Ca2+ and cAMP Signaling in Human Embryonic Stem Cell-Derived Dopamine Neurons

Human embryonic stem (hES) cell differentiation into dopamine neurons is considered a promising strategy for cell replacement therapy in Parkinson's disease, yet the functional properties of hES cell-derived dopamine neurons remain poorly defined. The objective of this study was to characterize intracellular calcium (Ca2+)and sub-plasma membrane cyclic AMP-signaling properties in hES cell-derived dopamine neurons. We found that hES cell-derived dopamine neurons and neural progenitors raised Ca2+ from intra-and extracellular compartments in response to depolarization, glutamate, ATP,and dopamine D-2 receptor activation, while undifferentiated hES cells only mobilized Ca2+ from intracellular stores in response to ATP and D 2 receptor-induced activation. Interestingly, we also found that hES cell-derived dopamine neurons in addition to primary ventral midbrain dopamine neurons were more prone to release Ca2+ from intracellular stores than non-dopamine neurons following treatment with the neuropeptide neurotensin. Furthermore, hES cell-derived dopamine neurons showed cAMP elevations in response to forskolin and 3-isobutyl-methylxanthine, similar to primary dopamine neurons. Taken together, these results unravel the temporal sequence by which hES cells acquire Ca2+ and cAMP signaling competence during dopamine differentiation.