Akt phosphorylates insulin receptor substrate to limit PI3K-mediated PIP3 synthesis
| Autor: | Sean J. Humphrey, James G. Burchfield, Milad Ghomlaghi, David E. James, Kristen C. Cooke, Thomas A Geddes, Luke Carroll, Guang Yang, Pengyi Yang, Lan K. Nguyen, Sung-Young Shin, Daniel J. Fazakerley, Dougall M. Norris, Martin Kin Lok Wong, Alison L Kearney |
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| Přispěvatelé: | Kearney, Alison L [0000-0002-5736-3393], Ghomlaghi, Milad [0000-0001-9047-1049], Nguyen, Lan K [0000-0003-4040-7705], James, David E [0000-0001-5946-5257], Burchfield, James G [0000-0002-6609-6151], Apollo - University of Cambridge Repository, Humphrey, Sean J [0000-0002-2666-9744], Fazakerley, Daniel [0000-0001-8241-2903] |
| Rok vydání: | 2021 |
| Předmět: |
0301 basic medicine
Mouse medicine.medical_treatment plasma membrane PI3K Mice Phosphatidylinositol 3-Kinases computational biology 0302 clinical medicine Insulin receptor substrate Biology (General) biology Chemistry phosphorylation General Neuroscience systems biology General Medicine Cell biology 030220 oncology & carcinogenesis Medicine Signal transduction signal transduction Research Article Computational and Systems Biology Human Cell signaling insulin QH301-705.5 Science Mechanistic Target of Rapamycin Complex 1 General Biochemistry Genetics and Molecular Biology 03 medical and health sciences Antigens CD Negative feedback medicine Animals Humans Protein kinase B PI3K/AKT/mTOR pathway General Immunology and Microbiology Insulin Akt Cell Membrane Cell Biology Receptor Insulin Insulin receptor Glucose 030104 developmental biology Insulin Receptor Substrate Proteins biology.protein Phosphatidylinositol 3-Kinase Proto-Oncogene Proteins c-akt |
| Zdroj: | eLife, Vol 10 (2021) eLife |
| Popis: | The phosphoinositide 3-kinase (PI3K)-Akt network is tightly controlled by feedback mechanisms that regulate signal flow and ensure signal fidelity. A rapid overshoot in insulin-stimulated recruitment of Akt to the plasma membrane has previously been reported, which is indicative of negative feedback operating on acute timescales. Here, we show that Akt itself engages this negative feedback by phosphorylating insulin receptor substrate (IRS) 1 and 2 on a number of residues. Phosphorylation results in the depletion of plasma membrane-localised IRS1/2, reducing the pool available for interaction with the insulin receptor. Together these events limit plasma membrane-associated PI3K and phosphatidylinositol (3,4,5)-trisphosphate (PIP3) synthesis. We identified two Akt-dependent phosphorylation sites in IRS2 at S306 (S303 in mouse) and S577 (S573 in mouse) that are key drivers of this negative feedback. These findings establish a novel mechanism by which the kinase Akt acutely controls PIP3 abundance, through post-translational modification of the IRS scaffold. eLife digest For the body to work properly, cells must constantly ‘talk’ to each other using signalling molecules. Receiving a chemical signal triggers a series of molecular events in a cell, a so-called ‘signal transduction pathway’ that connects a signal with a precise outcome. Disturbing cell signalling can trigger disease, and strict control mechanisms are therefore in place to ensure that communication does not break down or become erratic. For instance, just as a thermostat turns off the heater once the right temperature is reached, negative feedback mechanisms in cells switch off signal transduction pathways when the desired outcome has been achieved. The hormone insulin is a signal for growth that increases in the body following a meal to promote the storage of excess blood glucose (sugar) in muscle and fat cells. The hormone binds to insulin receptors at the cell surface and switches on a signal transduction pathway that makes the cell take up glucose from the bloodstream. If the signal is not engaged diseases such as diabetes develop. Conversely, if the signal cannot be adequately switched of cancer can develop. Determining exactly how insulin works would help to understand these diseases better and to develop new treatments. Kearney et al. therefore set out to examine the biochemical ‘fail-safes’ that control insulin signalling. Experiments using computer simulations of the insulin signalling pathway revealed a potential new mechanism for negative feedback, which centred on a molecule known as Akt. The models predicted that if the negative feedback were removed, then Akt would become hyperactive and accumulate at the cell’s surface after stimulation with insulin. Further manipulation of the ‘virtual’ insulin signalling pathway and studies of live cells in culture confirmed that this was indeed the case. The cell biology experiments also showed how Akt, once at the cell surface, was able to engage the negative feedback and shut down further insulin signalling. Akt did this by inactivating a protein required to pass the signal from the insulin receptor to the rest of the cell. Overall, this work helps to understand cell communication by revealing a previously unknown, and critical component of the insulin signalling pathway. |
| Databáze: | OpenAIRE |
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