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Glutamate transporter splice variant expression in an enriched pyramidal cell population in schizophrenia.

O'Donovan SM, Hasselfeld K, Bauer D, Simmons M, Roussos P, Haroutunian V, Meador-Woodruff JH, McCullumsmith RE - Transl Psychiatry (2015)

Bottom Line: There was no significant change in other EAAT variants.EAAT2 single-nucleotide polymorphisms were significantly associated with changes in EAAT2 isoform expression.Haloperidol decanoate-treated animals, acting as controls for possible antipsychotic effects, did not have significantly altered neuronal EAAT2b mRNA levels.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati, Cincinnati, OH, USA.

ABSTRACT
Dysregulation of the glutamate transporters EAAT1 and EAAT2 and their isoforms have been implicated in schizophrenia. EAAT1 and EAAT2 expression has been studied in different brain regions but the prevalence of astrocytic glutamate transporter expression masks the more subtle changes in excitatory amino acid transporters (EAATs) isoforms in neurons in the cortex. Using laser capture microdissection, pyramidal neurons were cut from the anterior cingulate cortex of postmortem schizophrenia (n = 20) and control (n = 20) subjects. The messenger RNA (mRNA) levels of EAAT1, EAAT2 and the splice variants EAAT1 exon9skipping, EAAT2 exon9skipping and EAAT2b were analyzed by real time PCR (RT-PCR) in an enriched population of neurons. Region-level expression of these transcripts was measured in postmortem schizophrenia (n = 25) and controls (n = 25). The relationship between selected EAAT polymorphisms and EAAT splice variant expression was also explored. Anterior cingulate cortex pyramidal cell expression of EAAT2b mRNA was increased (P < 0.001; 67%) in schizophrenia subjects compared with controls. There was no significant change in other EAAT variants. EAAT2 exon9skipping mRNA was increased (P < 0.05; 38%) at region level in the anterior cingulate cortex with no significant change in other EAAT variants at region level. EAAT2 single-nucleotide polymorphisms were significantly associated with changes in EAAT2 isoform expression. Haloperidol decanoate-treated animals, acting as controls for possible antipsychotic effects, did not have significantly altered neuronal EAAT2b mRNA levels. The novel finding that EAAT2b levels are increased in populations of anterior cingulate cortex pyramidal cells further demonstrates a role for neuronal glutamate transporter splice variant expression in schizophrenia.

No MeSH data available.


Related in: MedlinePlus

There were significant associations between EAAT2 SNPs and the log-normalized mRNA expression of EAAT2 splice variants in region-level ACC following Mann–Whitney U analysis. EAAT2 mRNA expression was significantly altered (P<0.05) in SNP rs7115246 (a) and rs3794087 (b) subjects with the A/A polymorphism compared with G-carriers or C-carriers, respectively. EAAT2b mRNA expression was significantly altered (P<0.05) in SNP rs16927393 (c) subjects with the C/C polymorphism compared with T-carriers. EAAT2 exon9skipping mRNA expression was significantly altered (P<0.05) in SNP rs4755404 (d) subjects with the C/C polymorphism compared with G-carriers. EAAT2, EAAT2b and EAAT2 exon9skipping mRNA expression was significantly altered (P<0.05–P<0.01) in SNP rs3818275 (e–g) subjects with the A/A polymorphism compared with G-carriers. Filled squares represent schizophrenia subjects, open squares represent control subjects. Data are expressed as mean±s.d., n=9–32 per group. *P<0.05, **P<0.01. EAAT, excitatory amino acid transporter; EAAT2ex9, EAAT2 exon9 skipping splice variant; mRNA, messenger RNA; SNP, single-nucleotide polymorphism.
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fig4: There were significant associations between EAAT2 SNPs and the log-normalized mRNA expression of EAAT2 splice variants in region-level ACC following Mann–Whitney U analysis. EAAT2 mRNA expression was significantly altered (P<0.05) in SNP rs7115246 (a) and rs3794087 (b) subjects with the A/A polymorphism compared with G-carriers or C-carriers, respectively. EAAT2b mRNA expression was significantly altered (P<0.05) in SNP rs16927393 (c) subjects with the C/C polymorphism compared with T-carriers. EAAT2 exon9skipping mRNA expression was significantly altered (P<0.05) in SNP rs4755404 (d) subjects with the C/C polymorphism compared with G-carriers. EAAT2, EAAT2b and EAAT2 exon9skipping mRNA expression was significantly altered (P<0.05–P<0.01) in SNP rs3818275 (e–g) subjects with the A/A polymorphism compared with G-carriers. Filled squares represent schizophrenia subjects, open squares represent control subjects. Data are expressed as mean±s.d., n=9–32 per group. *P<0.05, **P<0.01. EAAT, excitatory amino acid transporter; EAAT2ex9, EAAT2 exon9 skipping splice variant; mRNA, messenger RNA; SNP, single-nucleotide polymorphism.

Mentions: All EAAT2 and EAAT1 polymorphisms were in Hardy–Weinberg equilibrium. We found several significant associations between SNPs in the EAAT2 (SLC1A2) gene and EAAT2 splice variant mRNA expression (Supplementary Table 3). SNP rs7115246 G-allele carriers had significantly increased (P<0.05) EAAT2 mRNA expression compared with homozygous A-allele carriers (Figure 4a). EAAT2 mRNA was significantly decreased (P<0.05) in SNP rs3794087 C-carriers compared with homozygous A-allele carriers (Figure 4b). EAAT2b mRNA was significantly decreased (P<0.05) in SNP rs16927393 T-carriers compared with homozygous C-allele carriers (Figure 4c). EAAT2 exon9skipping mRNA was significantly increased (P<0.05) in SNP rs4755404 G-carriers compared with homozygous C-allele carriers (Figure 4d). SNP rs3818275 was associated with increases in EAAT2 (P<0.05), EAAT2b (P<0.05) and EAAT2 exon9skipping (P<0.01) mRNA levels in G-carriers compared with homozygous A-allele carriers (Figure 4e–g). There were no significant effects of the EAAT1 (SLC1A3) SNPs on EAAT1 or EAAT1 exon9skipping mRNA expression (Supplementary Table 3).


Glutamate transporter splice variant expression in an enriched pyramidal cell population in schizophrenia.

O'Donovan SM, Hasselfeld K, Bauer D, Simmons M, Roussos P, Haroutunian V, Meador-Woodruff JH, McCullumsmith RE - Transl Psychiatry (2015)

There were significant associations between EAAT2 SNPs and the log-normalized mRNA expression of EAAT2 splice variants in region-level ACC following Mann–Whitney U analysis. EAAT2 mRNA expression was significantly altered (P<0.05) in SNP rs7115246 (a) and rs3794087 (b) subjects with the A/A polymorphism compared with G-carriers or C-carriers, respectively. EAAT2b mRNA expression was significantly altered (P<0.05) in SNP rs16927393 (c) subjects with the C/C polymorphism compared with T-carriers. EAAT2 exon9skipping mRNA expression was significantly altered (P<0.05) in SNP rs4755404 (d) subjects with the C/C polymorphism compared with G-carriers. EAAT2, EAAT2b and EAAT2 exon9skipping mRNA expression was significantly altered (P<0.05–P<0.01) in SNP rs3818275 (e–g) subjects with the A/A polymorphism compared with G-carriers. Filled squares represent schizophrenia subjects, open squares represent control subjects. Data are expressed as mean±s.d., n=9–32 per group. *P<0.05, **P<0.01. EAAT, excitatory amino acid transporter; EAAT2ex9, EAAT2 exon9 skipping splice variant; mRNA, messenger RNA; SNP, single-nucleotide polymorphism.
© Copyright Policy - open-access
Related In: Results  -  Collection

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fig4: There were significant associations between EAAT2 SNPs and the log-normalized mRNA expression of EAAT2 splice variants in region-level ACC following Mann–Whitney U analysis. EAAT2 mRNA expression was significantly altered (P<0.05) in SNP rs7115246 (a) and rs3794087 (b) subjects with the A/A polymorphism compared with G-carriers or C-carriers, respectively. EAAT2b mRNA expression was significantly altered (P<0.05) in SNP rs16927393 (c) subjects with the C/C polymorphism compared with T-carriers. EAAT2 exon9skipping mRNA expression was significantly altered (P<0.05) in SNP rs4755404 (d) subjects with the C/C polymorphism compared with G-carriers. EAAT2, EAAT2b and EAAT2 exon9skipping mRNA expression was significantly altered (P<0.05–P<0.01) in SNP rs3818275 (e–g) subjects with the A/A polymorphism compared with G-carriers. Filled squares represent schizophrenia subjects, open squares represent control subjects. Data are expressed as mean±s.d., n=9–32 per group. *P<0.05, **P<0.01. EAAT, excitatory amino acid transporter; EAAT2ex9, EAAT2 exon9 skipping splice variant; mRNA, messenger RNA; SNP, single-nucleotide polymorphism.
Mentions: All EAAT2 and EAAT1 polymorphisms were in Hardy–Weinberg equilibrium. We found several significant associations between SNPs in the EAAT2 (SLC1A2) gene and EAAT2 splice variant mRNA expression (Supplementary Table 3). SNP rs7115246 G-allele carriers had significantly increased (P<0.05) EAAT2 mRNA expression compared with homozygous A-allele carriers (Figure 4a). EAAT2 mRNA was significantly decreased (P<0.05) in SNP rs3794087 C-carriers compared with homozygous A-allele carriers (Figure 4b). EAAT2b mRNA was significantly decreased (P<0.05) in SNP rs16927393 T-carriers compared with homozygous C-allele carriers (Figure 4c). EAAT2 exon9skipping mRNA was significantly increased (P<0.05) in SNP rs4755404 G-carriers compared with homozygous C-allele carriers (Figure 4d). SNP rs3818275 was associated with increases in EAAT2 (P<0.05), EAAT2b (P<0.05) and EAAT2 exon9skipping (P<0.01) mRNA levels in G-carriers compared with homozygous A-allele carriers (Figure 4e–g). There were no significant effects of the EAAT1 (SLC1A3) SNPs on EAAT1 or EAAT1 exon9skipping mRNA expression (Supplementary Table 3).

Bottom Line: There was no significant change in other EAAT variants.EAAT2 single-nucleotide polymorphisms were significantly associated with changes in EAAT2 isoform expression.Haloperidol decanoate-treated animals, acting as controls for possible antipsychotic effects, did not have significantly altered neuronal EAAT2b mRNA levels.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati, Cincinnati, OH, USA.

ABSTRACT
Dysregulation of the glutamate transporters EAAT1 and EAAT2 and their isoforms have been implicated in schizophrenia. EAAT1 and EAAT2 expression has been studied in different brain regions but the prevalence of astrocytic glutamate transporter expression masks the more subtle changes in excitatory amino acid transporters (EAATs) isoforms in neurons in the cortex. Using laser capture microdissection, pyramidal neurons were cut from the anterior cingulate cortex of postmortem schizophrenia (n = 20) and control (n = 20) subjects. The messenger RNA (mRNA) levels of EAAT1, EAAT2 and the splice variants EAAT1 exon9skipping, EAAT2 exon9skipping and EAAT2b were analyzed by real time PCR (RT-PCR) in an enriched population of neurons. Region-level expression of these transcripts was measured in postmortem schizophrenia (n = 25) and controls (n = 25). The relationship between selected EAAT polymorphisms and EAAT splice variant expression was also explored. Anterior cingulate cortex pyramidal cell expression of EAAT2b mRNA was increased (P < 0.001; 67%) in schizophrenia subjects compared with controls. There was no significant change in other EAAT variants. EAAT2 exon9skipping mRNA was increased (P < 0.05; 38%) at region level in the anterior cingulate cortex with no significant change in other EAAT variants at region level. EAAT2 single-nucleotide polymorphisms were significantly associated with changes in EAAT2 isoform expression. Haloperidol decanoate-treated animals, acting as controls for possible antipsychotic effects, did not have significantly altered neuronal EAAT2b mRNA levels. The novel finding that EAAT2b levels are increased in populations of anterior cingulate cortex pyramidal cells further demonstrates a role for neuronal glutamate transporter splice variant expression in schizophrenia.

No MeSH data available.


Related in: MedlinePlus