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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

Influence of Aβ42 on mushroom spines in vivo. a The spine shape of CA1 hippocampal neurons from the 3.5 months old line M mice injected with Aβ42 and control mice was visualized by two-photon imaging. Scale bar corresponds to 5 μm. On the Ctrl panel all quantified types of spines are indicated: M (mushroom) with an arrow, T (thin) with a triangle and S (stubby) with a square. b, c Total spine density and percentages of mushroom, thin and stubby spines in neurons from CA1 hippocampal area. Graph represents the data of three independent experiments with control mice and the mice injected with Aβ42. For spine quantification n = 21–30 neurons were analyzed. Values are shown as mean ± SEM. ***: p < 0.0005 by t-test
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Fig5: Influence of Aβ42 on mushroom spines in vivo. a The spine shape of CA1 hippocampal neurons from the 3.5 months old line M mice injected with Aβ42 and control mice was visualized by two-photon imaging. Scale bar corresponds to 5 μm. On the Ctrl panel all quantified types of spines are indicated: M (mushroom) with an arrow, T (thin) with a triangle and S (stubby) with a square. b, c Total spine density and percentages of mushroom, thin and stubby spines in neurons from CA1 hippocampal area. Graph represents the data of three independent experiments with control mice and the mice injected with Aβ42. For spine quantification n = 21–30 neurons were analyzed. Values are shown as mean ± SEM. ***: p < 0.0005 by t-test

Mentions: Do amyloid oligomers result in loss of mushroom spines in vivo? To answer this question, we performed stereotaxic injections of synthetic Aβ42 oligomers to CA1 region of 2 months old line Thy1-GFP line M mice [22]. In control AFM analyses and SDS gel Western blotting experiments we confirmed formation of oligomeric Aβ42 species in these preparations (Additional file 1: Figure S1A, B). The stock concentrations of Aβ42 injection solution in these experiments was equal to 1 μM based on the initial peptide content. Control line M mice were injected with secondary antibodies conjugated to Alexa-555 fluorophore. Six week after injections synaptic morphology in these mice was analysed by two-photon imaging performed with hippocampal slices (Fig. 5a). When obtained results were analysed, we discovered that injection of Aβ42 oligomers resulted in significant reduction in total spine density (Fig. 5b). We also found that the fraction of mushroom spines was significantly reduced and the fraction of stubby spines was significantly increased in CA1 (stratum radiatum) area of hippocampus of the mice injected with Aβ42 oligomers (Fig. 5c). The fraction of thin spines was not affected in these experiments (Fig. 5c). The shift from mushroom to stubby spines observed in these experiments in response to injection of Aβ42 oligomers is similar to results obtained in our primary culture experiments (Fig. 2) and in published reports with organotypic hippocampal slices [21].Fig. 5


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)

Influence of Aβ42 on mushroom spines in vivo. a The spine shape of CA1 hippocampal neurons from the 3.5 months old line M mice injected with Aβ42 and control mice was visualized by two-photon imaging. Scale bar corresponds to 5 μm. On the Ctrl panel all quantified types of spines are indicated: M (mushroom) with an arrow, T (thin) with a triangle and S (stubby) with a square. b, c Total spine density and percentages of mushroom, thin and stubby spines in neurons from CA1 hippocampal area. Graph represents the data of three independent experiments with control mice and the mice injected with Aβ42. For spine quantification n = 21–30 neurons were analyzed. Values are shown as mean ± SEM. ***: p < 0.0005 by t-test
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4536802&req=5

Fig5: Influence of Aβ42 on mushroom spines in vivo. a The spine shape of CA1 hippocampal neurons from the 3.5 months old line M mice injected with Aβ42 and control mice was visualized by two-photon imaging. Scale bar corresponds to 5 μm. On the Ctrl panel all quantified types of spines are indicated: M (mushroom) with an arrow, T (thin) with a triangle and S (stubby) with a square. b, c Total spine density and percentages of mushroom, thin and stubby spines in neurons from CA1 hippocampal area. Graph represents the data of three independent experiments with control mice and the mice injected with Aβ42. For spine quantification n = 21–30 neurons were analyzed. Values are shown as mean ± SEM. ***: p < 0.0005 by t-test
Mentions: Do amyloid oligomers result in loss of mushroom spines in vivo? To answer this question, we performed stereotaxic injections of synthetic Aβ42 oligomers to CA1 region of 2 months old line Thy1-GFP line M mice [22]. In control AFM analyses and SDS gel Western blotting experiments we confirmed formation of oligomeric Aβ42 species in these preparations (Additional file 1: Figure S1A, B). The stock concentrations of Aβ42 injection solution in these experiments was equal to 1 μM based on the initial peptide content. Control line M mice were injected with secondary antibodies conjugated to Alexa-555 fluorophore. Six week after injections synaptic morphology in these mice was analysed by two-photon imaging performed with hippocampal slices (Fig. 5a). When obtained results were analysed, we discovered that injection of Aβ42 oligomers resulted in significant reduction in total spine density (Fig. 5b). We also found that the fraction of mushroom spines was significantly reduced and the fraction of stubby spines was significantly increased in CA1 (stratum radiatum) area of hippocampus of the mice injected with Aβ42 oligomers (Fig. 5c). The fraction of thin spines was not affected in these experiments (Fig. 5c). The shift from mushroom to stubby spines observed in these experiments in response to injection of Aβ42 oligomers is similar to results obtained in our primary culture experiments (Fig. 2) and in published reports with organotypic hippocampal slices [21].Fig. 5

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