Figure 2. miR-21 regulates astrocyte activation and secretion of CSPGs, NGF, and BDNF. To determine the effects of miR-21 and TGF-β1 on astrocytes, we examined GFAP expression with or without miR-21 and TGF-β1 (10 ng/mL). (A) Astrocytes were treated with PBS alone or in combination with transfection of miR-21 OE, miR-21 KD, or NC (n = 3). (B) Astrocytes were treated with TGF-β1 alone or in combination with transfection of miR-21 OE, miR-21 KD, or NC. GFAP protein expression was examined by western blot (n = 3). (C) Effects of transfection were verified by qRT-PCR (n = 3). To determine changes in secretory function influenced by miR-21 and TGF-β1, astrocytes were treated with PBS alone or in combination with transfection of miR-21 OE, miR-21 KD, and NC (n = 3). RNA expression levels of BDNF (D), CSPGs (E), and NGF (F) were detected by qRT-PCR (n = 3). Data are expressed as mean ± SD. *P < 0.05, **P < 0.01, ***P < 0.001 compared with NC or TGF-β1 groups; #P < 0.05, ##P < 0.01, ###P < 0.001 compared with NC group. BDNF, brain-derived neurotrophic factor; CSPGs, chondroitin sulfate proteoglycans; GFAP, glial fibrillary acidic protein; miR, microRNA; NGF, nerve growth factor; miR-21 KD, LV-mmu-miR-21a-inhibition; miR-21 OE, LV-mmu-miR-21a; NC, negative control; qRT-PCR, quantitative real-time polymerase chain reaction; SCI, spinal cord injury; SD, standard deviation; TGF-β1, transforming growth factor beta 1.