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Investigation of the mechanisms underlying the effect of oleic acid and docosahexaenoic acid on DNA methylation in Jurkat cells

Investigation of the mechanisms underlying the effect of oleic acid and docosahexaenoic acid on DNA methylation in Jurkat cells
Investigation of the mechanisms underlying the effect of oleic acid and docosahexaenoic acid on DNA methylation in Jurkat cells
There is evidence that olive oil, rich in oleic acid (OA), and fish oil, rich in docosa-hexaenoic acid (DHA), can modify the DNA methylation in human blood cells in vivo. However, the mechanisms underlying such effect are not well understood. To address this, a model to study DNA methylation changes was developed using the in vitro treatment of Jurkat cells with OA or DHA. Analysis showed that 15μM OA or DHA treatment for eight days altered the DNA methylation of 563 or 1596 CpG sites (294 or 508 increased), respectively, using the Infinium Methylation EPIC BeadChip. Only 78 CpG sites were altered in common by both treatments. Further characterisation of 5 candidate CpG sites showed that DNA methylation changes were just significant after the 3rd day of DHA treatment which suggested and indirect mechanism. Pathway analysis of genes with at least one CpG site with altered DNA methylation by OA or DHA treatment (348 or 935, respectively) showed an enrichment of genes under the control of peroxisome proliferator-activated receptor alpha (PPARα) in DHA-treated cells only. PPARα has been reported to participate in the global hypermethylation of THP1 monocytes induced by arachidonic acid treatment. How-ever, treatment of Jurkat cells with PPARα agonist GW7647 or PPARα antagonist GW6471 showed no difference in the DNA methylation of 5 candidate CpG sites analysed here by pyrosequencing. Therefore, other factors related to DNA methylation such as chromatin modification of histones and DNA motifs were investigated. Results showed that H3K4me3 was decreased in 5 candidate regions that changed DNA methylation status. Motif analysis indicated that sequences in the proximity of CpG sites that changed methylation were enriched in response elements including those for transcription factor SP1 and SP3. To further characterise the participation of transcription factors, transcriptome changes by OA or DHA were assessed using the Human HT-12 v4 Expression BeadChip. Analysis showed that DHA, but not OA treatment, downregulated SP3mRNA and altered the activity of different transcription factors and enzymes. Together, results showed in this thesis suggest that DNA methylation changes by OA or DHA showed specificity, took more than three days to be established and may be associated with decrease H3K4me3 and the activity of different transcription factors and enzymes.
University of Southampton
Perez Mojica, Jose Eduardo
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Perez Mojica, Jose Eduardo
7c601fa8-8ee2-4382-9715-a6ed849ee958
Burdge, Graham
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Calder, Philip
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Lillycrop, Karen
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Cooper, Cyrus
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Perez Mojica, Jose Eduardo (2019) Investigation of the mechanisms underlying the effect of oleic acid and docosahexaenoic acid on DNA methylation in Jurkat cells. University of Southampton, Doctoral Thesis, 306pp.

Record type: Thesis (Doctoral)

Abstract

There is evidence that olive oil, rich in oleic acid (OA), and fish oil, rich in docosa-hexaenoic acid (DHA), can modify the DNA methylation in human blood cells in vivo. However, the mechanisms underlying such effect are not well understood. To address this, a model to study DNA methylation changes was developed using the in vitro treatment of Jurkat cells with OA or DHA. Analysis showed that 15μM OA or DHA treatment for eight days altered the DNA methylation of 563 or 1596 CpG sites (294 or 508 increased), respectively, using the Infinium Methylation EPIC BeadChip. Only 78 CpG sites were altered in common by both treatments. Further characterisation of 5 candidate CpG sites showed that DNA methylation changes were just significant after the 3rd day of DHA treatment which suggested and indirect mechanism. Pathway analysis of genes with at least one CpG site with altered DNA methylation by OA or DHA treatment (348 or 935, respectively) showed an enrichment of genes under the control of peroxisome proliferator-activated receptor alpha (PPARα) in DHA-treated cells only. PPARα has been reported to participate in the global hypermethylation of THP1 monocytes induced by arachidonic acid treatment. How-ever, treatment of Jurkat cells with PPARα agonist GW7647 or PPARα antagonist GW6471 showed no difference in the DNA methylation of 5 candidate CpG sites analysed here by pyrosequencing. Therefore, other factors related to DNA methylation such as chromatin modification of histones and DNA motifs were investigated. Results showed that H3K4me3 was decreased in 5 candidate regions that changed DNA methylation status. Motif analysis indicated that sequences in the proximity of CpG sites that changed methylation were enriched in response elements including those for transcription factor SP1 and SP3. To further characterise the participation of transcription factors, transcriptome changes by OA or DHA were assessed using the Human HT-12 v4 Expression BeadChip. Analysis showed that DHA, but not OA treatment, downregulated SP3mRNA and altered the activity of different transcription factors and enzymes. Together, results showed in this thesis suggest that DNA methylation changes by OA or DHA showed specificity, took more than three days to be established and may be associated with decrease H3K4me3 and the activity of different transcription factors and enzymes.

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Published date: March 2019

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Local EPrints ID: 435100
URI: http://eprints.soton.ac.uk/id/eprint/435100
PURE UUID: 1ec2a287-27da-4e6f-93ef-309da76d7cc1
ORCID for Jose Eduardo Perez Mojica: ORCID iD orcid.org/0000-0003-4123-0649
ORCID for Graham Burdge: ORCID iD orcid.org/0000-0002-7665-2967
ORCID for Karen Lillycrop: ORCID iD orcid.org/0000-0001-7350-5489
ORCID for Cyrus Cooper: ORCID iD orcid.org/0000-0003-3510-0709

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Date deposited: 22 Oct 2019 16:30
Last modified: 29 Oct 2019 02:08

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Contributors

Author: Jose Eduardo Perez Mojica ORCID iD
Thesis advisor: Graham Burdge ORCID iD
Thesis advisor: Philip Calder
Thesis advisor: Karen Lillycrop ORCID iD
Thesis advisor: Cyrus Cooper ORCID iD

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