Modulation of calcium signaling depends on the oligosaccharide of GM1 in Neuro2a mouse neuroblastoma cells

Abstract

Recently, we demonstrated that the oligosaccharide portion of ganglioside GM1 is responsible, via direct interaction and activation of the TrkA pathway, for the ability of GM1 to promote neuritogenesis and to confer neuroprotection in Neuro2a mouse neuroblastoma cells. Recalling the knowledge that ganglioside GM1 modulates calcium channels activity, thus regulating the cytosolic calcium concentration necessary for neuronal functions, we investigated if the GM1-oligosaccharide would be able to overlap the GM1 properties in the regulation of calcium signaling, excluding a specific role played by the ceramide moiety inserted into the external layer of plasma membrane. We observed, by calcium imaging, that GM1-oligosaccharide administration to undifferentiated Neuro2a cells resulted in an increased calcium influx, which turned out to be mediated by the activation of TrkA receptor. The biochemical analysis demonstrated that PLCγ and PKC activation follows the TrkA stimulation by GM1-oligosaccharide, leading to the opening of calcium channels both on the plasma membrane and on intracellular storages, as confirmed by calcium imaging experiments performed with IP3 receptor inhibitor. Subsequently, we found that neurite elongation in Neuro2a cells was blocked by subtoxic administration of extracellular and intracellular calcium chelators, suggesting that the increase of intracellular calcium is responsible of GM1-oligosaccharide mediated differentiation. These results suggest that GM1-oligosaccharide is responsible for the regulation of calcium signaling and homeostasis at the base of the neuronal functions mediated by plasma membrane GM1.

Turning the spotlight on the oligosaccharide chain of GM1 ganglioside

“…d The chronic injection of OligoGM1 is able to completely counteract the PD phenotype: recovery of motor symptoms, rescue of dopaminergic neurons, dopamine levels and clearance of α-syn aggregates [94]. Sugar representation is according to [36] capable, even when isolated from the parental compound, to induce neuritogenesis and prevent neuronal toxicity at the same extent as GM1 was reported to do [28][29][30][31][32][33]. These cellular phenotypic effects are due to the carbohydrate interactions with membrane receptors, among which the neurotrophin's receptor TrkA has been identified as a direct partner of the saccharide [28][29][30][31][32][33].…”

“…Studies on the OligoGM1 biological properties have been developed in relation to neuronal differentiation, maturation and protection, explaining some mechanistic aspects on how GM1 is able to regulate multiple cellular processes using the carbohydrate portion, and to initiate signal transduction cascades on the plasma membrane [28][29][30][31][32][33]. and NanT but cannot be degraded because of β-galactosidase (LacZ) and aldolase (NanA) deletion.…”

“…MPTP), the enhancement of mitochondrial bioenergetics. This image is updated from [ 28 , 29 , 31 , 33 ]. GM1 saccharide representation is according to [ 36 ].…”

“…1 Structure of ganglioside GM1, II 3 Neu5AcGg 4 -Cer mixture called Cronassial, and then the pure GM1 called Sygen) for the therapy of peripheral neuropathies [24][25][26][27]. 30 years later, detailed studies on OligoGM1 have been showing that several fundamental GM1 properties are completely linked to the sole ganglioside head, its oligosaccharide [28][29][30][31][32][33].…”

“…30 years later, detailed studies on OligoGM1 have been showing that several fundamental GM1 properties are completely linked to the sole ganglioside head, its oligosaccharide [ 28 – 33 ].…”