Fluctuations in AKT and PTEN Activity Are Linked by the E3 Ubiquitin Ligase cCBL
3-Poly-phosphoinositides (PIP<sub>3</sub>) regulate cell survival, division, and migration. Both PI3-kinase (phosphoinositide-3-kinase) and PTEN (phosphatase and tensin-homolog in chromosome 10) control PIP<sub>3</sub> levels, but the mechanisms connecting PI3-kinase and PTEN...
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| Autores principales: | , , , , , , |
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| Formato: | article |
| Lenguaje: | EN |
| Publicado: |
MDPI AG
2021
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| Materias: | |
| Acceso en línea: | https://doaj.org/article/ffa2fdd3b6c6481f85c696403eaaae8b |
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| Sumario: | 3-Poly-phosphoinositides (PIP<sub>3</sub>) regulate cell survival, division, and migration. Both PI3-kinase (phosphoinositide-3-kinase) and PTEN (phosphatase and tensin-homolog in chromosome 10) control PIP<sub>3</sub> levels, but the mechanisms connecting PI3-kinase and PTEN are unknown. Using non-transformed cells, the activation kinetics of PTEN and of the PIP<sub>3</sub>-effector AKT were examined after the addition of growth factors. Both epidermal growth factor and serum induced the early activation of AKT and the simultaneous inactivation of PTEN (at ~5 min). This PIP<sub>3</sub>/AKT peak was followed by a general reduction in AKT activity coincident with the recovery of PTEN phosphatase activity (at ~10–15 min). Subsequent AKT peaks and troughs followed. The fluctuation in AKT activity was linked to that of PTEN; PTEN reconstitution in PTEN-null cells restored AKT fluctuations, while PTEN depletion in control cells abrogated them. The analysis of PTEN activity fluctuations after the addition of growth factors showed its inactivation at ~5 min to be simultaneous with its transient ubiquitination, which was regulated by the ubiquitin E3 ligase cCBL (casitas B-lineage lymphoma proto-oncogene). Protein-protein interaction analysis revealed cCBL to be brought into the proximity of PTEN in a PI3-kinase-dependent manner. These results reveal a mechanism for PI3-kinase/PTEN crosstalk and suggest that cCBL could be new target in strategies designed to modulate PTEN activity in cancer. |
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