Dataset Information

Halofuginone, a tRNA-synthetase inhibitor, decreases bulk protein synthesis independently of the integrated stress response

ABSTRACT: The integrated stress response (ISR), a vital homeostatic pathway, is an emerging therapeutic target for a broad range of clinical indications. Halofuginone (HF) is a phase 2 clinical compound that induces the ISR by inhibiting the glutamyl-prolyl-tRNA synthetase (EPRS). Here we report that although HF induces the predicted canonical ISR adaptations consisting of attenuation of protein synthesis and gene expression reprogramming, the former surprisingly occurs independently of GCN2 and eIF2 phosphorylation. Proline supplementation rescues the observed HF-induced changes indicating that they result from an on-target effect due to inhibition of EPRS. We find that attenuation of translation initiation through GCN2-to-eIF2 signaling is not robust enough to prevent translation elongation defects caused by HF. Exploiting this vulnerability, we show that cancer cells presenting an increased proline dependency are sensitized to HF. This work provides novel insights on ISR signaling and a molecular framework to guide the targeted development of HF.

INSTRUMENT(S): Q Exactive

ORGANISM(S): Homo Sapiens (human) Mus Musculus (mouse)

TISSUE(S): Cell Culture

SUBMITTER: Sew Peak-Chew

LAB HEAD: Anne Bertolotti

PROVIDER: PXD028744 | Pride | 2022-04-27

REPOSITORIES: Pride

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Publications

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

Pitera Aleksandra P AP Szaruga Maria M Peak-Chew Sew-Yeu SY Wingett Steven W SW Bertolotti Anne A

The EMBO journal 20220425 11

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. Pr ...[more]

PMID: 35466425

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Project description:In eukaryotes, regulation of mRNA translation enables a fast, localized and finely tuned expression of gene products. Within the translation process, the first stage of translation initiation is most rigorously modulated by the actions of eukaryotic initiation factors (eIFs) and their associated proteins. These 11 eIFs catalyze the joining of the tRNA, mRNA and rRNA into a functional translation complex. Their activity is influenced by a wide variety of extra- and intracellular signals, ranging from global, such as hormone signaling and unfolded proteins, to specific, such as single amino acid imbalance and iron deficiency. Their action is correspondingly comprehensive, in increasing or decreasing recruitment and translation of most cellular mRNAs, and specialized, in targeting translation of mRNAs with regulatory features such as a 5’ terminal oligopyrimidine tract (TOP), upstream open reading frames (uORFs), or an internal ribosomal entry site (IRES). In mammals, two major pathways are linked to targeted mRNA translation. The target of rapamycin (TOR) kinase induces translation of TOP and perhaps other subsets of mRNAs, whereas a family of eIF2 kinases does so with mRNAs containing uORFs or an IRES. TOR targets translation of mRNAs that code for proteins involved in translation, an action compatible with its widely accepted role in regulating cellular growth. The four members of the eIF2 kinase family increase translation of mRNAs coding for stress response proteins such as transcription factors and chaperones. Though all four kinases act on one main substrate, eIF2, published literature demonstrates both common and unique effects by each kinase in response to its specific activating stress. This suggests that the activated eIF2 kinases regulate the translation of both a global and a specific set of mRNAs. Up to now, few studies have attempted to test such a hypothesis; none has been done in mammals. We use array analysis to determine the global mRNA shift into polysomes following a stress response, and to compare the translational response following activation of GCN2 versus PERK, two of the four eIF2alpha kinases. Experiment Overall Design: Gcn2 wild-type or knockout mouse liver were perfused with complete amino acids media or media lacking methionine for RNA extraction and hybridization of Affymetrix microarrays. RNA was extracted from unfractionated liver samples and polysome fraction of samples separated on sucrose density gradient. To minimize biological variations, we pooled RNA from two perfused liver samples to use in each array analysis. The conditions were total and polysome fraction of Gcn2+/+, +Met or -Met; total and polysome fraction of Gcn2-/-, +Met or -Met. Each array analysis was done in duplicate.

Dataset Information

Halofuginone, a tRNA-synthetase inhibitor, decreases bulk protein synthesis independently of the integrated stress response

Publications

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

Similar Datasets

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