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pT305-CaMKII stabilizes a learning-induced increase in AMPA receptors for ongoing memory consolidation after classical conditioning.

Naskar S, Wan H, Kemenes G - Nat Commun (2014)

Bottom Line: CaMKIINtide treatment significantly reduces the learning-induced elevation of both pT305-CaMKII and GluA1 levels and impairs associative long-term memory.Inhibition of proteasomal activity offsets the deleterious effects of CaMKIINtide on both GluA1 levels and long-term memory.These findings suggest that increased levels of pT305-CaMKII play a role in AMPAR-dependent memory consolidation by reducing proteasomal degradation of GluA1 receptor subunits.

View Article: PubMed Central - PubMed

Affiliation: 1] Sussex Neuroscience, School of Life Sciences, University of Sussex, Brighton BN1 9QG, UK [2].

ABSTRACT
The role of CaMKII in learning-induced activation and trafficking of AMPA receptors (AMPARs) is well established. However, the link between the phosphorylation state of CaMKII and the agonist-triggered proteasomal degradation of AMPARs during memory consolidation remains unknown. Here we describe a novel CaMKII-dependent mechanism by which a learning-induced increase in AMPAR levels is stabilized for consolidation of associative long-term memory. Six hours after classical conditioning the levels of both autophosphorylated pT305-CaMKII and GluA1 type AMPAR subunits are significantly elevated in the ganglia containing the learning circuits of the snail Lymnaea stagnalis. CaMKIINtide treatment significantly reduces the learning-induced elevation of both pT305-CaMKII and GluA1 levels and impairs associative long-term memory. Inhibition of proteasomal activity offsets the deleterious effects of CaMKIINtide on both GluA1 levels and long-term memory. These findings suggest that increased levels of pT305-CaMKII play a role in AMPAR-dependent memory consolidation by reducing proteasomal degradation of GluA1 receptor subunits.

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Co-localization of GluA1 and CaMKII in the ‘learning ganglia’Top set of panels: example from the buccal ganglia, bottom set of panels: example from the cerebral ganglia. GluA1 (green) and CaMKII (red) fluorescent signal is shown in the same section. The pT305-CaMKII signal (originally green, but pseudo-colored in blue here) is shown in the sections consecutive to the ones in which the GluA1 and CaMKII signal was detected. GluA1 and CaMKII are ubiquitously expressed in the neuronal somata of the same sections from both the buccal and cerebral ganglia. GluA1 and pT305-CaMKII are both strongly expressed in the neuropile (asterisks). Arrows indicate examples of neuronal cell bodies with particularly strong co-localization of GluA1 with CaMKII and also showing strong pT305-CaMKII expression in the consecutive section. The CaMKII content of the neuropile is smaller compared to that of the neuronal cell bodies. Scale bars represent 50 μm. This experiment was replicated three times.
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Figure 5: Co-localization of GluA1 and CaMKII in the ‘learning ganglia’Top set of panels: example from the buccal ganglia, bottom set of panels: example from the cerebral ganglia. GluA1 (green) and CaMKII (red) fluorescent signal is shown in the same section. The pT305-CaMKII signal (originally green, but pseudo-colored in blue here) is shown in the sections consecutive to the ones in which the GluA1 and CaMKII signal was detected. GluA1 and CaMKII are ubiquitously expressed in the neuronal somata of the same sections from both the buccal and cerebral ganglia. GluA1 and pT305-CaMKII are both strongly expressed in the neuropile (asterisks). Arrows indicate examples of neuronal cell bodies with particularly strong co-localization of GluA1 with CaMKII and also showing strong pT305-CaMKII expression in the consecutive section. The CaMKII content of the neuropile is smaller compared to that of the neuronal cell bodies. Scale bars represent 50 μm. This experiment was replicated three times.

Mentions: First, using immunohistochemistry, we found a very high level of co-localization of GluA1 and CaMKII immunostaining in both the buccal and cerebral ganglia (Fig. 5). In alternating sections, we found a close correspondence between the localization of pT305-CaMKII and AMPARs (Fig. 5). However, unlike GluA1 and PSD-95, or GluA1 and CaMKII, the co-localization of GluA1 and pT305-CaMKII could not be investigated in the same sections because we had to use the same secondary antibody for the detection of these two different proteins (see Methods). Furthermore, we found that the immunohistochemical method was not well-suited for a quantitative analysis of the combined effects of training and CaMKIINtide on CaMKII phosphorylation levels, because these need to be normalized to CaMKII, whose expression was ubiquitous (Fig. 5), but quite variable. Therefore we used the western blot method for our quantitative analysis of pT305-CaMKII levels in the ‘learning ganglia’, which allowed us to make more robust statistical comparisons.


pT305-CaMKII stabilizes a learning-induced increase in AMPA receptors for ongoing memory consolidation after classical conditioning.

Naskar S, Wan H, Kemenes G - Nat Commun (2014)

Co-localization of GluA1 and CaMKII in the ‘learning ganglia’Top set of panels: example from the buccal ganglia, bottom set of panels: example from the cerebral ganglia. GluA1 (green) and CaMKII (red) fluorescent signal is shown in the same section. The pT305-CaMKII signal (originally green, but pseudo-colored in blue here) is shown in the sections consecutive to the ones in which the GluA1 and CaMKII signal was detected. GluA1 and CaMKII are ubiquitously expressed in the neuronal somata of the same sections from both the buccal and cerebral ganglia. GluA1 and pT305-CaMKII are both strongly expressed in the neuropile (asterisks). Arrows indicate examples of neuronal cell bodies with particularly strong co-localization of GluA1 with CaMKII and also showing strong pT305-CaMKII expression in the consecutive section. The CaMKII content of the neuropile is smaller compared to that of the neuronal cell bodies. Scale bars represent 50 μm. This experiment was replicated three times.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4048835&req=5

Figure 5: Co-localization of GluA1 and CaMKII in the ‘learning ganglia’Top set of panels: example from the buccal ganglia, bottom set of panels: example from the cerebral ganglia. GluA1 (green) and CaMKII (red) fluorescent signal is shown in the same section. The pT305-CaMKII signal (originally green, but pseudo-colored in blue here) is shown in the sections consecutive to the ones in which the GluA1 and CaMKII signal was detected. GluA1 and CaMKII are ubiquitously expressed in the neuronal somata of the same sections from both the buccal and cerebral ganglia. GluA1 and pT305-CaMKII are both strongly expressed in the neuropile (asterisks). Arrows indicate examples of neuronal cell bodies with particularly strong co-localization of GluA1 with CaMKII and also showing strong pT305-CaMKII expression in the consecutive section. The CaMKII content of the neuropile is smaller compared to that of the neuronal cell bodies. Scale bars represent 50 μm. This experiment was replicated three times.
Mentions: First, using immunohistochemistry, we found a very high level of co-localization of GluA1 and CaMKII immunostaining in both the buccal and cerebral ganglia (Fig. 5). In alternating sections, we found a close correspondence between the localization of pT305-CaMKII and AMPARs (Fig. 5). However, unlike GluA1 and PSD-95, or GluA1 and CaMKII, the co-localization of GluA1 and pT305-CaMKII could not be investigated in the same sections because we had to use the same secondary antibody for the detection of these two different proteins (see Methods). Furthermore, we found that the immunohistochemical method was not well-suited for a quantitative analysis of the combined effects of training and CaMKIINtide on CaMKII phosphorylation levels, because these need to be normalized to CaMKII, whose expression was ubiquitous (Fig. 5), but quite variable. Therefore we used the western blot method for our quantitative analysis of pT305-CaMKII levels in the ‘learning ganglia’, which allowed us to make more robust statistical comparisons.

Bottom Line: CaMKIINtide treatment significantly reduces the learning-induced elevation of both pT305-CaMKII and GluA1 levels and impairs associative long-term memory.Inhibition of proteasomal activity offsets the deleterious effects of CaMKIINtide on both GluA1 levels and long-term memory.These findings suggest that increased levels of pT305-CaMKII play a role in AMPAR-dependent memory consolidation by reducing proteasomal degradation of GluA1 receptor subunits.

View Article: PubMed Central - PubMed

Affiliation: 1] Sussex Neuroscience, School of Life Sciences, University of Sussex, Brighton BN1 9QG, UK [2].

ABSTRACT
The role of CaMKII in learning-induced activation and trafficking of AMPA receptors (AMPARs) is well established. However, the link between the phosphorylation state of CaMKII and the agonist-triggered proteasomal degradation of AMPARs during memory consolidation remains unknown. Here we describe a novel CaMKII-dependent mechanism by which a learning-induced increase in AMPAR levels is stabilized for consolidation of associative long-term memory. Six hours after classical conditioning the levels of both autophosphorylated pT305-CaMKII and GluA1 type AMPAR subunits are significantly elevated in the ganglia containing the learning circuits of the snail Lymnaea stagnalis. CaMKIINtide treatment significantly reduces the learning-induced elevation of both pT305-CaMKII and GluA1 levels and impairs associative long-term memory. Inhibition of proteasomal activity offsets the deleterious effects of CaMKIINtide on both GluA1 levels and long-term memory. These findings suggest that increased levels of pT305-CaMKII play a role in AMPAR-dependent memory consolidation by reducing proteasomal degradation of GluA1 receptor subunits.

Show MeSH
Related in: MedlinePlus