Tunicamycin-induced reporter expression is blocked by inhibiting ATF6 translation and binding. (A) After injection of an atf6 morpholino (atf6 MO) at the one- to four-cell stage to inhibit ATF6 translation, 1-dpf embryos were treated with Tunicamycin (Tunic) and expression at 3 dpf in the head region (dashed line) was quantified. atf6-MO-injected embryos had significantly less 5XATF6RE:eGFP expression compared to tunicamycin-only-treated embryos (P=0.0150). Only embryos with detectable 5XATF6RE:eGFP expression were analyzed. *P<0.05; unpaired Student's t-test. (B) Embryos expressing hsp70:Gal4 and 5XATF6RE:d2GFP transgenes were injected with an mCherry-tagged UAS plasmid to mosaically overexpress dominant-negative ATF6 (dnATF6) that inhibits endogenous ATF6 binding. 2-dpf embryos were heat shocked, treated with tunicamycin, and expression of GFP and mCherry was quantified in the head region (dashed line) 12 h later. Representative images show that, compared to a DMSO-treated injection control, embryos with tunicamycin treatment show increased 5XATF6RE:d2GFP expression, which decreases with increasing dnATF6-2A-mCherry expression, resulting in a significant negative correlation (R2=0.4712, P=0.0284). *P≤0.05; Pearson's correlation coefficient. All error bars are s.e.m. Scale bars: 1 mm.
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