Figure 5.

Expression of genes induced in reactive astrocytes over time. A, The top 317 genes significantly upregulated in MCAO reactive astrocytes over 7 d were clustered using the k-means method with the standard Pearson correlation coefficient. Each line represents the relative expression of one gene at time points sham, 1 d, 3 d, and 7 d after MCAO. Genes are grouped into six patterns of expression, containing 14–135 members, that are represented in graphs 1–6. B, Diverse genes in group 3 are strongly induced at 1 d and are rapidly downregulated to near-quiescent levels by 7 d. Lcn2 is downregulated to near-baseline levels. Serpina3n expression remains elevated at 7 d. C, Expression of a subset of chemokines (CXCL1, CXCL2, and CXCL10) remains elevated over the course of 1 week (group 5 expression pattern). In contrast, macrophage chemokine CCL2 follows a group 3 expression pattern in which expression is rapidly moderated. D, In situ hybridization on coronal brain sections from healthy and injured mice confirms the time course indicated by the GeneChip expression profiles. Rows 1 (MCAO) and 2 (LPS), Lcn2 is upregulated by 1 d after injury but is rapidly downregulated; rows 3 (MCAO) and 4 (LPS), Serpina3n is upregulated by 1 d after injury and is downregulated, but remains elevated, 7 d after injury. Scale bar, 100 μm.