The association between personal sun exposure, serum vitamin D and global methylation in human lymphocytes in a population of healthy adults in South Australia.
BACKGROUND
There is a positive association between solar UV exposure and micronucleus frequency in peripheral blood lymphocytes (PBL) and this association may be stronger when serum vitamin D (25(OH)D) levels are insufficient (<50 nmol/L). Micronucleus formation can result from global hypomethylation of DNA repeat sequences. The aim of this analysis was to evaluate the relationship between solar UV exposure and methylation pattern in LINE-1 repetitive elements in PBL DNA and to see if serum 25(OH)D levels modify it.


METHOD
Personal solar UV exposure was estimated from hours of outdoor exposure over 6 weeks recalled at the time of blood collection in 208 male and female participants living in South Australia. Methylation in LINE-1 repetitive elements was assessed in PBL using pyrosequencing.


RESULTS
Methylation in LINE-1 decreased with increasing solar UV exposure (% decrease = 0.5% per doubling of sUV; 95%CI: -0.7 to -0.2 p(value) = 0.00003). Although there was no correlation between LINE-1 methylation and micronucleus frequency, there was a 4.3% increase (95%CI: 0.6-8.1 p-value = 0.02) in nucleoplasmic bridges and a 4.3% increase in necrosis (CI: 1.9-6.8 p-value = 0.0005) for every 1% increase in LINE-1 methylation. Serum 25(OH)D was not associated with DNA methylation; or did it modify the association of solar UV with DNA methylation.


CONCLUSION
Exposure to solar UV radiation may reduce DNA methylation in circulating lymphocytes. This association does not appear to be influenced or mediated by vitamin D status.
['Nair-Shalliker|Visalini|V|', 'Dhillon|Varinderpal|V|', 'Clements|Mark|M|', 'Armstrong|Bruce K|BK|', 'Fenech|Michael|M|']
D000328:Adult D001315:Australia D002112:Calcifediol D019175:DNA Methylation D005260:Female D006801:Humans D020084:Long Interspersed Nucleotide Elements D008214:Lymphocytes D008297:Male D048629:Micronuclei, Chromosome-Defective D008875:Middle Aged D013472:Sunlight D014466:Ultraviolet Rays
Vitamin D Global methylation Solar UV exposure LINE-1 repetitive elements DNA damage