Conditional Deletion of the L-Type Calcium Channel Cav1.2 in NG2-Positive Cells Impairs Remyelination in Mice

Abstract

Exploring the molecular mechanisms that drive the maturation of oligodendrocyte progenitor cells (OPCs) during the remyelination process is essential to developing new therapeutic tools to intervene in demyelinating diseases such as multiple sclerosis. To determine whether L-type voltage-gated calcium channels (L-VGCCs) are required for OPC development during remyelination, we generated an inducible conditional knock-out mouse in which the L-VGCC isoform Cav1.2 was deleted in NG2-positive OPCs (Cav1.2). Using the cuprizone (CPZ) model of demyelination and mice of either sex, we establish that Cav1.2 deletion in OPCs leads to less efficient remyelination of the adult brain. Specifically, Cav1.2 OPCs mature slower and produce less myelin than control oligodendrocytes during the recovery period after CPZ intoxication. This reduced remyelination was accompanied by an important decline in the number of myelinating oligodendrocytes and in the rate of OPC proliferation. Furthermore, during the remyelination phase of the CPZ model, the corpus callosum of Cav1.2 animals presented a significant decrease in the percentage of myelinated axons and a substantial increase in the mean g-ratio of myelinated axons compared with controls. In addition, in a mouse line in which the Cav1.2 OPCs were identified by a reporter, we establish that Cav1.2 OPCs display a reduced maturational rate through the entire remyelination process. These results suggest that Ca influx mediated by L-VGCCs in oligodendroglial cells is necessary for normal remyelination and is an essential Ca channel for OPC maturation during the remyelination of the adult brain. Ion channels implicated in oligodendrocyte differentiation and maturation may induce positive signals for myelin recovery. Voltage-gated Ca channels (VGCCs) are important for normal myelination by acting at several critical steps during oligodendrocyte progenitor cell (OPC) development. To determine whether voltage Ca entry is involved in oligodendrocyte differentiation and remyelination, we used a conditional knockout mouse for VGCCs in OPCs. Our results indicate that VGCCs can modulate oligodendrocyte maturation in the demyelinated brain and suggest that voltage-gated Ca influx in OPCs is critical for remyelination. These findings could lead to novel approaches for obtaining a better understanding of the factors that control OPC maturation in order to stimulate this pool of progenitors to replace myelin in demyelinating diseases.

The voltage‐gated calcium channel CaV1.2 promotes adult oligodendrocyte progenitor cell survival in the mouse corpus callosum but not motor cortex

“…Consistent with this finding, the deletion of CaV1.2 from adult OPCs was reported to reduce their capacity to remyelinate the corpus callosum following cuprizone-induced demyelination (Santiago González et al, 2017), suggesting that CaV1.2 can, at least following an injury, regulate adult OPC function. However, it is also possible that CaV1.2 may differentially regulate developmental versus adult OPCs or OPCs in the healthy versus injured CNS.…”

“…While it is unclear how callosal OPC inputs and signaling can change with aging, it is interesting to note that demyelination restores neuron‐OPC synaptic communication in the rat caudal cerebellar peduncle (Gautier et al, ) and causes adult OPCs in the corpus callosum to revert to a transcriptional state similar to that of developmental OPCs (Moyon et al, ). Such changes could account for CaV1.2 having no effect on adult myelination in the healthy adult mouse brain but acting to expedite or enhance remyelination of the corpus callosum following cuprizone‐induced demyelination (Santiago González et al, ).…”

The K2P‐channel TASK1 affects Oligodendroglial differentiation but not myelin restoration

“…In many studies, several ion channels have already been shown to be relevant for the initiation or regulation of basal oligodendroglial cell functions (proliferation, migration and differentiation). In this context, voltage‐gated Ca 2+ entry (via Ca V 1.2 channels) has not only been shown to promote oligodendrocyte maturation and myelination in vitro (Cheli, Santiago Gonzalez, Spreuer, & Paez, ) but also to be crucial for remyelination in the cuprizone model (Santiago Gonzalez et al, ). Also, Ca 2+ ‐release from internal stores seems to be involved in mechanisms of oligodendrocyte differentiation (Li et al, ; Weider et al, ).…”

Deletion of Voltage-Gated Calcium Channels in Astrocytes during Demyelination Reduces Brain Inflammation and Promotes Myelin Regeneration in Mice

“…Protein samples were extracted using lysis buffer as described by Santiago González et al (2017). Twenty mg of proteins were separated with NuPAGE Novex 4-2% Bis-Tris Protein Gels (Life Technologies) and electro-blotted onto PVDF membranes.…”

“…Removal of exon 2 leads to a truncated, non-functional protein. Conditional Cav1.2 deletion in cortical and hippocampal neurons as well as immature oligodendrocytes has been successfully generated in previous experiments (Cheli et al, 2016b;Santiago González et al, 2017). The GFAPCreER T2 transgenic line expresses a tamoxifen-inducible Cre recombinase under the control of the human GFAP promoter (Hirrlinger et al, 2006).…”