DACH1 decreases tPA expression in hepatocytes by repressing the Plat inducer ATF6. (A) Human primary hepatocytes were transduced with adeno-LacZ or adenovirus expressing dominant-negative ΔDS-DACH1 and then assayed for PLAT and ATF6 mRNA and for tPA and ATF6 by immunoblot. (B) tPA concentration by ELISA and tPA activity by enzymatic assay in the culture medium of the cells in (A). In (A-B), results are shown as mean ± SEM (n = 3 sets of cells per each group). (C) A conserved ATF6 binding consensus sequence in exon 9 of the PLAT gene. (D) Mouse liver nuclear extracts were subjected to a chromatin immunoprecipitation assay using anti-ATF6 or control immunoglobulin G. The exon 9 region containing the ATF6 binding sequence and a nonconsensus sequence in the Plat gene as control were amplified by quantitative polymerase chain reaction and normalized to the values obtained from input DNA. Results are shown as mean ± SEM (n = 3 mice per group). (E) Immunoblots of ATF6 and tPA and quantification of relative PLAT mRNA in primary human hepatocytes transduced with adeno-LacZ or adeno-shATF6. (F) Immunoblots of ATF6 and tPA and PLAT mRNA in primary human hepatocytes treated with control adeno-LacZ or adeno–ATF6-N. In (E-F), results are shown as mean ± SEM (n = 3 sets of cells per each group). Shorter film exposure time was used for developing immunoblots in panel D vs panel E to obtain signals within linear range. *P < .05, **P < .01, 2-tailed Student t test. n.s., not significant (P ≥ .05).