Contributions
Abstract: P959
Type: Poster
Abstract Category: Pathology and pathogenesis of MS - Genetics /Epigenetics and Pharmacogenetics
Background: The brain is a major target organ of autoimmune attacks in Multiple Sclerosis (MS). DNA methylation, also referred to as 5-methylcytosine (5mC), is a stable epigenetic mark in the form of a methyl group covalently bound to DNA, which is better preserved compared to for example RNA and proteins in postmortem autopsy brain tissue. Furthermore, DNA methylation reflects underlying genome activity (i.e. hypermethylation of promoters is typically associated with gene repression) and therefore comprises a useful system for examining altered cellular mechanisms. Recently, an additional epigenetic mark, referred to as hydroxymethylation (or 5hmC), has gained particular attention due to high abundance in brain tissue. Noticeably, 5hmC displays a unique genomic distribution compared to 5mC, which suggest distinct functional roles of 5mC and 5hmC.
We aim to characterize 5mC and 5hmC in post-mortem brain tissue from MS patients and controls.
Methods and Results: Genomic DNA was extracted from snap frozen brain tissue blocks collected within 24h post-mortem and treated in parallel with oxidative bisulfite (oxBS) and BS for detection of 5mC and cumulative 5mC+5hmC levels, respectively, using the Infinium HumanMethylation450 BeadChip (450K) array, which covers 99% of RefSeq genes.
We have set up a bioinformatics analysis pipeline to quantify levels of 5mC and 5hmC from 450K array data. First, we filtered only specific probes with high detection value using the ChAMP Bioconductor package. Subsequently between array and within array normalization was applied prior to subtraction of oxBS from BS for quantification of 5hmC. Multidimensional scaling, principal component analysis and cluster analysis revealed a significant impact of tissue composition and brain regionality, which are necessary to be taken into account prior to further examining global and local difference in 5hmC and 5mC between MS patients and controls.
Conclusion: We have set up a method to address 5mC and 5hmC in post-mortem brain tissue. Preliminary data suggest that this enables identification of differential DNA methylation and altered pathways in MS brains.
Disclosure: Maria Needhamsen: nothing to disclose
Lara Kular: nothing to disclose
Tatiana Kramarova: nothing to disclose
David Gomez-Cabrero: nothing to disclose
Ewoud Ewing: nothing to disclose
Milena Z Adzemovic: nothing to disclose
Jesper Tegnér: nothing to disclose
Lou Brundin: has received honoraria for lectures, consultancy and educational activities from BiogenIdec, Merck Serono, SanofiAventis and Teva, and personal compensation for activities with SAS, Biogen Idec, Novartis and Teva as participant on advisory boards, consulting and/or speaking and commercial engagements.
Maja Jagodic has received research grants from the Swedish Research Council, the Swedish Association for Persons with Neurological Disabilities, the Swedish Brain Foundation, the Swedish Medical Society, Petrus and Augusta Hedlunds Foundation, the regional agreement on medical training and clinical research (ALF) between Stockholm County Council and Karolinska Institutet, and AstraZeneca-Science for Life Laboratory collaboration.
Abstract: P959
Type: Poster
Abstract Category: Pathology and pathogenesis of MS - Genetics /Epigenetics and Pharmacogenetics
Background: The brain is a major target organ of autoimmune attacks in Multiple Sclerosis (MS). DNA methylation, also referred to as 5-methylcytosine (5mC), is a stable epigenetic mark in the form of a methyl group covalently bound to DNA, which is better preserved compared to for example RNA and proteins in postmortem autopsy brain tissue. Furthermore, DNA methylation reflects underlying genome activity (i.e. hypermethylation of promoters is typically associated with gene repression) and therefore comprises a useful system for examining altered cellular mechanisms. Recently, an additional epigenetic mark, referred to as hydroxymethylation (or 5hmC), has gained particular attention due to high abundance in brain tissue. Noticeably, 5hmC displays a unique genomic distribution compared to 5mC, which suggest distinct functional roles of 5mC and 5hmC.
We aim to characterize 5mC and 5hmC in post-mortem brain tissue from MS patients and controls.
Methods and Results: Genomic DNA was extracted from snap frozen brain tissue blocks collected within 24h post-mortem and treated in parallel with oxidative bisulfite (oxBS) and BS for detection of 5mC and cumulative 5mC+5hmC levels, respectively, using the Infinium HumanMethylation450 BeadChip (450K) array, which covers 99% of RefSeq genes.
We have set up a bioinformatics analysis pipeline to quantify levels of 5mC and 5hmC from 450K array data. First, we filtered only specific probes with high detection value using the ChAMP Bioconductor package. Subsequently between array and within array normalization was applied prior to subtraction of oxBS from BS for quantification of 5hmC. Multidimensional scaling, principal component analysis and cluster analysis revealed a significant impact of tissue composition and brain regionality, which are necessary to be taken into account prior to further examining global and local difference in 5hmC and 5mC between MS patients and controls.
Conclusion: We have set up a method to address 5mC and 5hmC in post-mortem brain tissue. Preliminary data suggest that this enables identification of differential DNA methylation and altered pathways in MS brains.
Disclosure: Maria Needhamsen: nothing to disclose
Lara Kular: nothing to disclose
Tatiana Kramarova: nothing to disclose
David Gomez-Cabrero: nothing to disclose
Ewoud Ewing: nothing to disclose
Milena Z Adzemovic: nothing to disclose
Jesper Tegnér: nothing to disclose
Lou Brundin: has received honoraria for lectures, consultancy and educational activities from BiogenIdec, Merck Serono, SanofiAventis and Teva, and personal compensation for activities with SAS, Biogen Idec, Novartis and Teva as participant on advisory boards, consulting and/or speaking and commercial engagements.
Maja Jagodic has received research grants from the Swedish Research Council, the Swedish Association for Persons with Neurological Disabilities, the Swedish Brain Foundation, the Swedish Medical Society, Petrus and Augusta Hedlunds Foundation, the regional agreement on medical training and clinical research (ALF) between Stockholm County Council and Karolinska Institutet, and AstraZeneca-Science for Life Laboratory collaboration.