Fig. 4.

Representation of our proposed model of adaptation to ER stress in the diabetic hippocampus. An intron of the unspliced (u) variant of Xbp1 mRNA is excised during the response to ER stress, yielding spliced (s) Xbp1 mRNA. Xbp1s mRNA encodes the protein XBP1s, which activates the synthesis of ER chaperones, whereas Xbp1u mRNA encodes the protein XBP1u, which inhibits the synthesis of ER chaperones. During adaptation to prolonged ER stress in the hippocampus, the ratio of XBP1s to XBP1u is altered to inhibit ER chaperone synthesis