Oscillatory calcium release and sustained store-operated oscillatory calcium signaling prevents differentiation of human oligodendrocyte progenitor cells

Abstract

Endogenous remyelination in demyelinating diseases such as multiple sclerosis is contingent upon the successful differentiation of oligodendrocyte progenitor cells (OPCs). Signaling via the Gαq-coupled muscarinic receptor (M1/3R) inhibits human OPC differentiation and impairs endogenous remyelination in experimental models. We hypothesized that calcium release following Gαq-coupled receptor (GqR) activation directly regulates human OPC (hOPC) cell fate. In this study, we show that specific GqR agonists activating muscarinic and metabotropic glutamate receptors induce characteristic oscillatory calcium release in hOPCs and that these agonists similarly block hOPC maturation in vitro. Both agonists induce calcium release from endoplasmic reticulum (ER) stores and store operated calcium entry (SOCE) likely via STIM/ORAI-based channels. siRNA mediated knockdown (KD) of obligate calcium sensors STIM1 and STIM2 decreased the magnitude of muscarinic agonist induced oscillatory calcium release and attenuated SOCE in hOPCs. In addition, STIM2 expression was necessary to maintain the frequency of calcium oscillations and STIM2 KD reduced spontaneous OPC differentiation. Furthermore, STIM2 siRNA prevented the effects of muscarinic agonist treatment on OPC differentiation suggesting that SOCE is necessary for the anti-differentiative action of muscarinic receptor-dependent signaling. Finally, using a gain-of-function approach with an optogenetic STIM lentivirus, we demonstrate that independent activation of SOCE was sufficient to significantly block hOPC differentiation and this occurred in a frequency dependent manner while increasing hOPC proliferation. These findings suggest that intracellular calcium oscillations directly regulate hOPC fate and that modulation of calcium oscillation frequency may overcome inhibitory Gαq-coupled signaling that impairs myelin repair.

Genetic ablation of GABABreceptors from oligodendrocyte precursor cells protects against demyelination in the mouse spinal cord

“…Glial Ca 2+ signaling is, as it is in other regions of the CNS, finely regulated and cell-specific in the mouse spinal cord ( 50 ), but we are far from understanding its determinants as well as its role in cell physiology. In the functional spinal cord, OPC Ca 2+ signals are known to be evoked by neurons and astroglia ( 24 ) and disturbances in OPC Ca 2+ (with excessively frequent Ca 2+ oscillations) has been linked to impaired proliferation during development ( 73, 74 ). Compared to physiological conditions in cKO mice, OPCs showed higher resilience to the pathological alteration of cellular Ca 2+ signaling induced by the cuprizone treatment.…”

Ectodomain shedding of EGFR ligands serves as an activation readout for TRP channels

“…This was evidenced by ectodomain shedding of EGF and BTC, substrates of ADAM10, which was triggered only by the downstream signal of TRP channels (Fig 2E -2I). The increase in intracellular Ca 2+ concentration induced by TRP channel activation is high and long-lasting, whereas that induced by GPCRs is oscillatory and transient [34][35][36]. Previous reports showed that Ca 2+ -induced ADAM10 activation is totally dependent on anoctamin 6 (ANO6), a Ca 2+ -sensitive phosphatidylserine scramblase [37,38].…”

The ER-mitochondria interface, where Ca2+ and cell death meet

“…The regulation of cell fate by Ca 2+ signaling is multi-faceted as it encompasses the processes of cell proliferation [27,28], differentiation [29][30][31], senescence [32][33][34][35], autophagy [28,[36][37][38][39][40], as well as the various forms of cell death [28,36,39,41,42]. Please see also the further papers on the subject in this Special Issue.…”