Dataset Information

Caspase-3 cleaved p65 fragment dampens NF-?B-mediated anti-apoptotic transcription by interfering with the p65/RPS3 interaction.

ABSTRACT: Caspase-3-mediated p65 cleavage is believed to suppress nuclear factor-kappa B (NF-?B)-mediated anti-apoptotic transactivation in cells undergoing apoptosis. However, only a small percentage of p65 is cleaved during apoptosis, not in proportion to the dramatic reduction in NF-?B transactivation. Here we show that the p65(1-97) fragment generated by Caspase-3 cleavage interferes with ribosomal protein S3 (RPS3), an NF-?B "specifier" subunit, and selectively retards the nuclear translocation of RPS3, thus dampening the RPS3/NF-?B-dependent anti-apoptotic gene expression. Our findings reveal a novel cell fate determination mechanism to ensure cells undergo programed cell death through interfering with RPS3/NF-?B-conferred anti-apoptotic transcription by the fragment from partial p65 cleavage by activated Caspase-3.

SUBMITTER: Wier EM

PROVIDER: S-EPMC4655178 | biostudies-literature | 2015 Nov

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Caspase-3 cleaved p65 fragment dampens NF-κB-mediated anti-apoptotic transcription by interfering with the p65/RPS3 interaction.

Wier Eric M EM Fu Kai K Hodgson Andrea A Sun Xin X Wan Fengyi F

FEBS letters 20151023 23

Caspase-3-mediated p65 cleavage is believed to suppress nuclear factor-kappa B (NF-κB)-mediated anti-apoptotic transactivation in cells undergoing apoptosis. However, only a small percentage of p65 is cleaved during apoptosis, not in proportion to the dramatic reduction in NF-κB transactivation. Here we show that the p65(1-97) fragment generated by Caspase-3 cleavage interferes with ribosomal protein S3 (RPS3), an NF-κB "specifier" subunit, and selectively retards the nuclear translocation of RP ...[more]

PMID: 26526615

Similar Datasets

Project description:Attaching/Effacing (A/E) pathogens including enteropathogenic Escherichia coli (EPEC), enterohemorrhagic E. coli (EHEC) and the rodent equivalent Citrobacter rodentium are important causative agents of foodborne diseases. Upon infection, a myriad of virulence proteins (effectors) encoded by A/E pathogens are injected through their conserved type III secretion systems (T3SS) into host cells where they interfere with cell signaling cascades, in particular the nuclear factor kappaB (NF-?B) signaling pathway that orchestrates both innate and adaptive immune responses for host defense. Among the T3SS-secreted non-LEE-encoded (Nle) effectors, NleC, a metalloprotease, has been recently elucidated to modulate host NF-?B signaling by cleaving NF-?B Rel subunits. However, it remains elusive how NleC recognizes NF-?B Rel subunits and how the NleC-mediated cleavage impacts on host immune responses in infected cells and animals. In this study, we show that NleC specifically targets p65/RelA through an interaction with a unique N-terminal sequence in p65. NleC cleaves p65 in intestinal epithelial cells, albeit a small percentage of the molecule, to generate the p65¹?³? fragment during C. rodentium infection in cultured cells. Moreover, the NleC-mediated p65 cleavage substantially affects the expression of a subset of NF-?B target genes encoding proinflammatory cytokines/chemokines, immune cell infiltration in the colon, and tissue injury in C. rodentium-infected mice. Mechanistically, the NleC cleavage-generated p65¹?³? fragment interferes with the interaction between p65 and ribosomal protein S3 (RPS3), a 'specifier' subunit of NF-?B that confers a subset of proinflammatory gene transcription, which amplifies the effect of cleaving only a small percentage of p65 to modulate NF-?B-mediated gene expression. Thus, our results reveal a novel mechanism for A/E pathogens to specifically block NF-?B signaling and inflammatory responses by cleaving a small percentage of p65 and targeting the p65/RPS3 interaction in host cells, thus providing novel insights into the pathogenic mechanisms of foodborne diseases.

Project description:BackgroundThe NF-κB family of transcription factors and associated signalling pathways are abundant and ubiquitous in human immune responses. Activation of NF-κB transcription factors by viral pathogen-associated molecular patterns, such as viral RNA and DNA, is fundamental to anti-viral innate immune defences and pro-inflammatory cytokine production that steers adaptive immune responses. Diverse non-viral stimuli, such as lipopolysaccharide and cytokines, also activate NF-κB and the same anti-pathogen gene networks. Viruses adapted to human cells often encode multiple proteins targeting the NF-κB pathway to mitigate the anti-viral effects of NF-κB-dependent host immunity.ResultsIn this study we have demonstrated using a variety of assays, in a number of different cell types including primary cells, that plasmid-encoded or virus-delivered simian immunodeficiency virus (SIV) accessory protein Vpx is a broad antagonist of NF-κB signalling active against diverse innate NF-κB agonists. Using targeted Vpx mutagenesis, we showed that this novel Vpx phenotype is independent of known Vpx cofactor DCAF1 and other cellular binding partners, including SAMHD1, STING and the HUSH complex. We found that Vpx co-immunoprecipitated with canonical NF-κB transcription factor p65, but not NF-κB family members p50 or p100, preventing nuclear translocation of p65. We found that broad antagonism of NF-κB activation by Vpx was conserved across distantly related lentiviruses as well as for Vpr from SIV Mona monkey (SIVmon), which has Vpx-like SAMHD1-degradation activity.ConclusionsWe have discovered a novel mechanism by which lentiviruses antagonise NF-κB activation by targeting p65. These findings extend our knowledge of how lentiviruses manipulate universal regulators of immunity to avoid the anti-viral sequelae of pro-inflammatory gene expression stimulated by both viral and extra-viral agonists. Importantly our findings are also relevant to the gene therapy field where virus-like particle associated Vpx is routinely used to enhance vector transduction through antagonism of SAMHD1, and perhaps also through manipulation of NF-κB.

Dataset Information

Caspase-3 cleaved p65 fragment dampens NF-?B-mediated anti-apoptotic transcription by interfering with the p65/RPS3 interaction.

Publications

Caspase-3 cleaved p65 fragment dampens NF-κB-mediated anti-apoptotic transcription by interfering with the p65/RPS3 interaction.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets