Reprogramming translation in mammalian cells by tRNA pool modification
Lead Research Organisation:
University of Leicester
Department Name: Neuroscience, Psychology and Behaviour
Abstract
mRNA translation is a crucial stage at which gene expression is regulated in all eukaryotic organisms. Numerous cellular signalling pathways converge upon the mRNA translation machinery, and exert different modes of control resulting in the co-ordinated regulation of different sets of genes in order to maintain healthy cellular functions. These findings are based almost wholly on studies in lower eukaryotes and cell culture, but very little is known about how these mechanisms contribute to the maintenance of human tissues in situ.
This project aims to further understand how two key tRNA-related mechanisms operate in the context of human cells and tissues: signalling via eukaryotic initiation factor 2 (eIF2) and tRNA pool reprogramming.
This project aims to further understand how two key tRNA-related mechanisms operate in the context of human cells and tissues: signalling via eukaryotic initiation factor 2 (eIF2) and tRNA pool reprogramming.
People |
ORCID iD |
Studentship Projects
| Project Reference | Relationship | Related To | Start | End | Student Name |
|---|---|---|---|---|---|
| BB/R506369/1 | 01/10/2017 | 01/10/2017 | |||
| 1915133 | Studentship | BB/R506369/1 | 01/10/2017 | 24/03/2022 |
| Description | eIF2 (Eukaryotic Initiation Factor 2) is involved in the initiation of protein translation. It is composed of three subunits; alpha, beta and gamma, and following cellular stress the alpha subunit becomes phosphorylated and global translation is reduced. Phosphorylated eIF2 alpha was directly measured and quantified by immunohistochemistry (IHC) in 928 human lung adenocarcinomas. H-scores were generated using Visiopharm® software based on the intensity and proportion of cytoplasmic p-eIF2 alpha staining. Two apps were developed for analysis; a tumour detection app used the cytokeratin stain to outline tumour area and the other detected individual cells and assigned a label based on the p-eIF2 alpha staining intensity. The automated scores were validated against manual H-scoring of a TMA (tissue microarray) containing 120 tumour cores, giving a Spearman's Rho of 0.939, p < 0.001. The associations between patient survival and p-eIF2 alpha were examined using overall, cancer-specific and recurrence-free survival models. Patients were divided into two groups based on a positive/negative cut-off value. For each survival model, patients with higher expression of p-eIF2 alpha was found to have a significantly poorer outcome compared to patients with lower p-eIF2 alpha. The association between phosphorylation of eIF2 alpha and WHO tumour type, growth pattern and invasiveness were examined. p-eIF2 alpha levels were higher in all invasive patterns, compared to in situ growth, and highest in solid growth pattern. Furthermore, the associations between p-eIF2 alpha and tumour cell proliferation, using Ki67 expression, was examined at the tissue core level. A significant positive relationship was found between p-eIF2 alpha and the proportion of Ki67 expression, giving a Spearman's Rho of 0.361, p < 0.001. eIF2 is activated by eIF2B, which aids eIF2 in initiating protein translation. When eIF2 alpha subunit is phosphorylated, eIF2 binds to and inactivates eIF2B. eIF2B is composed of 5 subunits of which eIF2B alpha and eIF2B gamma were directly measured and qualified by immunofluorescence in the same lung adenocarcinoma cohort. eIF2B was found to be associated with poor outcome, invasiveness and cellular proliferation, similar to p-eIF2 alpha. However, eIF2B gamma was found to have no relationship with patient survival or hallmarks. |
| Exploitation Route | The finding that p-eIF2 alpha is associated with cellular proliferation, invasion and poor outcome is surprising considering that phosphorylation of the alpha subunit leads to a reduction in global protein translation. Therefore, further research in the role of eIF2 and its regulation in a stressed cellular environment could aid understanding of these new findings. |
| Sectors | Healthcare Pharmaceuticals and Medical Biotechnology |