FIGURE 8.
RIP-DN Hnf1α mouse islets express less BiP and Chop mRNA and are sensitized to ER stress. A, fasting glycemia of DN Hnf1α (n = 19) or littermate control (n = 15) mice. B and C, Q-PCR of BiP and Chop mRNA in control or DN Hnf1α islets after overnight culture followed by 6 h of 40 μm CPA or vehicle (n = 3). D, Q-PCR of BiP mRNA in control or DN Hnf1α islets with or without 30 mm glucose for 4 days (n = 3). Expression was normalized to cyclophilin D in this experiment because Rps29 mRNA was increased by high glucose treatment (not shown). E, Q-PCR of total Xbp1 mRNA in control or DN Hnf1α islets with or without 6 h of 40 μm CPA (n = 3). F, Q-PCR of spliced Xbp1 mRNA in control or DN Hnf1α islets with or without 6 h of 40 μm CPA (n = 3). G, Q-PCR of total Xbp1 mRNA in control or Hnf1α knock-out islets and liver (n = 3 wild type and 4 knock-out mice for islet expression and 6 wild type and 5 knock-out mice for liver expression). Four of the Hnf1α knock-out mice and two wild type mice were analyzed for both islet and liver expression; the remainder were different animals. Expression was normalized to cyclophilin D in this experiment because ribosomal protein mRNA expression can vary widely between tissues (58). H, islet insulin content of control or DN Hnf1α islets (n = 6 control and 6 DN Hnf1α mice). I, TUNEL assay for apoptosis in control or DN Hnf1α islets with insulin immunostaining to identify β-cells (n = 3 control and 4 DN Hnf1α mice). J, cell death ELISAPLUS assay of control or DN Hnf1α islets with or without 6 h of 40 μm CPA. Results are expressed as mean ± S.E. (error bars) of the percentage increase in cytoplasmic nucleosome content in the CPA-treated relative to the vehicle-treated islets (n = 3). For Q-PCR experiments with DN Hnf1α islets, islet mRNA was pooled from 2–5 mice each time. For Q-PCR with Hnf1α knock-out islets and liver, the islet insulin measurements and the apoptosis assay, samples from each mouse were analyzed individually.