Endosomal sorting complex required for transport (ESCRT) system drives various cellular processes, including endosome sorting, organelle biogenesis, vesicle transport, maintenance of plasma membrane integrity, membrane fission during cytokinesis, nuclear membrane reformation after mitosis, closure of autophagic vacuoles, and enveloped virus budding. Increasing evidence suggests that the ESCRT system can be hijacked by different family viruses for their proliferation. At different stages of the virus life cycle, viruses can interfere with or exploit ESCRT-mediated physiological processes in various ways to maximize their chance of infecting the host. In addition, many retroviral and RNA viral proteins possess "late domain" motifs, which can recruit host ESCRT subunit proteins to assist in virus endocytosis, transport, replicate, budding and efflux. Therefore, the "late domain" motifs of viruses and ESCRT subunit proteins could serve as promising drug targets in antiviral therapy. This review focuses on the composition and functions of the ESCRT system, the effects of ESCRT subunits and virus "late domain" motifs on viral replication, and the antiviral effects mediated by the ESCRT system, aiming to provide a reference for the development and utilization of antiviral drugs.
Endosomal Sorting Complexes Required for Transport/metabolism* ; Viruses/metabolism* ; Protein Transport ; Virus Replication ; Endosomes/metabolism* ; Virus Release

In eukaryotic cells, multivesicular bodies (MVBs) are required for trafficking of membrane proteins to lysosomes for selective destruction. The sorting of ubiquitylated membrane proteins into multivesicular bodies and the biogenesis of MVBs are mediated by the endosomal sorting complex required for transport (ESCRT). Topologically equivalent to the budding of intralumenal vesicles from the limiting membrane of the MVBs, the ESCRT complex is also involved in cytokinetic abscission, phagophore formation, and enveloped virus budding. Many retroviruses and RNA viruses encode "late-domain" motifs that are able to interact with the components of the ESCRT complex, and the interactions recruit ESCRT-III and VPS4 to the viral assembly and budding sites. Recently, few studies revealed that the ESCRT complex is also required for efficient egress of some DNA viruses, including Hepatitis B, Herpes simplex virus type-1, and Autographa californica multiple nucleopolyhedrovirus. Further examination of virus-ESCRT interactions should shed light on the detailed mechanism of virus assembly and budding.
Endosomal Sorting Complexes Required for Transport ; physiology ; Humans ; Viral Envelope Proteins ; metabolism ; Virus Assembly ; Virus Physiological Phenomena ; Virus Release ; Viruses ; growth & development

OBJECTIVE: To verify the effect of the mutant gene vps4b on the expression of tooth development-related proteins, dentin sialophosphoprotein (DSPP) and collagenⅠ (COL-Ⅰ). METHODS: Paraffin tissue sections of the first molar tooth germ were obtained from the heads of fetal mice at the embryonic stages of 13.5, 14.5, and 16.5 days and from the mandibles of larvae aged 2.5 and 7 days after birth. The immunohistochemical method was used to detect the expression and location of DSPP and COL-Ⅰ in wild-type mouse and vps4b knockout mouse. RESULTS: DSPP and COL-Ⅰ were not found in the bud and cap stages of wild-type mouse molar germ. In the bell stage, DSPP was positively expressed in the inner enamel epithelium and dental papilla, whereas COL-Ⅰ was strongly expressed in the dental papilla and dental follicle. During the secretory and mineralized periods, DSPP and COL-Ⅰ were intensely observed in ameloblasts, odontoblasts, and dental follicles, but COL-Ⅰ was also expressed in the dental papilla. After vps4b gene knockout, DSPP was not expressed in the dental papilla of the bell stage and in the dental papilla and dental follicle of the secretory phase. The expression position of COL-Ⅰ in the bell and mineralization phase was consistent with that in the wild-type mice. Moreover, the expression of COL-Ⅰ in the dental papilla changed in the secretory stage. CONCLUSIONS Gene vps4b plays a significant role in the development of tooth germ. The expression of DSPP and COL-Ⅰ may be controlled by gene vps4b and regulates the development of tooth dentin and cementum together with vps4b.
ATPases Associated with Diverse Cellular Activities ; genetics ; Animals ; Collagen ; metabolism ; Endosomal Sorting Complexes Required for Transport ; genetics ; Extracellular Matrix Proteins ; metabolism ; Mice ; Mice, Knockout ; Molar ; Odontoblasts ; Phosphoproteins ; metabolism ; Sialoglycoproteins ; metabolism ; Tooth Germ

Chemically defined medium is widely used for culturing mouse embryonic stem cells (mESCs), in which N2B27 works as a substitution for serum, and GSK3β and MEK inhibitors (2i) help to promote ground-state pluripotency. However, recent studies suggested that MEKi might cause irreversible defects that compromise the developmental potential of mESCs. Here, we demonstrated the deficient bone morphogenetic protein (BMP) signal in the chemically defined condition is one of the main causes for the impaired pluripotency. Mechanistically, activating the BMP signal pathway by BMP4 could safeguard the chromosomal integrity and proliferation capacity of mESCs through regulating downstream targets Ube2s and Chmp4b. More importantly, BMP4 promotes a distinct in vivo developmental potential and a long-term pluripotency preservation. Besides, the pluripotent improvements driven by BMP4 are superior to those by attenuating MEK suppression. Taken together, our study shows appropriate activation of BMP signal is essential for regulating functional pluripotency and reveals that BMP4 should be applied in the serum-free culture system.
Animals ; Bone Morphogenetic Protein 4/metabolism* ; Cell Differentiation ; Chromosomal Instability ; Endosomal Sorting Complexes Required for Transport ; Mice ; Mitogen-Activated Protein Kinase Kinases/metabolism* ; Mouse Embryonic Stem Cells/cytology* ; Pluripotent Stem Cells/cytology* ; Signal Transduction ; Ubiquitin-Conjugating Enzymes

This study examined the anti-hepatitis B virus (HBV) effect of wild-type (WT) vacuolar protein sorting 4B (VPS4B) and its dominant negative (DN) mutant VPS4B-K180Q in vivo in order to further explore the relationship between HBV and the host cellular factor VPS4. VPS4B gene was amplified from Huh7 cells by RT-PCR and cloned into the eukaryotic expression vector pXF3H. Then, the VPS4B plasmid and the VPS4B-K180Q mutation plasmid were constructed by using the overlap extension PCR site-directed mutagenesis technique. VPS4B and HBV vectors were co-delivered into mice by the hydrodynamic tail-vein injection to establish HBV vector-based models. Quantities of HBsAg and HBeAg in the mouse sera were determined by ElectroChemiLuminescence (ECL). HBV DNA in sera was measured by real-time quantitative PCR. Southern blot analysis was used to assay the intracellular HBV nuclear capsid-related DNA, real-time quantitative PCR to detect the HBV-related mRNA and immunohistochemical staining to observe the HBcAg expression in the mouse liver tissues. Our results showed that VPS4B and its mutant VPS4B-K180Q could decrease the levels of serum HBsAg, HBeAg and HBV-DNA. In addition, the HBV DNA replication and the mRNA level of HBV in the liver tissues of treated mice could be suppressed by VPS4B and VPS4B-K180Q. It was also found that VPS4B and VPS4B-K180Q had an ability to inhibit core antigen expression in the infected mouse liver. Furthermore, the anti-HBV effect of mutant VPS4B-K180Q was more potent than that of wild-type VPS4B. Taken together, it was concluded that VPS4B and its DN mutant VPS4B-K180Q have anti-HBV effect in vivo, which helps develop molecular therapeutic strategies for HBV infection.
ATPases Associated with Diverse Cellular Activities ; Adenosine Triphosphatases ; physiology ; Animals ; Endosomal Sorting Complexes Required for Transport ; physiology ; Female ; Genes, Dominant ; genetics ; Hepatitis B ; metabolism ; virology ; Hepatitis B virus ; physiology ; Liver ; virology ; Mice ; Mice, Inbred BALB C ; Mutation ; genetics ; Virus Inactivation

OBJECTIVETo study the feasibility of using methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA) for the detection of DNA methylation in placenta tissue.

METHODSFor blood cells from 13 non-pregnant women and 9 euploid placenta, the ratios of DNA methylation were evaluated for 4 genes including CGI149, CGI113, HLCS and ACTB with MS-MLPA and bisulfite sequencing, respectively.

RESULTSThe methylation ratio of the ACTB gene was 0-0.1 for the blood cells when the digestion control was completely digested. The cutoff value for the methylation ratio of MS-MLPA has been determined as 0.1. For the 9 placenta samples, results of MS-MLPA and bisulfite sequencing were concordant for all of the four genes.

CONCLUSIONMS-MLPA is an effective alternative to bisulfite sequencing for the assessment of methylation ratios in placental tissues.

Actins ; genetics ; Adult ; Carbon-Nitrogen Ligases ; genetics ; CpG Islands ; genetics ; DNA Methylation ; Endosomal Sorting Complexes Required for Transport ; genetics ; Feasibility Studies ; Female ; Humans ; Multiplex Polymerase Chain Reaction ; methods ; Placenta ; metabolism ; Pregnancy ; Reproducibility of Results ; Ribosomal Proteins ; genetics ; Young Adult

OBJECTIVE: To study whether TGF-α possesses similar EGF effect of enforcing neuroendocrine differentiation (NED) in prostate cancer cell line DU145 and determine the influence of NED induced by TGF-α on chemoresistance. METHODS: DU145 cells were divided into 3 groups: a group with 2% FBS, a group with 2%FBS+TGF-α 5 ng/mL and a group with 2%FBS+TGF-α 10 ng/mL. Morphological change in DU145 cells was observed after TGF-α treatment. Expression levels of NSE mRNA were detected with real time RT-PCR. Western blot was used to detect the expression levels of protein NSE, P-gp, MRP1 and Bcl-2. Cell cycles of DU145 cells in the 3 groups were examined with flow cytometry. MTT assay was used to evaluate the influence of TGF-α in chemoresistance. RESULTS: Compared with DU145 cells cultured with 2% FBS, cells treated with 2% FBS+TGF-α were pleomorphic and pseudopodia extended. The expression level of NSE mRNA upregulated to (3.6±0.5) folds (P<0.05) and (10.1±0.1) folds (P<0.01). Western blot showed that the expression levels of protein NSE, Bcl-2, and MRP1 increased after treatment with different concentrations of TGF-α; P-gp was not detected. The proportion of DU145 cells in phase G1 decreased; proportions of cells in phase S and phase G2/M were increased after TGF-α treatment (5 μg/mL). At the same time, chemoresistance of DU145 cells to cisplatin increased. CONCLUSION TGF-α can increase NED in DU145 cells and enforce the chemoresistance to cisplatin.
Antineoplastic Agents ; pharmacology ; Cell Line, Tumor ; Cisplatin ; pharmacology ; Drug Resistance, Neoplasm ; drug effects ; Endosomal Sorting Complexes Required for Transport ; pharmacology ; Humans ; Male ; Prostatic Neoplasms ; metabolism ; pathology ; Transforming Growth Factor alpha ; pharmacology

To investigate the effects of HIV-1 infection on the expression of host factors TSG101 (Tumor Susceptibility Gene 101) and Alix (ALG-2-interacting protein X). HIV-1 infectious clone pNL4-3 was used to infect TZM-bl, PM1, Jurkat cell lines and human peripheral blood mononuclear cells (PBMC). Twenty-four hours post-infection, the infected or uninfected cells were harvested respectively for extraction of total RNAs and total cellular proteins, which were subsequently used in RT-PCR and Western-blotting respectively to quantify TSG101 and Alix, respectively. Our data showed that HIV-1 infection resulted in various influences on the expression of TSG101 and Alix in the cell lines and the primary PBMC. A down-regulation was mainly observed in the cell lines, whereas an up-regulation of TSG101 was identified in primary PBMC. Three patterns were observed for down-regulation, including dual down-regulation of TSG101 and Alix for Jurkat cells, single down-regulation of Alix for TZM-bl cells and marginal or no influence on PM1 cells. The dual down-regulation of Alix and TSG101 in Jurkat cells coincided with less expression of HIV-1 p24 protein. This is the first-line evidence that HIV-1 infection affects the expression of host factors TSG101 and Alix, the down-regulation of these molecules may influence the HIV-1 replication. The underlying mechanism remains to be addressed.
Calcium-Binding Proteins ; genetics ; metabolism ; Cell Cycle Proteins ; genetics ; metabolism ; DNA-Binding Proteins ; genetics ; metabolism ; Endosomal Sorting Complexes Required for Transport ; genetics ; metabolism ; Gene Expression Regulation ; HEK293 Cells ; HIV-1 ; physiology ; Humans ; Jurkat Cells ; Leukocytes, Mononuclear ; metabolism ; virology ; RNA, Messenger ; genetics ; metabolism ; Transcription Factors ; genetics ; metabolism

OBJECTIVETo explore whether docetaxel-resistant cells (MCF-7/Doc) and doxorubicin-resistant cells (MCF-7/ADM) can secrete Exosomes and their potential role in cell-cell drug-resistance transfer.

METHODSExosomes were extracted from the cell culture supernatants of MCF-7/Doc and MCF-7/ADM cells by fractionation ultracentrifugation, and were identified by transmission electron microscopy and Western blot analysis. GFP-MCF-7/S, a breast cancer parental sensitive cell line stably expressing green fluorescent protein (GFP), was constructed by recombinant lentiviral vector with GFP. Then the resistance experiment of cells and the experiment of resistance transfer by exosomes were designed to observe the phenomenon of cell-to-cell drug-resistance transfer.

RESULTSSimilar to the breast cancer parental sensitive cells (MCF-7/S), the breast cancer resistant sublines could secrete exosomes, which exhibited round or elliptic shape ranging from 30 to 100 nm in diameter with intact membrane, and only expressed the protein marker of exosomes, Tsg101, did not express the endoplasmic reticulum marker calnexin. After MCF-7/S, MCF-7/DOC and MCF-7/ADM cells we cocultured with GFP-MCF-7/S cells for 72 h, there were no significant differences in the expression of fluorescence-labeled cells among the four groups. When treated by the drug ADM or DOC for 24 hours, the MCF-7/DOC+GFP-MCF-7/S group was in favor of a significant higher survival rate of fluorescence-labeled cells compared with the MCF-7/S+GFP-MCF-7/S group (65.5% vs. 25.5%, P < 0.001), and so did the MCF-7/ADM+GFP-MCF-7/S group (53.6% vs. 25.4%, P < 0.001). The exosomes extracted from MCF-7/S, MCF-7/DOC and MCF-7/ADM cells were cultured with the GFP-MCF-7/S cells for 48 h. Among these groups, no significant differences in the expression of fluorescence-labeled cells were found. After treated by the drug ADM or DOC for 24 hours, the exosomes extracted from MCF-7/DOC+GFP-MCF-7/S group was associated with a significant higher survival rate of fluorescence-labeled cells compared with the exosomes extracted from MCF-7/S+GFP-MCF-7/S group (59.9% vs. 32.4%, P < 0.001), and so did the exosomes extracted from the MCF-7/ADM)+GFP-MCF-7/S group (58.3% vs. 27.2%, P < 0.001).

CONCLUSIONOur results suggest that drug-resistance can be transferred between breast cancer cells, and exosomes are probably the transporter of the drug resistance.

Antibiotics, Antineoplastic ; pharmacology ; Antineoplastic Agents ; pharmacology ; Cell Survival ; Coculture Techniques ; DNA-Binding Proteins ; metabolism ; Doxorubicin ; pharmacology ; Drug Resistance, Neoplasm ; Endosomal Sorting Complexes Required for Transport ; metabolism ; Exosomes ; metabolism ; pathology ; Green Fluorescent Proteins ; metabolism ; Humans ; MCF-7 Cells ; pathology ; Taxoids ; pharmacology ; Transcription Factors ; metabolism

BACKGROUNDTwo recent whole-exome sequencing researches identifying somatic mutations in the ubiquitin-specific protease 8 (USP8) gene in pituitary corticotroph adenomas provide exciting advances in this field. These mutations drive increased epidermal growth factor receptor (EGFR) signaling and promote adrenocorticotropic hormone (ACTH) production. This study was to investigate whether the inhibition of USP8 activity could be a strategy for the treatment of Cushing's disease (CD).

METHODSThe anticancer effect of USP8 inhibitor was determined by testing cell viability, colony formation, apoptosis, and ACTH secretion. The immunoblotting and quantitative reverse transcription polymerase chain reaction were conducted to explore the signaling pathway by USP8 inhibition.

RESULTSInhibition of USP8-induced degradation of receptor tyrosine kinases including EGFR, EGFR-2 (ERBB2), and Met leading to a suppression of AtT20 cell growth and ACTH secretion. Moreover, treatment with USP8 inhibitor markedly induced AtT20 cells apoptosis.

CONCLUSIONSInhibition of USP8 activity could be an effective strategy for CD. It might provide a novel pharmacological approach for the treatment of CD.

Adrenocorticotropic Hormone ; metabolism ; Animals ; Apoptosis ; drug effects ; Cell Proliferation ; drug effects ; physiology ; Cell Survival ; drug effects ; physiology ; Endopeptidases ; metabolism ; Endosomal Sorting Complexes Required for Transport ; antagonists & inhibitors ; metabolism ; Enzyme Inhibitors ; pharmacology ; Humans ; Indenes ; pharmacology ; Mice ; Pyrazines ; pharmacology ; Receptor, Epidermal Growth Factor ; metabolism ; Ubiquitin Thiolesterase ; antagonists & inhibitors ; metabolism