Positive and negative phosphorylation regulates RIP1- and RIP3-induced programmed necrosis
Thomas McQuade1, Youngsik Cho, Francis Ka-Ming Chan
1*Department of Pathology, University of Massachusetts Medical School, Worcester, MA 01655, U.S.A.
The Biochemical Journal
|September 25, 2013
Summary
Programmed necrosis, or necroptosis, is regulated by RIP1 and RIP3 kinases. This study reveals inhibitory phosphorylation at RIP1 Ser89 and activating phosphorylation at RIP3 Ser204, controlling necroptosis signaling.
Area of Science:
- Molecular Biology
- Cell Death Pathways
- Signal Transduction
Background:
- Programmed necrosis (necroptosis) is a regulated form of cell death.
- RIP1 and RIP3 kinases are key mediators of necroptosis.
- Phosphorylation of RIP1 and RIP3 is crucial for necrosome formation and signal transmission.
Purpose of the Study:
- To investigate the role of specific phosphorylation sites on RIP1 and RIP3 in TNF-induced necroptosis.
- To identify regulatory phosphorylation events controlling necroptosis.
Main Methods:
- Site-directed mutagenesis of RIP1 and RIP3.
- Analysis of RIP1 kinase activity.
- Assessment of TNF-induced programmed necrosis.
- Evaluation of necrosome formation.
- Use of RIP1 siRNA and necrostatin-1 inhibition.
Main Results:
- Mutation of individual serine residues in RIP1 kinase domain had minimal impact on necroptosis.
- Substitution of RIP1 Ser89 with alanine enhanced kinase activity and necroptosis, indicating an inhibitory role for Ser89 phosphorylation.
- A phosphomimetic RIP3 mutant (S204D) induced necroptosis independent of RIP1 and necrostatin-1.
- Necroptosis is regulated by both positive and negative phosphorylation events.
Conclusions:
- RIP1 Ser89 acts as an inhibitory site, dampening necroptosis.
- RIP3 phosphorylation at Ser204 can promote necroptosis.
- These findings elucidate the complex phosphorylation-dependent regulation of programmed necrosis.
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