Calcium Transport Mechanisms of PC12 Cells

Abstract

Many studies of Ca2+ signaling use PC12 cells, yet the balance of Ca2+ clearance mechanisms in these cells is unknown. We used pharmacological inhibition of Ca2+ transporters to characterize Ca2+ clearance after depolarizations in both undifferentiated and nerve growth factor-differentiated PC12 cells. Sarco-endoplasmic reticulum Ca2+ ATPase (SERCA), plasma membrane Ca2+ ATPase (PMCA), and Na+/Ca2+ exchanger (NCX) account for almost all Ca2+ clearance in both cell states, with NCX and PMCA making the greatest contributions. Any contribution of mitochondrial uniporters is small. The ATP pool in differentiated cells was much more labile than that of undifferentiated cells in the presence of agents that dissipated mitochondrial proton gradients. Differentiated PC12 cells have a small component of Ca2+ clearance possessing pharmacological characteristics consistent with secretory pathway Ca2+ ATPase (SPCA), potentially residing on Golgi and/or secretory granules. Undifferentiated and differentiated cells are similar in overall Ca2+ transport and in the small transport due to SERCA, but they differ in the fraction of transport by PMCA and NCX. Transport in neurites of differentiated PC12 cells was qualitatively similar to that in the somata, except that the ER stores in neurites sometimes released Ca2+ instead of clearing it after depolarization. We formulated a mathematical model to simulate the observed Ca2+ clearance and to describe the differences between these undifferentiated and NGF-differentiated states quantitatively. The model required a value for the endogenous Ca2+ binding ratio of PC12 cell cytoplasm, which we measured to be 268 ± 85. Our results indicate that Ca2+ transport in undifferentiated PC12 cells is quite unlike transport in adrenal chromaffin cells, for which they often are considered models. Transport in both cell states more closely resembles that of sympathetic neurons, for which differentiated PC12 cells often are considered models. Comparison with other cell types shows that different cells emphasize different Ca2+ transport mechanisms.

Effects of UV wavelength on cell damages caused by UV irradiation in PC12 cells

“…Many studies support this [30][31][32]. The PC12 cell line system is widely used in research because of its ability for rapid division, differentiation ability, and the presence of Na, K, and Ca channels and other membrane receptors [33,34]. PC12 cells have stronger UV resistance compared to other cell lines.…”

Na+/Ca2+ Exchanger Inhibitors Inhibit Neurite Outgrowth in PC12 Cells

“…Formisano et al reported on the native expression of Na + /Ca 2+ exchanger (NCX) and the regulation of NCX by Akt in PC12 cells (5). Moreover, NCX contributes to the regulation of [Ca 2+ ] i in PC12 cells (6). Therefore, it is possible that the regulation of [Ca 2+ ] i by NCX plays important roles in neurite outgrowth in PC12 cells.…”

“…Regulation of [Ca 2+ ] i has been shown to play important roles in neurite outgrowth (3) and NCX is important for regulation of [Ca 2+ ] i in PC12 cells (6). However, involvement of NCX in neurite outgrowth is unclear.…”

Muscarinic-induced Recruitment of Plasma Membrane Ca2+-ATPase Involves PSD-95/Dlg/Zo-1-mediated Interactions

“…Low resting [Ca 2ϩ ] i is maintained by the sequestration of Ca 2ϩ into intracellular stores or the extrusion of Ca 2ϩ across the plasma membrane by transporters such as the ubiquitous plasma membrane Ca 2ϩ -ATPase (PMCA) 3 (1). Many G-protein-coupled receptors (GPCRs) (such as purinergic and muscarinic receptors) signal via transient increases in [Ca 2ϩ ] i to effect physiological responses (2).…”

“…The increase in [Ca 2ϩ ] i is biphasic, with an initial mobilization of Ca 2ϩ from intracellular stores which in turn triggers Ca 2ϩ influx via ion channels in the plasma membrane. Following termination of receptor signaling, [Ca 2ϩ ] i returns rapidly to resting levels due to refilling of the sarcoplasmic/ endoplasmic reticulum as well as Ca 2ϩ efflux mediated by PMCA and/or Na ϩ -Ca 2ϩ exchange (3). Thus the magnitude and duration of the increase in [Ca 2ϩ ] i during the activation of a GPCR signaling cascade reflects a dynamic equilibrium between influx, reuptake, and efflux.…”