Objective To investigate the DNA methylation transferase 1 (DNMT1) transcription and protein expression in peripheral blood of patients with endemic fluorosis induced by coal burning, and explore the role of DNMT1 in fluorosis pathogenesis.
Methods Following the principle of informed consent, urine samples were collected from 380 individuals residing in a coal-burning endemic fluorosis area of Guizhou. Urinary fluorine (UF) content was determined by fluoride ion selective electrode, according to which the investigated individuals were stratified into normal (UF<1.96 mg/gCr, 140 cases), low (1.96 mg/gCr ≤ UF<3.92 mg/gCr, 93 cases), medium (3.92 mg/gCr ≤UF<7.84 mg/gCr, 82 cases), and high UF groups (UF ≥ 7.84 mg/gCr, 65 cases). The mRNA transcription of DNMT1 was detected by real-time fluorescent quantitative polymerase chain reaction (FQ-PCR). The DNMT1 protein was detected by enzyme linked immune sorbent assay (ELISA).
Results The transcription levels of DNMT1 mRNA in respondents' peripheral blood samples significantly varied among the groups (F=3.125, P<0.05). The results of pairwise comparison found that the low and middle UF groups presented higher expression of DNMT1 mRNA transcription than the normal UF group (P<0.05); the low UF group also showed higher expression of DNMT1 mRNA transcription than the medium and high fluoride exposure groups (P<0.05). The contents of DNMT1 protein in respondents' peripheral blood samples were different among the groups (F=3.113, P<0.05). The results of pair-wise comparison showed that the low UF group presented higher DNMT1 protein content than the normal UF group and the high UF group (P<0.05).
Conclusion The elevated DNMT1 expression of its transcription and protein is involved in the fluorosis pathogenesis and could be early molecular events of fluorosis．
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