Cellular Zinc Homeostasis Contributes to Neuronal Differentiation in Human Induced Pluripotent Stem Cells

Figure 4

Altered zinc levels affect glutamatergic signaling. (a) Representative image of a neuron used for patch-clamp electrophysiological studies (left panel). Right panel: a significant difference in resting potentials was detected between cells grown under zinc deficient and zinc supplemented conditions (-test, ; : and −Zn, : , and : +Zn). (b) A significant difference in membrane capacity was detected between cells grown under zinc deficient and zinc supplemented conditions (-test, versus  −Zn, ; versus +Zn, ; −Zn versus +Zn, ; : and −Zn; : , : +Zn). (c) A significant difference in membrane resistance was detected between cells grown under zinc deficient and zinc supplemented conditions (-test, versus  −Zn, ; −Zn versus +Zn, ; : and −Zn; : ; : +Zn). (d) Single cell patch-clamp electrophysiology did not show any significant differences in the half-width of induced action potentials (AP) and sodium currents (e). (f) A significant increase in acetylcholine (ACh) induced currents was observed in zinc deficient cells when compared to zinc supplemented cells (-test, −Zn versus +Zn, ; : and −Zn, : , and : +Zn). (g) A decrease in glutamate (Glut) induced currents can be seen under zinc deficient conditions as trend. (h) AMPAR currents and NMDAR currents (i) as well as GABAR currents (j) were significantly decreased after differentiation of cells in zinc depletion conditions (-test, AMPAR, ; NMDAR, ; GABAR, ; : , : −Zn, : , and : +Zn). (k) The number of cells showing ACh induced currents was higher in zinc deficient conditions. (l) The number of cells showing Glut induced currents was significantly less under zinc deficient conditions when compared to zinc supplemented cells (contingency (Chi square) test, ). The fraction of cells with Glut induced currents was also significantly increased in zinc supplemented cells compared to controls (contingency (Chi square) test, ) (: , : −Zn, : , and : +Zn). (m) The fraction of cells with AMPAR currents (m) and NMDAR currents (n) as well as GABAR currents (o) was decreased after differentiation of cells in zinc depletion conditions (contingency (Chi square) test, AMPAR, ; NMDAR, ; GABAR, ; : ; -18: −Zn). All currents were normalized to cell size. trend ( value between 0.05 and 0.1). ; .

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