Deciphering BK Channel Function in Human Oligodendrocyte Progenitor Cells
Kantak, Divyangi Krantikumar
MetadataShow full item record
Demyelination in neurodegenerative disorders, is characterized by chronic destruction of myelin leading to attenuated saltatory conduction and ultimately axonal dystrophy. Remyelination, the regeneration of lost myelin, is dependent on differentiation of oligodendrocyte progenitor cells (OPCs) into myelinating oligodendrocytes. Recently, inhibitory muscarinic receptor signaling acting via M1R and M3R has been shown to hinder spontaneous remyelination. Previously, we found that treatment of human OPCs (hOPCs) with a non-selective muscarinic agonist oxotremorine (oxo-M) induced intracellular calcium release and store-operated calcium entry (SOCE). In this study, we hypothesized that muscarinic agonist-induced SOCE leads to the activation of calcium-activated BK potassium channels (KCa1.1) which mediate the anti-differentiative effects of M1/3R signaling. BK channels are known to play a functional role in various physiological processes including membrane hyperpolarization during action potential, proliferation, and transcriptional regulation. To test this hypothesis, primary PDGFαR+ hOPCs were treated with pharmacological inhibitors of BK channels, iberiotoxin (IBTx) and paxilline (Pax), in the presence or absence of oxo-M. Consistent with our previous data, oxo-M treatment impaired hOPC differentiation to O4+ oligodendrocytes. Interestingly, we found that pharmacological inhibition of BK channels by both IBTx and Pax dose-dependently rescued the anti-differentiative effects of oxo-M treatment leading to increased oligodendrocyte differentiation. On the other hand, BK channel activation with NS19504 attenuated hOPC differentiation to O4+ oligodendrocytes presence or absence of Oxo-M. Furthermore, siRNA mediated knockdown of the pore forming BK α-subunit also mitigated the inhibitory effect of oxo-M on hOPC differentiation. Additionally, we also investigated the effect of ß4 subunit knockdown on OPC differentiation which suggests that auxiliary subunits of BK channel may be essential to regulate hOPC differentiation. These results suggest that BK channels are a necessary component of the muscarinic receptor pathway and provide insights into mechanisms that govern commitment of OPCs to a myelinogenic fate.