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Expression of DNA methyltransferases in adult dorsal root ganglia is cell-type specific and up regulated in a rodent model of neuropathic pain.

Pollema-Mays SL, Centeno MV, Apkarian AV, Martina M - Front Cell Neurosci (2014)

Bottom Line: Real-time RT PCR analysis revealed robust and time-dependent changes in DNMT transcript expression in ipsilateral DRGs from spared nerve injury (SNI) but not sham rats.Interestingly, DNMT3b transcript showed a robust upregulation that appeared already 1 week after surgery and persisted at 4 weeks (our endpoint); in contrast, DNMT1 and DNMT3a transcripts showed only moderate upregulation that was transient and did not appear until the second week.We suggest that DNMT regulation in adult DRGs may be a contributor to the pain phenotype and merits further study.

View Article: PubMed Central - PubMed

Affiliation: Department of Physiology, Northwestern University Feinberg School of Medicine Chicago, IL, USA.

ABSTRACT
Neuropathic pain is associated with hyperexcitability and intrinsic firing of dorsal root ganglia (DRG) neurons. These phenotypical changes can be long lasting, potentially spanning the entire life of animal models, and depend on altered expression of numerous proteins, including many ion channels. Yet, how DRGs maintain long-term changes in protein expression in neuropathic conditions remains unclear. DNA methylation is a well-known mechanism of epigenetic control of gene expression and is achieved by the action of three enzymes: DNA methyltransferase (DNMT) 1, 3a, and 3b, which have been studied primarily during development. We first performed immunohistochemical analysis to assess whether these enzymes are expressed in adult rat DRGs (L4-5) and found that DNMT1 is expressed in both glia and neurons, DNMT3a is preferentially expressed in glia and DNMT3b is preferentially expressed in neurons. A rat model of neuropathic pain was then used to determine whether nerve injury may induce epigenetic changes in DRGs at multiple time points after pain onset. Real-time RT PCR analysis revealed robust and time-dependent changes in DNMT transcript expression in ipsilateral DRGs from spared nerve injury (SNI) but not sham rats. Interestingly, DNMT3b transcript showed a robust upregulation that appeared already 1 week after surgery and persisted at 4 weeks (our endpoint); in contrast, DNMT1 and DNMT3a transcripts showed only moderate upregulation that was transient and did not appear until the second week. We suggest that DNMT regulation in adult DRGs may be a contributor to the pain phenotype and merits further study.

No MeSH data available.


Related in: MedlinePlus

Nerve injury induces a robust and long lasting increase in DNMT3b expression. Gene expression is normalized to GAPDH. All SNI data are normalized to sham controls. (A) At 1 week post nerve injury, qRT-PCR experiments demonstrate a significant, almost fourfold increase in DNMT3b transcript in the DRG ipsilateral to the injured nerve. DRGs contralateral to nerve injury showed no significant changes, *p < 0.001. n = 8 SNI and 8 sham. (B) At 2 weeks post nerve injury, qRT-PCR experiments demonstrate a significant increase in DNMT1 (38%), DNMT3a (58%), and DNMT3b (twofold) transcripts in the DRGs ipsilateral to the injured nerve. DRGs contralateral to nerve injury showed no changes, *p < 0.05. n = 4 SNI and 4 sham animals. (C) At 4 weeks post nerve injury, qRT-PCR experiments demonstrate a significant, approximately 40% increase in DNMT3b transcripts in the DRGs ipsilateral to the injured nerve. DRGs contralateral to nerve injury showed no changes. For DRGs ipsilateral to injury in SNI rats, DNMT1 showed a trend toward being increased by 27% with p = 0.09 while DNMT3a also showed a slight trend of being increased by 42% with p = 0.22, *p < 0.05. n = 6 SNI and 6 sham.
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Figure 4: Nerve injury induces a robust and long lasting increase in DNMT3b expression. Gene expression is normalized to GAPDH. All SNI data are normalized to sham controls. (A) At 1 week post nerve injury, qRT-PCR experiments demonstrate a significant, almost fourfold increase in DNMT3b transcript in the DRG ipsilateral to the injured nerve. DRGs contralateral to nerve injury showed no significant changes, *p < 0.001. n = 8 SNI and 8 sham. (B) At 2 weeks post nerve injury, qRT-PCR experiments demonstrate a significant increase in DNMT1 (38%), DNMT3a (58%), and DNMT3b (twofold) transcripts in the DRGs ipsilateral to the injured nerve. DRGs contralateral to nerve injury showed no changes, *p < 0.05. n = 4 SNI and 4 sham animals. (C) At 4 weeks post nerve injury, qRT-PCR experiments demonstrate a significant, approximately 40% increase in DNMT3b transcripts in the DRGs ipsilateral to the injured nerve. DRGs contralateral to nerve injury showed no changes. For DRGs ipsilateral to injury in SNI rats, DNMT1 showed a trend toward being increased by 27% with p = 0.09 while DNMT3a also showed a slight trend of being increased by 42% with p = 0.22, *p < 0.05. n = 6 SNI and 6 sham.

Mentions: At 1 week post injury, qRT-PCR experiments for DNMT transcripts demonstrated no significant changes in expression levels for both DNMT1 and DNMT3a transcripts, in the DRGs ipsi- or contralateral to the injured nerve relative to sham controls (Figure 4A). However, analysis of the DNMT3b transcript in the DRG ipsilateral to the injured nerve revealed a significant, almost fourfold increase (p < 0.001) in expression levels relative to sham (Figure 4A). DNMT3b expression was unchanged in the DRG contralateral to nerve injury.


Expression of DNA methyltransferases in adult dorsal root ganglia is cell-type specific and up regulated in a rodent model of neuropathic pain.

Pollema-Mays SL, Centeno MV, Apkarian AV, Martina M - Front Cell Neurosci (2014)

Nerve injury induces a robust and long lasting increase in DNMT3b expression. Gene expression is normalized to GAPDH. All SNI data are normalized to sham controls. (A) At 1 week post nerve injury, qRT-PCR experiments demonstrate a significant, almost fourfold increase in DNMT3b transcript in the DRG ipsilateral to the injured nerve. DRGs contralateral to nerve injury showed no significant changes, *p < 0.001. n = 8 SNI and 8 sham. (B) At 2 weeks post nerve injury, qRT-PCR experiments demonstrate a significant increase in DNMT1 (38%), DNMT3a (58%), and DNMT3b (twofold) transcripts in the DRGs ipsilateral to the injured nerve. DRGs contralateral to nerve injury showed no changes, *p < 0.05. n = 4 SNI and 4 sham animals. (C) At 4 weeks post nerve injury, qRT-PCR experiments demonstrate a significant, approximately 40% increase in DNMT3b transcripts in the DRGs ipsilateral to the injured nerve. DRGs contralateral to nerve injury showed no changes. For DRGs ipsilateral to injury in SNI rats, DNMT1 showed a trend toward being increased by 27% with p = 0.09 while DNMT3a also showed a slight trend of being increased by 42% with p = 0.22, *p < 0.05. n = 6 SNI and 6 sham.
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Figure 4: Nerve injury induces a robust and long lasting increase in DNMT3b expression. Gene expression is normalized to GAPDH. All SNI data are normalized to sham controls. (A) At 1 week post nerve injury, qRT-PCR experiments demonstrate a significant, almost fourfold increase in DNMT3b transcript in the DRG ipsilateral to the injured nerve. DRGs contralateral to nerve injury showed no significant changes, *p < 0.001. n = 8 SNI and 8 sham. (B) At 2 weeks post nerve injury, qRT-PCR experiments demonstrate a significant increase in DNMT1 (38%), DNMT3a (58%), and DNMT3b (twofold) transcripts in the DRGs ipsilateral to the injured nerve. DRGs contralateral to nerve injury showed no changes, *p < 0.05. n = 4 SNI and 4 sham animals. (C) At 4 weeks post nerve injury, qRT-PCR experiments demonstrate a significant, approximately 40% increase in DNMT3b transcripts in the DRGs ipsilateral to the injured nerve. DRGs contralateral to nerve injury showed no changes. For DRGs ipsilateral to injury in SNI rats, DNMT1 showed a trend toward being increased by 27% with p = 0.09 while DNMT3a also showed a slight trend of being increased by 42% with p = 0.22, *p < 0.05. n = 6 SNI and 6 sham.
Mentions: At 1 week post injury, qRT-PCR experiments for DNMT transcripts demonstrated no significant changes in expression levels for both DNMT1 and DNMT3a transcripts, in the DRGs ipsi- or contralateral to the injured nerve relative to sham controls (Figure 4A). However, analysis of the DNMT3b transcript in the DRG ipsilateral to the injured nerve revealed a significant, almost fourfold increase (p < 0.001) in expression levels relative to sham (Figure 4A). DNMT3b expression was unchanged in the DRG contralateral to nerve injury.

Bottom Line: Real-time RT PCR analysis revealed robust and time-dependent changes in DNMT transcript expression in ipsilateral DRGs from spared nerve injury (SNI) but not sham rats.Interestingly, DNMT3b transcript showed a robust upregulation that appeared already 1 week after surgery and persisted at 4 weeks (our endpoint); in contrast, DNMT1 and DNMT3a transcripts showed only moderate upregulation that was transient and did not appear until the second week.We suggest that DNMT regulation in adult DRGs may be a contributor to the pain phenotype and merits further study.

View Article: PubMed Central - PubMed

Affiliation: Department of Physiology, Northwestern University Feinberg School of Medicine Chicago, IL, USA.

ABSTRACT
Neuropathic pain is associated with hyperexcitability and intrinsic firing of dorsal root ganglia (DRG) neurons. These phenotypical changes can be long lasting, potentially spanning the entire life of animal models, and depend on altered expression of numerous proteins, including many ion channels. Yet, how DRGs maintain long-term changes in protein expression in neuropathic conditions remains unclear. DNA methylation is a well-known mechanism of epigenetic control of gene expression and is achieved by the action of three enzymes: DNA methyltransferase (DNMT) 1, 3a, and 3b, which have been studied primarily during development. We first performed immunohistochemical analysis to assess whether these enzymes are expressed in adult rat DRGs (L4-5) and found that DNMT1 is expressed in both glia and neurons, DNMT3a is preferentially expressed in glia and DNMT3b is preferentially expressed in neurons. A rat model of neuropathic pain was then used to determine whether nerve injury may induce epigenetic changes in DRGs at multiple time points after pain onset. Real-time RT PCR analysis revealed robust and time-dependent changes in DNMT transcript expression in ipsilateral DRGs from spared nerve injury (SNI) but not sham rats. Interestingly, DNMT3b transcript showed a robust upregulation that appeared already 1 week after surgery and persisted at 4 weeks (our endpoint); in contrast, DNMT1 and DNMT3a transcripts showed only moderate upregulation that was transient and did not appear until the second week. We suggest that DNMT regulation in adult DRGs may be a contributor to the pain phenotype and merits further study.

No MeSH data available.


Related in: MedlinePlus