scholarly journals tRNA biogenesis and specific aminoacyl-tRNA synthetases regulate senescence stability under the control of mTOR

PLoS Genetics ◽  
2021 ◽  
Vol 17 (12) ◽  
pp. e1009953
Author(s):  
Jordan Guillon ◽  
Hugo Coquelet ◽  
Géraldine Leman ◽  
Bertrand Toutain ◽  
Coralie Petit ◽  
...  
Keyword(s):  
Cancer Progression ◽  
Target Genes ◽  
Chemotherapy Resistance ◽  
Experimental Models ◽  
Mtor Inhibition ◽  
Trna Synthetases ◽  
Aminoacyl Trna Synthetases ◽  
Complete Cell ◽  
The Stability ◽  
Pol Iii

Oncogenes or chemotherapy treatments trigger the induction of suppressive pathways such as apoptosis or senescence. Senescence was initially defined as a definitive arrest of cell proliferation but recent results have shown that this mechanism is also associated with cancer progression and chemotherapy resistance. Senescence is therefore much more heterogeneous than initially thought. How this response varies is not really understood, it has been proposed that its outcome relies on the secretome of senescent cells and on the maintenance of their epigenetic marks. Using experimental models of senescence escape, we now described that the stability of this proliferative arrest relies on specific tRNAs and aminoacyl-tRNA synthetases. Following chemotherapy treatment, the DNA binding of the type III RNA polymerase was reduced to prevent tRNA transcription and induce a complete cell cycle arrest. By contrast, during senescence escape, specific tRNAs such as tRNA-Leu-CAA and tRNA-Tyr-GTA were up-regulated. Reducing tRNA transcription appears necessary to control the strength of senescence since RNA pol III inhibition through BRF1 depletion maintained senescence and blocked the generation of escaping cells. mTOR inhibition also prevented chemotherapy-induced senescence escape in association with a reduction of tRNA-Leu-CAA and tRNA-Tyr-GTA expression. Further confirming the role of the tRNA-Leu-CAA and tRNA-Tyr-GTA, results showed that their corresponding tRNA ligases, LARS and YARS, were necessary for senescence escape. This effect was specific since the CARS ligase had no effect on persistence. By contrast, the down-regulation of LARS and YARS reduced the emergence of persistent cells and this was associated with the modulation of E2F1 target genes expression. Overall, these findings highlight a new regulation of tRNA biology during senescence and suggest that specific tRNAs and ligases contribute to the strength and heterogeneity of this tumor suppressive pathway.

scholarly journals tRNA biogenesis and specific Aminoacyl-tRNA Synthetases regulate senescence stability under the control of mTOR

2020 ◽  
Author(s):  
Jordan Guillon ◽  
Bertrand Toutain ◽  
Alice Boissard ◽  
Catherine Guette ◽  
Olivier Coqueret
Keyword(s):  
Rna Polymerase ◽  
Cancer Progression ◽  
Chemotherapy Resistance ◽  
Experimental Models ◽  
Trna Synthetases ◽  
Aminoacyl Trna Synthetases ◽  
Abnormal Cells ◽  
Secretory Phenotype ◽  
The Stability ◽  
Pol Iii

ABSTRACTSenescence normally prevents the propagation of abnormal cells but is also associated with cancer progression and chemotherapy resistance. These contradictory effects are related to the stability of epigenetic marks and to the senescence-associated secretory phenotype (SASP). The SASP reinforces the proliferative arrest but also induces tumor growth and inflammation during aging. Senescence is therefore much more heterogeneous than initially thought. How this response varies is not really understood.Using experimental models of senescence escape, we now described that the deregulation of tRNA biogenesis affects the stability of this suppression, leading to chemotherapy resistance. Proteomic analyses showed that several aminoacyl-tRNA synthetases were down-regulated in senescent cells. tRNA transcription was also inhibited as a consequence of a reduced DNA binding of the type III RNA polymerase. Reducing RNA Pol III activity by BRF1 depletion maintained senescence and blocked cell persistence. Results showed that the YARS1 and LARS1 aminoacyl-tRNA synthetases were necessary for cell emergence and that their corresponding tRNA-Leu-CAA and tRNA-Tyr-GTA were up-regulated in persistent cells. On the contrary, the CARS1 ligase had no effect on persistence and the expression of the corresponding tRNA-Cys was not modified. Results also showed that these tRNAs were regulated by mTOR and that this abnormal tRNA biogenesis induced an ER stress which was resolved by the kinase during chemotherapy escape.Overall, these findings highlight a new regulation of tRNA biology during senescence and suggest that specific tRNAs and ligases contribute to the strength and heterogeneity of this suppression and to chemotherapy resistance.

Calcineurin regulates the stability and activity of estrogen receptor α

2021 ◽  
Vol 118 (44) ◽  
pp. e2114258118
Author(s):  
Takahiro Masaki ◽  
Makoto Habara ◽  
Yuki Sato ◽  
Takahiro Goshima ◽  
Keisuke Maeda ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Estrogen Receptor ◽  
Cancer Cells ◽  
Cancer Progression ◽  
Breast Cancer Cells ◽  
Molecular Mechanisms ◽  
Target Genes ◽  
Estrogen Receptor Α ◽  
The Stability ◽  
Positive Breast Cancer

Estrogen receptor α (ER-α) mediates estrogen-dependent cancer progression and is expressed in most breast cancer cells. However, the molecular mechanisms underlying the regulation of the cellular abundance and activity of ER-α remain unclear. We here show that the protein phosphatase calcineurin regulates both ER-α stability and activity in human breast cancer cells. Calcineurin depletion or inhibition down-regulated the abundance of ER-α by promoting its polyubiquitination and degradation. Calcineurin inhibition also promoted the binding of ER-α to the E3 ubiquitin ligase E6AP, and calcineurin mediated the dephosphorylation of ER-α at Ser294 in vitro. Moreover, the ER-α (S294A) mutant was more stable and activated the expression of ER-α target genes to a greater extent compared with the wild-type protein, whereas the extents of its interaction with E6AP and polyubiquitination were attenuated. These results suggest that the phosphorylation of ER-α at Ser294 promotes its binding to E6AP and consequent degradation. Calcineurin was also found to be required for the phosphorylation of ER-α at Ser118 by mechanistic target of rapamycin complex 1 and the consequent activation of ER-α in response to β-estradiol treatment. Our study thus indicates that calcineurin controls both the stability and activity of ER-α by regulating its phosphorylation at Ser294 and Ser118. Finally, the expression of the calcineurin A–α gene (PPP3CA) was associated with poor prognosis in ER-α–positive breast cancer patients treated with tamoxifen or other endocrine therapeutic agents. Calcineurin is thus a promising target for the development of therapies for ER-α–positive breast cancer.

Aminoacyl-tRNA synthetases of Halobacterium cutirubrum: preliminary fractionation studies

1970 ◽  
Vol 48 (8) ◽  
pp. 944-946 ◽  
Author(s):  
E. Griffiths
Keyword(s):  
Ionic Strength ◽  
Gel Filtration ◽  
Halophilic Bacterium ◽  
Trna Synthetase ◽  
Partial Purification ◽  
Trna Synthetases ◽  
Aminoacyl Trna Synthetases ◽  
Fractionation Procedure ◽  
The Stability ◽  
Low Ionic Strength

The stability, in solutions of low ionic strength, of aminoacyl-tRNA synthetases from the extremely halophilic bacterium Halobacterium cutirubrum was studied as a preliminary to their fractionation. The enzymes differed considerably in their sensitivity to such solutions. Conditions were found where reactivation from the salt-free and inactive state could be achieved. Removal of both K+ and Mg2+ together generally resulted in better stability than the removal of K+ alone. A low temperature (4°) was also important for stability in buffers of low ionic strength. In some cases the L-amino acid substrates afforded protection against inactivation in the salt-free state. Gel filtration in low ionic strength medium was found to work well as a fractionation procedure; a partial purification of phenylalanyl-tRNA synthetase was effected in this way. The use of other conventional protein fractionation procedures is now possible.

scholarly journals Interspecies analysis of MYC targets identifies tRNA synthetases as mediators of growth and survival in MYC-overexpressing cells

2019 ◽  
Vol 116 (29) ◽  
pp. 14614-14619 ◽  
Author(s):  
Jonathan Zirin ◽  
Xiaochun Ni ◽  
Laura M. Sack ◽  
Donghui Yang-Zhou ◽  
Yanhui Hu ◽  
...  
Keyword(s):  
General Principle ◽  
Target Genes ◽  
Growth Control ◽  
Protein Homeostasis ◽  
Growth And Survival ◽  
Trna Synthetases ◽  
Myc Oncogene ◽  
Aminoacyl Trna Synthetases ◽  
Oncogene Activation ◽  
Pharmacologic Inhibition

Aberrant MYC oncogene activation is one of the most prevalent characteristics of cancer. By overlapping datasets of Drosophila genes that are insulin-responsive and also regulate nucleolus size, we enriched for Myc target genes required for cellular biosynthesis. Among these, we identified the aminoacyl tRNA synthetases (aaRSs) as essential mediators of Myc growth control in Drosophila and found that their pharmacologic inhibition is sufficient to kill MYC-overexpressing human cells, indicating that aaRS inhibitors might be used to selectively target MYC-driven cancers. We suggest a general principle in which oncogenic increases in cellular biosynthesis sensitize cells to disruption of protein homeostasis.

Role of MicroRNAs in Colon Cancer Progression and Metastasis

2020 ◽  
Vol 20 ◽  
Author(s):  
Shruthi Sanjitha Sampath ◽  
Sivaramakrishnan Venkatabalsubramanian ◽  
Satish Ramalingam
Keyword(s):  
Colon Cancer ◽  
Cancer Progression ◽  
Target Genes ◽  
Tumour Progression ◽  
Intestinal Barrier ◽  
Colon Cancer Progression ◽  
Bowel Diseases ◽  
Inflammatory Bowel ◽  
Novel Therapeutic Strategies

: MicroRNAs regulate gene expression at the posttranscriptional level by binding to the mRNA of their target genes. The dysfunction of miRNAs is strongly associated with the inflammation of the colon. Besides, some microRNAs are shown to suppress tumours while others promote tumour progression and metastasis. Inflammatory bowel diseases include Crohn’s disease and Ulcerative colitis which increase the risk factor for inflammation-associated colon cancer. MicroRNAs are shown to be involved in gastrointestinal pathologies, by targeting the transcripts encoding proteins of the intestinal barrier and their regulators that are associated with inflammation and colon cancer. Detection of these microRNAs in the blood, serum, tissues, faecal matter, etc will enable us to use these microRNAs as biomarkers for early detection of the associated malignancies and design novel therapeutic strategies to overcome the same. Information on MicroRNAs can be applied for the development of targeted therapies against inflammation-mediated colon cancer.

scholarly journals Mutated p53 in HGSC—From a Common Mutation to a Target for Therapy

Cancers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 3465
Author(s):  
Aya Saleh ◽  
Ruth Perets
Keyword(s):  
Cancer Progression ◽  
Target Genes ◽  
P53 Protein ◽  
Genetic Alterations ◽  
Common Mutation ◽  
Missense Mutations ◽  
P53 Expression ◽  
Histologic Subtype ◽  
Tp53 Mutations

Mutations in tumor suppressor gene TP53, encoding for the p53 protein, are the most ubiquitous genetic variation in human ovarian HGSC, the most prevalent and lethal histologic subtype of epithelial ovarian cancer (EOC). The majority of TP53 mutations are missense mutations, leading to loss of tumor suppressive function of p53 and gain of new oncogenic functions. This review presents the clinical relevance of TP53 mutations in HGSC, elaborating on several recently identified upstream regulators of mutant p53 that control its expression and downstream target genes that mediate its roles in the disease. TP53 mutations are the earliest genetic alterations during HGSC pathogenesis, and we summarize current information related to p53 function in the pathogenesis of HGSC. The role of p53 is cell autonomous, and in the interaction between cancer cells and its microenvironment. We discuss the reduction in p53 expression levels in tumor associated fibroblasts that promotes cancer progression, and the role of mutated p53 in the interaction between the tumor and its microenvironment. Lastly, we discuss the potential of TP53 mutations to serve as diagnostic biomarkers and detail some more advanced efforts to use mutated p53 as a therapeutic target in HGSC.

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