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The E3 ligase TRAF6 regulates Akt ubiquitination and activation.

ABSTRACT: Akt signaling plays a central role in many biological functions, such as cell proliferation and apoptosis. Because Akt (also known as protein kinase B) resides primarily in the cytosol, it is not known how these signaling molecules are recruited to the plasma membrane and subsequently activated by growth factor stimuli. We found that the protein kinase Akt undergoes lysine-63 chain ubiquitination, which is important for Akt membrane localization and phosphorylation. TRAF6 was found to be a direct E3 ligase for Akt and was essential for Akt ubiquitination, membrane recruitment, and phosphorylation upon growth-factor stimulation. The human cancer-associated Akt mutant displayed an increase in Akt ubiquitination, in turn contributing to the enhancement of Akt membrane localization and phosphorylation. Thus, Akt ubiquitination is an important step for oncogenic Akt activation.

SUBMITTER: Yang WL

PROVIDER: S-EPMC3008763 | biostudies-literature | 2009 Aug

REPOSITORIES: biostudies-literature

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The E3 ligase TRAF6 regulates Akt ubiquitination and activation.

Yang Wei-Lei WL Wang Jing J Chan Chia-Hsin CH Lee Szu-Wei SW Campos Alejandro D AD Lamothe Betty B Hur Lana L Grabiner Brian C BC Lin Xin X Darnay Bryant G BG Lin Hui-Kuan HK

Science (New York, N.Y.) 20090801 5944

Akt signaling plays a central role in many biological functions, such as cell proliferation and apoptosis. Because Akt (also known as protein kinase B) resides primarily in the cytosol, it is not known how these signaling molecules are recruited to the plasma membrane and subsequently activated by growth factor stimuli. We found that the protein kinase Akt undergoes lysine-63 chain ubiquitination, which is important for Akt membrane localization and phosphorylation. TRAF6 was found to be a direc ...[more]

PMID: 19713527

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E3 ubiquitin ligase NEDD4L negatively regulates inflammation by promoting ubiquitination of MEKK2

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Site-specific ubiquitination of the E3 ligase HOIP regulates apoptosis and immune signaling

Project description:HOIP, the catalytic component of the Linear Ubiquitin chain Assembly Complex (LUBAC), is a critical regulator of inflammation. However, how HOIP itself is regulated to control inflammatory responses is unclear. Here, we discover that site-specific ubiquitination of K784 within human HOIP promotes Tumor Necrosis Factor (TNF)-induced inflammatory signaling. A HOIP K784R mutant is catalytically active but shows reduced induction of an NF-?B reporter relative to wild type HOIP. HOIP K784 is evolutionarily conserved, equivalent to HOIP K778 in mice. We generated HoipK778R/K778R knock in mice, which show no overt developmental phenotypes; however, in response to TNF, HoipK778R/K778R mouse embryonic fibroblasts display mildly suppressed NF-?B activation and increased apoptotic markers. On the other hand, HOIP K778R enhances the TNF-induced formation of TNFR complex II, and an interaction between TNFR complex II and LUBAC. Loss of the LUBAC component SHARPIN leads to embryonic lethality in HoipK778R/K778R mice, which is rescued by knockout of TNFR1. We propose that site-specific ubiquitination of HOIP regulates a LUBAC-dependent switch between survival and apoptosis in TNF-signaling.

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