Biomedical subjects

Danying Chen

Publications and source records attributed to Danying Chen.

11 recordsLinked to original sources

PubMed2006

The Ret finger protein inhibits signaling mediated by the noncanonical and canonical IkappaB kinase family members.

IFN regulatory factor-3 is a transcription factor that is required for the rapid induction of type I IFNs in the innate antiviral response. Two noncanonical IkappaB kinase (IKK) family members, IKKepsilon and TRAF family-associated NF-kappaB activator-binding kinase-1, have been shown to phosphorylate IFN regulatory factor-3 and are critically involved in virus-triggered and TLR3-mediated signaling leading to induction of type I IFNs. In yeast two-hybrid screens for potential IKKepsilon-interacting proteins, we identified Ret finger protein (RFP) as an IKKepsilon-interacting protein. Coimmunoprecipitation experiments indicated that RFP interacted with IKKepsilon and TRAF family-associated NF-kappaB activator-binding kinase-1 as well as the two canonical IKK family members, IKKbeta and IKKalpha. RFP inhibited activation of the IFN-stimulated response element and/or NF-kappaB mediated by the IKK family members and triggered by TNF, IL-1, polyinosinic-polycytidylic acid (ligand for TLR3), and viral infection. Moreover, knockdown of RFP expression by RNA interference-enhanced activation of IFN-stimulated response element and/or NF-kappaB triggered by polyinosinic-polycytidylic acid, TNF, and IL-1. Taken together, our findings suggest that RFP negatively regulates signaling involved in the antiviral response and inflammation by targeting the IKKs.

Active Transport, Cell Nucleus↗

PubMed2006

TNF receptor-associated factor-1 (TRAF1) negatively regulates Toll/IL-1 receptor domain-containing adaptor inducing IFN-beta (TRIF)-mediated signaling.

Toll-like receptor 3 (TLR3) plays an important role in antiviral responses through recognizing viral double-stranded RNA produced during viral infection and mediating induction of type I IFN. TRIF is a Toll/IL-1 receptor (TIR) domain-containing adaptor protein that is associated with TLR3 and critically involved in TLR3-mediated signaling. In yeast two-hybrid screens, we identified TNF receptor-associated factor (TRAF)1 as a TRIF-interacting protein. The TRAF-C domain of TRAF1 and the TIR domain of TRIF were responsible for their interaction. Overexpression of TRAF1 inhibited TRIF- and TLR3-mediated activation of NF-kappaB, IFN-stimulated response element and the IFN-beta promoter. Overexpression of TRIF caused caspase-dependent cleavage of TRAF1. The cleaved N-terminal but not C-terminal fragment of TRAF1 was responsible for inhibiting TRIF signaling. Mutation of the caspase cleavage site of TRAF1 or addition of the caspase inhibitor crmA inhibited TRAF1 cleavage and abolished the ability of TRAF1 to inhibit TRIF signaling, suggesting that TRIF-induced cleavage of TRAF1 is required for its inhibition of TRIF signaling. Our findings provide a novel mechanism for negative regulation of TRIF-mediated signaling.

Adaptor Proteins, Vesicular Transport↗

PubMed2005

SIKE is an IKK epsilon/TBK1-associated suppressor of TLR3- and virus-triggered IRF-3 activation pathways.

Viral infection or TLR3 engagement causes activation of the transcription factors IRF-3 and NF-kappaB, which collaborate to induce transcription of type I IFN genes. IKKepsilon and TBK1 are two IKK-related kinases critically involved in virus- and TLR3-triggered activation of IRF-3. We identified a protein termed SIKE (for Suppressor of IKKepsilon) that interacts with IKKepsilon and TBK1. SIKE is associated with TBK1 under physiological condition and dissociated from TBK1 upon viral infection or TLR3 stimulation. Overexpression of SIKE disrupted the interactions of IKKepsilon or TBK1 with TRIF, RIG-I and IRF-3, components in virus- and TLR3-triggered IRF-3 activation pathways, but did not disrupt the interactions of TRIF with TRAF6 and RIP, components in TLR3-triggered NF-kappaB activation pathway. Consistently, overexpression of SIKE inhibited virus- and TLR3-triggered interferon-stimulated response elements (ISRE) but not NF-kappaB activation. Knockdown of SIKE potentiated virus- and TLR3-triggered ISRE but not NF-kappaB activation. Moreover, overexpression of SIKE inhibited IKKepsilon- and TBK1-mediated antiviral response. These findings suggest that SIKE is a physiological suppressor of IKKepsilon and TBK1 and plays an inhibitory role in virus- and TLR3-triggered IRF-3 but not NF-kappaB activation pathways.

Adaptor Proteins, Vesicular Transport↗

PubMed2005

TRIP6 is a RIP2-associated common signaling component of multiple NF-kappaB activation pathways.

Receptor-interacting protein 2 (RIP2) is a member of the RIP kinase family that has been shown to be crucially involved in inflammation, innate and adaptive immune responses. The physiological and pathological roles of RIP2 are mediated through its involvement in multiple NF-kappaB activation pathways, including those triggered by tumor necrosis factor (TNF), interleukin 1 (IL-1), Toll-like receptor 2 (TLR2), TLR3, TLR4 and Nod1. In this report, we identified the LIM-domain-containing protein TRIP6 as a RIP2-interacting protein in yeast two-hybrid screens. In mammalian cells, TRIP6 interacts with RIP2 in a TNF- or IL-1-dependent manner. Overexpression of TRIP6 potentiates RIP2-mediated NF-kappaB activation in a dose-dependent manner. The LIM domains of TRIP6 are responsible for its interaction with RIP2. TRIP6 also interacts with TRAF2, a protein that is crucially involved in TNF signaling, as well as the IL-1 receptor, TLR2 and Nod1. Overexpression of TRIP6 potentiates NF-kappaB activation by TNF, IL-1, TLR2 or Nod1, whereas a dominant negative mutant or RNA-interference construct of TRIP6 inhibits NF-kappaB activation by TNF, IL-1, TLR2 or Nod1. Moreover, TRIP6 also potentiates RIP2- and Nod1-mediated ERK activation. These data have established a physical and functional association between TRIP6 and RIP2, and suggest that RIP2's involvement in multiple NF-kappaB and ERK activation pathways is mediated through TRIP6.

ATPases Associated with Diverse Cellular Activitie↗

PubMed2004

RIP5 is a RIP-homologous inducer of cell death.

Members of the RIP serine/threonine kinase family are involved in activation of NF-kappaB, JNK, and p38, and induction of apoptosis. Here we report the identification of a novel RIP-homologous protein designated as RIP5. The C-terminus of RIP5 contains a kinase domain, which is mostly homologous with the kinase domain of RIP. RIP5 also contains a large unconserved N-terminal domain. Overexpression of RIP5 induces cell death with characteristic apoptotic morphology. Overexpression of RIP5 also induces DNA fragmentation and this is blocked by the caspase inhibitor crmA. However, RIP5-induced apoptotic morphology is not blocked by crmA. These findings suggest that RIP5 may induce both caspase-dependent apoptosis and caspase-independent cell death.

Amino Acid Sequence↗

PubMed2004

ZNF216 Is an A20-like and IkappaB kinase gamma-interacting inhibitor of NFkappaB activation.

The transcription factor NFkappaB plays important roles in immune regulation, inflammatory responses, and anti-apoptosis. Activation of NFkappaB requires the activity of IkappaB kinase, a kinase complex that contains two catalytic subunits, IKKalpha and IKKbeta, and a non-enzymatic regulatory subunit, IKKgamma. To understand how NFkappaB activation is regulated at the IKKgamma level, we searched for IKKgamma-interacting proteins by the yeast two-hybrid system. This search identified ZNF216, a zinc finger protein with unknown biological functions. ZNF216 contains an A20-like zinc finger domain (ZnF-A20) at its N terminus and an AN1-like domain (ZnF-AN1) at its C terminus. Similar to A20, ZNF216 interacted with IKKgamma, RIP, and TRAF6 in co-immunoprecipitation experiments. Domain mapping experiments indicated that the ZnF-A20 domain was responsible for interacting with IKKgamma and RIP, whereas the ZnF-AN1 domain interacted with TRAF6. ZNF216 inhibited NFkappaB activation triggered by overexpression of RIP and TRAF6 but not of p65. ZNF216 also inhibited tumor necrosis factor (TNF)-, interleukin-1-, and Toll-like receptor 4-induced NFkappaB activation in a dose-dependent manner. The ZnF-A20 domain was essential for ZNF216-mediated inhibition of NFkappaB activation. The ZnF-A20 and ZnF-AN1 domains of ZNF216 could interact with each other, whereas ZNF216 could form homo-oligomers or hetero-oligomers with A20. Unlike A20, which inhibits TNF-induced apoptosis, overexpression of ZNF216 sensitized cells to TNF-induced apoptosis. Our findings suggest that ZNF216 and A20 have redundant and distinct roles in regulating NFkappaB activation and apoptosis.

Apoptosis↗

PubMed2003

Identification of a nuclear protein that promotes NF-kappaB activation.

Receptor-interacting protein (RIP) is a serine/threonine protein kinase that is critically involved in tumor necrosis factor receptor-1 (TNF-R1)-induced NF-kappaB activation. In a yeast two-hybrid screening for potential RIP-interacting proteins, we identified a novel protein designated as NKAP. Although NKAP interacts with RIP in yeast, NKAP does not interact with RIP in mammalian cells in co-immunoprecipitation experiments. When overexpressed in 293 cells, NKAP activated NF-kappaB in a dose-dependent manner. Moreover, down-regulation of NKAP by antisense RNA significantly inhibited TNF- and IL-1-induced NF-kappaB activation. Immunofluorescent staining indicated that NKAP was localized in the nucleus. Our findings suggest that NKAP is a novel nuclear regulator of TNF- and IL-1-induced NF-kappaB activation.

Amino Acid Sequence↗

PubMed2003

Identification of a novel serine/threonine kinase that inhibits TNF-induced NF-kappaB activation and p53-induced transcription.

SINK is a p65-interacting protein that inhibits PKAc-induced phosphorylation of p65 and NF-kappaB transcriptional competence. We identified a SINK-homologous serine/threonine kinase SHIK. SHIK is ubiquitously expressed and is localized in the cytoplasm. Overexpression of SHIK inhibits TNF-triggered NF-kappaB activation in reporter gene assays. Overexpression of SHIK also inhibits p53-mediated transcription in reporter gene assays, while a point mutant (D197-->I) of SHIK potentiates p53-mediated transcription. Our findings suggest that SHIK is a negative regulator of NF-kappaB- and p53-mediated gene transcription.

Amino Acid Sequence↗

PubMed2003

Casper/c-FLIP is physically and functionally associated with NF-kappaB1 p105.

Casper/c-FLIP is a caspase-8-related molecule critically involved in regulation of death receptor-induced apoptosis. It has been shown that Casper can either promote or antagonize apoptosis and can activate the transcription factor NF-kappaB. The exact functions of Casper are controversial. To further understand how Casper signals, we searched Casper-interacting proteins by yeast two-hybrid screening. This effort identified NF-kappaB1 (p105), an atypical IkappaB molecule and the precursor of NF-kappaB subunit p50. Co-immunoprecipitation experiments indicated that Casper interacted with p105 in 293 cells and this interaction was mediated through the C-terminal IkappaB-like domain (IkappaBgamma). Overexpression of p105 and IkappaBgamma inhibited Casper-induced NF-kappaB activation and potentiated Casper-induced apoptosis. Furthermore, Casper and its C-terminal caspase-like domain inhibited p105 processing into p50. Our findings suggest that p105 is involved in Casper-mediated regulation of apoptosis and NF-kappaB activation.

CASP8 and FADD-Like Apoptosis Regulating Protein↗

PubMed2003

NIK is a component of the EGF/heregulin receptor signaling complexes.

Nuclear factor kappaB-inducing kinase (NIK) is a member of the MAP kinase kinase kinase family that was first identified as a component of the TNF-R1-induced NF-kappaB activation pathway (TNF, tumor necrosis factor; nuclear factor kappaB, NF-kappaB). Gene knockout study, however, suggests that NIK is dispensable for TNF-R1- but required for lymphotoxin-beta receptor-induced NF-kappaB activation. A NIK kinase inactive mutant is a potent inhibitor of NF-kappaB activation triggered by various stimuli, suggesting that NIK is involved in a broad range of NF-kappaB activation pathways. To unambiguously identify signaling pathways that NIK participates in, we screened antibody arrays for proteins that are associated with NIK. This effort identified ErbB4, one of the EGF/heregulin receptors, and Grb7, an adapter protein associated with ErbB4 (ErbB, epidermal growth factor receptor family protein; EGF, epidermal growth factor; Grb, growth factor receptor bound). Coimmunoprecipitation experiments demonstrated that NIK interacted with Grb7, as well as Grb10 and Grb14, but not Grb2. Domain mapping experiments indicated that the central GM domain of Grb7 was sufficient for its interaction with NIK. Coimmunoprecipitation experiments also indicated that Grb7 and NIK could be simultaneously recruited into signaling complexes of all known EGF/heregulin receptors, including EGFR, ErbB2, ErbB3, and ErbB4. In reporter gene assays, NIK could potentiate Grb7, ErbB2/ErbB4, and EGF-induced NF-kappaB activation. A NIK kinase inactive mutant could block ErbB2/ErbB4 and EGF-induced NF-kappaB activation. Moreover, EGF/heregulin receptors activated NF-kappaB in wild-type, but not NIK-/- embryonic fibroblasts. Our findings suggest that NIK is a component of the EGF/heregulin receptor signaling complexes and involved in NF-kappaB activation triggered by these receptors.

ErbB Receptors↗

PubMed2002

A novel zinc finger protein interacts with receptor-interacting protein (RIP) and inhibits tumor necrosis factor (TNF)- and IL1-induced NF-kappa B activation.

Receptor-interacting protein (RIP) is a serine/threonine protein kinase that is critically involved in tumor necrosis factor receptor-1 (TNF-R1)-induced NF-kappa B activation. In a yeast two-hybrid screening for potential RIP-interacting proteins, we identified ZIN (zinc finger protein inhibiting NF-kappa B), a novel protein that specifically interacts with RIP. ZIN contains four RING-like zinc finger domains at the middle and a proline-rich domain at the C terminus. Overexpression of ZIN inhibits RIP-, IKK beta-, TNF-, and IL1-induced NF-kappa B activation in a dose-dependent manner in 293 cells. Domain mapping experiments indicate that the RING-like zinc finger domains of ZIN are required for its interaction with RIP and inhibition of RIP-mediated NF-kappa B activation. Overexpression of ZIN also potentiates RIP- and TNF-induced apoptosis. Moreover, immunofluorescent staining indicates that ZIN is a cytoplasmic protein and that it colocalizes with RIP. Our findings suggest that ZIN is an inhibitor of TNF- and IL1-induced NF-kappa B activation pathways.

Amino Acid Sequence↗