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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.


Coverage of the primary sequences of all proteins shown in Figure 1C (continued).See caption above.DOI:http://dx.doi.org/10.7554/eLife.12637.005
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fig1s2: Coverage of the primary sequences of all proteins shown in Figure 1C (continued).See caption above.DOI:http://dx.doi.org/10.7554/eLife.12637.005

Mentions: Therefore, these two antibodies were used for affinity purifications combined with quantitative mass spectrometry (see Materials and methods). The results demonstrated that both antibodies robustly purified MPP2 and co-purified SK2 as well as SK3. In addition, these experiments identified DLG1 (SAP97) and Lin-homologs 7A and 7C as proteins co-assembling with MPP2 in rodent brain (Figure 1C; Supplementary file 1; Figure 1—figure supplement 1; Figure 1—figure supplement 2). To rule out off-target effects of the two MPP2 antibodies, we tested their binding of C8-tagged of SAP97, Lin7A, or Lin7C, C8-tagged versions of each of these proteins after expression in HEK293 cells (Figure 1D). While all 8-tagged proteins were recognized by anti-C8 antibody only C8-MPP2 was recognized by anti-MPP2 antibodies (Figure 1D). MPP2, a member of the p55 Stardust family of MAGUK proteins, is predicted to be a 552 amino acid protein. Like most MAGUKs, MPP2 is a modular protein comprised of several distinct protein-protein interaction domains. There are two predicted L27 domains, followed by a single predicted PDZ domain, and then the SH3-HOOK-GK domains.


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)

Coverage of the primary sequences of all proteins shown in Figure 1C (continued).See caption above.DOI:http://dx.doi.org/10.7554/eLife.12637.005
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4764564&req=5

fig1s2: Coverage of the primary sequences of all proteins shown in Figure 1C (continued).See caption above.DOI:http://dx.doi.org/10.7554/eLife.12637.005
Mentions: Therefore, these two antibodies were used for affinity purifications combined with quantitative mass spectrometry (see Materials and methods). The results demonstrated that both antibodies robustly purified MPP2 and co-purified SK2 as well as SK3. In addition, these experiments identified DLG1 (SAP97) and Lin-homologs 7A and 7C as proteins co-assembling with MPP2 in rodent brain (Figure 1C; Supplementary file 1; Figure 1—figure supplement 1; Figure 1—figure supplement 2). To rule out off-target effects of the two MPP2 antibodies, we tested their binding of C8-tagged of SAP97, Lin7A, or Lin7C, C8-tagged versions of each of these proteins after expression in HEK293 cells (Figure 1D). While all 8-tagged proteins were recognized by anti-C8 antibody only C8-MPP2 was recognized by anti-MPP2 antibodies (Figure 1D). MPP2, a member of the p55 Stardust family of MAGUK proteins, is predicted to be a 552 amino acid protein. Like most MAGUKs, MPP2 is a modular protein comprised of several distinct protein-protein interaction domains. There are two predicted L27 domains, followed by a single predicted PDZ domain, and then the SH3-HOOK-GK domains.

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.