PMID:23083102

Citation	Wang, F, Jiang, Z, Li, Y, He, X, Zhao, J, Yang, X, Zhu, L, Yin, Z, Li, X, Wang, X, Liu, W, Shang, W, Yang, Z, Wang, S, Zhen, Q, Zhang, Z, Yu, Y, Zhong, H, Ye, Q, Huang, L and Yuan, J (2013) Shigella flexneri T3SS effector IpaH4.5 modulates the host inflammatory response via interaction with NF-κB p65 protein. Cell. Microbiol. 15:474-85
Abstract	Shigella species possess a type III secretion system (T3SS), which is required for human infection and that delivers effector proteins into target host cells. Here, we show that the effector, IpaH4.5 dampens the pro-inflammatory cytokine response. In both the Sereny test and a murine lung infection model, the Shigella ΔipaH4.5 mutant strain caused more severe inflammatory responses and significantly induced higher pro-inflammatory cytokine levels (MIP-2 and TNF-α) in the lung homogenates of wild type-infected mice. Moreover, there was a threefold decrease in bacterial colonization of the mutant compared with the WT and ΔipaH4.5/ipaH4.5-rescued strains. Yeast two-hybrid screening showed that IpaH4.5 specifically interacts with the p65 subunit of NF-κB. Ten truncated versions of IpaH4.5 and p65 spanning different regions were constructed and expressed to further map the IpaH binding sites with p65. The results revealed thatthe p65 region spanning amino acids 1-190 of p65 interacted with the IpaH4.5/1-293 N-terminal region. In vitro, IpaH4.5 displayed ubiquitin ligase activity towards ubiquitin and p65. Furthermore, the transcriptional activity of NF-κB was shown to be inhibited by IpaH4.5 utilizing a dual-luciferase reporter gene detection system containing NF-κB promoter response elements. Thus, we conclude that the IpaH4.5 protein is an E3 ubiquitin ligase capable of directly regulating the host inflammatory response by inhibiting the NF-κB signalling pathway.
Links	PubMed Online version:10.1111/cmi.12052
Keywords	Animals; Antigens, Bacterial/genetics; Antigens, Bacterial/immunology; Antigens, Bacterial/metabolism; Bacterial Proteins/genetics; Bacterial Proteins/immunology; Bacterial Proteins/metabolism; Cell Line; DNA Mutational Analysis; Disease Models, Animal; Dysentery, Bacillary/microbiology; Dysentery, Bacillary/pathology; Guinea Pigs; Host-Pathogen Interactions; Humans; Immune Evasion; Keratitis/microbiology; Keratitis/pathology; Mice; Pneumonia, Bacterial/microbiology; Pneumonia, Bacterial/pathology; Protein Binding; Protein Interaction Mapping; Shigella flexneri/genetics; Shigella flexneri/immunology; Shigella flexneri/pathogenicity; Transcription Factor RelA/antagonists & inhibitors; Transcription Factor RelA/immunology; Transcription Factor RelA/metabolism; Two-Hybrid System Techniques; Virulence Factors/genetics; Virulence Factors/immunology; Virulence Factors/metabolism
edit table

Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
SHIFL:IPA4		GO:0044074: negative regulation by symbiont of host translation	ECO:0000314:		P		organism: Shigella flexneri Fig 5A shows that cells with IPA4 had less transcriptional activity of NF-κB. "IpaH4.5 inhibits the transcriptional activity of NF-κB. "	complete CACAO 12965
SHIFL:IPA4		GO:0051865: protein autoubiquitination	ECO:0000314:		P		Shigella flexneri The author concludes from figure 4A that IPA4 can autoubiquitinate from a western blot "Thus, IpaH4.5 exhibited the ability to (i) autoubiquitinate and (ii) polyubiquitinate HA-tagged ubiquitin (Fig. 4A... "	complete CACAO 12983
SHIFL:IPA4		GO:0000209: protein polyubiquitination	ECO:0000314:		P		Shigella flexneri Figure 4B is a western blot that shows that IPA4 is able to polyubiquitinate " Thus, IpaH4.5 exhibited the ability to (i) autoubiquitinate and (ii) polyubiquitinate HA-tagged ubiquitin (Fig. 4A and B)."	complete CACAO 12984
SHIFL:IPA4		GO:0052083: negative regulation by symbiont of host cell-mediated immune response	ECO:0000315:		P		Organism: Shigella flexneri protein: IPA4 but called IPAH4.5 in paper. Fig 2C: Wild type IPA4 shows a lower cytokine production in the host when compared to delta IPA4 and the mutated IPA4 thus showing negative regulation of cytokine secretion by the symbiont (s. flexneri). The modulation of cytokine production is proved by the mutant, which has a higher cytokine production than the wild type IPA4. Cytokine production is part of the cell mediated immune response in the host meaning that IPA4 is negatively regulating the response.	complete CACAO 13018
SHIFL:IPA9		GO:0051865: protein autoubiquitination	ECO:0000314:		P		Shigella flexneri. The protein is called IPA9 however it is referred to as IPA9.8 in the article. Figure 4A is an immunoblot assay that shows that IPA9 is able to autoubiquitinate. "...these results suggested that IpaH4.5 possess an autoubiquitination activity as well as IpaH9.8."	complete CACAO 12986

References

See Help:References for how to manage references in GONUTS.