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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

Cell-level ACC log-normalized mRNA expression of the EAAT splice variants EAAT1 (a), EAAT1 exon9skipping (b), EAAT2 (c), EAAT2 exon9skipping (d) and EAAT2b (e). Following Student's t-test analysis, there was a significant difference in EAAT2b splice variant expression in schizophrenia subjects compared with controls in ACC pyramidal cells (P<0.001). There was a trend toward an increase in EAAT1 exon9skipping mRNA expression in schizophrenia subjects (P<0.07). Data are expressed as mean±s.d., n=16–19 per group. ***P<0.001, #P<0.07. ACC, anterior cingulate cortex; EAAT, excitatory amino acid transporter; mRNA, messenger RNA.
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fig1: Cell-level ACC log-normalized mRNA expression of the EAAT splice variants EAAT1 (a), EAAT1 exon9skipping (b), EAAT2 (c), EAAT2 exon9skipping (d) and EAAT2b (e). Following Student's t-test analysis, there was a significant difference in EAAT2b splice variant expression in schizophrenia subjects compared with controls in ACC pyramidal cells (P<0.001). There was a trend toward an increase in EAAT1 exon9skipping mRNA expression in schizophrenia subjects (P<0.07). Data are expressed as mean±s.d., n=16–19 per group. ***P<0.001, #P<0.07. ACC, anterior cingulate cortex; EAAT, excitatory amino acid transporter; mRNA, messenger RNA.

Mentions: In the ACC cell-level study, there was no significant association between expression of the target mRNAs EAAT1, EAAT2, EAAT1 exon9skipping, EAAT2 exon9skipping, EAAT2b and age, sex or RIN values. Student's t-test revealed a significant increase (67%) in EAAT2b mRNA expression (F(1,36)=13.762, P=0.0007) in an enriched population of ACC pyramidal neurons in schizophrenia compared with controls (Figure 1e). There was no significant effect of sex or medication on expression. There was a trend toward an increase (10%) in EAAT1 exon9skipping mRNA expression (F(1,33)=3.565,P=0.068; Figure 1b). There was no sex or medication effect for EAAT1 exon9skipping. There were no significant changes in mRNA expression for EAAT1, EAAT2 or EAAT2 exon9skipping (Figures 1a, c and d).


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)

Cell-level ACC log-normalized mRNA expression of the EAAT splice variants EAAT1 (a), EAAT1 exon9skipping (b), EAAT2 (c), EAAT2 exon9skipping (d) and EAAT2b (e). Following Student's t-test analysis, there was a significant difference in EAAT2b splice variant expression in schizophrenia subjects compared with controls in ACC pyramidal cells (P<0.001). There was a trend toward an increase in EAAT1 exon9skipping mRNA expression in schizophrenia subjects (P<0.07). Data are expressed as mean±s.d., n=16–19 per group. ***P<0.001, #P<0.07. ACC, anterior cingulate cortex; EAAT, excitatory amino acid transporter; mRNA, messenger RNA.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4490284&req=5

fig1: Cell-level ACC log-normalized mRNA expression of the EAAT splice variants EAAT1 (a), EAAT1 exon9skipping (b), EAAT2 (c), EAAT2 exon9skipping (d) and EAAT2b (e). Following Student's t-test analysis, there was a significant difference in EAAT2b splice variant expression in schizophrenia subjects compared with controls in ACC pyramidal cells (P<0.001). There was a trend toward an increase in EAAT1 exon9skipping mRNA expression in schizophrenia subjects (P<0.07). Data are expressed as mean±s.d., n=16–19 per group. ***P<0.001, #P<0.07. ACC, anterior cingulate cortex; EAAT, excitatory amino acid transporter; mRNA, messenger RNA.
Mentions: In the ACC cell-level study, there was no significant association between expression of the target mRNAs EAAT1, EAAT2, EAAT1 exon9skipping, EAAT2 exon9skipping, EAAT2b and age, sex or RIN values. Student's t-test revealed a significant increase (67%) in EAAT2b mRNA expression (F(1,36)=13.762, P=0.0007) in an enriched population of ACC pyramidal neurons in schizophrenia compared with controls (Figure 1e). There was no significant effect of sex or medication on expression. There was a trend toward an increase (10%) in EAAT1 exon9skipping mRNA expression (F(1,33)=3.565,P=0.068; Figure 1b). There was no sex or medication effect for EAAT1 exon9skipping. There were no significant changes in mRNA expression for EAAT1, EAAT2 or EAAT2 exon9skipping (Figures 1a, c and d).

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