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Methionine increases BDNF DNA methylation and improves memory in epilepsy.

Parrish RR, Buckingham SC, Mascia KL, Johnson JJ, Matyjasik MM, Lockhart RM, Lubin FD - Ann Clin Transl Neurol (2015)

Bottom Line: We found that behaviorally driven BdnfDNA methylation was associated with hippocampus-dependent memory deficits.Methyl supplementation via methionine (Met) increased BdnfDNA methylation and reduced BdnfmRNA levels in the epileptic hippocampus during memory consolidation.Met administration reduced interictal spike activity, increased theta rhythm power, and reversed memory deficits in epileptic animals.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurobiology, University of Alabama - Birmingham Birmingham, Alabama.

ABSTRACT

Objective: Temporal lobe epilepsy (TLE) patients exhibit signs of memory impairments even when seizures are pharmacologically controlled. Surprisingly, the underlying molecular mechanisms involved in TLE-associated memory impairments remain elusive. Memory consolidation requires epigenetic transcriptional regulation of genes in the hippocampus; therefore, we aimed to determine how epigenetic DNA methylation mechanisms affect learning-induced transcription of memory-permissive genes in the epileptic hippocampus.

Methods: Using the kainate rodent model of TLE and focusing on the brain-derived neurotrophic factor (Bdnf) gene as a candidate of DNA methylation-mediated transcription, we analyzed DNA methylation levels in epileptic rats following learning. After detection of aberrant DNA methylation at the Bdnf gene, we investigated functional effects of altered DNA methylation on hippocampus-dependent memory formation in our TLE rodent model.

Results: We found that behaviorally driven BdnfDNA methylation was associated with hippocampus-dependent memory deficits. Bisulfite sequencing revealed that decreased BdnfDNA methylation levels strongly correlated with abnormally high levels of BdnfmRNA in the epileptic hippocampus during memory consolidation. Methyl supplementation via methionine (Met) increased BdnfDNA methylation and reduced BdnfmRNA levels in the epileptic hippocampus during memory consolidation. Met administration reduced interictal spike activity, increased theta rhythm power, and reversed memory deficits in epileptic animals. The rescue effect of Met treatment on learning-induced BdnfDNA methylation, Bdnf gene expression, and hippocampus-dependent memory, were attenuated by DNA methyltransferase blockade.

Interpretation: Our findings suggest that manipulation of DNA methylation in the epileptic hippocampus should be considered as a viable treatment option to ameliorate memory impairments associated with TLE.

No MeSH data available.


Related in: MedlinePlus

DNA methyltransferases (DNMT) inhibition prevents the effect of methyl supplementation on hippocampal brain-derived neurotrophic factor (Bdnf) DNA methylation, Bdnf expression and memory formation. (a) Diagram of experimental setup. (b) The increase in BdnfDNA methylation due to methyl supplementation is blocked by DNMT inhibition (F4,18 = 6.93, P < 0.01, n = 3–6, one-way analysis of variance [ANOVA] with post hoc test, *significance relative to non-epileptic group; # significance relative to epileptic group; §significance relative to epileptic + Met group). (c) DNMT inhibition attenuated the effect of methyl supplementation with Met on BdnfmRNA levels in the epileptic hippocampus (F4,24 = 11.96, P < 0.001, n = 5–8, one-way ANOVA with post hoc test, *significance relative to non-epileptic group; #significance between experimental groups). (d) BDNF protein expression was significantly reduced in Met-treated epileptic animals compared to nontreated epileptic animals. DNMT inhibition attenuated the decrease in BDNF protein expression due to methyl supplementation with Met. Duplicates of each sample were run and normalized to valosin-containing protein (VCP) and beta-actin 4 as within-lane loading controls. Representative blots of samples from each treatment group are shown (F3,14 = 3.84, P < 0.05, n = 5–6, one-way ANOVA with post hoc test, *significance relative to epileptic group). (e) DNMT inhibition blocked Met-induced memory enhancement (F4,31 = 7.81, P < 0.001, n = 7–8, one-way ANOVA with post hoc test, *significance relative to non-epileptic group; #significance between experimental groups). Error bars are SEM. (f) Potential mechanism of the effect of methionine treatment on memory restoration in epileptic animals. Shaded words represent the molecular mechanisms demonstrated in the present study. Unshaded words and dotted lines are potential pathways that could also be involved in the memory restoration process with methionine. Thus, methionine can be rapidly converted to S-adenosyl methionine (SAM), the universal methyl donor in the brain. SAM donates a CH3 group that leads to increased DNA methylation and gene transcription changes in the epileptic hippocampus. Once SAM donates a methyl group, it is converted to S-adenosyl-l-homocysteine (SAH), which leads to the production of adenosine. Adenosine production can lead to decreases in cell excitability that could subsequently decrease interictal spike activity in the epileptic hippocampus. Arginine is also a downstream by product of SAH hydrolysis that can lead to changes in nitric oxide production and can affect cell excitability.
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fig06: DNA methyltransferases (DNMT) inhibition prevents the effect of methyl supplementation on hippocampal brain-derived neurotrophic factor (Bdnf) DNA methylation, Bdnf expression and memory formation. (a) Diagram of experimental setup. (b) The increase in BdnfDNA methylation due to methyl supplementation is blocked by DNMT inhibition (F4,18 = 6.93, P < 0.01, n = 3–6, one-way analysis of variance [ANOVA] with post hoc test, *significance relative to non-epileptic group; # significance relative to epileptic group; §significance relative to epileptic + Met group). (c) DNMT inhibition attenuated the effect of methyl supplementation with Met on BdnfmRNA levels in the epileptic hippocampus (F4,24 = 11.96, P < 0.001, n = 5–8, one-way ANOVA with post hoc test, *significance relative to non-epileptic group; #significance between experimental groups). (d) BDNF protein expression was significantly reduced in Met-treated epileptic animals compared to nontreated epileptic animals. DNMT inhibition attenuated the decrease in BDNF protein expression due to methyl supplementation with Met. Duplicates of each sample were run and normalized to valosin-containing protein (VCP) and beta-actin 4 as within-lane loading controls. Representative blots of samples from each treatment group are shown (F3,14 = 3.84, P < 0.05, n = 5–6, one-way ANOVA with post hoc test, *significance relative to epileptic group). (e) DNMT inhibition blocked Met-induced memory enhancement (F4,31 = 7.81, P < 0.001, n = 7–8, one-way ANOVA with post hoc test, *significance relative to non-epileptic group; #significance between experimental groups). Error bars are SEM. (f) Potential mechanism of the effect of methionine treatment on memory restoration in epileptic animals. Shaded words represent the molecular mechanisms demonstrated in the present study. Unshaded words and dotted lines are potential pathways that could also be involved in the memory restoration process with methionine. Thus, methionine can be rapidly converted to S-adenosyl methionine (SAM), the universal methyl donor in the brain. SAM donates a CH3 group that leads to increased DNA methylation and gene transcription changes in the epileptic hippocampus. Once SAM donates a methyl group, it is converted to S-adenosyl-l-homocysteine (SAH), which leads to the production of adenosine. Adenosine production can lead to decreases in cell excitability that could subsequently decrease interictal spike activity in the epileptic hippocampus. Arginine is also a downstream by product of SAH hydrolysis that can lead to changes in nitric oxide production and can affect cell excitability.

Mentions: Next, we considered whether DNMT inhibition would block outcomes of methyl supplementation with Met including Bdnf DNA methylation and mRNA expression, and reversal of memory deficits (Fig.6a). 5-Aza-2′-deoxycytidine (5-AZA) was chosen for DNMT inhibition because it can be i.p. injected and at the administered dose, has been previously reported to alter behavior, DNA methylation, and BDNF expression in the hippocampus.46 DNMT inhibition with 5-AZA blocked the effect of methyl supplementation via Met on Bdnf DNA methylation, specifically at CpG sites 1, 2, 3, 4, 5, 8, and 12 within the Bdnf gene (Fig.6b). Interestingly, CpG site 1 encompasses a binding site for the transcription factor cAMP response element-binding (CREB) protein,47 while CpG site 8 encompasses a putative Sp1 transcription factor-binding site as mentioned earlier, suggesting that aberrant methylation at these sites could affect Bdnf expression by disrupting transcription factor binding (Fig.2f). Additionally, DNMT blockade partially attenuated the decrease in Bdnf mRNA (Fig.6c) and protein expression observed with methyl supplementation (Fig.6d). These findings strongly support that the effect of methyl supplementation on Bdnf gene and protein expression is partly due to DNA methylation mechanisms in the epileptic hippocampus during memory consolidation. Importantly, DNMT inhibition also prevented the memory rescue observed with Met treatment of epileptic CFC-trained animals (Fig.6e), suggesting that methyl supplementation reversed memory impairments in a rodent model of TLE via DNA methylation mechanisms.


Methionine increases BDNF DNA methylation and improves memory in epilepsy.

Parrish RR, Buckingham SC, Mascia KL, Johnson JJ, Matyjasik MM, Lockhart RM, Lubin FD - Ann Clin Transl Neurol (2015)

DNA methyltransferases (DNMT) inhibition prevents the effect of methyl supplementation on hippocampal brain-derived neurotrophic factor (Bdnf) DNA methylation, Bdnf expression and memory formation. (a) Diagram of experimental setup. (b) The increase in BdnfDNA methylation due to methyl supplementation is blocked by DNMT inhibition (F4,18 = 6.93, P < 0.01, n = 3–6, one-way analysis of variance [ANOVA] with post hoc test, *significance relative to non-epileptic group; # significance relative to epileptic group; §significance relative to epileptic + Met group). (c) DNMT inhibition attenuated the effect of methyl supplementation with Met on BdnfmRNA levels in the epileptic hippocampus (F4,24 = 11.96, P < 0.001, n = 5–8, one-way ANOVA with post hoc test, *significance relative to non-epileptic group; #significance between experimental groups). (d) BDNF protein expression was significantly reduced in Met-treated epileptic animals compared to nontreated epileptic animals. DNMT inhibition attenuated the decrease in BDNF protein expression due to methyl supplementation with Met. Duplicates of each sample were run and normalized to valosin-containing protein (VCP) and beta-actin 4 as within-lane loading controls. Representative blots of samples from each treatment group are shown (F3,14 = 3.84, P < 0.05, n = 5–6, one-way ANOVA with post hoc test, *significance relative to epileptic group). (e) DNMT inhibition blocked Met-induced memory enhancement (F4,31 = 7.81, P < 0.001, n = 7–8, one-way ANOVA with post hoc test, *significance relative to non-epileptic group; #significance between experimental groups). Error bars are SEM. (f) Potential mechanism of the effect of methionine treatment on memory restoration in epileptic animals. Shaded words represent the molecular mechanisms demonstrated in the present study. Unshaded words and dotted lines are potential pathways that could also be involved in the memory restoration process with methionine. Thus, methionine can be rapidly converted to S-adenosyl methionine (SAM), the universal methyl donor in the brain. SAM donates a CH3 group that leads to increased DNA methylation and gene transcription changes in the epileptic hippocampus. Once SAM donates a methyl group, it is converted to S-adenosyl-l-homocysteine (SAH), which leads to the production of adenosine. Adenosine production can lead to decreases in cell excitability that could subsequently decrease interictal spike activity in the epileptic hippocampus. Arginine is also a downstream by product of SAH hydrolysis that can lead to changes in nitric oxide production and can affect cell excitability.
© Copyright Policy - open-access
Related In: Results  -  Collection

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fig06: DNA methyltransferases (DNMT) inhibition prevents the effect of methyl supplementation on hippocampal brain-derived neurotrophic factor (Bdnf) DNA methylation, Bdnf expression and memory formation. (a) Diagram of experimental setup. (b) The increase in BdnfDNA methylation due to methyl supplementation is blocked by DNMT inhibition (F4,18 = 6.93, P < 0.01, n = 3–6, one-way analysis of variance [ANOVA] with post hoc test, *significance relative to non-epileptic group; # significance relative to epileptic group; §significance relative to epileptic + Met group). (c) DNMT inhibition attenuated the effect of methyl supplementation with Met on BdnfmRNA levels in the epileptic hippocampus (F4,24 = 11.96, P < 0.001, n = 5–8, one-way ANOVA with post hoc test, *significance relative to non-epileptic group; #significance between experimental groups). (d) BDNF protein expression was significantly reduced in Met-treated epileptic animals compared to nontreated epileptic animals. DNMT inhibition attenuated the decrease in BDNF protein expression due to methyl supplementation with Met. Duplicates of each sample were run and normalized to valosin-containing protein (VCP) and beta-actin 4 as within-lane loading controls. Representative blots of samples from each treatment group are shown (F3,14 = 3.84, P < 0.05, n = 5–6, one-way ANOVA with post hoc test, *significance relative to epileptic group). (e) DNMT inhibition blocked Met-induced memory enhancement (F4,31 = 7.81, P < 0.001, n = 7–8, one-way ANOVA with post hoc test, *significance relative to non-epileptic group; #significance between experimental groups). Error bars are SEM. (f) Potential mechanism of the effect of methionine treatment on memory restoration in epileptic animals. Shaded words represent the molecular mechanisms demonstrated in the present study. Unshaded words and dotted lines are potential pathways that could also be involved in the memory restoration process with methionine. Thus, methionine can be rapidly converted to S-adenosyl methionine (SAM), the universal methyl donor in the brain. SAM donates a CH3 group that leads to increased DNA methylation and gene transcription changes in the epileptic hippocampus. Once SAM donates a methyl group, it is converted to S-adenosyl-l-homocysteine (SAH), which leads to the production of adenosine. Adenosine production can lead to decreases in cell excitability that could subsequently decrease interictal spike activity in the epileptic hippocampus. Arginine is also a downstream by product of SAH hydrolysis that can lead to changes in nitric oxide production and can affect cell excitability.
Mentions: Next, we considered whether DNMT inhibition would block outcomes of methyl supplementation with Met including Bdnf DNA methylation and mRNA expression, and reversal of memory deficits (Fig.6a). 5-Aza-2′-deoxycytidine (5-AZA) was chosen for DNMT inhibition because it can be i.p. injected and at the administered dose, has been previously reported to alter behavior, DNA methylation, and BDNF expression in the hippocampus.46 DNMT inhibition with 5-AZA blocked the effect of methyl supplementation via Met on Bdnf DNA methylation, specifically at CpG sites 1, 2, 3, 4, 5, 8, and 12 within the Bdnf gene (Fig.6b). Interestingly, CpG site 1 encompasses a binding site for the transcription factor cAMP response element-binding (CREB) protein,47 while CpG site 8 encompasses a putative Sp1 transcription factor-binding site as mentioned earlier, suggesting that aberrant methylation at these sites could affect Bdnf expression by disrupting transcription factor binding (Fig.2f). Additionally, DNMT blockade partially attenuated the decrease in Bdnf mRNA (Fig.6c) and protein expression observed with methyl supplementation (Fig.6d). These findings strongly support that the effect of methyl supplementation on Bdnf gene and protein expression is partly due to DNA methylation mechanisms in the epileptic hippocampus during memory consolidation. Importantly, DNMT inhibition also prevented the memory rescue observed with Met treatment of epileptic CFC-trained animals (Fig.6e), suggesting that methyl supplementation reversed memory impairments in a rodent model of TLE via DNA methylation mechanisms.

Bottom Line: We found that behaviorally driven BdnfDNA methylation was associated with hippocampus-dependent memory deficits.Methyl supplementation via methionine (Met) increased BdnfDNA methylation and reduced BdnfmRNA levels in the epileptic hippocampus during memory consolidation.Met administration reduced interictal spike activity, increased theta rhythm power, and reversed memory deficits in epileptic animals.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurobiology, University of Alabama - Birmingham Birmingham, Alabama.

ABSTRACT

Objective: Temporal lobe epilepsy (TLE) patients exhibit signs of memory impairments even when seizures are pharmacologically controlled. Surprisingly, the underlying molecular mechanisms involved in TLE-associated memory impairments remain elusive. Memory consolidation requires epigenetic transcriptional regulation of genes in the hippocampus; therefore, we aimed to determine how epigenetic DNA methylation mechanisms affect learning-induced transcription of memory-permissive genes in the epileptic hippocampus.

Methods: Using the kainate rodent model of TLE and focusing on the brain-derived neurotrophic factor (Bdnf) gene as a candidate of DNA methylation-mediated transcription, we analyzed DNA methylation levels in epileptic rats following learning. After detection of aberrant DNA methylation at the Bdnf gene, we investigated functional effects of altered DNA methylation on hippocampus-dependent memory formation in our TLE rodent model.

Results: We found that behaviorally driven BdnfDNA methylation was associated with hippocampus-dependent memory deficits. Bisulfite sequencing revealed that decreased BdnfDNA methylation levels strongly correlated with abnormally high levels of BdnfmRNA in the epileptic hippocampus during memory consolidation. Methyl supplementation via methionine (Met) increased BdnfDNA methylation and reduced BdnfmRNA levels in the epileptic hippocampus during memory consolidation. Met administration reduced interictal spike activity, increased theta rhythm power, and reversed memory deficits in epileptic animals. The rescue effect of Met treatment on learning-induced BdnfDNA methylation, Bdnf gene expression, and hippocampus-dependent memory, were attenuated by DNA methyltransferase blockade.

Interpretation: Our findings suggest that manipulation of DNA methylation in the epileptic hippocampus should be considered as a viable treatment option to ameliorate memory impairments associated with TLE.

No MeSH data available.


Related in: MedlinePlus