Dissecting signalling by individual Akt/PKB isoforms, three steps at once
| Autor: | Cesar Osorio-Fuentealba, Amira Klip |
|---|---|
| Rok vydání: | 2015 |
| Předmět: |
Gene isoform
Adipogenesis Proto-Oncogene Proteins c-akt Adipocytes White AKT1 AKT2 FOXO1 Cell Biology Biology adipocyte Biochemistry AKT3 glucose transporter 4 (GLUT4) Akt isoform signalling MK-2206 Cancer research Animals insulin action Signal transduction Molecular Biology Protein kinase B Research Articles Signal Transduction Research Article |
| Zdroj: | Biochemical Journal |
| ISSN: | 1470-8728 0264-6021 |
| DOI: | 10.1042/bj20150750 |
| Popis: | Our study describes the development and validation of a new model system that allows for acute control of signalling by specific Akt isoforms. This model system revealed new insights into the role of Akt kinases in glucose transport and adipogenesis. Protein kinase B (Akt) kinases are critical signal transducers mediating insulin action. Genetic studies revealed that Akt1 and Akt2 signalling differentially contribute to sustain lipid and glucose homoeostasis; however Akt isoform-specific effectors remain elusive due to the lack of a suitable model system to mechanistically interrogate Akt isoform-specific signalling. To overcome those technical limitations we developed a novel model system that provides acute and specific control of signalling by Akt isoforms. We generated mutants of Akt1 and Akt2 resistant to the allosteric Akt inhibitor MK-2206. We then developed adipocyte cell lines, in which endogenous Akt1 or Akt2 has been replaced by their corresponding drug-resistant Akt mutant. Treatment of those cells with MK-2206 allowed for acute and specific control of either Akt1 or Akt2 function. Our data showed that Akt1W80A and Akt2W80A mutants are resistant to MK-2206, dynamically regulated by insulin and able to signal to Akt downstream effectors. Analyses of insulin action in this cellular system showed that Akt1 and Akt2 are both able to mediate insulin regulation of the transcription factor forkhead box O1 (FoxO1) and the glucose transporter 4 (GLUT4), revealing a redundant role for these Akt kinases in the control of glucose transport into fat cells. In contrast, Akt1 signalling is uniquely required for adipogenesis, by controlling the mitotic clonal expansion (MCE) of pre-adipocytes that precedes white adipose cell differentiation. Our data provide new insights into the role of Akt kinases in glucose transport and adipogenesis and support our model system as a valuable tool for the biochemical characterization of signalling by specific Akt isoforms. |
| Databáze: | OpenAIRE |
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