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Selective Effects of PDE10A Inhibitors on Striatopallidal Neurons Require Phosphatase Inhibition by DARPP-32(1,2,3).

Polito M, Guiot E, Gangarossa G, Longueville S, Doulazmi M, Valjent E, Hervé D, Girault JA, Paupardin-Tritsch D, Castro LR, Vincent P - eNeuro (2015)

Bottom Line: PDE10A inhibitors have pharmacological and behavioral effects suggesting an antipsychotic profile, but the cellular bases of these effects are unclear.The PKA-dependent effects in D2 MSNs were prevented in brain slices and in vivo by mutation of the PKA-regulated phosphorylation site of 32 kDa dopamine- and cAMP-regulated phosphoprotein (DARPP-32), which is required for protein phosphatase-1 inhibition.These data highlight differences in the integration of the cAMP signal in D1 and D2 MSNs, resulting from stronger inhibition of protein phosphatase-1 by DARPP-32 in D2 MSNs than in D1 MSNs.

View Article: PubMed Central - HTML - PubMed

Affiliation: CNRS, UMR8256 "Biological Adaptation and Ageing", Institut de Biologie Paris-Seine (IBPS) , F-75005 Paris, France ; Université Pierre et Marie Curie (UPMC, Paris 6), Sorbonne Universités , Paris, F-75005, France.

ABSTRACT
Type 10A phosphodiesterase (PDE10A) is highly expressed in the striatum, in striatonigral and striatopallidal medium-sized spiny neurons (MSNs), which express D1 and D2 dopamine receptors, respectively. PDE10A inhibitors have pharmacological and behavioral effects suggesting an antipsychotic profile, but the cellular bases of these effects are unclear. We analyzed the effects of PDE10A inhibition in vivo by immunohistochemistry, and imaged cAMP, cAMP-dependent protein kinase A (PKA), and cGMP signals with biosensors in mouse brain slices. PDE10A inhibition in mouse striatal slices produced a steady-state increase in intracellular cAMP concentration in D1 and D2 MSNs, demonstrating that PDE10A regulates basal cAMP levels. Surprisingly, the PKA-dependent AKAR3 phosphorylation signal was strong in D2 MSNs, whereas D1 MSNs remained unresponsive. This effect was also observed in adult mice in vivo since PDE10A inhibition increased phospho-histone H3 immunoreactivity selectively in D2 MSNs in the dorsomedial striatum. The PKA-dependent effects in D2 MSNs were prevented in brain slices and in vivo by mutation of the PKA-regulated phosphorylation site of 32 kDa dopamine- and cAMP-regulated phosphoprotein (DARPP-32), which is required for protein phosphatase-1 inhibition. These data highlight differences in the integration of the cAMP signal in D1 and D2 MSNs, resulting from stronger inhibition of protein phosphatase-1 by DARPP-32 in D2 MSNs than in D1 MSNs. This study shows that PDE10A inhibitors share with antipsychotic medications the property of activating preferentially PKA-dependent signaling in D2 MSNs.

No MeSH data available.


PDE10A inhibition triggers positive PKA responses in dendrites and nuclei preferentially in D2 MSNs. A, B, Brain slices expressed the PKA sensor AKAR3 (A) or AKAR2-NLS (B) and were imaged by two-photon microscopy during the application of PQ-10 (100 nm). Images show the raw fluorescence at 535 nm (left in grayscale) and the ratio (in pseudocolor) indicating the PKA-dependent phosphorylation level of the biosensor, at the times indicated by the arrows on the graph below. The calibration square in A indicates the spatial scale (above, in micrometers), and shows the ranges of intensity (horizontally) and ratio (vertically). Each trace on the graph indicates the F535/F480 emission ratio measured on regions indicated by the color contour drawn on the raw image. Traces are plotted in two groups according to their response to either CGS 21680 (CGS, 1 µm) or SKF-38393 (SKF, 1 µm). The thick black line represents the average of all the traces in a group. FSK (13 µm) was applied at the end of the recording to determine the maximal response.
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Figure 2: PDE10A inhibition triggers positive PKA responses in dendrites and nuclei preferentially in D2 MSNs. A, B, Brain slices expressed the PKA sensor AKAR3 (A) or AKAR2-NLS (B) and were imaged by two-photon microscopy during the application of PQ-10 (100 nm). Images show the raw fluorescence at 535 nm (left in grayscale) and the ratio (in pseudocolor) indicating the PKA-dependent phosphorylation level of the biosensor, at the times indicated by the arrows on the graph below. The calibration square in A indicates the spatial scale (above, in micrometers), and shows the ranges of intensity (horizontally) and ratio (vertically). Each trace on the graph indicates the F535/F480 emission ratio measured on regions indicated by the color contour drawn on the raw image. Traces are plotted in two groups according to their response to either CGS 21680 (CGS, 1 µm) or SKF-38393 (SKF, 1 µm). The thick black line represents the average of all the traces in a group. FSK (13 µm) was applied at the end of the recording to determine the maximal response.

Mentions: PDE10A may be addressed differentially in the cytoplasm and membranes (Kotera et al., 2004; Charych et al., 2010), and cAMP dynamics could differ in subcellular domains of different geometry, like dendrites (Castro et al., 2010). An increase in AKAR3 ratio was observed exclusively in the dendritic branches that responded to the A2A agonist, whereas dendrites, which responded to the D1 agonist, showed no response to 100 nm PQ-10 (Fig. 2A). This is consistent with other biosensor recordings in which dendrites of D1 MSNs also exhibited no baseline response to PDE10A inhibition (Yagishita et al., 2014).


Selective Effects of PDE10A Inhibitors on Striatopallidal Neurons Require Phosphatase Inhibition by DARPP-32(1,2,3).

Polito M, Guiot E, Gangarossa G, Longueville S, Doulazmi M, Valjent E, Hervé D, Girault JA, Paupardin-Tritsch D, Castro LR, Vincent P - eNeuro (2015)

PDE10A inhibition triggers positive PKA responses in dendrites and nuclei preferentially in D2 MSNs. A, B, Brain slices expressed the PKA sensor AKAR3 (A) or AKAR2-NLS (B) and were imaged by two-photon microscopy during the application of PQ-10 (100 nm). Images show the raw fluorescence at 535 nm (left in grayscale) and the ratio (in pseudocolor) indicating the PKA-dependent phosphorylation level of the biosensor, at the times indicated by the arrows on the graph below. The calibration square in A indicates the spatial scale (above, in micrometers), and shows the ranges of intensity (horizontally) and ratio (vertically). Each trace on the graph indicates the F535/F480 emission ratio measured on regions indicated by the color contour drawn on the raw image. Traces are plotted in two groups according to their response to either CGS 21680 (CGS, 1 µm) or SKF-38393 (SKF, 1 µm). The thick black line represents the average of all the traces in a group. FSK (13 µm) was applied at the end of the recording to determine the maximal response.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4596023&req=5

Figure 2: PDE10A inhibition triggers positive PKA responses in dendrites and nuclei preferentially in D2 MSNs. A, B, Brain slices expressed the PKA sensor AKAR3 (A) or AKAR2-NLS (B) and were imaged by two-photon microscopy during the application of PQ-10 (100 nm). Images show the raw fluorescence at 535 nm (left in grayscale) and the ratio (in pseudocolor) indicating the PKA-dependent phosphorylation level of the biosensor, at the times indicated by the arrows on the graph below. The calibration square in A indicates the spatial scale (above, in micrometers), and shows the ranges of intensity (horizontally) and ratio (vertically). Each trace on the graph indicates the F535/F480 emission ratio measured on regions indicated by the color contour drawn on the raw image. Traces are plotted in two groups according to their response to either CGS 21680 (CGS, 1 µm) or SKF-38393 (SKF, 1 µm). The thick black line represents the average of all the traces in a group. FSK (13 µm) was applied at the end of the recording to determine the maximal response.
Mentions: PDE10A may be addressed differentially in the cytoplasm and membranes (Kotera et al., 2004; Charych et al., 2010), and cAMP dynamics could differ in subcellular domains of different geometry, like dendrites (Castro et al., 2010). An increase in AKAR3 ratio was observed exclusively in the dendritic branches that responded to the A2A agonist, whereas dendrites, which responded to the D1 agonist, showed no response to 100 nm PQ-10 (Fig. 2A). This is consistent with other biosensor recordings in which dendrites of D1 MSNs also exhibited no baseline response to PDE10A inhibition (Yagishita et al., 2014).

Bottom Line: PDE10A inhibitors have pharmacological and behavioral effects suggesting an antipsychotic profile, but the cellular bases of these effects are unclear.The PKA-dependent effects in D2 MSNs were prevented in brain slices and in vivo by mutation of the PKA-regulated phosphorylation site of 32 kDa dopamine- and cAMP-regulated phosphoprotein (DARPP-32), which is required for protein phosphatase-1 inhibition.These data highlight differences in the integration of the cAMP signal in D1 and D2 MSNs, resulting from stronger inhibition of protein phosphatase-1 by DARPP-32 in D2 MSNs than in D1 MSNs.

View Article: PubMed Central - HTML - PubMed

Affiliation: CNRS, UMR8256 "Biological Adaptation and Ageing", Institut de Biologie Paris-Seine (IBPS) , F-75005 Paris, France ; Université Pierre et Marie Curie (UPMC, Paris 6), Sorbonne Universités , Paris, F-75005, France.

ABSTRACT
Type 10A phosphodiesterase (PDE10A) is highly expressed in the striatum, in striatonigral and striatopallidal medium-sized spiny neurons (MSNs), which express D1 and D2 dopamine receptors, respectively. PDE10A inhibitors have pharmacological and behavioral effects suggesting an antipsychotic profile, but the cellular bases of these effects are unclear. We analyzed the effects of PDE10A inhibition in vivo by immunohistochemistry, and imaged cAMP, cAMP-dependent protein kinase A (PKA), and cGMP signals with biosensors in mouse brain slices. PDE10A inhibition in mouse striatal slices produced a steady-state increase in intracellular cAMP concentration in D1 and D2 MSNs, demonstrating that PDE10A regulates basal cAMP levels. Surprisingly, the PKA-dependent AKAR3 phosphorylation signal was strong in D2 MSNs, whereas D1 MSNs remained unresponsive. This effect was also observed in adult mice in vivo since PDE10A inhibition increased phospho-histone H3 immunoreactivity selectively in D2 MSNs in the dorsomedial striatum. The PKA-dependent effects in D2 MSNs were prevented in brain slices and in vivo by mutation of the PKA-regulated phosphorylation site of 32 kDa dopamine- and cAMP-regulated phosphoprotein (DARPP-32), which is required for protein phosphatase-1 inhibition. These data highlight differences in the integration of the cAMP signal in D1 and D2 MSNs, resulting from stronger inhibition of protein phosphatase-1 by DARPP-32 in D2 MSNs than in D1 MSNs. This study shows that PDE10A inhibitors share with antipsychotic medications the property of activating preferentially PKA-dependent signaling in D2 MSNs.

No MeSH data available.