Plasma Membrane Calcium ATPase-Neuroplastin Complexes Are Selectively Stabilized in GM1-Containing Lipid Rafts

• Published in: International journal of molecular sciences 2021-12, Vol.22 (24), p.13590
• Main Authors: Ilic, Katarina, Lin, Xiao, Malci, Ayse, Stojanović, Mario, Puljko, Borna, Rožman, Marko, Vukelić, Željka, Heffer, Marija, Montag, Dirk, Schnaar, Ronald L, Kalanj-Bognar, Svjetlana, Herrera-Molina, Rodrigo, Mlinac-Jerkovic, Kristina
• Format: Article
• Language: English
• Subjects: Alzheimer's disease; Animals; Antibodies; B4galnt1; Brain; Brain - metabolism; Ca2+-transporting ATPase; Calcium homeostasis; Calcium ions; Calcium signalling; Cell surface; Cells, Cultured; Composition; Confocal microscopy; Extrusion; G(M1) Ganglioside - analysis; G(M1) Ganglioside - metabolism; gangliosides; Gene expression; glycosphingolipids; GM2/GD2 synthase; Hippocampus; Homeostasis; Isoforms; Lipid rafts; Lipids; Localization; Male; Membrane Glycoproteins - analysis; Membrane Glycoproteins - metabolism; membrane microdomains; Membrane Microdomains - metabolism; Membranes; Mice; Mice, Inbred C57BL; neuronal calcium homeostasis; Neurons; Neurons - metabolism; Plasma Membrane Calcium-Transporting ATPases - analysis; Plasma Membrane Calcium-Transporting ATPases - metabolism; Proteins; Rafts; Regression analysis; Rodents
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms222413590

The recent identification of plasma membrane (Ca )-ATPase (PMCA)-Neuroplastin (Np) complexes has renewed attention on cell regulation of cytosolic calcium extrusion, which is of particular relevance in neurons. Here, we tested the hypothesis that PMCA-Neuroplastin complexes exist in specific ganglioside-containing rafts, which could affect calcium homeostasis. We analyzed the abundance of all four PMCA paralogs (PMCA1-4) and Neuroplastin isoforms (Np65 and Np55) in lipid rafts and bulk membrane fractions from GM2/GD2 synthase-deficient mouse brains. In these fractions, we found altered distribution of Np65/Np55 and selected PMCA isoforms, namely PMCA1 and 2. Cell surface staining and confocal microscopy identified GM1 as the main complex ganglioside co-localizing with Neuroplastin in cultured hippocampal neurons. Furthermore, blocking GM1 with a specific antibody resulted in delayed calcium restoration of electrically evoked calcium transients in the soma of hippocampal neurons. The content and composition of all ganglioside species were unchanged in Neuroplastin-deficient mouse brains. Therefore, we conclude that altered composition or disorganization of ganglioside-containing rafts results in changed regulation of calcium signals in neurons. We propose that GM1 could be a key sphingolipid for ensuring proper location of the PMCA-Neuroplastin complexes into rafts in order to participate in the regulation of neuronal calcium homeostasis.