Chemogenetic Activation of Oligodendrocytes Delays Postnatal Myelination by Promoting Progenitor Proliferation and Inhibiting Maturation

Chemogenetic strategies such as Designer Receptors Exclusively Activated by Designer Drugs (DREADDs) enable precise manipulation of cell signaling. While previous studies have demonstrated that excitatory DREADDs modulate Ca²⁺ signaling and excitability in neurons and astrocytes, their role within the oligodendrocyte lineage remained unexplored. In this study, we utilized the hM3Dq receptor to examine how excitatory DREADDs modulate Ca²⁺ dynamics and oligodendrocyte biology, and to evaluate their potential for regulating oligodendrocyte development and function across both developmental and adult stages of the brain. Utilizing Cre-mediated recombination, the hM3Dq receptor was selectively expressed within the oligodendrocyte lineage. Activation of hM3Dq in oligodendrocytes induces the release of Ca²⁺ from internal stores and increases Ca²⁺ influx mediated by voltage-gated and glutamate channels. In vitro, hM3Dq activity promoted oligodendrocyte progenitor cell (OPC) proliferation and reduced oligodendrocyte maturation and myelin protein synthesis. In vivo, hM3Dq activation in NG2- or Sox10-positive oligodendrocytes during early postnatal development significantly delayed the myelination process, reduced the density of mature oligodendrocytes, and increased the number of proliferating OPCs in several brain areas. In contrast, hM3Dq activation in mature oligodendrocytes induced myelin loss and oligodendrocyte apoptotic cell death in the adult brain. RNA sequencing of hM3Dq-expressing OPCs revealed transcriptional changes in genes regulating cell cycle progression, potassium channel activity, and p53-associated signaling, along with disruptions in oligodendrocyte maturation programs. These findings demonstrate that chemogenetic modulation of intracellular signaling and Ca²⁺ dynamics via DREADDs provides a powerful tool to dissect and control oligodendrocyte development, with implications for understanding and treating myelin-related disorders.