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Membrane palmitoylated protein 2 is a synaptic scaffold protein required for synaptic SK2-containing channel function.

Kim G, Luján R, Schwenk J, Kelley MH, Aguado C, Watanabe M, Fakler B, Maylie J, Adelman JP - Elife (2016)

Bottom Line: We have identified a novel synaptic scaffold, MPP2 (membrane palmitoylated protein 2; p55), a member of the membrane-associated guanylate kinase (MAGUK) family that interacts with SK2-containing channels.Knocking down MPP2 expression selectively abolished the SK2-containing channel contribution to synaptic responses and decreased LTP.Thus, MPP2 is a novel synaptic scaffold that is required for proper synaptic localization and function of SK2-containing channels.

View Article: PubMed Central - PubMed

Affiliation: Vollum Institute, Oregon Health and Science University, Portland, United States.

ABSTRACT
Mouse CA1 pyramidal neurons express apamin-sensitive SK2-containing channels in the post-synaptic membrane, positioned close to NMDA-type (N-methyl-D-aspartate) glutamate receptors. Activated by synaptically evoked NMDAR-dependent Ca(2+) influx, the synaptic SK2-containing channels modulate excitatory post-synaptic responses and the induction of synaptic plasticity. In addition, their activity- and protein kinase A-dependent trafficking contributes to expression of long-term potentiation (LTP). We have identified a novel synaptic scaffold, MPP2 (membrane palmitoylated protein 2; p55), a member of the membrane-associated guanylate kinase (MAGUK) family that interacts with SK2-containing channels. MPP2 and SK2 co-immunopurified from mouse brain, and co-immunoprecipitated when they were co-expressed in HEK293 cells. MPP2 is highly expressed in the post-synaptic density of dendritic spines on CA1 pyramidal neurons. Knocking down MPP2 expression selectively abolished the SK2-containing channel contribution to synaptic responses and decreased LTP. Thus, MPP2 is a novel synaptic scaffold that is required for proper synaptic localization and function of SK2-containing channels.

No MeSH data available.


Co-expression of sh-immune MPP2 with MPP2 shRNA rescues synaptic SK2 function.(A) Time course of the normalized EPSP amplitude (mean ± s.e.m.) for baseline in control ACSF and during wash-in of apamin (100 nM) as indicated above in cells transfected MPP2 sh and MPP2 sh immune (n = 13). Inset: representative cell showing average of 15 EPSPs taken from indicated shaded time points in ACSF (black) and 16–20 min after application of apamin (red); shaded areas are mean ± s.e.m. (B). Scatter plot of relative ESPS peak compared to baseline from the individual slices for non-fluorescent control, MPP2 sh-transfected cells and MPP2 sh transfected with immune MPP2 (rescue). Horizontal bar reflects mean.DOI:http://dx.doi.org/10.7554/eLife.12637.012
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fig6: Co-expression of sh-immune MPP2 with MPP2 shRNA rescues synaptic SK2 function.(A) Time course of the normalized EPSP amplitude (mean ± s.e.m.) for baseline in control ACSF and during wash-in of apamin (100 nM) as indicated above in cells transfected MPP2 sh and MPP2 sh immune (n = 13). Inset: representative cell showing average of 15 EPSPs taken from indicated shaded time points in ACSF (black) and 16–20 min after application of apamin (red); shaded areas are mean ± s.e.m. (B). Scatter plot of relative ESPS peak compared to baseline from the individual slices for non-fluorescent control, MPP2 sh-transfected cells and MPP2 sh transfected with immune MPP2 (rescue). Horizontal bar reflects mean.DOI:http://dx.doi.org/10.7554/eLife.12637.012

Mentions: To demonstrate that the effects of shRNA transfection were specifically due to MPP2 knock-down, the shRNA (GFP) plasmid was co-transfected with a plasmid that directed expression of shRNA-immune MPP2 and a plasmid that expressed the red fluorophore, mApple. In doubly transfected neurons, apamin increased EPSPs similar to control, non-transfected neurons (148.2 ± 4.2%; n = 13; p<0.0001, compared to shRNA knock-down) (Figure 6A,B). Thus, the consequences of the shRNA expression are mediated by knock-down of MPP2.10.7554/eLife.12637.012Figure 6.Co-expression of sh-immune MPP2 with MPP2 shRNA rescues synaptic SK2 function.


Membrane palmitoylated protein 2 is a synaptic scaffold protein required for synaptic SK2-containing channel function.

Kim G, Luján R, Schwenk J, Kelley MH, Aguado C, Watanabe M, Fakler B, Maylie J, Adelman JP - Elife (2016)

Co-expression of sh-immune MPP2 with MPP2 shRNA rescues synaptic SK2 function.(A) Time course of the normalized EPSP amplitude (mean ± s.e.m.) for baseline in control ACSF and during wash-in of apamin (100 nM) as indicated above in cells transfected MPP2 sh and MPP2 sh immune (n = 13). Inset: representative cell showing average of 15 EPSPs taken from indicated shaded time points in ACSF (black) and 16–20 min after application of apamin (red); shaded areas are mean ± s.e.m. (B). Scatter plot of relative ESPS peak compared to baseline from the individual slices for non-fluorescent control, MPP2 sh-transfected cells and MPP2 sh transfected with immune MPP2 (rescue). Horizontal bar reflects mean.DOI:http://dx.doi.org/10.7554/eLife.12637.012
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Related In: Results  -  Collection

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fig6: Co-expression of sh-immune MPP2 with MPP2 shRNA rescues synaptic SK2 function.(A) Time course of the normalized EPSP amplitude (mean ± s.e.m.) for baseline in control ACSF and during wash-in of apamin (100 nM) as indicated above in cells transfected MPP2 sh and MPP2 sh immune (n = 13). Inset: representative cell showing average of 15 EPSPs taken from indicated shaded time points in ACSF (black) and 16–20 min after application of apamin (red); shaded areas are mean ± s.e.m. (B). Scatter plot of relative ESPS peak compared to baseline from the individual slices for non-fluorescent control, MPP2 sh-transfected cells and MPP2 sh transfected with immune MPP2 (rescue). Horizontal bar reflects mean.DOI:http://dx.doi.org/10.7554/eLife.12637.012
Mentions: To demonstrate that the effects of shRNA transfection were specifically due to MPP2 knock-down, the shRNA (GFP) plasmid was co-transfected with a plasmid that directed expression of shRNA-immune MPP2 and a plasmid that expressed the red fluorophore, mApple. In doubly transfected neurons, apamin increased EPSPs similar to control, non-transfected neurons (148.2 ± 4.2%; n = 13; p<0.0001, compared to shRNA knock-down) (Figure 6A,B). Thus, the consequences of the shRNA expression are mediated by knock-down of MPP2.10.7554/eLife.12637.012Figure 6.Co-expression of sh-immune MPP2 with MPP2 shRNA rescues synaptic SK2 function.

Bottom Line: We have identified a novel synaptic scaffold, MPP2 (membrane palmitoylated protein 2; p55), a member of the membrane-associated guanylate kinase (MAGUK) family that interacts with SK2-containing channels.Knocking down MPP2 expression selectively abolished the SK2-containing channel contribution to synaptic responses and decreased LTP.Thus, MPP2 is a novel synaptic scaffold that is required for proper synaptic localization and function of SK2-containing channels.

View Article: PubMed Central - PubMed

Affiliation: Vollum Institute, Oregon Health and Science University, Portland, United States.

ABSTRACT
Mouse CA1 pyramidal neurons express apamin-sensitive SK2-containing channels in the post-synaptic membrane, positioned close to NMDA-type (N-methyl-D-aspartate) glutamate receptors. Activated by synaptically evoked NMDAR-dependent Ca(2+) influx, the synaptic SK2-containing channels modulate excitatory post-synaptic responses and the induction of synaptic plasticity. In addition, their activity- and protein kinase A-dependent trafficking contributes to expression of long-term potentiation (LTP). We have identified a novel synaptic scaffold, MPP2 (membrane palmitoylated protein 2; p55), a member of the membrane-associated guanylate kinase (MAGUK) family that interacts with SK2-containing channels. MPP2 and SK2 co-immunopurified from mouse brain, and co-immunoprecipitated when they were co-expressed in HEK293 cells. MPP2 is highly expressed in the post-synaptic density of dendritic spines on CA1 pyramidal neurons. Knocking down MPP2 expression selectively abolished the SK2-containing channel contribution to synaptic responses and decreased LTP. Thus, MPP2 is a novel synaptic scaffold that is required for proper synaptic localization and function of SK2-containing channels.

No MeSH data available.