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. Author manuscript; available in PMC: 2013 Oct 3.
Published in final edited form as: Cell Metab. 2012 Oct 3;16(4):473–486. doi: 10.1016/j.cmet.2012.09.003

Figure 6. Overexpression of PDI, but not MTP, promotes TG secretion in Ire1α-deleted hepatocytes.

Figure 6

(A) PDI expression is reduced in L-Ire1α-KO livers. Relative gene expression was normalized to actin mRNA levels and values are compared to mRNA levels from LIre1α-Het mice. *P< 0.05 vs L-Ire1α-Het. (B) and (C) Adenovirus-mediated overexpression of XBP1s increases PDI expression. (B) Values are relative to mRNA levels of L-Ire1α-KO hepatocytes infected with adenovirus expressing GFP. (C) PDI and MTP protein levels were measured at 48-hr after infection of hepatocytes with adenovirus expressing GFP (Ad-GFP), XBP1s (Ad-XBP1s), MTP (Ad-MTP), PDI (Ad-PDI) or mutant PDI (Ad-PDIMu). Actin was used as a loading control. (D) and (E) Overexpression of PDI restores MTP activity and promotes hepatic TG secretion in LIre1α-Het hepatocytes. (D) TG synthesis and secretion rates were measured at 48-hr after of infection with the indicated adenoviruses (n=6). *P< 0.05 vs Ad-PDI or mutant PDI Ad-PDIMu; **P< 0.05 vs Ad-XBP1s. (E) MTP activity was measured in each sample of (D). *P< 0.05 vs Ad-PDI or Ad-PDIMu. (F), (G) and (H) XBP1 knockdown decreases PDI levels, MTP activity and TG secretion in hepatocytes. (F) XBP1 and PDI levels were measured in hepatocytes transfected with control siRNA or XBP1 siRNA. (G) MTP activity was measured in hepatocytes transfected with above siRNAs (n=6). **P<0.05 vs control. (H) TG synthesis and secretion were measured in hepatocytes transfected with above siRNAs (n=6). **P<0.05 vs control.