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RBFOX3/NeuN is Required for Hippocampal Circuit Balance and Function.

Wang HY, Hsieh PF, Huang DF, Chin PS, Chou CH, Tung CC, Chen SY, Lee LJ, Gau SS, Huang HS - Sci Rep (2015)

Bottom Line: RBFOX3 mutations are linked to epilepsy and cognitive impairments, but the underlying pathophysiology of these disorders is poorly understood.Focusing on hippocampal phenotypes, we found Rbfox3 knockout mice showed increased expression of plasticity genes Egr4 and Arc, and the synaptic transmission and plasticity were defective in the mutant perforant pathway.The mutant dentate granules cells exhibited an increased frequency, but normal amplitude, of excitatory synaptic events, and this change was associated with an increase in the neurotransmitter release probability and dendritic spine density.

View Article: PubMed Central - PubMed

Affiliation: Graduate Institute of Brain and Mind Sciences, College of Medicine, National Taiwan University, Taipei, 10051, Taiwan.

ABSTRACT
RBFOX3 mutations are linked to epilepsy and cognitive impairments, but the underlying pathophysiology of these disorders is poorly understood. Here we report replication of human symptoms in a mouse model with disrupted Rbfox3. Rbfox3 knockout mice displayed increased seizure susceptibility and decreased anxiety-related behaviors. Focusing on hippocampal phenotypes, we found Rbfox3 knockout mice showed increased expression of plasticity genes Egr4 and Arc, and the synaptic transmission and plasticity were defective in the mutant perforant pathway. The mutant dentate granules cells exhibited an increased frequency, but normal amplitude, of excitatory synaptic events, and this change was associated with an increase in the neurotransmitter release probability and dendritic spine density. Together, our results demonstrate anatomical and functional abnormality in Rbfox3 knockout mice, and may provide mechanistic insights for RBFOX3-related human brain disorders.

No MeSH data available.


Related in: MedlinePlus

Granule cells of adult Rbfox3−/− mice exhibit increased spine density and dendritic complexity.Dendritic spines were counted in granule cells of Golgi stained tissue from the hippocampal DG. (a) Schematic of hippocampal slices for granule cell analysis at P49. (b) Representative image of distal dendritic spines (top) and spine density (bottom). WT, n = 85 segments, 20 cells, 3 mice; KO, n = 120 segments, 29 cells, 3 mice. Mann-Whitney rank sum test, ***P < 0.001. (c) Representative image of proximal dendritic spines (top) and spine density (bottom). WT, n = 87 segments, 27 cells, 3 mice; KO, n = 93 segments, 28 cells, 3 mice. Student’s t-test, two-tailed, ***P < 0.001. All data are presented as mean ± s.e.m. Scale bar represents 3 μm. (d) Representative images of reconstructed DG granule cells from WT and KO mice. Scale bar represents 50 μm. (e) Sholl analysis-derived distribution of granule cells mean number and length of intersections of dendritic branches with consecutive 20 μm-spaced concentric spheres. WT, n = 37 cells, 5 mice; KO, n = 37 cells, 5 mice. Student’s t-test, two tailed, *P < 0.05. (f) Quantification of parameters of dendritic morphology. WT, n = 37 cells, 5 mice; KO, n = 37 cells, 5 mice. Student’s t-test, two-tailed, *P < 0.05, ***P < 0.001. Dendritic segment length was analyzed under different branch order without (g) and with (h) terminal ends. WT, n = 37 cells, 5 mice; KO, n = 37 cells, 5 mice. Student’s t-test, two-tailed, *P < 0.05, **P < 0.01. All data are presented as mean ± s.e.m.
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f6: Granule cells of adult Rbfox3−/− mice exhibit increased spine density and dendritic complexity.Dendritic spines were counted in granule cells of Golgi stained tissue from the hippocampal DG. (a) Schematic of hippocampal slices for granule cell analysis at P49. (b) Representative image of distal dendritic spines (top) and spine density (bottom). WT, n = 85 segments, 20 cells, 3 mice; KO, n = 120 segments, 29 cells, 3 mice. Mann-Whitney rank sum test, ***P < 0.001. (c) Representative image of proximal dendritic spines (top) and spine density (bottom). WT, n = 87 segments, 27 cells, 3 mice; KO, n = 93 segments, 28 cells, 3 mice. Student’s t-test, two-tailed, ***P < 0.001. All data are presented as mean ± s.e.m. Scale bar represents 3 μm. (d) Representative images of reconstructed DG granule cells from WT and KO mice. Scale bar represents 50 μm. (e) Sholl analysis-derived distribution of granule cells mean number and length of intersections of dendritic branches with consecutive 20 μm-spaced concentric spheres. WT, n = 37 cells, 5 mice; KO, n = 37 cells, 5 mice. Student’s t-test, two tailed, *P < 0.05. (f) Quantification of parameters of dendritic morphology. WT, n = 37 cells, 5 mice; KO, n = 37 cells, 5 mice. Student’s t-test, two-tailed, *P < 0.05, ***P < 0.001. Dendritic segment length was analyzed under different branch order without (g) and with (h) terminal ends. WT, n = 37 cells, 5 mice; KO, n = 37 cells, 5 mice. Student’s t-test, two-tailed, *P < 0.05, **P < 0.01. All data are presented as mean ± s.e.m.

Mentions: Because the increase in mEPSC frequency could be due to an increase in probability of release at the presynaptic site37 and/or an increase in synaptic inputs38, we examined whether Rbfox3 deletion altered synaptic density. Most excitatory synapses in the brain are located on dendritic spines, highly specialized subcellular structures that compartmentalize biochemical responses to activation of individual synapses39. Thus, the density of dendritic spines has been used an indicator of excitatory synapse density. Accordingly, we investigated spine density on the distal and proximal dendrites of hippocampal granule cells using Golgi staining analysis. We observed increased spine density in the distal (Fig. 6b) and proximal (Fig. 6c) regions of dendrites of granule cells in Rbfox3−/− mice. To better understand the dendritic branching characteristics of individual granule cells, we performed Sholl analysis (Fig. 6e) and dendritic morphology analysis (Fig. 6f–h). Increased dendritic complexity in Rbfox3−/− mice was observed compared to wild-type counterparts. These data indicate increased spine density and dendritic complexity of dentate granule cells could partly, directly or indirectly, contribute to increased neurotransmission in Rbfox3−/− mice.


RBFOX3/NeuN is Required for Hippocampal Circuit Balance and Function.

Wang HY, Hsieh PF, Huang DF, Chin PS, Chou CH, Tung CC, Chen SY, Lee LJ, Gau SS, Huang HS - Sci Rep (2015)

Granule cells of adult Rbfox3−/− mice exhibit increased spine density and dendritic complexity.Dendritic spines were counted in granule cells of Golgi stained tissue from the hippocampal DG. (a) Schematic of hippocampal slices for granule cell analysis at P49. (b) Representative image of distal dendritic spines (top) and spine density (bottom). WT, n = 85 segments, 20 cells, 3 mice; KO, n = 120 segments, 29 cells, 3 mice. Mann-Whitney rank sum test, ***P < 0.001. (c) Representative image of proximal dendritic spines (top) and spine density (bottom). WT, n = 87 segments, 27 cells, 3 mice; KO, n = 93 segments, 28 cells, 3 mice. Student’s t-test, two-tailed, ***P < 0.001. All data are presented as mean ± s.e.m. Scale bar represents 3 μm. (d) Representative images of reconstructed DG granule cells from WT and KO mice. Scale bar represents 50 μm. (e) Sholl analysis-derived distribution of granule cells mean number and length of intersections of dendritic branches with consecutive 20 μm-spaced concentric spheres. WT, n = 37 cells, 5 mice; KO, n = 37 cells, 5 mice. Student’s t-test, two tailed, *P < 0.05. (f) Quantification of parameters of dendritic morphology. WT, n = 37 cells, 5 mice; KO, n = 37 cells, 5 mice. Student’s t-test, two-tailed, *P < 0.05, ***P < 0.001. Dendritic segment length was analyzed under different branch order without (g) and with (h) terminal ends. WT, n = 37 cells, 5 mice; KO, n = 37 cells, 5 mice. Student’s t-test, two-tailed, *P < 0.05, **P < 0.01. All data are presented as mean ± s.e.m.
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Related In: Results  -  Collection

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Show All Figures
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f6: Granule cells of adult Rbfox3−/− mice exhibit increased spine density and dendritic complexity.Dendritic spines were counted in granule cells of Golgi stained tissue from the hippocampal DG. (a) Schematic of hippocampal slices for granule cell analysis at P49. (b) Representative image of distal dendritic spines (top) and spine density (bottom). WT, n = 85 segments, 20 cells, 3 mice; KO, n = 120 segments, 29 cells, 3 mice. Mann-Whitney rank sum test, ***P < 0.001. (c) Representative image of proximal dendritic spines (top) and spine density (bottom). WT, n = 87 segments, 27 cells, 3 mice; KO, n = 93 segments, 28 cells, 3 mice. Student’s t-test, two-tailed, ***P < 0.001. All data are presented as mean ± s.e.m. Scale bar represents 3 μm. (d) Representative images of reconstructed DG granule cells from WT and KO mice. Scale bar represents 50 μm. (e) Sholl analysis-derived distribution of granule cells mean number and length of intersections of dendritic branches with consecutive 20 μm-spaced concentric spheres. WT, n = 37 cells, 5 mice; KO, n = 37 cells, 5 mice. Student’s t-test, two tailed, *P < 0.05. (f) Quantification of parameters of dendritic morphology. WT, n = 37 cells, 5 mice; KO, n = 37 cells, 5 mice. Student’s t-test, two-tailed, *P < 0.05, ***P < 0.001. Dendritic segment length was analyzed under different branch order without (g) and with (h) terminal ends. WT, n = 37 cells, 5 mice; KO, n = 37 cells, 5 mice. Student’s t-test, two-tailed, *P < 0.05, **P < 0.01. All data are presented as mean ± s.e.m.
Mentions: Because the increase in mEPSC frequency could be due to an increase in probability of release at the presynaptic site37 and/or an increase in synaptic inputs38, we examined whether Rbfox3 deletion altered synaptic density. Most excitatory synapses in the brain are located on dendritic spines, highly specialized subcellular structures that compartmentalize biochemical responses to activation of individual synapses39. Thus, the density of dendritic spines has been used an indicator of excitatory synapse density. Accordingly, we investigated spine density on the distal and proximal dendrites of hippocampal granule cells using Golgi staining analysis. We observed increased spine density in the distal (Fig. 6b) and proximal (Fig. 6c) regions of dendrites of granule cells in Rbfox3−/− mice. To better understand the dendritic branching characteristics of individual granule cells, we performed Sholl analysis (Fig. 6e) and dendritic morphology analysis (Fig. 6f–h). Increased dendritic complexity in Rbfox3−/− mice was observed compared to wild-type counterparts. These data indicate increased spine density and dendritic complexity of dentate granule cells could partly, directly or indirectly, contribute to increased neurotransmission in Rbfox3−/− mice.

Bottom Line: RBFOX3 mutations are linked to epilepsy and cognitive impairments, but the underlying pathophysiology of these disorders is poorly understood.Focusing on hippocampal phenotypes, we found Rbfox3 knockout mice showed increased expression of plasticity genes Egr4 and Arc, and the synaptic transmission and plasticity were defective in the mutant perforant pathway.The mutant dentate granules cells exhibited an increased frequency, but normal amplitude, of excitatory synaptic events, and this change was associated with an increase in the neurotransmitter release probability and dendritic spine density.

View Article: PubMed Central - PubMed

Affiliation: Graduate Institute of Brain and Mind Sciences, College of Medicine, National Taiwan University, Taipei, 10051, Taiwan.

ABSTRACT
RBFOX3 mutations are linked to epilepsy and cognitive impairments, but the underlying pathophysiology of these disorders is poorly understood. Here we report replication of human symptoms in a mouse model with disrupted Rbfox3. Rbfox3 knockout mice displayed increased seizure susceptibility and decreased anxiety-related behaviors. Focusing on hippocampal phenotypes, we found Rbfox3 knockout mice showed increased expression of plasticity genes Egr4 and Arc, and the synaptic transmission and plasticity were defective in the mutant perforant pathway. The mutant dentate granules cells exhibited an increased frequency, but normal amplitude, of excitatory synaptic events, and this change was associated with an increase in the neurotransmitter release probability and dendritic spine density. Together, our results demonstrate anatomical and functional abnormality in Rbfox3 knockout mice, and may provide mechanistic insights for RBFOX3-related human brain disorders.

No MeSH data available.


Related in: MedlinePlus