Limits...
Astrocytes contribute to synapse elimination via type 2 inositol 1,4,5-trisphosphate receptor-dependent release of ATP.

Yang J, Yang H, Liu Y, Li X, Qin L, Lou H, Duan S, Wang H - Elife (2016)

Bottom Line: Selective elimination of unwanted synapses is vital for the precise formation of neuronal circuits during development, but the underlying mechanisms remain unclear.Interestingly, intracerebroventricular injection of ATP, but not adenosine, rescued the deficit in synapse elimination in Itpr2(-/-) mice.Our results uncovered a novel mechanism suggesting that astrocytes release ATP in an IP3R2-dependent manner to regulate synapse elimination.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurobiology, Key Laboratory of Medical Neurobiology of Ministry of Health of China, Key Laboratory of Neurobiology, Zhejiang University School of Medicine, Hangzhou, China.

ABSTRACT
Selective elimination of unwanted synapses is vital for the precise formation of neuronal circuits during development, but the underlying mechanisms remain unclear. Using inositol 1,4,5-trisphosphate receptor type 2 knockout (Itpr2(-/-)) mice to specifically disturb somatic Ca(2+) signaling in astrocytes, we showed that developmental elimination of the ventral posteromedial nucleus relay synapse was impaired. Interestingly, intracerebroventricular injection of ATP, but not adenosine, rescued the deficit in synapse elimination in Itpr2(-/-) mice. Further studies showed that developmental synapse elimination was also impaired in P2ry1(-/-) mice and was not rescued by ATP, indicating a possible role of purinergic signaling. This hypothesis was confirmed by MRS-2365, a selective P2Y1 agonist, could also rescue the deficient of synapse elimination in Itpr2(-/-) mice. Our results uncovered a novel mechanism suggesting that astrocytes release ATP in an IP3R2-dependent manner to regulate synapse elimination.

No MeSH data available.


Related in: MedlinePlus

Deficient of synapse elimination at P30 in Itpr2−/− mice.(a) Sample images of neurons and VGluT2 immunostaining in P30 WT (left panel) and Itpr2−/− (right panel) mice. Neurons were visualized with the NeuN antibody (green), and Pr5 axonal terminals were labeled by the VGluT2 antibody (red). Inset is higher-magnification of the boxed area. Scale bar, 10 µm. (b) Histogram summary of VGluT2 puncta/soma (left panel, n = 44 cells per group) and VGluT2 puncta/neuron (right panel, n = 9 sections from 3 mice per group) for WT and Itpr2−/− mice at P30. ***p<0.001, unpaired Student’s t test. Error bars indicate SEM.DOI:http://dx.doi.org/10.7554/eLife.15043.009
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4829431&req=5

fig2s1: Deficient of synapse elimination at P30 in Itpr2−/− mice.(a) Sample images of neurons and VGluT2 immunostaining in P30 WT (left panel) and Itpr2−/− (right panel) mice. Neurons were visualized with the NeuN antibody (green), and Pr5 axonal terminals were labeled by the VGluT2 antibody (red). Inset is higher-magnification of the boxed area. Scale bar, 10 µm. (b) Histogram summary of VGluT2 puncta/soma (left panel, n = 44 cells per group) and VGluT2 puncta/neuron (right panel, n = 9 sections from 3 mice per group) for WT and Itpr2−/− mice at P30. ***p<0.001, unpaired Student’s t test. Error bars indicate SEM.DOI:http://dx.doi.org/10.7554/eLife.15043.009

Mentions: To distinguish whether the deficit in synapse elimination was due to the failure of developmental elimination or abnormal synaptogenesis at an early age, we tested the connectivity of the Pr5-VPm projection at P7. We found that the number of inputs received by VPm neurons was comparable in the WT and Itpr2−/− mice (Figure 2a–d). Neither the numbers of VGluT2 puncta per soma nor per neuron differed between WT and Itpr2−/− mice at this age, indicating similar numbers of synapses in these mice (Figure 2e,f). These results suggested that synapse formation was normal at early postnatal stage in Itpr2−/− mice. To address the possibility that the deficit in synapse elimination we found at P16 was due to a delay in development, we assessed the synapse numbers at P30 by immunostaining for VGluT2. We found that even at P30, there were more Pr5-VPm synapses in Itpr2−/− mice than in WT mice (Figure 2—figure supplement 1a,b). Therefore, knockout of IP3R2 disrupted developmental synapse elimination at the VPm relay synapses.10.7554/eLife.15043.008Figure 2.Connectivity of Pr5-VPm pathway was comparable in WT and Itpr2−/− mice at P7.


Astrocytes contribute to synapse elimination via type 2 inositol 1,4,5-trisphosphate receptor-dependent release of ATP.

Yang J, Yang H, Liu Y, Li X, Qin L, Lou H, Duan S, Wang H - Elife (2016)

Deficient of synapse elimination at P30 in Itpr2−/− mice.(a) Sample images of neurons and VGluT2 immunostaining in P30 WT (left panel) and Itpr2−/− (right panel) mice. Neurons were visualized with the NeuN antibody (green), and Pr5 axonal terminals were labeled by the VGluT2 antibody (red). Inset is higher-magnification of the boxed area. Scale bar, 10 µm. (b) Histogram summary of VGluT2 puncta/soma (left panel, n = 44 cells per group) and VGluT2 puncta/neuron (right panel, n = 9 sections from 3 mice per group) for WT and Itpr2−/− mice at P30. ***p<0.001, unpaired Student’s t test. Error bars indicate SEM.DOI:http://dx.doi.org/10.7554/eLife.15043.009
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4829431&req=5

fig2s1: Deficient of synapse elimination at P30 in Itpr2−/− mice.(a) Sample images of neurons and VGluT2 immunostaining in P30 WT (left panel) and Itpr2−/− (right panel) mice. Neurons were visualized with the NeuN antibody (green), and Pr5 axonal terminals were labeled by the VGluT2 antibody (red). Inset is higher-magnification of the boxed area. Scale bar, 10 µm. (b) Histogram summary of VGluT2 puncta/soma (left panel, n = 44 cells per group) and VGluT2 puncta/neuron (right panel, n = 9 sections from 3 mice per group) for WT and Itpr2−/− mice at P30. ***p<0.001, unpaired Student’s t test. Error bars indicate SEM.DOI:http://dx.doi.org/10.7554/eLife.15043.009
Mentions: To distinguish whether the deficit in synapse elimination was due to the failure of developmental elimination or abnormal synaptogenesis at an early age, we tested the connectivity of the Pr5-VPm projection at P7. We found that the number of inputs received by VPm neurons was comparable in the WT and Itpr2−/− mice (Figure 2a–d). Neither the numbers of VGluT2 puncta per soma nor per neuron differed between WT and Itpr2−/− mice at this age, indicating similar numbers of synapses in these mice (Figure 2e,f). These results suggested that synapse formation was normal at early postnatal stage in Itpr2−/− mice. To address the possibility that the deficit in synapse elimination we found at P16 was due to a delay in development, we assessed the synapse numbers at P30 by immunostaining for VGluT2. We found that even at P30, there were more Pr5-VPm synapses in Itpr2−/− mice than in WT mice (Figure 2—figure supplement 1a,b). Therefore, knockout of IP3R2 disrupted developmental synapse elimination at the VPm relay synapses.10.7554/eLife.15043.008Figure 2.Connectivity of Pr5-VPm pathway was comparable in WT and Itpr2−/− mice at P7.

Bottom Line: Selective elimination of unwanted synapses is vital for the precise formation of neuronal circuits during development, but the underlying mechanisms remain unclear.Interestingly, intracerebroventricular injection of ATP, but not adenosine, rescued the deficit in synapse elimination in Itpr2(-/-) mice.Our results uncovered a novel mechanism suggesting that astrocytes release ATP in an IP3R2-dependent manner to regulate synapse elimination.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurobiology, Key Laboratory of Medical Neurobiology of Ministry of Health of China, Key Laboratory of Neurobiology, Zhejiang University School of Medicine, Hangzhou, China.

ABSTRACT
Selective elimination of unwanted synapses is vital for the precise formation of neuronal circuits during development, but the underlying mechanisms remain unclear. Using inositol 1,4,5-trisphosphate receptor type 2 knockout (Itpr2(-/-)) mice to specifically disturb somatic Ca(2+) signaling in astrocytes, we showed that developmental elimination of the ventral posteromedial nucleus relay synapse was impaired. Interestingly, intracerebroventricular injection of ATP, but not adenosine, rescued the deficit in synapse elimination in Itpr2(-/-) mice. Further studies showed that developmental synapse elimination was also impaired in P2ry1(-/-) mice and was not rescued by ATP, indicating a possible role of purinergic signaling. This hypothesis was confirmed by MRS-2365, a selective P2Y1 agonist, could also rescue the deficient of synapse elimination in Itpr2(-/-) mice. Our results uncovered a novel mechanism suggesting that astrocytes release ATP in an IP3R2-dependent manner to regulate synapse elimination.

No MeSH data available.


Related in: MedlinePlus