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STIM2 protects hippocampal mushroom spines from amyloid synaptotoxicity.

Popugaeva E, Pchitskaya E, Speshilova A, Alexandrov S, Zhang H, Vlasova O, Bezprozvanny I - Mol Neurodegener (2015)

Bottom Line: Generation of amyloidogenic peptides and accumulation of amyloid plaques is one of the pathological hallmarks of AD.We discovered that application of Aβ42 oligomers to hippocampal cultures or injection of Aβ42 oligomers directly into hippocampal region resulted in reduction of mushroom spines and activity of synaptic calcium-calmodulin-dependent kinase II (CaMKII).Obtained results suggest that downregulation of STIM2-dependent stability of mushroom spines and reduction in activity of synaptic CaMKII is a mechanism of hippocampal synaptic loss in AD model of amyloid synaptotoxicity and that modulators/activators of this pathway may have a potential therapeutic value for treatment of AD.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Molecular Neurodegeneration, Department of Medical Physics, Peter the Great St.Petersburg Polytechnic University, St. Petersburg, Russian Federation. lena.popugaeva@gmail.com.

ABSTRACT

Background: Alzheimer disease (AD) is a disease of lost memories. Mushroom postsynaptic spines play a key role in memory storage, and loss of mushroom spines has been proposed to be linked to memory loss in AD. Generation of amyloidogenic peptides and accumulation of amyloid plaques is one of the pathological hallmarks of AD. It is important to evaluate effects of amyloid on stability of mushroom spines.

Results: In this study we used in vitro and in vivo models of amyloid synaptotoxicity to investigate effects of amyloid peptides on hippocampal mushroom spines. We discovered that application of Aβ42 oligomers to hippocampal cultures or injection of Aβ42 oligomers directly into hippocampal region resulted in reduction of mushroom spines and activity of synaptic calcium-calmodulin-dependent kinase II (CaMKII). We further discovered that expression of STIM2 protein rescued CaMKII activity and protected mushroom spines from amyloid toxicity in vitro and in vivo.

Conclusions: Obtained results suggest that downregulation of STIM2-dependent stability of mushroom spines and reduction in activity of synaptic CaMKII is a mechanism of hippocampal synaptic loss in AD model of amyloid synaptotoxicity and that modulators/activators of this pathway may have a potential therapeutic value for treatment of AD.

No MeSH data available.


Related in: MedlinePlus

Amyloid oligomers cause loss of hippocampal mushroom spines in vitro.a Primary hippocampal neurons from WT mice were transfected with TD-Tomato and visualized by confocal imaging. Representative images are shown for cultures exposed to Aβ40, Aβ42 or vehicle (Ctrl). Scale bar corresponds to 5 μm. On the Aβ42 panel all quantified types of spines are indicated: MS with an arrow, T with a triangle, S with a square, dendritic elements that were not counted as spines are labelled with a yellow star. The mean data from four independent experiments are shown. b Average percentages of mushroom (M), stubby (S) and thin (T) spines are shown for cultures exposed to Aβ40, Aβ42 or vehicle (Ctrl). For spine quantification n = 8–10 (for each treatment per one experiment) neurons were analyzed. Values are shown as mean ± SEM. **: p < 0.005 by ANOVA one-way and post hoc tests
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Fig2: Amyloid oligomers cause loss of hippocampal mushroom spines in vitro.a Primary hippocampal neurons from WT mice were transfected with TD-Tomato and visualized by confocal imaging. Representative images are shown for cultures exposed to Aβ40, Aβ42 or vehicle (Ctrl). Scale bar corresponds to 5 μm. On the Aβ42 panel all quantified types of spines are indicated: MS with an arrow, T with a triangle, S with a square, dendritic elements that were not counted as spines are labelled with a yellow star. The mean data from four independent experiments are shown. b Average percentages of mushroom (M), stubby (S) and thin (T) spines are shown for cultures exposed to Aβ40, Aβ42 or vehicle (Ctrl). For spine quantification n = 8–10 (for each treatment per one experiment) neurons were analyzed. Values are shown as mean ± SEM. **: p < 0.005 by ANOVA one-way and post hoc tests

Mentions: Previous studies demonstrated a shift from mushroom to stubby synaptic spines in organotypic hippocampal slice preparation from APPSDL transgenic mice [21]. To analyse how synaptic spine shape is affected by application of soluble amyloid oligomers, we adopted spine morphology analysis approach that was used in our previous study with PS1-M146V KI cultures [10]. In these experiments primary hippocampal cultures were transfected at DIV7 with plasmid expressing TD-Tomato fluorescent protein. On DIV11 cells were treated with Aβ40 or Aβ42 oligomers or vehicle treated. The neurons were fixed at DIV14, imaged by confocal microscopy and spine shapes were automatically analysed by a software (see Methods for details). Consistent with the previous report [10], mushroom spines constituted 35 % of total spines in control (vehicle treated) cultures at DIV 14 (Fig. 2a, 2b). Addition of Aβ40 oligomers had no significant effect on mushroom spines in neuronal cultures (Fig. 2a, 2b). In contrast, addition of Aβ42 oligomers resulted in significant reduction in mushroom spine proportion (Fig. 2a). On average, the fraction of mushroom spines was reduced to 20 % in cultures treated with Aβ42 oligomers (Fig. 2b). Following treatment with Aβ42, the fraction of stubby spines was increased from 35 to 50 % and the fraction of thin spines remained constant at 26 % (Fig. 2b). The shift from mushroom towards stubby spines induced by application of Aβ42 oligomers is consistent with the previous results obtained in organotypic hippocampal slices from APPSLD transgenic model [21]. This is in contrast with our previous studies with neurons from the PS1-M146V KI mice, where we observed the shift between mushroom and thin spines [10].Fig. 2


STIM2 protects hippocampal mushroom spines from amyloid synaptotoxicity.

Popugaeva E, Pchitskaya E, Speshilova A, Alexandrov S, Zhang H, Vlasova O, Bezprozvanny I - Mol Neurodegener (2015)

Amyloid oligomers cause loss of hippocampal mushroom spines in vitro.a Primary hippocampal neurons from WT mice were transfected with TD-Tomato and visualized by confocal imaging. Representative images are shown for cultures exposed to Aβ40, Aβ42 or vehicle (Ctrl). Scale bar corresponds to 5 μm. On the Aβ42 panel all quantified types of spines are indicated: MS with an arrow, T with a triangle, S with a square, dendritic elements that were not counted as spines are labelled with a yellow star. The mean data from four independent experiments are shown. b Average percentages of mushroom (M), stubby (S) and thin (T) spines are shown for cultures exposed to Aβ40, Aβ42 or vehicle (Ctrl). For spine quantification n = 8–10 (for each treatment per one experiment) neurons were analyzed. Values are shown as mean ± SEM. **: p < 0.005 by ANOVA one-way and post hoc tests
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4536802&req=5

Fig2: Amyloid oligomers cause loss of hippocampal mushroom spines in vitro.a Primary hippocampal neurons from WT mice were transfected with TD-Tomato and visualized by confocal imaging. Representative images are shown for cultures exposed to Aβ40, Aβ42 or vehicle (Ctrl). Scale bar corresponds to 5 μm. On the Aβ42 panel all quantified types of spines are indicated: MS with an arrow, T with a triangle, S with a square, dendritic elements that were not counted as spines are labelled with a yellow star. The mean data from four independent experiments are shown. b Average percentages of mushroom (M), stubby (S) and thin (T) spines are shown for cultures exposed to Aβ40, Aβ42 or vehicle (Ctrl). For spine quantification n = 8–10 (for each treatment per one experiment) neurons were analyzed. Values are shown as mean ± SEM. **: p < 0.005 by ANOVA one-way and post hoc tests
Mentions: Previous studies demonstrated a shift from mushroom to stubby synaptic spines in organotypic hippocampal slice preparation from APPSDL transgenic mice [21]. To analyse how synaptic spine shape is affected by application of soluble amyloid oligomers, we adopted spine morphology analysis approach that was used in our previous study with PS1-M146V KI cultures [10]. In these experiments primary hippocampal cultures were transfected at DIV7 with plasmid expressing TD-Tomato fluorescent protein. On DIV11 cells were treated with Aβ40 or Aβ42 oligomers or vehicle treated. The neurons were fixed at DIV14, imaged by confocal microscopy and spine shapes were automatically analysed by a software (see Methods for details). Consistent with the previous report [10], mushroom spines constituted 35 % of total spines in control (vehicle treated) cultures at DIV 14 (Fig. 2a, 2b). Addition of Aβ40 oligomers had no significant effect on mushroom spines in neuronal cultures (Fig. 2a, 2b). In contrast, addition of Aβ42 oligomers resulted in significant reduction in mushroom spine proportion (Fig. 2a). On average, the fraction of mushroom spines was reduced to 20 % in cultures treated with Aβ42 oligomers (Fig. 2b). Following treatment with Aβ42, the fraction of stubby spines was increased from 35 to 50 % and the fraction of thin spines remained constant at 26 % (Fig. 2b). The shift from mushroom towards stubby spines induced by application of Aβ42 oligomers is consistent with the previous results obtained in organotypic hippocampal slices from APPSLD transgenic model [21]. This is in contrast with our previous studies with neurons from the PS1-M146V KI mice, where we observed the shift between mushroom and thin spines [10].Fig. 2

Bottom Line: Generation of amyloidogenic peptides and accumulation of amyloid plaques is one of the pathological hallmarks of AD.We discovered that application of Aβ42 oligomers to hippocampal cultures or injection of Aβ42 oligomers directly into hippocampal region resulted in reduction of mushroom spines and activity of synaptic calcium-calmodulin-dependent kinase II (CaMKII).Obtained results suggest that downregulation of STIM2-dependent stability of mushroom spines and reduction in activity of synaptic CaMKII is a mechanism of hippocampal synaptic loss in AD model of amyloid synaptotoxicity and that modulators/activators of this pathway may have a potential therapeutic value for treatment of AD.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Molecular Neurodegeneration, Department of Medical Physics, Peter the Great St.Petersburg Polytechnic University, St. Petersburg, Russian Federation. lena.popugaeva@gmail.com.

ABSTRACT

Background: Alzheimer disease (AD) is a disease of lost memories. Mushroom postsynaptic spines play a key role in memory storage, and loss of mushroom spines has been proposed to be linked to memory loss in AD. Generation of amyloidogenic peptides and accumulation of amyloid plaques is one of the pathological hallmarks of AD. It is important to evaluate effects of amyloid on stability of mushroom spines.

Results: In this study we used in vitro and in vivo models of amyloid synaptotoxicity to investigate effects of amyloid peptides on hippocampal mushroom spines. We discovered that application of Aβ42 oligomers to hippocampal cultures or injection of Aβ42 oligomers directly into hippocampal region resulted in reduction of mushroom spines and activity of synaptic calcium-calmodulin-dependent kinase II (CaMKII). We further discovered that expression of STIM2 protein rescued CaMKII activity and protected mushroom spines from amyloid toxicity in vitro and in vivo.

Conclusions: Obtained results suggest that downregulation of STIM2-dependent stability of mushroom spines and reduction in activity of synaptic CaMKII is a mechanism of hippocampal synaptic loss in AD model of amyloid synaptotoxicity and that modulators/activators of this pathway may have a potential therapeutic value for treatment of AD.

No MeSH data available.


Related in: MedlinePlus