Fig. 8

Spliced XBP1 participated in Trap1 expression at transcriptional regulation. a XBP1s mRNA expression levels were determined by semi-quantitative PCR. HK-2 cells were transfected with 1ug of pLAS3W-XBP1s. b Trap1 mRNA expression was evaluated by qPCR in HK-2 cells overexpressed with XBP1s. N = 4 for each group. Data are expressed as means ± SEM. ***P < 0.0001 as compared with empty vector (EV). c Trap1 promoter binding ability of XBP1 was examined by luciferase reporter assay. Upper panel: schematic diagrams of Trap1 promoter-luciferase reporter. Lower panel: relative luciferase activity in HK-2 cells transfected with a Trap1 promoter-luciferase reporter plasmid or empty vector (pGL3 basic), along with EV or XBP1s plasmid. Renilla luciferase activity was used as an internal control and for normalization of transfection efficiency. N = 3 for each group. Data are expressed as means ± SEM. d–f ChIP-PCR assay was performed to analyze the binding of XBP1s to Trap1 promoter in 293 T cells. d Three sets of primer pairs covered the − 296 ~ − 451, − 559 ~ 694, − 749 ~ 903 regions, and qPCR showed that XBP1s bound to − 296 ~ − 451 region (e and f)