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Ryanodine Receptor Activation Induces Long-Term Plasticity of Spine Calcium Dynamics.

Johenning FW, Theis AK, Pannasch U, Rückl M, Rüdiger S, Schmitz D - PLoS Biol. (2015)

Bottom Line: Ca2+ is a major upstream effector in this transduction cascade, serving both as a depolarising electrical charge carrier at the membrane and an intracellular second messenger.We demonstrate that RyRs can form specific Ca2+ signalling nanodomains within single spines.Functionally, RyR mediated Ca2+ release in these nanodomains induces a new form of Ca2+ transient plasticity that constitutes a spine specific storage mechanism of neuronal suprathreshold activity patterns.

View Article: PubMed Central - PubMed

Affiliation: Neuroscience Research Center, Charité-Universitätsmedizin, Berlin, Germany; Berlin Institute of Health (BIH), Berlin, Germany.

ABSTRACT
A key feature of signalling in dendritic spines is the synapse-specific transduction of short electrical signals into biochemical responses. Ca2+ is a major upstream effector in this transduction cascade, serving both as a depolarising electrical charge carrier at the membrane and an intracellular second messenger. Upon action potential firing, the majority of spines are subject to global back-propagating action potential (bAP) Ca2+ transients. These transients translate neuronal suprathreshold activation into intracellular biochemical events. Using a combination of electrophysiology, two-photon Ca2+ imaging, and modelling, we demonstrate that bAPs are electrochemically coupled to Ca2+ release from intracellular stores via ryanodine receptors (RyRs). We describe a new function mediated by spine RyRs: the activity-dependent long-term enhancement of the bAP-Ca2+ transient. Spines regulate bAP Ca2+ influx independent of each other, as bAP-Ca2+ transient enhancement is compartmentalized and independent of the dendritic Ca2+ transient. Furthermore, this functional state change depends exclusively on bAPs travelling antidromically into dendrites and spines. Induction, but not expression, of bAP-Ca2+ transient enhancement is a spine-specific function of the RyR. We demonstrate that RyRs can form specific Ca2+ signalling nanodomains within single spines. Functionally, RyR mediated Ca2+ release in these nanodomains induces a new form of Ca2+ transient plasticity that constitutes a spine specific storage mechanism of neuronal suprathreshold activity patterns.

No MeSH data available.


Related in: MedlinePlus

bAP-Ca2+ transient enhancement depends on Ca2+ release from intracellular stores.(a1) Z-projection of the imaged spine segment (scale bar corresponds to 2 μm). Asterisk marks imaged spine. (a2) Averaged baseline bAP-Ca2+ transients 0 to 5 min after bAP stimulation onset (grey) and averaged bAP-Ca2+ transients 15 to 20 min after bAP stimulation onset (red) of a spine in the presence of 30 μM CPA. (a3) Time plot of normalized doublet evoked bAP-Ca2+ transient enhancement in spines with small baseline amplitudes comparing control (black) spines to spines in the presence of 30 μM CPA (red). One doublet was applied every 60 s, the data is plotted in 3 min bins. (b1) Z-projection of the imaged spine segment (scale bar corresponds to 2 μm). Asterisk marks imaged spine. (b2) Averaged baseline bAP-Ca2+ transients 0 to 5 min after bAP stimulation onset (grey) and averaged bAP-Ca2+ transients 15 to 20 min after bAP stimulation onset (blue) of a spine in the presence of 100 μM ryanodine. (b3) Time plot of normalized doublet evoked bAP-Ca2+ transient enhancement in spines with small baseline amplitudes comparing control (black) spines to spines in the presence of 100 μM ryanodine (blue). One doublet was applied every 60 s, the data is plotted in 3 min bins. (c1) Z-projection of the imaged spine segment (scale bar corresponds to 2 μm). Asterisk marks imaged spine. (c2) Averaged baseline bAP-Ca2+ transients 0 to 5 min after bAP stimulation onset (grey) and averaged bAP-Ca2+ transients 15 to 20 min after bAP stimulation onset (green) of a spine in the presence of 10 μM Xestospongin-C. (c3) Time plot of normalized doublet evoked bAP-Ca2+ transient enhancement in spines with small baseline amplitudes comparing control (black) spines to spines in the presence of 10 μM Xestospongin C (green). One doublet was applied every 60 s, the data is plotted in 3 min bins. (d1) Bar graph of normalized enhancement 15 to 20 min after bAP stimulation onset for spines with small baseline amplitudes in control spines (black, +33 ± 6%, n = 53/31 spines/cells), CPA (red, 0 ± 6%, n = 24/10 spines/cells), ryanodine (blue, -2 ± 7%, n = 27/16 spines/cells) and Xestospongin C (green, +14 ± 4%, n = 56/18 spines/cells). In comparison to the control group, CPA and ryanodine blocked the enhancement (p < 0.01 and p < 0.001, respectively), whereas enhancement was not significantly reduced by Xestospongin C (n.s., Kruskal-Wallis test with Dunn’s posthoc correction). (d2) Cumulative distribution plot of normalized bAP-Ca2+ transient enhancement. Dataset corresponds to d1. Data are expressed as mean SEM ** p < 0.01, *** p < 0.001.
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pbio.1002181.g006: bAP-Ca2+ transient enhancement depends on Ca2+ release from intracellular stores.(a1) Z-projection of the imaged spine segment (scale bar corresponds to 2 μm). Asterisk marks imaged spine. (a2) Averaged baseline bAP-Ca2+ transients 0 to 5 min after bAP stimulation onset (grey) and averaged bAP-Ca2+ transients 15 to 20 min after bAP stimulation onset (red) of a spine in the presence of 30 μM CPA. (a3) Time plot of normalized doublet evoked bAP-Ca2+ transient enhancement in spines with small baseline amplitudes comparing control (black) spines to spines in the presence of 30 μM CPA (red). One doublet was applied every 60 s, the data is plotted in 3 min bins. (b1) Z-projection of the imaged spine segment (scale bar corresponds to 2 μm). Asterisk marks imaged spine. (b2) Averaged baseline bAP-Ca2+ transients 0 to 5 min after bAP stimulation onset (grey) and averaged bAP-Ca2+ transients 15 to 20 min after bAP stimulation onset (blue) of a spine in the presence of 100 μM ryanodine. (b3) Time plot of normalized doublet evoked bAP-Ca2+ transient enhancement in spines with small baseline amplitudes comparing control (black) spines to spines in the presence of 100 μM ryanodine (blue). One doublet was applied every 60 s, the data is plotted in 3 min bins. (c1) Z-projection of the imaged spine segment (scale bar corresponds to 2 μm). Asterisk marks imaged spine. (c2) Averaged baseline bAP-Ca2+ transients 0 to 5 min after bAP stimulation onset (grey) and averaged bAP-Ca2+ transients 15 to 20 min after bAP stimulation onset (green) of a spine in the presence of 10 μM Xestospongin-C. (c3) Time plot of normalized doublet evoked bAP-Ca2+ transient enhancement in spines with small baseline amplitudes comparing control (black) spines to spines in the presence of 10 μM Xestospongin C (green). One doublet was applied every 60 s, the data is plotted in 3 min bins. (d1) Bar graph of normalized enhancement 15 to 20 min after bAP stimulation onset for spines with small baseline amplitudes in control spines (black, +33 ± 6%, n = 53/31 spines/cells), CPA (red, 0 ± 6%, n = 24/10 spines/cells), ryanodine (blue, -2 ± 7%, n = 27/16 spines/cells) and Xestospongin C (green, +14 ± 4%, n = 56/18 spines/cells). In comparison to the control group, CPA and ryanodine blocked the enhancement (p < 0.01 and p < 0.001, respectively), whereas enhancement was not significantly reduced by Xestospongin C (n.s., Kruskal-Wallis test with Dunn’s posthoc correction). (d2) Cumulative distribution plot of normalized bAP-Ca2+ transient enhancement. Dataset corresponds to d1. Data are expressed as mean SEM ** p < 0.01, *** p < 0.001.

Mentions: Previous work demonstrated that VGCC mediated Ca2+ transients can directly activate the RyR intracellular Ca2+ release channel [24]. We hypothesized that the observed activity-dependent enhancement constitutes a new functional role for intracellular Ca2+ release from RyRs in spines. Depletion of intracellular Ca2+ stores by pre-incubation with 30 μM of CPA indeed blocked activity-dependent enhancement of bAP-Ca2+ transients (Figs 6A and 6D and S5A). To directly inhibit the RyR, we used 100 μM of ryanodine. At this concentration, ryanodine blocks the channel rather than locking it in a subconductance state [25,26]. Pre-incubation with ryanodine also inhibited the activity-dependent enhancement of bAP-Ca2+ transients (Figs 6B and 6D and S5B). We also investigated whether IP3Rs, the other family of intracellular Ca2+ release channels [27], are involved in enhancement. Using the IP3R antagonist Xestospongin C (10 μM) in the pipette, enhancement was not significantly affected when compared to controls (Figs 6C and 6D and S5C).


Ryanodine Receptor Activation Induces Long-Term Plasticity of Spine Calcium Dynamics.

Johenning FW, Theis AK, Pannasch U, Rückl M, Rüdiger S, Schmitz D - PLoS Biol. (2015)

bAP-Ca2+ transient enhancement depends on Ca2+ release from intracellular stores.(a1) Z-projection of the imaged spine segment (scale bar corresponds to 2 μm). Asterisk marks imaged spine. (a2) Averaged baseline bAP-Ca2+ transients 0 to 5 min after bAP stimulation onset (grey) and averaged bAP-Ca2+ transients 15 to 20 min after bAP stimulation onset (red) of a spine in the presence of 30 μM CPA. (a3) Time plot of normalized doublet evoked bAP-Ca2+ transient enhancement in spines with small baseline amplitudes comparing control (black) spines to spines in the presence of 30 μM CPA (red). One doublet was applied every 60 s, the data is plotted in 3 min bins. (b1) Z-projection of the imaged spine segment (scale bar corresponds to 2 μm). Asterisk marks imaged spine. (b2) Averaged baseline bAP-Ca2+ transients 0 to 5 min after bAP stimulation onset (grey) and averaged bAP-Ca2+ transients 15 to 20 min after bAP stimulation onset (blue) of a spine in the presence of 100 μM ryanodine. (b3) Time plot of normalized doublet evoked bAP-Ca2+ transient enhancement in spines with small baseline amplitudes comparing control (black) spines to spines in the presence of 100 μM ryanodine (blue). One doublet was applied every 60 s, the data is plotted in 3 min bins. (c1) Z-projection of the imaged spine segment (scale bar corresponds to 2 μm). Asterisk marks imaged spine. (c2) Averaged baseline bAP-Ca2+ transients 0 to 5 min after bAP stimulation onset (grey) and averaged bAP-Ca2+ transients 15 to 20 min after bAP stimulation onset (green) of a spine in the presence of 10 μM Xestospongin-C. (c3) Time plot of normalized doublet evoked bAP-Ca2+ transient enhancement in spines with small baseline amplitudes comparing control (black) spines to spines in the presence of 10 μM Xestospongin C (green). One doublet was applied every 60 s, the data is plotted in 3 min bins. (d1) Bar graph of normalized enhancement 15 to 20 min after bAP stimulation onset for spines with small baseline amplitudes in control spines (black, +33 ± 6%, n = 53/31 spines/cells), CPA (red, 0 ± 6%, n = 24/10 spines/cells), ryanodine (blue, -2 ± 7%, n = 27/16 spines/cells) and Xestospongin C (green, +14 ± 4%, n = 56/18 spines/cells). In comparison to the control group, CPA and ryanodine blocked the enhancement (p < 0.01 and p < 0.001, respectively), whereas enhancement was not significantly reduced by Xestospongin C (n.s., Kruskal-Wallis test with Dunn’s posthoc correction). (d2) Cumulative distribution plot of normalized bAP-Ca2+ transient enhancement. Dataset corresponds to d1. Data are expressed as mean SEM ** p < 0.01, *** p < 0.001.
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Related In: Results  -  Collection

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Show All Figures
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pbio.1002181.g006: bAP-Ca2+ transient enhancement depends on Ca2+ release from intracellular stores.(a1) Z-projection of the imaged spine segment (scale bar corresponds to 2 μm). Asterisk marks imaged spine. (a2) Averaged baseline bAP-Ca2+ transients 0 to 5 min after bAP stimulation onset (grey) and averaged bAP-Ca2+ transients 15 to 20 min after bAP stimulation onset (red) of a spine in the presence of 30 μM CPA. (a3) Time plot of normalized doublet evoked bAP-Ca2+ transient enhancement in spines with small baseline amplitudes comparing control (black) spines to spines in the presence of 30 μM CPA (red). One doublet was applied every 60 s, the data is plotted in 3 min bins. (b1) Z-projection of the imaged spine segment (scale bar corresponds to 2 μm). Asterisk marks imaged spine. (b2) Averaged baseline bAP-Ca2+ transients 0 to 5 min after bAP stimulation onset (grey) and averaged bAP-Ca2+ transients 15 to 20 min after bAP stimulation onset (blue) of a spine in the presence of 100 μM ryanodine. (b3) Time plot of normalized doublet evoked bAP-Ca2+ transient enhancement in spines with small baseline amplitudes comparing control (black) spines to spines in the presence of 100 μM ryanodine (blue). One doublet was applied every 60 s, the data is plotted in 3 min bins. (c1) Z-projection of the imaged spine segment (scale bar corresponds to 2 μm). Asterisk marks imaged spine. (c2) Averaged baseline bAP-Ca2+ transients 0 to 5 min after bAP stimulation onset (grey) and averaged bAP-Ca2+ transients 15 to 20 min after bAP stimulation onset (green) of a spine in the presence of 10 μM Xestospongin-C. (c3) Time plot of normalized doublet evoked bAP-Ca2+ transient enhancement in spines with small baseline amplitudes comparing control (black) spines to spines in the presence of 10 μM Xestospongin C (green). One doublet was applied every 60 s, the data is plotted in 3 min bins. (d1) Bar graph of normalized enhancement 15 to 20 min after bAP stimulation onset for spines with small baseline amplitudes in control spines (black, +33 ± 6%, n = 53/31 spines/cells), CPA (red, 0 ± 6%, n = 24/10 spines/cells), ryanodine (blue, -2 ± 7%, n = 27/16 spines/cells) and Xestospongin C (green, +14 ± 4%, n = 56/18 spines/cells). In comparison to the control group, CPA and ryanodine blocked the enhancement (p < 0.01 and p < 0.001, respectively), whereas enhancement was not significantly reduced by Xestospongin C (n.s., Kruskal-Wallis test with Dunn’s posthoc correction). (d2) Cumulative distribution plot of normalized bAP-Ca2+ transient enhancement. Dataset corresponds to d1. Data are expressed as mean SEM ** p < 0.01, *** p < 0.001.
Mentions: Previous work demonstrated that VGCC mediated Ca2+ transients can directly activate the RyR intracellular Ca2+ release channel [24]. We hypothesized that the observed activity-dependent enhancement constitutes a new functional role for intracellular Ca2+ release from RyRs in spines. Depletion of intracellular Ca2+ stores by pre-incubation with 30 μM of CPA indeed blocked activity-dependent enhancement of bAP-Ca2+ transients (Figs 6A and 6D and S5A). To directly inhibit the RyR, we used 100 μM of ryanodine. At this concentration, ryanodine blocks the channel rather than locking it in a subconductance state [25,26]. Pre-incubation with ryanodine also inhibited the activity-dependent enhancement of bAP-Ca2+ transients (Figs 6B and 6D and S5B). We also investigated whether IP3Rs, the other family of intracellular Ca2+ release channels [27], are involved in enhancement. Using the IP3R antagonist Xestospongin C (10 μM) in the pipette, enhancement was not significantly affected when compared to controls (Figs 6C and 6D and S5C).

Bottom Line: Ca2+ is a major upstream effector in this transduction cascade, serving both as a depolarising electrical charge carrier at the membrane and an intracellular second messenger.We demonstrate that RyRs can form specific Ca2+ signalling nanodomains within single spines.Functionally, RyR mediated Ca2+ release in these nanodomains induces a new form of Ca2+ transient plasticity that constitutes a spine specific storage mechanism of neuronal suprathreshold activity patterns.

View Article: PubMed Central - PubMed

Affiliation: Neuroscience Research Center, Charité-Universitätsmedizin, Berlin, Germany; Berlin Institute of Health (BIH), Berlin, Germany.

ABSTRACT
A key feature of signalling in dendritic spines is the synapse-specific transduction of short electrical signals into biochemical responses. Ca2+ is a major upstream effector in this transduction cascade, serving both as a depolarising electrical charge carrier at the membrane and an intracellular second messenger. Upon action potential firing, the majority of spines are subject to global back-propagating action potential (bAP) Ca2+ transients. These transients translate neuronal suprathreshold activation into intracellular biochemical events. Using a combination of electrophysiology, two-photon Ca2+ imaging, and modelling, we demonstrate that bAPs are electrochemically coupled to Ca2+ release from intracellular stores via ryanodine receptors (RyRs). We describe a new function mediated by spine RyRs: the activity-dependent long-term enhancement of the bAP-Ca2+ transient. Spines regulate bAP Ca2+ influx independent of each other, as bAP-Ca2+ transient enhancement is compartmentalized and independent of the dendritic Ca2+ transient. Furthermore, this functional state change depends exclusively on bAPs travelling antidromically into dendrites and spines. Induction, but not expression, of bAP-Ca2+ transient enhancement is a spine-specific function of the RyR. We demonstrate that RyRs can form specific Ca2+ signalling nanodomains within single spines. Functionally, RyR mediated Ca2+ release in these nanodomains induces a new form of Ca2+ transient plasticity that constitutes a spine specific storage mechanism of neuronal suprathreshold activity patterns.

No MeSH data available.


Related in: MedlinePlus