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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 overexpression rescues levels of PSD95 and pCAMKII proteins in conditions of amyloid toxicity in vivo.a The expression levels of STIM1, PSD95, pCaMKII, and CaMKII were analyzed by Western blotting of hippocampal lysates taken from 3.5 months old mice injected with AAV1-mSTIM2 (S2), Aβ42, control mice (Ctrl), and Aβ42 together with AAV1-mSTIM2 (S2). Each band on WB panel represents one mice. Tubulin was used as a loading control. b Expression of STIM1, PSD95, pCaMKII, CaMKII proteins was normalized to tubulin. Mean values from 3 independent experiments are shown as mean ± SEM for the mice injected with AAV1-mSTIM2 (S2), Aβ42, control mice (Ctrl), and Aβ42 together with AAV1-mSTIM2 (S2). *: p < 0.05, **: p < 0.005 by t-test
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Fig8: STIM2 overexpression rescues levels of PSD95 and pCAMKII proteins in conditions of amyloid toxicity in vivo.a The expression levels of STIM1, PSD95, pCaMKII, and CaMKII were analyzed by Western blotting of hippocampal lysates taken from 3.5 months old mice injected with AAV1-mSTIM2 (S2), Aβ42, control mice (Ctrl), and Aβ42 together with AAV1-mSTIM2 (S2). Each band on WB panel represents one mice. Tubulin was used as a loading control. b Expression of STIM1, PSD95, pCaMKII, CaMKII proteins was normalized to tubulin. Mean values from 3 independent experiments are shown as mean ± SEM for the mice injected with AAV1-mSTIM2 (S2), Aβ42, control mice (Ctrl), and Aβ42 together with AAV1-mSTIM2 (S2). *: p < 0.05, **: p < 0.005 by t-test

Mentions: To evaluate potential neuroprotective effects of STIM2 expression in vivo, we performed stereotaxic injections of AAV1-mSTIM2 virus together with Aβ42 oligomers (at 1 μM concentration) to CA1 region of 2 months old Thy1-GFP line M mice. Control mice were injected with AAV1-mSTIM2 together with the secondary antibodies. Neuronal and synaptic morphology in CA1 area (stratum radiatum) was analysed by two-photon imaging with hippocampal brain slices six weeks after injection (Fig. 7a). Consistent with the previous findings (Fig. 5), we found that injection of Aβ42 oligomers results in significant loss of synaptic spines (Fig. 7b) and reduction in the fraction of mushroom spines (Fig. 7c). Expression of STIM2 protein had no effect on total spine density or the fraction of mushroom spines in control experiments, but resulted in complete rescue of total spine loss and mushroom spine loss induced by Aβ42 oligomers (Fig. 7b, 7c). To further confirm these findings we performed Western blotting of hippocampal lysates from these mice (Fig. 8). In these experiments we discovered that expression of STIM2 prevents reduction of PSD95 and pCaMKII levels in hippocampal region of Aβ42-injected mice (Fig. 8a, 8b).Fig. 7


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 overexpression rescues levels of PSD95 and pCAMKII proteins in conditions of amyloid toxicity in vivo.a The expression levels of STIM1, PSD95, pCaMKII, and CaMKII were analyzed by Western blotting of hippocampal lysates taken from 3.5 months old mice injected with AAV1-mSTIM2 (S2), Aβ42, control mice (Ctrl), and Aβ42 together with AAV1-mSTIM2 (S2). Each band on WB panel represents one mice. Tubulin was used as a loading control. b Expression of STIM1, PSD95, pCaMKII, CaMKII proteins was normalized to tubulin. Mean values from 3 independent experiments are shown as mean ± SEM for the mice injected with AAV1-mSTIM2 (S2), Aβ42, control mice (Ctrl), and Aβ42 together with AAV1-mSTIM2 (S2). *: p < 0.05, **: p < 0.005 by t-test
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4536802&req=5

Fig8: STIM2 overexpression rescues levels of PSD95 and pCAMKII proteins in conditions of amyloid toxicity in vivo.a The expression levels of STIM1, PSD95, pCaMKII, and CaMKII were analyzed by Western blotting of hippocampal lysates taken from 3.5 months old mice injected with AAV1-mSTIM2 (S2), Aβ42, control mice (Ctrl), and Aβ42 together with AAV1-mSTIM2 (S2). Each band on WB panel represents one mice. Tubulin was used as a loading control. b Expression of STIM1, PSD95, pCaMKII, CaMKII proteins was normalized to tubulin. Mean values from 3 independent experiments are shown as mean ± SEM for the mice injected with AAV1-mSTIM2 (S2), Aβ42, control mice (Ctrl), and Aβ42 together with AAV1-mSTIM2 (S2). *: p < 0.05, **: p < 0.005 by t-test
Mentions: To evaluate potential neuroprotective effects of STIM2 expression in vivo, we performed stereotaxic injections of AAV1-mSTIM2 virus together with Aβ42 oligomers (at 1 μM concentration) to CA1 region of 2 months old Thy1-GFP line M mice. Control mice were injected with AAV1-mSTIM2 together with the secondary antibodies. Neuronal and synaptic morphology in CA1 area (stratum radiatum) was analysed by two-photon imaging with hippocampal brain slices six weeks after injection (Fig. 7a). Consistent with the previous findings (Fig. 5), we found that injection of Aβ42 oligomers results in significant loss of synaptic spines (Fig. 7b) and reduction in the fraction of mushroom spines (Fig. 7c). Expression of STIM2 protein had no effect on total spine density or the fraction of mushroom spines in control experiments, but resulted in complete rescue of total spine loss and mushroom spine loss induced by Aβ42 oligomers (Fig. 7b, 7c). To further confirm these findings we performed Western blotting of hippocampal lysates from these mice (Fig. 8). In these experiments we discovered that expression of STIM2 prevents reduction of PSD95 and pCaMKII levels in hippocampal region of Aβ42-injected mice (Fig. 8a, 8b).Fig. 7

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