Fig. 8.

A schematic diagram illustrates the proposed model for the modulatory effect of C/EBPδ on astrocyte migration and glial scar formation after SCI. In response to the injury, inflammatory cytokine IL-1β released in the lesion epicenter activates astrocytic expression of C/EBPδ, which in turn inhibits RhoA expression and thus impedes the migration of the astrocytes located along the lesion border. Simultaneously, C/EBPδ upregulates astrocytic expression of MMP-3. Diffusion of MMP-3 promotes the migration of neighboring astrocytes, particularly those in the penumbral region between the lesion border and less injured cord tissue. Consequently, astrocytes in the penumbral region with relatively high RhoA expression and an enriched MMP-3 environment migrate toward the lesion border where they aggregate to form a glial scar. Relative gradients of C/EBPδ, RhoA, and MMP-3 are illustrated on the right