| 1. |
- Ekman, Maria, 1979-, et al.
(författare)
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APC and Smad7 link TGF beta type I receptors to the microtubule system to promote cell migration
- 2012
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Ingår i: Molecular Biology of the Cell. - : American Society of Cell Biology, USA. - 1059-1524 .- 1939-4586. ; 23:11, s. 2109-2121
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Tidskriftsartikel (refereegranskat)abstract
- Cell migration occurs by activation of complex regulatory pathways that are spatially and temporally integrated in response to extracellular cues. Binding of adenomatous polyposis coli (APC) to the microtubule plus ends in polarized cells is regulated by glycogen synthase kinase 3 beta (GSK-3 beta). This event is crucial for establishment of cell polarity during directional migration. However, the role of APC for cellular extension in response to extracellular signals is less clear. Smad7 is a direct target gene for transforming growth factor-beta (TGF beta) and is known to inhibit various TGF beta-induced responses. Here we report a new function for Smad7. We show that Smad7 and p38 mitogen-activated protein kinase together regulate the expression of APC and cell migration in prostate cancer cells in response to TGF beta stimulation. In addition, Smad7 forms a complex with APC and acts as an adaptor protein for p38 and GSK-3 beta kinases to facilitate local TGF beta/p38-dependent inactivation of GSK-3 beta, accumulation of beta-catenin, and recruitment of APC to the microtubule plus end in the leading edge of migrating prostate cancer cells. Moreover, the Smad7-APC complex links the TGF beta type I receptor to the microtubule system to regulate directed cellular extension and migratory responses evoked by TGF beta.
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| 2. |
- Hamidi, Anahita, et al.
(författare)
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TGF-β promotes PI3K-AKT signaling and prostate cancer cell migration through the TRAF6-mediated ubiquitylation of p85α
- 2017
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Ingår i: Science Signaling. - : American Association for the Advancement of Science. - 1945-0877 .- 1937-9145. ; 10:486
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- TGF-β signaling stimulates various intracellular pathways that can promote migration in tumor cells. These pathways are generally thought to be either dependent or independent of transcription factors called SMADs. One of the SMAD-independent pathways (PI3K-AKT) is mediated by a direct interaction between PI3K and the TGF-β type I receptor. However, Hamidi et al. found that the TGF-β–induced activation of PI3K depends on another ubiquitin ligase–mediated mechanism and a SMAD protein but is independent of the kinase function of TβRI. The binding of TGF-β to its receptor triggered the recruitment of PI3K and the ubiquitin ligase TRAF6, which polyubiquitylated the regulatory PI3K subunit p85α, thus enabling phosphorylation of the catalytic PI3K subunit p110, but only in the presence of SMAD7. The abundance of ubiquitylated p85α correlated with migration in cultured cells and prostate tumor grade in patient samples. TRAF6 mediates activation of the other “SMAD-independent” (JNK) pathway. These data suggest that, although distinct, the TGF-β signaling pathways are not as insulated from each other as was once thought.
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| 6. |
- Mu, Yabing, et al.
(författare)
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TRAF6 ubiquitinates TGFβ type I receptor to promote its cleavage and nuclear translocation in cancer
- 2011
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Ingår i: Nature Communications. - London : Macmillan Publishers Limited. - 2041-1723. ; 2:330
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Tidskriftsartikel (refereegranskat)abstract
- Transforming growth factor β (TGFβ) is a pluripotent cytokine promoting epithelial cell plasticity during morphogenesis and tumour progression. TGFβ binding to type II and type I serine/threonine kinase receptors (TβRII and TβRI) causes activation of different intracellular signaling pathways. TβRI is associated with the ubiquitin ligase tumor necrosis factor receptor (TNFR)-associated factor 6 (TRAF6). Here we show that TGFβ, via TRAF6, causes Lys63-linked polyubiquitination of TβRI, promoting cleavage of TβRI by TNF-alpha converting enzyme (TACE), in a PKCζ-dependent manner. The liberated intracellular domain (ICD) of TβRI associates with the transcriptional regulator p300 to activate genes involved in tumour cell invasiveness, such as Snail and MMP2. Moreover, TGFβ-induced invasion of cancer cells is TACE- and PKCζ- dependent and the TβRI ICD is localized in the nuclei of different kinds of tumour cells in tissue sections. Thus, our data reveal a specific role for TβRI in TGFβ mediated tumour invasion.
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| 7. |
- Sorrentino, Alessandro, et al.
(författare)
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The type I TGF-beta receptor engages TRAF6 to activate TAK1 in a receptor kinase-independent manner
- 2008
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Ingår i: Nature Cell Biology. - : Springer Science and Business Media LLC. - 1465-7392 .- 1476-4679. ; 10:10, s. 1199-1207
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Tidskriftsartikel (refereegranskat)abstract
- Transforming growth factor-β (TGF-β) is a multifunctional cytokine that regulates embryonic development and tissue homeostasis; however, aberrations of its activity occur in cancer. TGF-β signals through its Type II and Type I receptors (TβRII and TβRI) causing phosphorylation of Smad proteins. TGF-β-associated kinase 1 (TAK1), a member of the mitogen-activated protein kinase kinase kinase (MAPKKK) family, was originally identified as an effector of TGF-β-induced p38 activation. However, the molecular mechanisms for its activation are unknown. Here we report that the ubiquitin ligase (E3) TRAF6 interacts with a consensus motif present in TβRI. The TβRI–TRAF6 interaction is required for TGF-β-induced autoubiquitylation of TRAF6 and subsequent activation of the TAK1–p38/JNK pathway, which leads to apoptosis. TβRI kinase activity is required for activation of the canonical Smad pathway, whereas E3 activity of TRAF6 regulates the activation of TAK1 in a receptor kinase-independent manner. Intriguingly, TGF-β-induced TRAF6-mediated Lys 63-linked polyubiquitylation of TAK1 Lys 34 correlates with TAK1 activation. Our data show that TGF-β specifically activates TAK1 through interaction of TβRI with TRAF6, whereas activation of Smad2 is not dependent on TRAF6.
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