Constitutive DREADD signalling modulates oligodendrocyte precursor cell bioelectrical membrane properties and fate

Oligodendrocyte precursor cells (OPCs) are small cells in the central nervous system that proliferate and differentiate into myelinating oligodendrocytes throughout life, allowing for myelin plasticity and repair. G protein-coupled neuromodulator receptors can regulate OPC fate, but the role of individual G protein families is unclear. Here, we use chemogenetics to directly investigate the role of Gq and Gi proteins in OPC fate. We find that expressing the DREADDs (Designer Receptors Exclusively Activated by Designer Drugs) hM3Dq or hM4Di in OPCs without activating them with designer agonists induces constitutive G protein signalling, which alters bioelectrical membrane properties such as voltage-gated ion channels and glutamate receptors in OPCs. Further, we find that hM3Dq or hM4Di expression alone modulates OPC fate, increasing or decreasing differentiation, respectively, suggesting that directly targeting G protein signalling can be used to bidirectionally regulate differentiation. Importantly, our data raise a note of caution regarding the use of DREADDs in both excitable and non-excitable small cells. SIGNIFICANCE STATEMENTDesigner Receptors Exclusively Activated by Designer Drugs (DREADDs) are widely used to manipulate neuronal excitability. Their use in other neural cell types is rapidly increasing; however, DREADDs have not been thoroughly characterized in non-neuronal cells. Here, we show that when expressed in small excitable cells like oligodendrocyte precursor cells, DREADDs are constitutively active, unlike in excitatory neurons. This constitutive DREADD signalling alters cell fate and bioelectrical membrane properties like voltage-gated ion channels and glutamate receptors. Our data highlight that constitutive DREADD activity represents a significant confound that needs to be considered and controlled for when expressing DREADDs in small cells, and demonstrate that G protein signalling is a potent regulator of OPC fate, with a potential for therapeutic implications.