XBP1: a link between the unfolded protein response, lipid biosynthesis, and biogenesis of the endoplasmic reticulum

R Sriburi, S Jackowski, K Mori, JW Brewer - The Journal of cell biology, 2004 - rupress.org
R Sriburi, S Jackowski, K Mori, JW Brewer
The Journal of cell biology, 2004rupress.org
When the protein folding capacity of the endoplasmic reticulum (ER) is challenged, the
unfolded protein response (UPR) maintains ER homeostasis by regulating protein synthesis
and enhancing expression of resident ER proteins that facilitate protein maturation and
degradation. Here, we report that enforced expression of XBP1 (S), the active form of the
XBP1 transcription factor generated by UPR-mediated splicing of XBP1 mRNA, is sufficient
to induce synthesis of phosphatidylcholine, the primary phospholipid of the ER membrane …
When the protein folding capacity of the endoplasmic reticulum (ER) is challenged, the unfolded protein response (UPR) maintains ER homeostasis by regulating protein synthesis and enhancing expression of resident ER proteins that facilitate protein maturation and degradation. Here, we report that enforced expression of XBP1(S), the active form of the XBP1 transcription factor generated by UPR-mediated splicing of XBP1 mRNA, is sufficient to induce synthesis of phosphatidylcholine, the primary phospholipid of the ER membrane. Cells overexpressing XBP1(S) exhibit elevated levels of membrane phospholipids, increased surface area and volume of rough ER, and enhanced activity of the cytidine diphosphocholine pathway of phosphatidylcholine biosynthesis. These data suggest that XBP1(S) links the mammalian UPR to phospholipid biosynthesis and ER biogenesis.
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