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Membrane-derived phospholipids control synaptic neurotransmission and plasticity.

García-Morales V, Montero F, González-Forero D, Rodríguez-Bey G, Gómez-Pérez L, Medialdea-Wandossell MJ, Domínguez-Vías G, García-Verdugo JM, Moreno-López B - PLoS Biol. (2015)

Bottom Line: LPA increased myosin light chain phosphorylation, which is known to trigger actomyosin contraction, and reduced the number of synaptic vesicles docked to active zones in excitatory boutons.However, LPA-induced depression of GABAergic transmission was correlated with an endocytosis-independent reduction of GABAA receptors, possibly by GABAAγ2 dephosphorylation and subsequent increased lateral diffusion.We propose that lysophospholipids serve as potential local messengers that tune synaptic strength to precedent activity of the neuron.

View Article: PubMed Central - PubMed

Affiliation: Grupo de Neurodegeneración y Neuroreparación (GRUNEDERE), Área de Fisiología, Facultad de Medicina, Universidad de Cádiz, Cádiz, Spain.

ABSTRACT
Synaptic communication is a dynamic process that is key to the regulation of neuronal excitability and information processing in the brain. To date, however, the molecular signals controlling synaptic dynamics have been poorly understood. Membrane-derived bioactive phospholipids are potential candidates to control short-term tuning of synaptic signaling, a plastic event essential for information processing at both the cellular and neuronal network levels in the brain. Here, we showed that phospholipids affect excitatory and inhibitory neurotransmission by different degrees, loci, and mechanisms of action. Signaling triggered by lysophosphatidic acid (LPA) evoked rapid and reversible depression of excitatory and inhibitory postsynaptic currents. At excitatory synapses, LPA-induced depression depended on LPA1/Gαi/o-protein/phospholipase C/myosin light chain kinase cascade at the presynaptic site. LPA increased myosin light chain phosphorylation, which is known to trigger actomyosin contraction, and reduced the number of synaptic vesicles docked to active zones in excitatory boutons. At inhibitory synapses, postsynaptic LPA signaling led to dephosphorylation, and internalization of the GABAAγ2 subunit through the LPA1/Gα12/13-protein/RhoA/Rho kinase/calcineurin pathway. However, LPA-induced depression of GABAergic transmission was correlated with an endocytosis-independent reduction of GABAA receptors, possibly by GABAAγ2 dephosphorylation and subsequent increased lateral diffusion. Furthermore, endogenous LPA signaling, mainly via LPA1, mediated activity-dependent inhibitory depression in a model of experimental synaptic plasticity. Finally, LPA signaling, most likely restraining the excitatory drive incoming to motoneurons, regulated performance of motor output commands, a basic brain processing task. We propose that lysophospholipids serve as potential local messengers that tune synaptic strength to precedent activity of the neuron.

No MeSH data available.


Related in: MedlinePlus

LPA induces dephosphorylation and internalization of the GABAAγ2 subunit in a ROCK/CaN-dependent manner.(A, B) Western blot (top) and averaged ratio (bottom) of total (T), cytosolic (C), and membrane-associated (M) GABAAγ2 in cultured SMNs incubated (10 min) with aCSF alone (control) or supplemented with indicated drugs (A). Dynasore (80 μM) or vehicle (0.2% DMSO) were added to the incubation solution 30 min before subsequent s-LPA coaddition for 10 min (B). β-actin was an internal loading reference for T and C fractions and an indicator for fractionation purity. The average densitometric signals for the GABAAγ2 C and M samples were expressed as a fraction of T GABAAγ2 of the same samples and normalized to the corresponding ratio determined for samples representing control conditions. *p < 0.05, one-way ANOVA on Ranks relative to control or vehicle condition. (C) Same as in Fig 6C under indicated treatments. Treatment with dynasore began at least 30 min before patch performance and was present all along the recording protocol. (D) Left, low-magnification photomicrographs showing a group of SMNs at 6 days in vitro treated for 40 min with aCSF alone and stained for GABAAγ2. Right, detail of a SMN exemplifying close association between GABAAγ2- and gephyrin-ir clusters. (E, F) Examples of GABAAγ2- and gephyrin-ir clusters in the surface of neurites obtained from SMNs treated for 40 min with dynasore (E) or 30 min with dynasore plus 10 min with s-LPA+dynasore (F). Scale bars: D, 50 μm; E, F, 5 μm. (G) Normalized mean cluster area (left) and fluorescence intensity (right) of GABAAγ2- and gephyrin-ir clusters analyzed under the indicated treatments (n > 1,200 clusters per condition). *p < 0.005, Student’s t test relative to control or dynasore condition. (H) Diagram of the proposed pathway mediating LPA-induced STD on GABAAR-mediated neurotransmission. Drug targets are also indicated. Plots data can be found in S1 Data.
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pbio.1002153.g007: LPA induces dephosphorylation and internalization of the GABAAγ2 subunit in a ROCK/CaN-dependent manner.(A, B) Western blot (top) and averaged ratio (bottom) of total (T), cytosolic (C), and membrane-associated (M) GABAAγ2 in cultured SMNs incubated (10 min) with aCSF alone (control) or supplemented with indicated drugs (A). Dynasore (80 μM) or vehicle (0.2% DMSO) were added to the incubation solution 30 min before subsequent s-LPA coaddition for 10 min (B). β-actin was an internal loading reference for T and C fractions and an indicator for fractionation purity. The average densitometric signals for the GABAAγ2 C and M samples were expressed as a fraction of T GABAAγ2 of the same samples and normalized to the corresponding ratio determined for samples representing control conditions. *p < 0.05, one-way ANOVA on Ranks relative to control or vehicle condition. (C) Same as in Fig 6C under indicated treatments. Treatment with dynasore began at least 30 min before patch performance and was present all along the recording protocol. (D) Left, low-magnification photomicrographs showing a group of SMNs at 6 days in vitro treated for 40 min with aCSF alone and stained for GABAAγ2. Right, detail of a SMN exemplifying close association between GABAAγ2- and gephyrin-ir clusters. (E, F) Examples of GABAAγ2- and gephyrin-ir clusters in the surface of neurites obtained from SMNs treated for 40 min with dynasore (E) or 30 min with dynasore plus 10 min with s-LPA+dynasore (F). Scale bars: D, 50 μm; E, F, 5 μm. (G) Normalized mean cluster area (left) and fluorescence intensity (right) of GABAAγ2- and gephyrin-ir clusters analyzed under the indicated treatments (n > 1,200 clusters per condition). *p < 0.005, Student’s t test relative to control or dynasore condition. (H) Diagram of the proposed pathway mediating LPA-induced STD on GABAAR-mediated neurotransmission. Drug targets are also indicated. Plots data can be found in S1 Data.

Mentions: It is generally accepted that dephosphorylation appears to be important for receptor endocytosis [4,9]. As a next step, we investigated whether LPA-triggered dephosphorylation was accompanied by further subunit internalization. We found that s-LPA (15 min) led to a strong reduction (−99.9 ± 0.01%) in the amount of GABAAγ2 allocated in M fraction in SMN cultures. A proportional increase (+109.4 ± 14.1%) in the quantity of GABAAγ2 was observed in the C fraction relative to total GABAAγ2 (Fig 7A). These outcomes suggest a translocation of at least this subunit from the SMN membrane to the cytosol triggered by s-LPA. The s-LPA-induced translocation was prevented by coincubation with either the ROCK inhibitor H1152 or the CaN inhibitor Cap (Fig 7A). GABAAγ2 compartmentalization in SMNs was maintained after treatment with H1152 or Cap per se (Fig 7A).


Membrane-derived phospholipids control synaptic neurotransmission and plasticity.

García-Morales V, Montero F, González-Forero D, Rodríguez-Bey G, Gómez-Pérez L, Medialdea-Wandossell MJ, Domínguez-Vías G, García-Verdugo JM, Moreno-López B - PLoS Biol. (2015)

LPA induces dephosphorylation and internalization of the GABAAγ2 subunit in a ROCK/CaN-dependent manner.(A, B) Western blot (top) and averaged ratio (bottom) of total (T), cytosolic (C), and membrane-associated (M) GABAAγ2 in cultured SMNs incubated (10 min) with aCSF alone (control) or supplemented with indicated drugs (A). Dynasore (80 μM) or vehicle (0.2% DMSO) were added to the incubation solution 30 min before subsequent s-LPA coaddition for 10 min (B). β-actin was an internal loading reference for T and C fractions and an indicator for fractionation purity. The average densitometric signals for the GABAAγ2 C and M samples were expressed as a fraction of T GABAAγ2 of the same samples and normalized to the corresponding ratio determined for samples representing control conditions. *p < 0.05, one-way ANOVA on Ranks relative to control or vehicle condition. (C) Same as in Fig 6C under indicated treatments. Treatment with dynasore began at least 30 min before patch performance and was present all along the recording protocol. (D) Left, low-magnification photomicrographs showing a group of SMNs at 6 days in vitro treated for 40 min with aCSF alone and stained for GABAAγ2. Right, detail of a SMN exemplifying close association between GABAAγ2- and gephyrin-ir clusters. (E, F) Examples of GABAAγ2- and gephyrin-ir clusters in the surface of neurites obtained from SMNs treated for 40 min with dynasore (E) or 30 min with dynasore plus 10 min with s-LPA+dynasore (F). Scale bars: D, 50 μm; E, F, 5 μm. (G) Normalized mean cluster area (left) and fluorescence intensity (right) of GABAAγ2- and gephyrin-ir clusters analyzed under the indicated treatments (n > 1,200 clusters per condition). *p < 0.005, Student’s t test relative to control or dynasore condition. (H) Diagram of the proposed pathway mediating LPA-induced STD on GABAAR-mediated neurotransmission. Drug targets are also indicated. Plots data can be found in S1 Data.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4440815&req=5

pbio.1002153.g007: LPA induces dephosphorylation and internalization of the GABAAγ2 subunit in a ROCK/CaN-dependent manner.(A, B) Western blot (top) and averaged ratio (bottom) of total (T), cytosolic (C), and membrane-associated (M) GABAAγ2 in cultured SMNs incubated (10 min) with aCSF alone (control) or supplemented with indicated drugs (A). Dynasore (80 μM) or vehicle (0.2% DMSO) were added to the incubation solution 30 min before subsequent s-LPA coaddition for 10 min (B). β-actin was an internal loading reference for T and C fractions and an indicator for fractionation purity. The average densitometric signals for the GABAAγ2 C and M samples were expressed as a fraction of T GABAAγ2 of the same samples and normalized to the corresponding ratio determined for samples representing control conditions. *p < 0.05, one-way ANOVA on Ranks relative to control or vehicle condition. (C) Same as in Fig 6C under indicated treatments. Treatment with dynasore began at least 30 min before patch performance and was present all along the recording protocol. (D) Left, low-magnification photomicrographs showing a group of SMNs at 6 days in vitro treated for 40 min with aCSF alone and stained for GABAAγ2. Right, detail of a SMN exemplifying close association between GABAAγ2- and gephyrin-ir clusters. (E, F) Examples of GABAAγ2- and gephyrin-ir clusters in the surface of neurites obtained from SMNs treated for 40 min with dynasore (E) or 30 min with dynasore plus 10 min with s-LPA+dynasore (F). Scale bars: D, 50 μm; E, F, 5 μm. (G) Normalized mean cluster area (left) and fluorescence intensity (right) of GABAAγ2- and gephyrin-ir clusters analyzed under the indicated treatments (n > 1,200 clusters per condition). *p < 0.005, Student’s t test relative to control or dynasore condition. (H) Diagram of the proposed pathway mediating LPA-induced STD on GABAAR-mediated neurotransmission. Drug targets are also indicated. Plots data can be found in S1 Data.
Mentions: It is generally accepted that dephosphorylation appears to be important for receptor endocytosis [4,9]. As a next step, we investigated whether LPA-triggered dephosphorylation was accompanied by further subunit internalization. We found that s-LPA (15 min) led to a strong reduction (−99.9 ± 0.01%) in the amount of GABAAγ2 allocated in M fraction in SMN cultures. A proportional increase (+109.4 ± 14.1%) in the quantity of GABAAγ2 was observed in the C fraction relative to total GABAAγ2 (Fig 7A). These outcomes suggest a translocation of at least this subunit from the SMN membrane to the cytosol triggered by s-LPA. The s-LPA-induced translocation was prevented by coincubation with either the ROCK inhibitor H1152 or the CaN inhibitor Cap (Fig 7A). GABAAγ2 compartmentalization in SMNs was maintained after treatment with H1152 or Cap per se (Fig 7A).

Bottom Line: LPA increased myosin light chain phosphorylation, which is known to trigger actomyosin contraction, and reduced the number of synaptic vesicles docked to active zones in excitatory boutons.However, LPA-induced depression of GABAergic transmission was correlated with an endocytosis-independent reduction of GABAA receptors, possibly by GABAAγ2 dephosphorylation and subsequent increased lateral diffusion.We propose that lysophospholipids serve as potential local messengers that tune synaptic strength to precedent activity of the neuron.

View Article: PubMed Central - PubMed

Affiliation: Grupo de Neurodegeneración y Neuroreparación (GRUNEDERE), Área de Fisiología, Facultad de Medicina, Universidad de Cádiz, Cádiz, Spain.

ABSTRACT
Synaptic communication is a dynamic process that is key to the regulation of neuronal excitability and information processing in the brain. To date, however, the molecular signals controlling synaptic dynamics have been poorly understood. Membrane-derived bioactive phospholipids are potential candidates to control short-term tuning of synaptic signaling, a plastic event essential for information processing at both the cellular and neuronal network levels in the brain. Here, we showed that phospholipids affect excitatory and inhibitory neurotransmission by different degrees, loci, and mechanisms of action. Signaling triggered by lysophosphatidic acid (LPA) evoked rapid and reversible depression of excitatory and inhibitory postsynaptic currents. At excitatory synapses, LPA-induced depression depended on LPA1/Gαi/o-protein/phospholipase C/myosin light chain kinase cascade at the presynaptic site. LPA increased myosin light chain phosphorylation, which is known to trigger actomyosin contraction, and reduced the number of synaptic vesicles docked to active zones in excitatory boutons. At inhibitory synapses, postsynaptic LPA signaling led to dephosphorylation, and internalization of the GABAAγ2 subunit through the LPA1/Gα12/13-protein/RhoA/Rho kinase/calcineurin pathway. However, LPA-induced depression of GABAergic transmission was correlated with an endocytosis-independent reduction of GABAA receptors, possibly by GABAAγ2 dephosphorylation and subsequent increased lateral diffusion. Furthermore, endogenous LPA signaling, mainly via LPA1, mediated activity-dependent inhibitory depression in a model of experimental synaptic plasticity. Finally, LPA signaling, most likely restraining the excitatory drive incoming to motoneurons, regulated performance of motor output commands, a basic brain processing task. We propose that lysophospholipids serve as potential local messengers that tune synaptic strength to precedent activity of the neuron.

No MeSH data available.


Related in: MedlinePlus