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1.
Chem Biodivers ; 16(7): e1900080, 2019 Jul.
Article in English | MEDLINE | ID: mdl-31111998

ABSTRACT

The objective of this study is to compare the efficacy of ethanol extracts from different parts of Sophora viciifolia. The content of polyphenols, flavonoids, alkaloids, and antioxidant capacity, antimicrobial activity were investigated, and individual polyphenols and alkaloids were analyzed and quantified by ultra-high performance liquid chromatography (UPLC). The microdilution method was used to determine the antimicrobial activity of extracts from S. viciifolia on six strains. The results for extracts from the different parts (flowers, leaves, and fruit) were compared in varying concentrations to determine whether one extract source is superior to another. Testing verified that extracts from the different parts of S. viciifolia did vary, as expected. For example, extract from the leaves had the best antimicrobial activity against pathogenic Candida albicans, but all extracts had good antimicrobial activity against the six tested strains. These results reveal that the active substances in S. viciifolia are abundant and have good antioxidant and antimicrobial activities, which can provide theoretical support for the subsequent development and utilization of S. viciifolia extracts.


Subject(s)
Anti-Bacterial Agents/pharmacology , Antioxidants/pharmacology , Biphenyl Compounds/antagonists & inhibitors , Candida albicans/drug effects , Phytochemicals/pharmacology , Picrates/antagonists & inhibitors , Sophora/chemistry , Anti-Bacterial Agents/chemistry , Anti-Bacterial Agents/isolation & purification , Antioxidants/chemistry , Antioxidants/isolation & purification , Dose-Response Relationship, Drug , Microbial Sensitivity Tests , Molecular Structure , Phytochemicals/chemistry , Phytochemicals/isolation & purification , Structure-Activity Relationship
2.
Biochem Biophys Res Commun ; 505(3): 651-656, 2018 11 02.
Article in English | MEDLINE | ID: mdl-30286953

ABSTRACT

Aspergillus fumigatus, an airborne pathogen, causes many diseases, including aspergilloma, invasive aspergillosis, and allergic bronchopulmonary aspergillosis. Phospholipase D (PLD) is an important virulence factor for A. fumigatus infection, but the manner by which PLD contributes to the virulence of this pathogen is not clear. Our results show that expression of A. fumigatus PLD in human cells was able to increase the production of reactive oxygen species (ROS), which play an important role in several signaling pathways as well as in lung infection. Meanwhile, A. fumigatus PLD was found to interact with human endogenous histone deacetylase 6 (HDAC6), a known regulator of ROS production and inflammatory responses; PLD significantly increased the expression level of HDAC6 protein without altering its mRNA level. These results suggest that A. fumigatus PLD may enhance the production of ROS via the accumulation of HDAC6, which may be involved in host immunomodulation during A. fumigatus infection.


Subject(s)
Fungal Proteins/metabolism , Histone Deacetylase 6/metabolism , Phospholipase D/metabolism , Reactive Oxygen Species/metabolism , Apoptosis/genetics , Aspergillus fumigatus/genetics , Aspergillus fumigatus/metabolism , Cell Cycle/genetics , Cell Proliferation/genetics , Fungal Proteins/genetics , HEK293 Cells , Histone Deacetylase 6/genetics , Humans , MAP Kinase Signaling System/genetics , Phospholipase D/genetics , Protein Binding , RNA Interference , Virulence Factors/genetics , Virulence Factors/metabolism
3.
Cell Tissue Res ; 368(1): 13-27, 2017 04.
Article in English | MEDLINE | ID: mdl-27726026

ABSTRACT

Recently, NIX, a pro-apoptotic BH3-only protein, was found to be a novel p75 neurotrophin receptor (p75NTR) binding protein by screening a human fetal brain two-hybrid library in our laboratory. We further study the interaction of these two proteins and the possible roles of p75NTR and NIX in intracerebral hemorrhage (ICH)-induced neuronal death. Using the split-ubiquitin yeast two-hybrid system, we found that the "Copper" domain in p75NTR and the TM region in NIX were sufficient for the interaction of these two proteins. Co-immunoprecipitation and in vitro binding assays demonstrated the direct interaction between p75NTR and NIX. NIX protein was stabilized by p75NTR at post-translational levels. Moreover, p75NTR was able to work together with NIX to promote apoptosis and affected the NIX-induced JNK-p53-Bax pathway in neuronal PC12 cells. Previous work has indicated that p75NTR and NIX are induced in neurons in human ICH and the rat ICH model, respectively. We confirm that both p75NTR and NIX levels were up-regulated in glutamate-treated primary cortical neurons (a cellular in vitro model for ICH) and in the rat ICH model. Glutamate exposure increased the association between p75NTR and NIX and elevated the activation of the JNK-p53-Bax pathway and neuronal apoptosis; all of these observations were similar in the rat ICH model. Importantly, p75NTR and NIX appeared to be involved in cortical neuronal apoptosis, because knockdown of p75NTR or NIX not only inhibited the JNK pathway but also impaired neuronal apoptosis. Thus, p75NTR and NIX may play critical roles in ICH-induced neuronal apoptosis in vitro and in vivo.


Subject(s)
Apoptosis , Cerebral Hemorrhage/metabolism , Cerebral Hemorrhage/pathology , Membrane Proteins/metabolism , Neurons/metabolism , Neurons/pathology , Proto-Oncogene Proteins/metabolism , Receptor, Nerve Growth Factor/metabolism , Tumor Suppressor Proteins/metabolism , Animals , Apoptosis/drug effects , Cells, Cultured , Cerebral Cortex/pathology , Cerebral Hemorrhage/enzymology , Disease Models, Animal , Enzyme Activation/drug effects , Glutamic Acid/pharmacology , HEK293 Cells , Humans , JNK Mitogen-Activated Protein Kinases/metabolism , Male , Membrane Proteins/chemistry , Protein Binding/drug effects , Protein Interaction Domains and Motifs , Protein Stability/drug effects , Proto-Oncogene Proteins/chemistry , Rats, Sprague-Dawley , Receptor, Nerve Growth Factor/chemistry , Signal Transduction/drug effects , Tumor Suppressor Protein p53/metabolism , Tumor Suppressor Proteins/chemistry , Two-Hybrid System Techniques , Ubiquitin/metabolism , Up-Regulation/drug effects , bcl-2-Associated X Protein/metabolism
4.
Cell Mol Neurobiol ; 35(3): 363-376, 2015 Apr.
Article in English | MEDLINE | ID: mdl-25354492

ABSTRACT

The proto-oncogene c-Fos is an important member of the activating protein 1 (AP-1) transcription complex involved in major cellular functions such as transformation, proliferation, differentiation, and apoptosis. The expression of c-Fos is very tightly regulated and responses rapidly and transiently to a plethora of apoptotic stimuli. However, it is still unclear how c-Fos functions on neuronal activities following intracerebral hemorrhage (ICH). In the present studies, we uncovered that the up-regulation of c-Fos is related to neuronal apoptosis following ICH probably via FasL/Fas apoptotic pathway. From the results of Western blot and immunohistochemistry, we obtained that c-Fos is significantly up-regulated surrounding the hematoma following ICH and co-locates with active caspase-3 in the neurons. Besides, electrophoretic mobility shift assay exhibits high AP-1 DNA-binding activities in ICH groups due to the increase of c-Fos expression. In addition, there are concomitant up-regulation of Fas ligand (FasL), which is the target protein of AP-1, Fas, active caspase-8, and active caspase-3 in vivo and in vitro studies. What is more, our in vitro study showed that using c-Fos-specific RNA interference in primary cortical neurons, the expression of FasL and active caspase-3 are suppressed. Thus, our results indicated that c-Fos might exert its pro-apoptotic function on neuronal apoptosis following ICH.


Subject(s)
Apoptosis/physiology , Cerebral Hemorrhage/metabolism , Neurons/metabolism , Proto-Oncogene Proteins c-fos/biosynthesis , Up-Regulation/physiology , Animals , Cells, Cultured , Cerebral Hemorrhage/pathology , Male , Neurons/pathology , Rats , Rats, Sprague-Dawley
5.
Zootaxa ; 3755: 230-40, 2014 Jan 22.
Article in English | MEDLINE | ID: mdl-24869818

ABSTRACT

In the present paper, the genus Spazigasteroides gen. nov. (Diptera, Syrphidae), with Spazigasteroides caeruleus sp. nov. as type species, is described from China. The new genus bears the following characters: Head strongly concave posteriorly and closely appressed to thorax so that the bare postpronota are entirely hidden. Face black in ground colour. Antennae short, with basoflagellomeres slightly longer than wide. Scutellum black. Postmetacoxal bridge

Subject(s)
Diptera/anatomy & histology , Diptera/classification , Animals , China , Demography , Diptera/physiology , Female , Male , Species Specificity
6.
J Transl Med ; 11: 52, 2013 Mar 01.
Article in English | MEDLINE | ID: mdl-23452395

ABSTRACT

BACKGROUND: Synovial sarcoma, X breakpoint 2 interacting protein (SSX2IP), which has been identified as an acute myeloid leukemia associated antigen, is a potential target for leukemia immunotherapy. In rodents, its homologous gene, ADIP, plays an important role in the regulation of cell adhesion and migration, underlying its potential role in promoting metastasis of other cancers. METHODS: To investigate the correlation between the expression level of SSX2IP and the clinicopathologic factors of hepatocellular carcinoma (HCC), 53 cases were studied by qPCR and statisted. To directly testing SSX2IP's contribution to HCC in animal models, 45 nude mice were enrolled in peritoneal spreading and liver metastasis models. For the migration and invasion assays, cell culture experiments were performed using QCMTM 24-Well Colorimetric Migration Assay Kit and Cell Invasion Assay Kit (Millipore). Moreover we examined the influence of SSX2IP overexpression on the chemosensitivity of hepatocellular carcinoma cells to two most common chemotherapy drugs (5-Fu and CDDP) using Cell counting kit-8 (CCK-8). The chemotherapeutic drugs sensitivity was evaluated by IC50 parameter. RESULTS: Statistical analysis of clinical cases revealed that the SSX2IP high expression group had inclinations towards larger tumor size, more tumor thrombus and shorter survival period, implying a strong correlation between the expression level of SSX2IP and HCC tumorigenesis. Consistently in abdominal cavity metastasis and liver metastasis models of immune-deficient mice, SSX2IP was able to promote the metastasis of hepatoma cells. At the cytological level, SSX2IP stimulates the wound healing, metastasis and invasion of hepatoma cells, and reduces the sensitivity of hepatoma cells to 5-Fu and CDDP. CONCLUSIONS: Our results showed that SSX2IP promotes the development and metastasis of hepatocellular carcinoma and contributes to the drug resistance of hepatoma cells, suggesting that SSX2IP is expected to become a new diagnostic and prognostic marker and a new target of the treatment of hepatocellular carcinoma.


Subject(s)
Carrier Proteins/physiology , Drug Resistance, Neoplasm/physiology , Cell Cycle Proteins , Humans , Microtubule-Associated Proteins , Neoplasm Metastasis
8.
Mol Biol Rep ; 40(10): 5759-67, 2013 Oct.
Article in English | MEDLINE | ID: mdl-24052230

ABSTRACT

In the present study, we characterized an evolutionarily conserved non-transmembrane ATP-binding cassette protein: hABCF3. Subcellular immunofluorescence staining demonstrated that hABCF3 localizes preferentially in cytoplasm, unlike its paralog protein hABCF1, which localizes in both cytoplasm and nucleus. Quantitative realtime PCR analysis revealed that hABCF3 is expressed in all tissues examined, with high expression level in heart, liver, and pancreas. Interestingly, ectopic hABCF3 promoted proliferation of human liver cancer cell lines. Moreover, knock down of hABCF3 protein expression by siRNA inhibited cell proliferation. In addition, we identified TPD52L2 (Tumor Protein D52-like 2) as a hABCF3 interacting protein via yeast two-hybrid. This interaction was further confirmed by in vivo co-immunoprecipitation and co-localization assays. Furthermore, we identified the interactional region of hABCF3 to be the first 200 amino acids uncharacterized region. Notably, the truncated version of hABCF3, which lacks the TPD52L2 binding region, remarkably impaired hABCF3-mediated cell proliferation. Taken together, these findings suggest that hABCF3 positively regulates cell proliferation, at least partially through the interaction with a tumor protein D52 protein family member: TPD52L2.


Subject(s)
ATP-Binding Cassette Transporters/metabolism , Liver Neoplasms/metabolism , Liver Neoplasms/pathology , Neoplasm Proteins/metabolism , ATP-Binding Cassette Transporters/chemistry , Amino Acid Sequence , Cell Line, Tumor , Cell Proliferation , Cytoplasm/metabolism , HEK293 Cells , Humans , Molecular Sequence Data , Neoplasm Proteins/chemistry , Protein Binding , Protein Interaction Domains and Motifs
9.
Cell Mol Biol Lett ; 18(2): 297-314, 2013 Jun.
Article in English | MEDLINE | ID: mdl-23666597

ABSTRACT

PTPN4 is a widely expressed non-receptor protein tyrosine phosphatase. Although its overexpression inhibits cell growth, the proteins with which it interacts to regulate cell growth are unknown. In this study, we identified CrkI as a PTPN4-interacting protein using a yeast two-hybrid, and confirmed this interaction using in vitro GST pull-down and co-immunoprecipitation and co-localization assays. We further determined the interactional regions as the SH3 domain of CrkI and the proline-rich region between amino acids 462 and 468 of PTPN4. Notably, overexpression of PTPN4 inhibits CrkI-mediated proliferation and wound healing of HEK293T cells, while knockdown of PTPN4 by siRNA in Hep3B cells enhances CrkI-mediated cell growth and motility. Moreover, our data show that ectopic expression of PTPN4 reduces the phosphorylation level of CrkI in HEK293T cells. These findings suggest that PTPN4 negatively regulates cell proliferation and motility through dephosphorylation of CrkI.


Subject(s)
Protein Tyrosine Phosphatase, Non-Receptor Type 4/metabolism , Proto-Oncogene Proteins c-crk/metabolism , Amino Acid Sequence , Cell Movement , Cell Proliferation , Gene Knockdown Techniques , HEK293 Cells , HeLa Cells , Humans , Molecular Sequence Data , Phosphorylation , Protein Binding , Protein Interaction Mapping , Protein Structure, Tertiary , Protein Tyrosine Phosphatase, Non-Receptor Type 4/chemistry , RNA Interference , Reproducibility of Results
10.
Carcinogenesis ; 33(8): 1581-8, 2012 Aug.
Article in English | MEDLINE | ID: mdl-22570270

ABSTRACT

Pirh2 is a Ring-H2 domain containing E3 ubiquitin ligase that targets several important tumor suppressor genes for proteasomal degradation. Overexpression of Pirh2 is frequently detected in many clinical tumor tissues including hepatocellular carcinoma (HCC). However, the molecular mechanism of Pirh2 activation in tumorigenesis still remains poorly understood. In this study, we find a Pirh2-binding protein, SCYL1 binding protein 1 (SCYL1BP1), that can promote the ubiquitin-dependent degradation of Pirh2. SCYL1BP1 colocalized with Pirh2 in the cytoplasm and prevented its localization to the nucleus. Ectopic expression of SCYL1BP1 increased the expression of p53 and further inhibited the G(1)/S transition of HCC cell lines. Conversely, knock down of SCYL1BP1 restored the expression of Pirh2 and inhibited p53 at protein level. Functional assays found that reintroduction of SCYL1BP1 into HCC cell lines significantly inhibited cell proliferation, foci formation, colony formation in soft agar and tumor formation in nude mice, suggesting the strong tumor-suppressive function of SCYL1BP1 in HCC progression. Furthermore, SCYL1BP1 was found to be frequently downregulated in HCC clinical specimens compared to their paired non-tumor tissues by immunohistochemical staining. Taken together, our data suggested that the interaction of SCYL1BP1/Pirh2 could accelerate Pirh2 degradation through an ubiquitin-dependent pathway. SCYL1BP1 may function as an important tumor suppressor gene in HCC development.


Subject(s)
Carcinoma, Hepatocellular/metabolism , Genes, Tumor Suppressor , Liver Neoplasms/metabolism , Transcription Factors/physiology , Ubiquitin-Protein Ligases/metabolism , Ubiquitin/metabolism , Adaptor Proteins, Vesicular Transport , Carcinoma, Hepatocellular/pathology , Cell Line, Tumor , DNA-Binding Proteins , Down-Regulation , Flow Cytometry , Humans , Immunohistochemistry , Liver Neoplasms/pathology , Proteolysis , Real-Time Polymerase Chain Reaction , Transcription Factors/genetics
11.
J Biol Chem ; 286(51): 43660-43667, 2011 Dec 23.
Article in English | MEDLINE | ID: mdl-22045814

ABSTRACT

Ufd2 is a U-box-containing ubiquitylation enzyme that promotes ubiquitin chain assembly on substrates. The physiological function of Ufd2 remains poorly understood. Here, we show that ubiquitylation and degradation of the cell cycle kinase Mps1, a known target of the anaphase-promoting complex E3, require Ufd2 enzyme. Yeast cells lacking UFD2 exhibit altered chromosome stability and several spindle-related phenotypes, expanding the biological function of Ufd2. We demonstrate that Ufd2-mediated Mps1 degradation is conserved in humans. Our results underscore the significance of Ufd2 in proteolysis and further suggest that Ufd2-like enzymes regulate far more substrates than previously envisioned.


Subject(s)
Candida albicans/genetics , Cell Cycle Proteins/metabolism , Gene Expression Regulation, Fungal , Protein Serine-Threonine Kinases/metabolism , Protein-Tyrosine Kinases/metabolism , Saccharomyces cerevisiae Proteins/metabolism , Ubiquitin-Conjugating Enzymes/metabolism , Ubiquitin-Protein Ligases/metabolism , Anaphase-Promoting Complex-Cyclosome , Animals , Bone Marrow Cells/metabolism , Candida albicans/metabolism , Cell Line, Tumor , Humans , Lectins/chemistry , Male , Mice , Mitosis , Proteolysis , Ubiquitin/chemistry , Ubiquitin-Protein Ligase Complexes/chemistry , Ubiquitin-Protein Ligases/chemistry
12.
Mol Syst Biol ; 7: 536, 2011 10 11.
Article in English | MEDLINE | ID: mdl-21988832

ABSTRACT

Proteome-scale protein interaction maps are available for many organisms, ranging from bacteria, yeast, worms and flies to humans. These maps provide substantial new insights into systems biology, disease research and drug discovery. However, only a small fraction of the total number of human protein-protein interactions has been identified. In this study, we map the interactions of an unbiased selection of 5026 human liver expression proteins by yeast two-hybrid technology and establish a human liver protein interaction network (HLPN) composed of 3484 interactions among 2582 proteins. The data set has a validation rate of over 72% as determined by three independent biochemical or cellular assays. The network includes metabolic enzymes and liver-specific, liver-phenotype and liver-disease proteins that are individually critical for the maintenance of liver functions. The liver enriched proteins had significantly different topological properties and increased our understanding of the functional relationships among proteins in a liver-specific manner. Our data represent the first comprehensive description of a HLPN, which could be a valuable tool for understanding the functioning of the protein interaction network of the human liver.


Subject(s)
Liver , Protein Interaction Mapping , Protein Interaction Maps , Proteome/metabolism , Proteomics/methods , Saccharomyces cerevisiae/metabolism , Systems Biology , Databases, Protein , Gene Silencing/drug effects , Genes, Reporter , HEK293 Cells , Humans , Immunoprecipitation , Liver/metabolism , Luciferases/analysis , Open Reading Frames , Plasmids , Proteins/genetics , Proteins/metabolism , Proteome/genetics , RNA, Small Interfering/pharmacology , Saccharomyces cerevisiae/genetics , Transfection , Two-Hybrid System Techniques
13.
Mitochondrial DNA B Resour ; 7(9): 1679-1681, 2022.
Article in English | MEDLINE | ID: mdl-36147365

ABSTRACT

The complete mitochondrial genome of Eristalinus viridis (Coquillett, 1898) was obtained for the first time using Next Generation Sequencing (NGS). The mitogenome assembly of E. viridis is 15,640 bp in length and its annotation confirms the presence of 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNAs), two ribosomal RNA genes (rRNAs), and one putative control region. The results of the phylogenetic analyses using Maximum Likelihood and Bayesian inference recover a highly supported sister relationship between E. viridis and Mallota bellus.

14.
Mitochondrial DNA B Resour ; 7(9): 1664-1665, 2022.
Article in English | MEDLINE | ID: mdl-36147375

ABSTRACT

In this study, the complete mitochondrial genome (mitogenome) of Melanostoma mellinum (Linnaeus, 1758) was sequenced using the-next generation sequencing technology. The assembled mitogenome of M. mellinum has a total length of 16,055bp and contains 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNAs), and 2 ribosomal RNA genes (rRNAs). The results of phylogenetic reconstruction based on the combined mitochondrial gene dataset indicated that M. mellinum belongs to Melanostoma genus with a close relationship to Melanostoma orientale, but the monophyly of the tribe Bacchini is not well supported.

15.
Zootaxa ; 5154(2): 225-238, 2022 Jun 14.
Article in English | MEDLINE | ID: mdl-36095626

ABSTRACT

The genus Psilota Meigen, 1822 is recorded for the first time from China, and the species Psilota bashanensis Huo and Zhao sp. nov. is described and illustrated based on the adult male. The complete cytochrome c oxidase subunit I (COI) gene of this new species has been successfully obtained and compared to that of other congeneric species. An updated key to adult males of the genus Psilota from the Palaearctic Region is also provided.


Subject(s)
Diptera , Animals , China , Diptera/genetics , Male
16.
Mol Cell Biochem ; 357(1-2): 209-15, 2011 Nov.
Article in English | MEDLINE | ID: mdl-21633900

ABSTRACT

SIAH-1, an E3 ubiquitin ligase, plays an important role in regulating cell cycle, tumorigenesis and several neurodegenerative diseases. In this study, we found a novel SIAH-1-interacting protein, EEF1D (Eukaryotic translation elongation factor 1 delta). The interaction was confirmed in vitro and in vivo, and both proteins were co-localized in the cytoplasm. The Cys-rich domain of SIAH-1 was essential for its interaction with EEF1D. Overexpressing SIAH-1 had no effect on the protein level of EEF1D, implying that EFF1D is not the substrate of SIAH-1. In contrast, the protein level of SIAH-1 increased significantly in the cells overexpressing EEF1D. Increased amount of SIAH-1 was caused by the EEF1D-mediated inhibition of auto-ubiquitination and degradation of SIAH-1. Furthermore, EEF1D was able to inhibit the degradation of HPH2, a known substrate of SIAH-1. Taken together, our data suggest EFF1D functions as a novel negative regulator of SIAH-1.


Subject(s)
Cytoplasm/metabolism , Nuclear Proteins/metabolism , Peptide Elongation Factor 1/metabolism , Ubiquitin-Protein Ligases/metabolism , Cysteine/metabolism , Gene Expression Regulation , HEK293 Cells , HeLa Cells , Humans , Nuclear Proteins/genetics , Peptide Elongation Factor 1/genetics , Polycomb Repressive Complex 2 , Protein Interaction Domains and Motifs/genetics , Proteolysis , Transcription Factors/genetics , Transcription Factors/metabolism , Ubiquitin-Protein Ligases/genetics
17.
Mitochondrial DNA B Resour ; 6(3): 1183-1185, 2021 Mar 24.
Article in English | MEDLINE | ID: mdl-33796780

ABSTRACT

In this study, we present the complete mitogenome of Lathyrophthalmu quinquestriatus (Fabricius, 1794), which has a total length of 16,198 base pairs and includes 13 protein-coding genes, 22 transfer RNA genes, 2 ribosomal RNA genes and one putative control region. Most PCGs started with ATN codons except COX1 (CAA), and ended with TAA, TAG (ND3) or single T(ND5). The results of phylogenetic tree reconstruction show that the monophyly of subfamily Eristalinae is not supported, and the closer relationship between genus Lathyrophthalmus and Eristalinus.

18.
Biochem Biophys Res Commun ; 392(3): 409-14, 2010 Feb 12.
Article in English | MEDLINE | ID: mdl-20079715

ABSTRACT

Tumor necrosis factor-associated factor 6 (TRAF6) is an essential adaptor protein for IL-1R or TLR-mediated NF-kappaB signaling pathway activation. In previous work we have found NUMBL interacts with TAB2 and negatively regulates NF-kappaB signaling pathway. Here, we report that NUMBL directly binds to TRAF6 in vivo and in vitro. NUMBL down-regulates TRAF6 protein level and shortens its half-life. Furthermore, knockdown of NUMBL significantly increases endogenous TRAF6 protein level in the cultured cortical neurons. In vivo ubiquitination assays indicate that NUMBL promotes the assembly of K48-linked polyubiquitination chains on TRAF6, but has no significant effect on its K63-linked polyubiquitination. Our results collectively reveal that NUMBL interacts with TRAF6 and promotes the degradation of TRAF6 in vivo, leading to the inhibition of NF-kappaB signaling pathway.


Subject(s)
Cerebral Cortex/metabolism , Intracellular Signaling Peptides and Proteins/metabolism , Neurons/metabolism , TNF Receptor-Associated Factor 6/metabolism , Ubiquitination , Cell Line , Gene Knockdown Techniques , Humans , Intracellular Signaling Peptides and Proteins/genetics , NF-kappa B/antagonists & inhibitors , NF-kappa B/metabolism , Protein Structure, Tertiary
19.
Biochem Biophys Res Commun ; 397(3): 391-6, 2010 Jul 02.
Article in English | MEDLINE | ID: mdl-20471960

ABSTRACT

Polycomb Group (PcG) genes encode proteins that form large multimeric and chromatin-associated complexes implicated in the stable repression of developmentally essential genes. HPH2, the Homo sapiens polyhomeotic homologue 2, functions as one of the subunits of PcG complex 1. In our study, SIAH-1, an E3 ligase, could directly associate with HPH2 both in vitro and in vivo. Both the cysteine-rich region of SIAH-1 and the PxVxAxP motif of HPH2 were essential for the interaction. HPH2 was co-localized with SIAH-1 in nuclei. Furthermore, SIAH-1 was able to facilitate the ubiquitination and degradation of HPH2 via ubiquitin-proteasome pathway in vivo. The ubiquitination activity was severely impaired in the SIAH-1 mutant that either lost E3 ligase activity or had weakened binding ability with HPH2, strongly suggesting that SIAH-1 was the direct E3 ligase of HPH2. Thus, our results propose a novel role of SIAH-1 in regulating the expression level of HPH2 through the ubiquitin-proteasome pathway.


Subject(s)
Nuclear Proteins/metabolism , Proteasome Endopeptidase Complex/metabolism , Transcription Factors/metabolism , Ubiquitin-Protein Ligases/metabolism , Ubiquitin/metabolism , Ubiquitination , Cell Line , HeLa Cells , Humans , Nuclear Proteins/genetics , Polycomb Repressive Complex 2 , Protein Stability , Two-Hybrid System Techniques , Ubiquitin-Protein Ligases/genetics
20.
Hepatology ; 50(1): 122-9, 2009 Jul.
Article in English | MEDLINE | ID: mdl-19441106

ABSTRACT

UNLABELLED: Amplification of 1q21 has been detected in 58% to 78% of primary hepatocellular carcinoma cases, suggesting that one or more oncogenes within the amplicon play a critical role in the development of this disease. The chromodomain helicase/adenosine triphosphatase DNA binding protein 1-like gene (CHD1L) is a recently identified oncogene localized at 1q21. Our previous studies have demonstrated that CHD1L has strong tumorigenic ability and confers high susceptibility to spontaneous tumors in a CHD1L-transgenic mouse model. In this study, we demonstrate that the antiapoptotic ability of CHD1L is associated with its interaction with Nur77, a critical member of a p53-independent apoptotic pathway. As the first cellular protein identified to bind Nur77, CHD1L is able to inhibit the nucleus-to-mitochondria translocation of Nur77, which is the key step of Nur77-mediated apoptosis, resulting in the hindrance of the release of cytochrome c and the initiation of apoptosis. Knock-down of CHD1L expression by RNA interference could rescue the mitochondrial targeting of Nur77 and the subsequent apoptosis. Further studies found that the C-terminal Macro domain of CHD1L is responsible for the interaction with Nur77, and a CHD1L mutant lacking residues 600-897 failed to interact with Nur77 and prevented Nur77-mediated apoptosis. More importantly, we found that the inhibition of Nur77-mediated apoptosis by endogenous CHD1L is a critical biological cellular process in hepatocarcinogenesis. CONCLUSION: We demonstrate in this study that overexpression of CHD1L could sustain tumor cell survival by preventing Nur77-mediated apoptosis.


Subject(s)
Carcinoma, Hepatocellular/enzymology , Carcinoma, Hepatocellular/pathology , Cell Nucleus , DNA Helicases/genetics , DNA-Binding Proteins/genetics , DNA-Binding Proteins/metabolism , Liver Neoplasms/enzymology , Liver Neoplasms/pathology , Mitochondria , Protein Transport , Receptors, Steroid/metabolism , Adenosine Triphosphatases/physiology , Cell Survival/genetics , Humans , Nuclear Receptor Subfamily 4, Group A, Member 1
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