[HTML][HTML] Bioactive small molecules reveal antagonism between the integrated stress response and sterol-regulated gene expression

HP Harding, Y Zhang, S Khersonsky, S Marciniak… - Cell metabolism, 2005 - cell.com
HP Harding, Y Zhang, S Khersonsky, S Marciniak, D Scheuner, RJ Kaufman, N Javitt
Cell metabolism, 2005cell.com
Phosphorylation of translation initiation factor 2α (eIF2α) coordinates a translational and
transcriptional program known as the integrated stress response (ISR), which adapts cells to
endoplasmic reticulum (ER) stress. A screen for small molecule activators of the ISR
identified two related compounds that also activated sterol-regulated genes by blocking
cholesterol biosynthesis at the level of CYP51. Ketoconazole, a known CYP51 inhibitor, had
similar effects, establishing that perturbed flux of precursors to cholesterol activates the ISR …
Summary
Phosphorylation of translation initiation factor 2α (eIF2α) coordinates a translational and transcriptional program known as the integrated stress response (ISR), which adapts cells to endoplasmic reticulum (ER) stress. A screen for small molecule activators of the ISR identified two related compounds that also activated sterol-regulated genes by blocking cholesterol biosynthesis at the level of CYP51. Ketoconazole, a known CYP51 inhibitor, had similar effects, establishing that perturbed flux of precursors to cholesterol activates the ISR. Surprisingly, compound-mediated activation of sterol-regulated genes was enhanced in cells with an ISR-blocking mutation in the regulatory phosphorylation site of eIF2α. Furthermore, induction of the ISR by an artificial drug-activated eIF2α kinase reduced the level of active sterol regulatory element binding protein (SREBP) and sterol-regulated mRNAs. These findings suggest a mechanism by which interactions between sterol metabolism, the ISR, and the SREBP pathway affect lipid metabolism during ER stress.
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