Fig. 3: Calcium signaling in early-stage oligodendrocytes regulates actin filament levels.

a Primary rat oligodendrocyte precursor cells (OPCs) were differentiated for 2 days and then treated overnight with BAPTA-AM, dimethyl-BAPTA-AM (DMB-AM), or DMSO. Cells were then fixed, stained, and imaged. Created with Biorender.com. b Epifluorescence representative micrograph of control (left) and BAPTA-AM treated (right) rat oligodendrocytes stained with cell mask blue (white) to label cytoplasmic regions of the cells and phalloidin (purple) to label actin filaments. Scale bar, 50 μm. c Quantification of phalloidin mean intensity of rat oligodendrocytes in c. Average ± SEM, N = 4 biological replicates (preps/bolded dots) p-value was determined by a one-way ANOVA; *p = 0.0188. d OPCs were isolated from WT or OL-CalEx mice and differentiated for 3 days before fixation and staining. Created with Biorender.com. e Epifluorescence representative micrograph of WT (left) and OL-CalEx (right) mouse oligodendrocytes stained with cell mask blue (white) to label cytoplasmic regions of the cells and phalloidin (purple) to label actin filaments. Scale bar, 50 μm. f Quantification of phalloidin mean intensity of mouse oligodendrocytes in e. Average ± SEM, N = 3 biological replicates (preps/bolded dots). Statistical significance determined by unpaired, two-tailed Student’s t test; *p = 0.020. g Confocal micrograph of WT (left) and OL-CalEx (right) myelin rings in P8 dorsal spinal cord sections. (bottom row) mCherry staining (middle row) myelin basic protein to label nascent myelin sheaths (top row) SiR-actin staining to label actin filaments. Scale bar, 1 μm. Created with Biorender.com. h Quantification of SiR-actin mean intensity in myelin basic protein positive rings. Average ± SEM, N = 5. Statistical significance determined by unpaired, two-tailed Student’s t test; *p = 0.0499.