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Cellular responses to halofuginone reveal a vulnerability of the GCN2 branch of the integrated stress response

ABSTRACT: Halofuginone (HF) is a phase 2 clinical compound that inhibits the glutamyl-prolyl-tRNA synthetase (EPRS) thereby inducing the integrated stress response (ISR). Here we report that halofuginone indeed triggers the predicted canonical ISR adaptations, consisting of attenuation of protein synthesis and gene expression reprogramming. However, the former is surprisingly atypical and occurs to a similar magnitude in wild type cells and cells lacking GCN2 and those incapable of phosphorylating eIF2. Proline supplementation rescues the observed HF-induced changes indicating that they result from inhibition of EPRS. The failure of the GCN2-to-eIF2 pathway to elicit a measurable protective attenuation of translation initiation allows translation elongation defects to prevail upon HF-treatment. Exploiting this vulnerability of the ISR, we show that cancer cells with increased proline dependency are more sensitive to halofuginone. This work reveals that the consequences of EPRS inhibition are more complex than anticipated, and provides novel insights into ISR signaling, as well as a molecular framework to guide the targeted development of halofuginone as a therapeutic.

SUBMITTER: Dr. Aleksandra, P. Pitera

PROVIDER: S-SCDT-EMBOJ-2021-109985 | biostudies-other |

REPOSITORIES: biostudies-other

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Cellular responses to halofuginone reveal a vulnerability of the GCN2 branch of the integrated stress response.

Project description:Halofuginone (HF) is a phase 2 clinical compound that inhibits the glutamyl-prolyl-tRNA synthetase (EPRS) thereby inducing the integrated stress response (ISR). Here, we report that halofuginone indeed triggers the predicted canonical ISR adaptations, consisting of attenuation of protein synthesis and gene expression reprogramming. However, the former is surprisingly atypical and occurs to a similar magnitude in wild-type cells, cells lacking GCN2 and those incapable of phosphorylating eIF2α. Proline supplementation rescues the observed HF-induced changes indicating that they result from inhibition of EPRS. The failure of the GCN2-to-eIF2α pathway to elicit a measurable protective attenuation of translation initiation allows translation elongation defects to prevail upon HF treatment. Exploiting this vulnerability of the ISR, we show that cancer cells with increased proline dependency are more sensitive to halofuginone. This work reveals that the consequences of EPRS inhibition are more complex than anticipated and provides novel insights into ISR signaling, as well as a molecular framework to guide the targeted development of halofuginone as a therapeutic.

| S-EPMC9156968 | biostudies-literature

Targeting the Integrated Stress Response Kinase GCN2 to Modulate Retroviral Integration.

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Reovirus induces and benefits from an integrated cellular stress response.

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Integrated stress response modulates cellular redox state via induction of cystathionine ?-lyase: cross-talk between integrated stress response and thiol metabolism.

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| S-EPMC3293561 | biostudies-literature

Signaling through alternative Integrated Stress Response pathways compensates for GCN2 loss in a mouse model of soft tissue sarcoma.

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| S-EPMC9449593 | biostudies-literature

Integrated single-cell transcriptomics and proteomics reveal cellular-specific responses and microenvironment remodeling in aristolochic acid nephropathy.

Project description:Aristolochic acid nephropathy (AAN) is characterized by acute proximal tubule necrosis and immune cell infiltration, contributing to the global burden of chronic kidney disease and urothelial cancer. Although the proximal tubule has been defined as the primary target of aristolochic acids I (AAI), the mechanistic underpinning of gross renal deterioration caused by AAI has not been explicitly explained, prohibiting effective therapeutic intervention. To this point, we employed integrated single-cell RNA-Seq, bulk RNA-Seq, and mass spectrometry-based proteomics to analyze the mouse kidney after acute AAI exposure. Our results reveal a dramatic reduction of proximal tubule epithelial cells, associated with apoptotic and inflammatory pathways, indicating permanent damage beyond repair. We found the enriched development pathways in other nephron segments, suggesting activation of reparative programs triggered by AAI. The divergent response may be attributed to the segment-specific distribution of organic anion channels along the nephron, including OAT1 and OAT3. Moreover, we observed dramatic activation and recruitment of cytotoxic T and macrophage M1 cells, highlighting inflammation as a principal contributor to permanent renal injury. Ligand-receptor pairing revealed that critical intercellular crosstalk underpins damage-induced activation of immune cells. These results provide potentially novel insight into the AAI-induced kidney injury and point out possible pathways for future therapeutic intervention.

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Integrated transcriptome and small RNA sequencing analyses reveal a drought stress response network in Sophora tonkinensis.

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| S-EPMC8641164 | biostudies-literature

Integrated stress response

Project description:Comparison of genes induced during activation of the Integrated Stress Response by tunicamycin or following AP20187 induced dimerization of a Fv2E-PERK chimera in wildtype cells and cells carrying mutations in key ISR signaling molecules. Keywords: other

2003-10-07 | GSE700 | GEO

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