plasma SAH concentration and decreased mRNA expression levels of DNMT3A and 3B are possibly involved in the pathogenesis of ITP although the precise mechanisms need further study.
Tao
Jie
J
State Key Laboratory of Experimental Hematology, Institute of Hematology and Hospital of Blood Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, 288 Nanjing Road, Tianjin 300020, People's Republic of China.
Yang
Ming
M
Chen
Zhong
Z
Huang
Ying
Y
Zhao
Qinjun
Q
Xu
Jianhui
J
Ren
He
H
Zhao
Hui
H
Chen
Zhenping
Z
Ren
Qian
Q
Yang
Renchi
R
D000293:Adolescent; D000328:Adult; D000368:Aged; D002851:Chromatography, High Pressure Liquid; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000097:blood / Q000235:genetics* / Q000276:immunology; D019175:DNA Methylation; D000090205:DNA Methyltransferase 3A; D005260:Female; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000201:enzymology*; D008297:Male; D008875:Middle Aged; D016553:Purpura, Thrombocytopenic, Idiopathic / Q000097:blood / Q000235:genetics* / Q000276:immunology; D012333:RNA, Messenger / Q000032:analysis / Q000276:immunology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012435:S-Adenosylhomocysteine / Q000097:blood* / Q000276:immunology; D012436:S-Adenosylmethionine / Q000097:blood / Q000276:immunology; D000097584:DNA Methyltransferase 3B
D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases; D000090205:DNA Methyltransferase 3A; D012333:RNA, Messenger; D012435:S-Adenosylhomocysteine; D012436:S-Adenosylmethionine; D000097584:DNA Methyltransferase 3B; C000717967:DNMT3A protein, human; C000619380:DNMT1 protein, human