-
Ying Li,
Haixia Zhao,
Yuzhong Wang,
Hao Zheng,
Wei Yu,
Hongyan Chai,
Jing Zhang,
John R Falck,
Austin M Guo,
Jiang Yue,
Renxiu Peng,
Jing Yang
[show abstract]
[hide abstract]
ABSTRACT: Arachidonic acid (AA)-derived eicosanoids and its downstream pathways have been demonstrated to play crucial roles in growth control of breast cancer. Here, we demonstrate that isoliquiritigenin, a flavonoid phytoestrogen from licorice, induces growth inhibition and apoptosis through downregulating multiple key enzymes in AA metabolic network and the deactivation of PI3K/Akt in human breast cancer. Isoliquiritigenin diminished cell viability, 5-bromo-2'-deoxyuridine (BrdU) incorporation, and clonogenic ability in both MCF-7 and MDA-MB-231cells, and induced apoptosis as evidenced by analysis of cytoplasmic histone-associated DNA fragmentation, flow cytometry and hoechst staining. Furthermore, isoliquiritigenin inhibited mRNA expression of multiple forms of AA-metabolizing enzymes, including phospholipase A2 (PLA2), cyclooxygenases (COX)-2 and cytochrome P450 (CYP) 4A, and decreased secretion of their products, including prostaglandin E2 (PGE2) and 20-hydroxyeicosatetraenoic acid (20-HETE), without affecting COX-1, 5-lipoxygenase (5-LOX), 5-lipoxygenase activating protein (FLAP), and leukotriene B4 (LTB4). In addition, it downregulated the levels of phospho-PI3K, phospho-PDK (Ser(241)), phospho-Akt (Thr(308)), phospho-Bad (Ser(136)), and Bcl-xL expression, thereby activating caspase cascades and eventually cleaving poly (ADP-ribose) polymerase (PARP). Conversely, addition of exogenous eicosanoids, including PGE2, LTB4 and a 20-HETE analog (WIT003), and caspase inhibitors, or overexpression of constitutively active Akt reversed isoliquiritigenin-induced apoptosis. Notably, isoliquiritigenin induced growth inhibition and apoptosis of MDA-MB-231 human breast cancer xenografts in nude mice, together with decreased intratumoral levels of eicosanoids and phospho-Akt (Thr(308)). Collectively, these data suggest that isoliquiritigenin induces growth inhibition and apoptosis through downregulating AA metabolic network and the deactivation of PI3K/Akt in human breast cancer.
Toxicology and Applied Pharmacology 06/2013; · 4.45 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Endoplasmic reticulum (ER) stress caused by excessive aggregation of misfolded proteins induces apoptosis. Although ER stress-induced apoptosis has been implicated in many diseases, the detailed mechanisms are not well understood. Here, we identified human Transmembrane Protein 214 (TMEM214) as a critical mediator of ER stress-induced apoptosis. Overexpression of TMEM214 induced apoptosis, whereas knockdown of TMEM214 inhibited ER stress-induced apoptosis. TMEM214 was localized on the outer membrane of ER and constitutively associated with procaspase-4, which was also critical for ER stress-induced apoptosis. TMEM214-induced apoptosis was abolished by a dominant negative mutant of procaspase-4, whereas caspase-4-induced apoptosis was inhibited by knockdown of TMEM214. Furthermore, knockdown of TMEM214 inhibited the activation and cleavage of procaspase-4 by impairing its recruitment to the ER. Our findings suggest that TMEM214 is essential for ER stress-induced apoptosis by acting as an anchor for recruitment of procaspase-4 to the ER and its subsequent activation.
Journal of Biological Chemistry 05/2013; · 4.77 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Detection of viral nucleic acids by pattern recognition receptors initiates type Iinterferon (IFN) induction and innate antiviral response. The RIG-I-like receptors (RLRs), including RIG-I and MDA5, recognize cytoplamsic viral RNA in most cell types and are critically involved in innate antiviral response. RIG-I and MDA5 are structurally related and mediate similar signaling pathways. While the regulation of RIG-I activity has been extensively investigated, little is known about the regulatory mechanisms of MDA5 activity. Here we identified ribonucleoprotein PTB-binding 1 (RAVER1) as a specific MDA5-interacting protein. RAVER1 was associated with MDA5 upon viral infection. Overexpression of RAVER1 at low dosages enhanced MDA5- but not RIG-I-mediated activation of the IFN-β promoter, whereas knockdown of RAVER1 inhibited MDA5- but not RIG-I-mediated induction of downstream antiviral genes. Mechanistically, overexpression of RAVER1 enhanced the binding of MDA5 to its ligand poly(I:C) whereas knockdown of RAVER1 had opposite effect. Our findings suggest that RAVER1 specifically regulates MDA5 activity, revealing a mechanism of differential regulation of MDA5- and RIG-I-mediated innate antiviral response.
Journal of Molecular Cell Biology 02/2013;
-
[show abstract]
[hide abstract]
ABSTRACT: Recognition of viral nucleic acids by pattern recognition receptors initiates type I IFN induction and innate antiviral immune response. Here we show that LSm14A, a member of the LSm family involved in RNA processing in the processing bodies, binds to synthetic or viral RNA and DNA and mediates IRF3 activation and IFN-β induction. Knockdown of LSm14A inhibits cytosolic RNA- and DNA-trigger type I IFN production and cellular antiviral response. Moreover, LSm14A is essential for early-phase induction of IFN-β after either RNA or DNA virus infection. We further found that LSm14A-mediated IFN-β induction requires RIG-I-VISA or MITA after RNA or DNA virus infection, respectively, and viral infection causes translocation of LSm14A to peroxisomes, where RIG-I, VISA, and MITA are located. These findings suggest that LSm14A is a sensor for both viral RNA and DNA and plays an important role in initiating IFN-β induction in the early phase of viral infection.
Proceedings of the National Academy of Sciences 06/2012; 109(29):11770-5. · 9.68 Impact Factor
-
Cell Research 12/2011; 22(3):603-6. · 8.19 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Transcription factor IRF3-mediated type I interferon induction is essential for antiviral innate immunity. We identified the deSUMOylating enzyme Sentrin/SUMO-specific protease (SENP) 2 as a negative regulator of virus-triggered IFN-β induction. Overexpression of SENP2 caused IRF3 deSUMOylation, K48-linked ubiquitination, and degradation, whereas depletion of SENP2 had opposite effects. Both the SUMOylation and K48-linked ubiquitination of IRF3 occurred at lysines 70 and 87, and these processes are competitive. The level of virus-triggered IFN-β was markedly up-regulated and viral replication was reduced in SENP2-deficient cells comparing with wild-type controls. Our findings suggest that SENP2 regulates antiviral innate immunity by deSUMOylating IRF3 and conditioning it for ubiquitination and degradation, and provide an example of cross-talk between the ubiquitin and SUMO pathways in innate immunity.
Journal of Molecular Cell Biology 10/2011; 3(5):283-92.
-
[show abstract]
[hide abstract]
ABSTRACT: Cluster analysis has long played an important role in a wide variety of data applications. When the clusters are irregular
or intertwined, density-based clustering is proved to be much more efficient. The quality of clustering result depends on
an adequate choice of the parameters. However, without enough domain knowledge the parameter setting is somewhat limited in
its operability. In this paper, a new method is proposed to automatically find out the optimal parameter value of the bandwidth.
It is to infer the most suitable parameter value by the constructed model on parameter estimation. Based on the Bayesian Theorem,
from which the most probability value for the bandwidth can be acquired in accordance with the inherent distribution characteristics
of the original data set. Clusters can then be identified by the determined parameter values. The results of the experiment
show that the proposed method has complementary advantages in the density-based clustering algorithm.
KeywordsDensity-based clustering–Bayesian posterior probability estimation–Optimal bandwidth selection
04/2011: pages 156-167;
-
[show abstract]
[hide abstract]
ABSTRACT: Viral RNAs produced during viral infection are recognized by the cytoplasmic RNA helicases retinoic acid-inducible gene-I (RIG-I) and melanoma differentiation-associated gene 5 (MDA5). A central adapter protein downstream of RIG-I and MDA5 is the mitochondrial membrane protein virus-induced signaling adaptor (VISA), which mediates the induction of type I interferons (IFNs) through the activation of transcription factors such as nuclear factor-kappaB (NF-kappaB) and IFN-regulatory factor-3 (IRF3). Here we found that hepatitis B virus (HBV)-encoded X protein (HBx) acts as an inhibitor of virus-triggered IRF3 activation and IFN-beta induction. Reporter and plaque assays indicate that HBx inhibits signaling by components upstream but not downstream of VISA. Immunoprecipitation experiments indicate that HBx interacts with VISA and disrupts the association of VISA with its upstream and downstream components. These findings suggest that HBx acts as a suppressor of virus-triggered induction of type I IFNs, which explains the observation that HBV causes transient and chronic infection in hepatocytes but fails to activate the pattern recognition receptor-mediated IFN induction pathways.
Cellular & molecular immunology 09/2010; 7(5):341-8. · 2.99 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Viral infection causes activation of transcription factors NF-kappaB and IRF3, which collaborate to induce type I interferons (IFNs) and cellular antiviral response. Here we show that knockdown of the E3 ubiquitin ligases cIAP1 and cIAP2 markedly inhibited virus-triggered activation of IRF3 and NF-kappaB as well as IFN-beta induction. Knockdown of cIAP1 and cIAP2 also inhibited cytoplasmic dsRNA-triggered cellular antiviral response. Endogenous coimmunoprecipitation experiments indicated that viral infection caused recruitment of cIAP1 and cIAP2 to TRAF3, TRAF6, and VISA. Furthermore, we demonstrated that cIAP1- and cIAP2-mediated virus-triggered ubiquitination of TRAF3 and TRAF6. These findings suggest that virus-triggered ubiquitination of TRAF3 and TRAF6 by cIAP1 and cIAP2 is essential for type I IFN induction and cellular antiviral response.
Journal of Biological Chemistry 03/2010; 285(13):9470-6. · 4.77 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Ubiquitination and deubiquitination have emerged as critical post-translational regulatory mechanisms for activation or attenuation
of the virus-triggered type I interferon (IFN)2 induction pathways. In this study, we identified two deubiquitinating enzymes, OTUB1 and OTUB2, as negative regulators of
virus-triggered type I IFN induction. Overexpression of OTUB1 and OTUB2 inhibited virus-induced activation of IRF3 and NF-κB,
transcription of the IFNB1 gene as well as cellular antiviral response, whereas knockdown of OTUB1 and OTUB2 had opposite
effects. Coimmunoprecipitations indicated OTUB1 and -2 interacted with TRAF3 and TRAF6, two E3 ubiquitin ligases required
for virus-triggered IRF3 and NF-κB activation, respectively. Furthermore, we found that OTUB1 and OTUB2 mediated virus-triggered
deubiquitination of TRAF3 and -6. These findings suggest that OTUB1 and OTUB2 negatively regulate virus-triggered type I IFN
induction and cellular antiviral response by deubiquitinating TRAF3 and -6.
Journal of Biological Chemistry 02/2010; 285(7):4291-4297. · 4.77 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Viral infection causes activation of the transcription factors NF-kappaB and IRF3, which collaborate to induce type I interferons (IFNs) and cellular antiviral response. The mitochondrial outer membrane protein VISA acts as a critical adapter for assembling a virus-induced complex that signals NF-kappaB and IRF3 activation. Using a biochemical purification approach, we identified the WD repeat protein WDR5 as a VISA-associated protein. WDR5 was recruited to VISA in a viral infection dependent manner. Viral infection also caused translocation of WDR5 from the nucleus to mitochondria. Knockdown of WDR5 impaired the formation of virus-induced VISA-associated complex. Consistently, knockdown of WDR5 inhibited virus-triggered activation of IRF3 and NF-kappaB as well as transcription of the IFNB1 gene. These findings suggest that WDR5 is essential in assembling a virus-induced VISA-associated complex and plays an important role in virus-triggered induction of type I IFNs.
Proceedings of the National Academy of Sciences 01/2010; 107(2):815-20. · 9.68 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Ubiquitination and deubiquitination have emerged as critical post-translational regulatory mechanisms for activation or attenuation of the virus-triggered type I interferon (IFN)(2) induction pathways. In this study, we identified two deubiquitinating enzymes, OTUB1 and OTUB2, as negative regulators of virus-triggered type I IFN induction. Overexpression of OTUB1 and OTUB2 inhibited virus-induced activation of IRF3 and NF-kappaB, transcription of the IFNB1 gene as well as cellular antiviral response, whereas knockdown of OTUB1 and OTUB2 had opposite effects. Coimmunoprecipitations indicated OTUB1 and -2 interacted with TRAF3 and TRAF6, two E3 ubiquitin ligases required for virus-triggered IRF3 and NF-kappaB activation, respectively. Furthermore, we found that OTUB1 and OTUB2 mediated virus-triggered deubiquitination of TRAF3 and -6. These findings suggest that OTUB1 and OTUB2 negatively regulate virus-triggered type I IFN induction and cellular antiviral response by deubiquitinating TRAF3 and -6.
Journal of Biological Chemistry 12/2009; 285(7):4291-7. · 4.77 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: IFN-stimulated gene 56 (ISG56) is one of the first identified proteins induced by viruses and type I IFNs. In this study, we identified ISG56 as a virus-induced protein associated with MITA, an adapter protein involved in virus-triggered induction of type I IFNs. Overexpression of ISG56 inhibited Sendai virus-triggered activation of IRF3, NF-kappaB, and the IFN-beta promoter, whereas knockdown of ISG56 had opposite effects. Consistently, overexpression of ISG56 reversed cytoplasmic poly(I:C)-induced inhibition of vesicular stomatitis virus (VSV) replication, whereas knockdown of ISG56 inhibited VSV replication. Competitive coimmunoprecipitation experiments indicated that ISG56 disrupted the interactions between MITA and VISA or TBK1, two components in the virus-triggered IFN signaling pathways. These results suggest that ISG56 is a mediator of negative-feedback regulation of virus-triggered induction of type I IFNs and cellular antiviral responses.
Proceedings of the National Academy of Sciences 06/2009; 106(19):7945-50. · 9.68 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Viral infection activates transcription factors NF-kappaB and IRF3, which collaborate to induce type I interferons (IFNs) and elicit innate antiviral response. MITA (also known as STING) has recently been identified as an adaptor that links virus-sensing receptors to IRF3 activation. Here, we showed that the E3 ubiquitin ligase RNF5 interacted with MITA in a viral-infection-dependent manner. Overexpression of RNF5 inhibited virus-triggered IRF3 activation, IFNB1 expression, and cellular antiviral response, whereas knockdown of RNF5 had opposite effects. RNF5 targeted MITA at Lys150 for ubiquitination and degradation after viral infection. Both MITA and RNF5 were located at the mitochondria and endoplasmic reticulum (ER) and viral infection caused their redistribution to the ER and mitochondria, respectively. We further found that virus-induced ubiquitination and degradation of MITA by RNF5 occurred at the mitochondria. These findings suggest that RNF5 negatively regulates virus-triggered signaling by targeting MITA for ubiquitination and degradation at the mitochondria.
Immunity 04/2009; 30(3):397-407. · 21.64 Impact Factor
-
Bo Zhong,
Yan Yang,
Shu Li,
Yan-Yi Wang, Ying Li,
Feici Diao,
Caoqi Lei,
Xiao He,
Lu Zhang,
Po Tien,
Hong-Bing Shu
[show abstract]
[hide abstract]
ABSTRACT: Viral infection triggers activation of transcription factors such as NF-kappaB and IRF3, which collaborate to induce type I interferons (IFNs) and elicit innate antiviral response. Here, we identified MITA as a critical mediator of virus-triggered type I IFN signaling by expression cloning. Overexpression of MITA activated IRF3, whereas knockdown of MITA inhibited virus-triggered activation of IRF3, expression of type I IFNs, and cellular antiviral response. MITA was found to localize to the outer membrane of mitochondria and to be associated with VISA, a mitochondrial protein that acts as an adaptor in virus-triggered signaling. MITA also interacted with IRF3 and recruited the kinase TBK1 to the VISA-associated complex. MITA was phosphorylated by TBK1, which is required for MITA-mediated activation of IRF3. Our results suggest that MITA is a critical mediator of virus-triggered IRF3 activation and IFN expression and further demonstrate the importance of certain mitochondrial proteins in innate antiviral immunity.
Immunity 10/2008; 29(4):538-50. · 21.64 Impact Factor
-
