Advanced search
1 file | 10.91 MB

Unraveling TNF-induced necrotic signaling pathways using RNA interference and live-cell imaging

(2011)
Author
Promoter
(UGent) and (UGent)
Organization
Abstract
The mouse fibrosarcoma cell line L929 die by RIP1- and RIP3-dependent necrosis or necroptosis upon TNF stimulation. In our study we have gained insight in the mechanisms regulating TNF-induced necroptosis First, we have found by live-cell imaging that necrosis induced by TNF or H2O2 and secondary necrosis following anti-Fas-induced apoptosis, share a cellular disintegration phase that is characterized by a similar sequence of subcellular events, including mitochondrial membrane hyperpolarization, lysosomal membrane permeabilization, oxidative burst and loss of plasma membrane integrity, albeit with different kinetics. Secondly, in an unbiased approach using a retroviral RNAi kinome library we have identified five novel kinases that modulate necroptotic cell death initiated by TNF. Interestingly, one of these five candidates is not only required for TNF-induced necroptosis but also for necrotic cell death triggered by dsRNA/IFNβ. Finally, using a hypothesis-driven RNAi approach, we have revealed that cIAP1 and A20, proteins involved in RIP1 ubiquitination, and LUBAC, known to stabilize TNFR1 complex I, protect L929 cells from TNF-induced necroptosis. We have also confirmed that the deubiquitinating enzyme CYLD is needed for the induction of necroptotic cell death by TNF. Furthermore, we have found that TAK1 negatively regulates TNF-mediated necroptosis. RNAi-mediated targeting of TNFR1 complex II proteins has demonstrated that the pro-apoptotic proteins caspase-8, FADD and c-FLIP counteract necroptosis initiated by TNF. Interestingly, we have also observed that knockdown of RIP1 induces a switch from TRADD-independent necroptosis to TRADD-dependent apoptosis. Even more, the deletion of both RIP1 and caspase-8 has revealed that TNF-induced necroptosis can occur in absence of RIP1 and relies in this case completely on RIP3. Together, our hypothesis-driven RNAi data show that: (i) proteins involved in ubiquitination are important regulators of TNF-induced necroptosis; (ii) TNF-induced apoptosis and necroptosis share regulatory components and mechanisms; (iii) apoptotic proteins counteract TNF-induced necroptosis and; (iv) RIP1 determines the type of cell death.
Keywords
TNF, necrosis, L929, RIP kinases

Downloads

  • (...).pdf
    • full text
    • |
    • UGent only
    • |
    • PDF
    • |
    • 10.91 MB

Citation

Please use this url to cite or link to this publication:

Chicago
Vanlangenakker, Nele. 2011. “Unraveling TNF-induced Necrotic Signaling Pathways Using RNA Interference and Live-cell Imaging”. Ghent, Belgium: Ghent University. Faculty of Sciences.
APA
Vanlangenakker, N. (2011). Unraveling TNF-induced necrotic signaling pathways using RNA interference and live-cell imaging. Ghent University. Faculty of Sciences, Ghent, Belgium.
Vancouver
1.
Vanlangenakker N. Unraveling TNF-induced necrotic signaling pathways using RNA interference and live-cell imaging. [Ghent, Belgium]: Ghent University. Faculty of Sciences; 2011.
MLA
Vanlangenakker, Nele. “Unraveling TNF-induced Necrotic Signaling Pathways Using RNA Interference and Live-cell Imaging.” 2011 : n. pag. Print.
@phdthesis{1852225,
  abstract     = {The mouse fibrosarcoma cell line L929 die by RIP1- and RIP3-dependent necrosis or necroptosis upon TNF stimulation. In our study we have gained insight in the mechanisms regulating TNF-induced necroptosis First, we have found by live-cell imaging that necrosis induced by TNF or H2O2 and secondary necrosis following anti-Fas-induced apoptosis, share a cellular disintegration phase that is characterized by a similar sequence of subcellular events, including mitochondrial membrane hyperpolarization, lysosomal membrane permeabilization, oxidative burst and loss of plasma membrane integrity, albeit with different kinetics. Secondly, in an unbiased approach using a retroviral RNAi kinome library we have identified five novel kinases that modulate necroptotic cell death initiated by TNF. Interestingly, one of these five candidates is not only required for TNF-induced necroptosis but also for necrotic cell death triggered by dsRNA/IFN\ensuremath{\beta}. Finally, using a hypothesis-driven RNAi approach, we have revealed that cIAP1 and A20, proteins involved in RIP1 ubiquitination, and LUBAC, known to stabilize TNFR1 complex I, protect L929 cells from TNF-induced necroptosis. We have also confirmed that the deubiquitinating enzyme CYLD is needed for the induction of necroptotic cell death by TNF. Furthermore, we have found that TAK1 negatively regulates TNF-mediated necroptosis. RNAi-mediated targeting of TNFR1 complex II proteins has demonstrated that the pro-apoptotic proteins caspase-8, FADD and c-FLIP counteract necroptosis initiated by TNF. Interestingly, we have also observed that knockdown of RIP1 induces a switch from TRADD-independent necroptosis to TRADD-dependent apoptosis. Even more, the deletion of both RIP1 and caspase-8 has revealed that TNF-induced necroptosis can occur in absence of RIP1 and relies in this case completely on RIP3. Together, our hypothesis-driven RNAi data show that: (i) proteins involved in ubiquitination are important regulators of TNF-induced necroptosis; (ii) TNF-induced apoptosis and necroptosis share regulatory components and mechanisms; (iii) apoptotic proteins counteract TNF-induced necroptosis and; (iv) RIP1 determines the type of cell death.},
  author       = {Vanlangenakker, Nele},
  language     = {eng},
  pages        = {221},
  publisher    = {Ghent University. Faculty of Sciences},
  school       = {Ghent University},
  title        = {Unraveling TNF-induced necrotic signaling pathways using RNA interference and live-cell imaging},
  year         = {2011},
}