The opposite effect of ELP4 and ZEB2 on TCF7L2-mediated microglia polarization in ischemic stroke

Microglia M1 polarization plays important role in the development of ischemic stroke (IS). This study explored the role of transcription factor 7 like 2 (TCF7L2) in regulating microglia M1 polarization during IS. TTC staining was used to determine the cerebral infarction, and Nissl staining was applied to examine neuronal injury. The secretion levels of cytokines were measured using ELISA. The interaction between Zinc finger E-Box binding homeobox 2 (ZEB2) and TCF7L2 was analyzed by Co-IP, and H3K27ac enrichment in the TCF7L2 promoter was detected by ChIP assay. TCF7L2 knockdown reduced MCAO/R-induced mice cerebral injury. TCF7L2 silencing or TAK-242 (TLR4 antagonist) injection inhibited OGD/R-induced microglia M1 polarization by repressing the TLR4/NF-κB signal, and TCF7L2 knockdown combined with TAK-242 treatment further inhibited microglia M1 polarization. TCF7L2 promoted transcriptional activation of TLR4. ELP4 enhanced H3K27ac-mediated transcriptional activation of TCF7L2, and ZEB2 promoted the K48-linked ubiquitination of TCF7L2. TCF7L2 overexpression abolished the inhibitory effect of ELP4 knockdown or ZEB2 overexpression on OGD/R-induced microglia M1 polarization. TCF7L2 exacerbated cerebral injury by promoting microglia M1 polarization during IS progression. Mechanistically, ELP4 promoted TCF7L2 expression by promoting H3K27ac enrichment in the TCF7L2 promoter, while ZEB2 promoted TCF7L2 ubiquitination degradation.