Cholesteryl glucoside stimulates activation of protein kinase B/Akt in the motor neuron-derived NSC34 cell line

Steryl glycosides and related compounds are commonly found in the environment and have been associated with neurodegenerative changes in vulnerable individuals. However, their mechanisms of action in mammalian cells have not been well investigated. In the present study the effects of cholesterol glucoside (CG), a variant form of steryl glycoside, was investigated in the motor neuron-derived NSC34 cell line. Prolonged treatment with CG was found to induce cell death in a dose- and time-dependent manner. However, transient exposure of CG preconditioned NSC34 cells for stress from serum deprivation. To study the signaling pathways activated by CG, we employed the Kinetworks KPSS 1.3 Phospho-site Screen to track the phosphorylation level of at least 35 diverse signaling proteins. The survival protein kinase B (PKB/Akt) displayed a 2-fold increase in phosphorylation at its Ser-473 activation site following CG stimulation. Akt signaling was important for conferring cytoprotection against serum deprivation-induced stress. Inhibition of phosphatidylinositol 3-kinase (PI3K), which indirectly triggers Akt stimulation, completely abolished CG preconditioning against serum deprivation. Our findings revealed that there may be a PI3K-independent pathway which also mediated Akt Ser-473 phosphorylation. Improved understanding of the mechanisms of action of CG should provide insights to the how other members of the steryl glycoside family induce toxicity in the mouse model of ALS-PDC, and how cells respond to these toxins.