Transcriptomic analysis of loss of Gli1 in neural stem cells responding to demyelination in the mouse brain

Abstract

In the adult mammalian brain, Gli1 expressing neural stem cells reside in the subventricular zone and their progeny are recruited to sites of demyelination in the white matter where they regenerate oligodendrocytes, the myelin forming cells. Remarkably, genetic loss or pharmacologic inhibition of Gli1 enhances the efficacy of remyelination by these neural stem cells. To understand the molecular mechanisms involved, we performed a transcriptomic analysis of this Gli1-pool of neural stem cells. We compared murine NSCs with either intact or deficient Gli1 expression from adult mice on a control diet or on a cuprizone diet to induce widespread demyelination. These data will be a valuable resource for identifying therapeutic targets for enhancing remyelination in demyelinating diseases like multiple sclerosis.

Gpnmb inhibits oligodendrocyte differentiation of adult neural stem cells by amplifying TGFβ1 signaling

“…Indeed, Gpnmb expression was significantly lower in Gli1 NULL vNSCs compared to Gli1 HET vNSCs following demyelination (Fig. 1A), although there was no difference in Gpnmb levels in the healthy brain (Samanta, 2021). This indicates that Gli1 is necessary for upregulation of Gpnmb following demyelination but not required for its baseline expression in healthy brains.…”

“…Our previous studies have shown that loss of Gli1 in vNSCs of the adult SVZ, results in enhanced recruitment and regeneration of myelinating oligodendrocytes in response to demyelination of the white matter corpus callosum (CC) (Radecki et al, 2020;Samanta et al, 2015). To determine the molecular mechanisms involved, we compared the transcriptomes of vNSCs isolated from the healthy and demyelinated brains of the knock-in Gli1 CreER/Wt (Gli1 HET ) mice with one copy of Gli1, and Gli1 CreER/CreER (Gli1 NULL ) mice with loss of Gli1 expression (Samanta, 2021). We probed the top 100 differentially expressed genes in the Gli1 HET vs. Gli1 NULL vNSCs following demyelination, for genes shared amongst three or more GO terms related to cell survival, migration and differentiation.…”

“…By performing an Ingenuity and Kegg pathway analyses of the RNAseq data (Samanta, 2021), we identified the TGFβ1 pathway as significantly activated in Gli1 HET vNSCs as compared to Gli1 NULL vNSCs following demyelination (Fig. 3A).…”

“…Since the RNAseq data (Samanta, 2021) showed significantly higher expression of the ligand binding subunit of TGFβ receptor, TGFβR2, in the Gli1 HET vNSCs compared to the Gli1 NULL vNSCs upon demyelination (Fig. 3 A), it suggested that Gpnmb can regulate the TGFβ1 pathway.…”

“…For bulk RNAseq analysis of Gli1 HET and Gli1 NULL SVZ, sample preparation, RNA collection and sequencing were performed as described in (Samanta, 2021) and the data were deposited to NCBI-GEO (GSE162683). Volcano plots were generated using the package EnhancedVolcano v1.8.0 (Blighe et al, 2020) under R v4.0.3 (R Core Team, 2020.…”