A Non-Neuronal Cholinergic System Regulates Cellular ATP Levels to Maintain Cell Viability
Background/Aims: We previously suggested that a non-neuronal cholinergic system modulates energy metabolism through the mitochondria. However, the mechanisms responsible for making this system crucial remained undetermined. Methods: In this study, we developed a fusion protein expression vector containing a luciferase gene fused to the folic acid receptor-α gene. Results: This protein of the vector was confirmed to target the plasma membrane of transfected HEK293 cells, and vector-derived luciferase activities and ATP levels in viable cells were positively correlated (r = 0.599). Using this luciferase vector, choline acetyltransferase (ChAT)-expressing cells (i.e., cells with an activated non-neuronal cholinergic system) had increased cellular ATP levels. ChAT-expressing cells also had upregulated IGF-1R and Glut-1 protein expressions as well as increased glucose uptake. This activated non-neuronal cholinergic system with efficient glucose metabolism rendered cells resistant to serum depletion-induced cell death. Conclusion: Our results indicate that a non-neuronal cholinergic system is involved in sustaining ATP levels to render cells resistant to a nutrient-deficient environment.