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Sustained expression of PGC-1α in the rat nigrostriatal system selectively impairs dopaminergic function.

Ciron C, Lengacher S, Dusonchet J, Aebischer P, Schneider BL - Hum. Mol. Genet. (2012)

Bottom Line: In the adult rat nigrostriatal system, adeno-associated virus (AAV)-mediated overexpression of PGC-1α induces the selective loss of dopaminergic markers and increases dopamine (DA) catabolism, leading to a reduction in striatal DA content.Finally, PGC-1α overexpression does not prevent nigrostriatal degeneration in pathologic conditions induced by α-synuclein overexpression.These results highlight the central role of PGC-1α in the function and survival of dopaminergic neurons and the critical need for maintaining physiological levels of PGC-1α activity.

View Article: PubMed Central - PubMed

Affiliation: Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.

ABSTRACT
Mitochondrial dysfunction and oxidative stress have been implicated in the etiology of Parkinson's disease. Therefore, pathways controlling mitochondrial activity rapidly emerge as potential therapeutic targets. Here, we explore the neuronal response to prolonged overexpression of peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α), a transcriptional regulator of mitochondrial function, both in vitro and in vivo. In neuronal primary cultures from the ventral midbrain, PGC-1α induces mitochondrial biogenesis and increases basal respiration. Over time, we observe an increasing proportion of the oxygen consumed by neurons which are dedicated to adenosine triphosphate production. In parallel to enhanced oxidative phosphorylation, PGC-1α progressively leads to a decrease in mitochondrial polarization. In the adult rat nigrostriatal system, adeno-associated virus (AAV)-mediated overexpression of PGC-1α induces the selective loss of dopaminergic markers and increases dopamine (DA) catabolism, leading to a reduction in striatal DA content. In addition, PGC-1α prevents the labeling of nigral neurons following striatal injection of the fluorogold retrograde tracer. When PGC-1α is expressed at higher levels following intranigral AAV injection, it leads to overt degeneration of dopaminergic neurons. Finally, PGC-1α overexpression does not prevent nigrostriatal degeneration in pathologic conditions induced by α-synuclein overexpression. Overall, we find that lasting overexpression of PGC-1α leads to major alterations in the metabolic activity of neuronal cells which dramatically impair dopaminergic function in vivo. These results highlight the central role of PGC-1α in the function and survival of dopaminergic neurons and the critical need for maintaining physiological levels of PGC-1α activity.

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Mitochondrial transcriptome analysis of neuronal cultures overexpressing PGC-1α. Seven-day-old primary neuronal cultures from mouse ventral midbrain were infected with either a NCV or a vector encoding PGC-1α (PGC1). PCR arrays were performed at days 5 (A) and 7 (B) post-infection, to measure changes in the expression of 84 nuclear genes involved in various mitochondrial functions. Dark grey columns indicate significant changes in gene expression (n = 4, Student's t-test, P < 0.05). (C and D) To analyze mitochondrial membrane potential, neurons were incubated with the JC-1 sensor at 5 (C) and 8 (D) days post-infection and the ratio green/red fluorescence measured. One-way ANOVA with Newman–Keuls post hoc test: NI, n = 7; NCV, n = 8; PGC1, n = 7; *P < 0.05.
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DDR618F3: Mitochondrial transcriptome analysis of neuronal cultures overexpressing PGC-1α. Seven-day-old primary neuronal cultures from mouse ventral midbrain were infected with either a NCV or a vector encoding PGC-1α (PGC1). PCR arrays were performed at days 5 (A) and 7 (B) post-infection, to measure changes in the expression of 84 nuclear genes involved in various mitochondrial functions. Dark grey columns indicate significant changes in gene expression (n = 4, Student's t-test, P < 0.05). (C and D) To analyze mitochondrial membrane potential, neurons were incubated with the JC-1 sensor at 5 (C) and 8 (D) days post-infection and the ratio green/red fluorescence measured. One-way ANOVA with Newman–Keuls post hoc test: NI, n = 7; NCV, n = 8; PGC1, n = 7; *P < 0.05.

Mentions: To further investigate how PGC-1α could impact on mitochondrial function in mesencephalic neuronal cultures over time, we measured changes in the expression of 84 mitochondrial genes. Seven-day-old midbrain cultures infected with either AAV2/6-PGC-1α or a non-coding vector were analyzed at 5 (Fig. 3A) and 7 days (Fig. 3B) post-infection. The real-time PCR array includes nuclear genes related to various mitochondrial functions, such as the intrinsic apoptotic pathway or molecular transport across inner and outer membranes, which controls the transfer of metabolites for the ETC and oxidative phosphorylation as well as ions implicated in mitochondrial membrane polarization. Several genes are also implicated in mitochondrial fusion, fission and localization.Figure 3.


Sustained expression of PGC-1α in the rat nigrostriatal system selectively impairs dopaminergic function.

Ciron C, Lengacher S, Dusonchet J, Aebischer P, Schneider BL - Hum. Mol. Genet. (2012)

Mitochondrial transcriptome analysis of neuronal cultures overexpressing PGC-1α. Seven-day-old primary neuronal cultures from mouse ventral midbrain were infected with either a NCV or a vector encoding PGC-1α (PGC1). PCR arrays were performed at days 5 (A) and 7 (B) post-infection, to measure changes in the expression of 84 nuclear genes involved in various mitochondrial functions. Dark grey columns indicate significant changes in gene expression (n = 4, Student's t-test, P < 0.05). (C and D) To analyze mitochondrial membrane potential, neurons were incubated with the JC-1 sensor at 5 (C) and 8 (D) days post-infection and the ratio green/red fluorescence measured. One-way ANOVA with Newman–Keuls post hoc test: NI, n = 7; NCV, n = 8; PGC1, n = 7; *P < 0.05.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC3313800&req=5

DDR618F3: Mitochondrial transcriptome analysis of neuronal cultures overexpressing PGC-1α. Seven-day-old primary neuronal cultures from mouse ventral midbrain were infected with either a NCV or a vector encoding PGC-1α (PGC1). PCR arrays were performed at days 5 (A) and 7 (B) post-infection, to measure changes in the expression of 84 nuclear genes involved in various mitochondrial functions. Dark grey columns indicate significant changes in gene expression (n = 4, Student's t-test, P < 0.05). (C and D) To analyze mitochondrial membrane potential, neurons were incubated with the JC-1 sensor at 5 (C) and 8 (D) days post-infection and the ratio green/red fluorescence measured. One-way ANOVA with Newman–Keuls post hoc test: NI, n = 7; NCV, n = 8; PGC1, n = 7; *P < 0.05.
Mentions: To further investigate how PGC-1α could impact on mitochondrial function in mesencephalic neuronal cultures over time, we measured changes in the expression of 84 mitochondrial genes. Seven-day-old midbrain cultures infected with either AAV2/6-PGC-1α or a non-coding vector were analyzed at 5 (Fig. 3A) and 7 days (Fig. 3B) post-infection. The real-time PCR array includes nuclear genes related to various mitochondrial functions, such as the intrinsic apoptotic pathway or molecular transport across inner and outer membranes, which controls the transfer of metabolites for the ETC and oxidative phosphorylation as well as ions implicated in mitochondrial membrane polarization. Several genes are also implicated in mitochondrial fusion, fission and localization.Figure 3.

Bottom Line: In the adult rat nigrostriatal system, adeno-associated virus (AAV)-mediated overexpression of PGC-1α induces the selective loss of dopaminergic markers and increases dopamine (DA) catabolism, leading to a reduction in striatal DA content.Finally, PGC-1α overexpression does not prevent nigrostriatal degeneration in pathologic conditions induced by α-synuclein overexpression.These results highlight the central role of PGC-1α in the function and survival of dopaminergic neurons and the critical need for maintaining physiological levels of PGC-1α activity.

View Article: PubMed Central - PubMed

Affiliation: Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.

ABSTRACT
Mitochondrial dysfunction and oxidative stress have been implicated in the etiology of Parkinson's disease. Therefore, pathways controlling mitochondrial activity rapidly emerge as potential therapeutic targets. Here, we explore the neuronal response to prolonged overexpression of peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α), a transcriptional regulator of mitochondrial function, both in vitro and in vivo. In neuronal primary cultures from the ventral midbrain, PGC-1α induces mitochondrial biogenesis and increases basal respiration. Over time, we observe an increasing proportion of the oxygen consumed by neurons which are dedicated to adenosine triphosphate production. In parallel to enhanced oxidative phosphorylation, PGC-1α progressively leads to a decrease in mitochondrial polarization. In the adult rat nigrostriatal system, adeno-associated virus (AAV)-mediated overexpression of PGC-1α induces the selective loss of dopaminergic markers and increases dopamine (DA) catabolism, leading to a reduction in striatal DA content. In addition, PGC-1α prevents the labeling of nigral neurons following striatal injection of the fluorogold retrograde tracer. When PGC-1α is expressed at higher levels following intranigral AAV injection, it leads to overt degeneration of dopaminergic neurons. Finally, PGC-1α overexpression does not prevent nigrostriatal degeneration in pathologic conditions induced by α-synuclein overexpression. Overall, we find that lasting overexpression of PGC-1α leads to major alterations in the metabolic activity of neuronal cells which dramatically impair dopaminergic function in vivo. These results highlight the central role of PGC-1α in the function and survival of dopaminergic neurons and the critical need for maintaining physiological levels of PGC-1α activity.

Show MeSH
Related in: MedlinePlus