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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

STIM2 and pCaMKII are downregulated in hippocampal cultures treated with amyloid. a The expression levels of STIM2, STIM1, pCaMKII, and CaMKII were analyzed by Western blotting of lysates from WT hippocampal cultures exposed to Aβ40, Aβ42 or vehicle (Ctrl). Actin was used as a loading control. b Quantification of STIM2, STIM1, pCaMKII and CaMKII expression levels in WT cultures exposed to Aβ40, Aβ42 or vehicle (Ctrl) (normalized to actin levels). Graph represents the data from three independent experiments. Values are shown as mean ± SEM. *: p < 0.05 by ANOVA one-way and post hoc tests, n.s. (non specific)
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Fig3: STIM2 and pCaMKII are downregulated in hippocampal cultures treated with amyloid. a The expression levels of STIM2, STIM1, pCaMKII, and CaMKII were analyzed by Western blotting of lysates from WT hippocampal cultures exposed to Aβ40, Aβ42 or vehicle (Ctrl). Actin was used as a loading control. b Quantification of STIM2, STIM1, pCaMKII and CaMKII expression levels in WT cultures exposed to Aβ40, Aβ42 or vehicle (Ctrl) (normalized to actin levels). Graph represents the data from three independent experiments. Values are shown as mean ± SEM. *: p < 0.05 by ANOVA one-way and post hoc tests, n.s. (non specific)

Mentions: In our recent publication [10] we demonstrated that stability of mushroom spines depends on STIM2-mediated neuronal store-operated calcium influx (nSOC) and continuous activity of Ca2+ /calmodulin-dependent protein kinase II (CaMKII) which is enriched in synaptic spines. To find out if this pathway affected by application of amyloid oligomers we performed a series of Western blotting experiments with lysates prepared from control cultures and the cultures treated with Aβ40 and Aβ42 oligomers. In these experiments we observed approximately 20 % reduction in STIM2 expression levels in Aβ40 and Aβ42 treated cultures (Fig. 3a, 3b). We also observed 30 % reduction of auto-phosphorylated form of CaMKII (pCaMKII) in Aβ42-treated cultures (Fig. 3a, 3b). There was a trend to reduction of pCaMKII levels in Aβ40-treated cells, but it did not reach statistical significance (Fig. 3a, 3b). The levels of STIM1 protein and total CaMKII levels were not affected in Aβ40 or Aβ42-treated cultures (Fig. 3a, 3b). Notably, selective reduction in STIM2 expression and reduced levels of pCaMKII are similar to changes observed in our previous experiments with PS1-M146V-KI neurons [10], suggesting that common signalling pathways are affected in synaptic spines in both cellular models of AD pathology. However, changes in PS1-M146V-KI neurons were more dramatic than in Aβ42-treated neurons, with 75 % reduction in STIM2 levels and 40 % reduction in pCaMKII signal [10].Fig. 3


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)

STIM2 and pCaMKII are downregulated in hippocampal cultures treated with amyloid. a The expression levels of STIM2, STIM1, pCaMKII, and CaMKII were analyzed by Western blotting of lysates from WT hippocampal cultures exposed to Aβ40, Aβ42 or vehicle (Ctrl). Actin was used as a loading control. b Quantification of STIM2, STIM1, pCaMKII and CaMKII expression levels in WT cultures exposed to Aβ40, Aβ42 or vehicle (Ctrl) (normalized to actin levels). Graph represents the data from three independent experiments. Values are shown as mean ± SEM. *: p < 0.05 by ANOVA one-way and post hoc tests, n.s. (non specific)
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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Fig3: STIM2 and pCaMKII are downregulated in hippocampal cultures treated with amyloid. a The expression levels of STIM2, STIM1, pCaMKII, and CaMKII were analyzed by Western blotting of lysates from WT hippocampal cultures exposed to Aβ40, Aβ42 or vehicle (Ctrl). Actin was used as a loading control. b Quantification of STIM2, STIM1, pCaMKII and CaMKII expression levels in WT cultures exposed to Aβ40, Aβ42 or vehicle (Ctrl) (normalized to actin levels). Graph represents the data from three independent experiments. Values are shown as mean ± SEM. *: p < 0.05 by ANOVA one-way and post hoc tests, n.s. (non specific)
Mentions: In our recent publication [10] we demonstrated that stability of mushroom spines depends on STIM2-mediated neuronal store-operated calcium influx (nSOC) and continuous activity of Ca2+ /calmodulin-dependent protein kinase II (CaMKII) which is enriched in synaptic spines. To find out if this pathway affected by application of amyloid oligomers we performed a series of Western blotting experiments with lysates prepared from control cultures and the cultures treated with Aβ40 and Aβ42 oligomers. In these experiments we observed approximately 20 % reduction in STIM2 expression levels in Aβ40 and Aβ42 treated cultures (Fig. 3a, 3b). We also observed 30 % reduction of auto-phosphorylated form of CaMKII (pCaMKII) in Aβ42-treated cultures (Fig. 3a, 3b). There was a trend to reduction of pCaMKII levels in Aβ40-treated cells, but it did not reach statistical significance (Fig. 3a, 3b). The levels of STIM1 protein and total CaMKII levels were not affected in Aβ40 or Aβ42-treated cultures (Fig. 3a, 3b). Notably, selective reduction in STIM2 expression and reduced levels of pCaMKII are similar to changes observed in our previous experiments with PS1-M146V-KI neurons [10], suggesting that common signalling pathways are affected in synaptic spines in both cellular models of AD pathology. However, changes in PS1-M146V-KI neurons were more dramatic than in Aβ42-treated neurons, with 75 % reduction in STIM2 levels and 40 % reduction in pCaMKII signal [10].Fig. 3

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