Virus hijacking ESCRT system to promote self-replication: a review / 生物工程学报

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.

Cushing disease due to a somatic USP8 mutation in a patient with evolving pituitary hormone deficiencies due to a germline GH1 splicing variant

SUMMARY We present the unique case of an adult Brazilian woman with severe short stature due to growth hormone deficiency with a heterozygous G to T substitution in the donor splice site of intron 3 of the growth hormone 1 (GH1) gene (c.291+1G>T). In this autosomal dominant form of growth hormone deficiency (type II), exon 3 skipping results in expression of the 17.5 kDa isoform of growth hormone, which has a dominant negative effect over the bioactive isoform, is retained in the endoplasmic reticulum, disrupts the Golgi apparatus, and impairs the secretion of other pituitary hormones in addition to growth hormone deficiency. This mechanism led to the progression of central hypothyroidism in the same patient. After 5 years of growth and thyroid hormone replacement, at the age of 33, laboratory evaluation for increased weight gain revealed high serum and urine cortisol concentrations, which could not be suppressed with dexamethasone. Magnetic resonance imaging of the sella turcica detected a pituitary macroadenoma, which was surgically removed. Histological examination confirmed an adrenocorticotropic hormone (ACTH)-secreting pituitary macroadenoma. A ubiquitin-specific peptidase 8 (USP8) somatic pathogenic variant (c.2159C>G/p.Pro720Arg) was found in the tumor. In conclusion, we report progression of isolated growth hormone deficiency due to a germline GH1 variant to combined pituitary hormone deficiency followed by hypercortisolism due to an ACTH-secreting macroadenoma with a somatic variant in USP8 in the same patient. Genetic studies allowed etiologic diagnosis and prognosis of this unique case.

Expressions of cytokeratin 14 and proliferating cell nuclear antigen in the Hertwig's epithelial root sheath of a Vps4b knockout mouse / 华西口腔医学杂志

OBJECTIVES@#The effect of Vps4b gene mutation on the expressions of cytokeratin 14 (CK14) and proliferating cell nuclear antigen (PCNA) in the Hertwig's epithelial root sheath (HERS) is investigated.@*METHODS@#The bilateral mandibular tissues of mouse on postnatal days 5, 9, 11, 15, and 19 were removed. The mandibular first molar tissue sections were obtained after paraffin embedding. The CK14 and PCNA expressions in the epithelial root sheath of the normal mouse and Vps4b knockout mouse were compared through immunohistochemistry.@*RESULTS@#On postnatal day 5, the normal mouse began to form HERS and had a strong positive PCNA expression in the HERS cells; on postnatal day 9, the HERS structure was continuous, and PCNA was positive in the HERS cells; on postnatal day 11, a small portion of HERS began to break, and PCNA was weakly positive in the HERS cells; on postnatal day 15, HERS continued to fracture; PCNA was weakly and positively expressed in the HERS cells on the root surface; on postnatal day 19, the tooth root reached normal physiological length, and PCNA was positively expressed in the HERS cells of the terminal part. Similar to the normal mouse, the gene knockout mouse also formed a HERS structure on postnatal day 5. However, HERS began to break on postnatal day 9. On postnatal day 19, only a few fragments of HERS were found on the root surface, and the root development was immature. Moreover, the expression intensity of PCNA in the gene knockout mouse was decreased.@*CONCLUSIONS@#The Vps4b gene mutation may change the CK14 and PCNA expressions, leading to abnormal root development.

VPS4B mutation impairs the osteogenic differentiation of dental follicle cells derived from a patient with dentin dysplasia type I / 国际口腔科学杂志·英文版

A splicing mutation in VPS4B can cause dentin dysplasia type I (DD-I), a hereditary autosomal-dominant disorder characterized by rootless teeth, the etiology of which is genetically heterogeneous. In our study, dental follicle cells (DFCs) were isolated and cultured from a patient with DD-I and compared with those from an age-matched, healthy control. In a previous study, this DD-I patient was confirmed to have a loss-of-function splicing mutation in VPS4B (IVS7 + 46C > G). The results from this study showed that the isolated DFCs were vimentin-positive and CK14-negative, indicating that the isolated cells were derived from the mesenchyme. DFCs harboring the VPS4B mutation had a significantly higher proliferation rate from day 3 to day 8 than control DFCs, indicating that VPS4B is involved in cell proliferation. The cells were then replenished with osteogenic medium to investigate how the VPS4B mutation affected osteogenic differentiation. Induction of osteogenesis, detected by alizarin red and alkaline phosphatase staining in vitro, was decreased in the DFCs from the DD-I patient compared to the control DFCs. Furthermore, we also found that the VPS4B mutation in the DD-I patient downregulated the expression of osteoblast-related genes, such as ALP, BSP, OCN, RUNX2, and their encoded proteins. These outcomes confirmed that the DD-I-associated VPS4B mutation could decrease the capacity of DFCs to differentiate during the mineralization process and may also impair physiological root formation and bone remodeling. This might provide valuable insights and implications for exploring the pathological mechanisms underlying DD-I root development.

Spatio-temporal expression of dentin sialophosphoprotein and collagen Ⅰ during molar tooth germ development in vps4b knockout mouse / 华西口腔医学杂志

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.

Inhibition of Ubiquitin-specific Peptidase 8 Suppresses Adrenocorticotropic Hormone Production and Tumorous Corticotroph Cell Growth in AtT20 Cells / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Two 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).</p><p><b>METHODS</b>The 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.</p><p><b>RESULTS</b>Inhibition 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.</p><p><b>CONCLUSIONS</b>Inhibition of USP8 activity could be an effective strategy for CD. It might provide a novel pharmacological approach for the treatment of CD.</p>

Study on the association of USP8 gene polymorphisms with male infertility in ethnic Han Chinese from Sichuan / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To assess the association of single nucleotide polymorphisms (SNPs) of ubiquitin-specific protease 8 gene (USP8) with male infertility among ethnic Han Chinese from Sichuan.</p><p><b>METHODS</b>A total of 316 infertile males were recruited (case group), which included 72 severe oligozoospermic (SO) cases and 244 non-obstructive azoospermic (NOA) cases. The control group consisted of 149 fertile males. The genotypes of 4 SNPs (rs2241769, rs11857513, rs7174015 and rs3743044) were determined with a Sequenom MassArray technique. The frequencies of genotype, allele and haploptye were analyzed.</p><p><b>RESULTS</b>No significant difference was detected in the allelic or genotypic frequencies of the 4 SNPs between the two groups (P>0.05). Based on linkage disequilibrium analysis and haplotype construction, the frequency distribution of haplotype CAAG showed a significant difference between non-obstructive azoospermic patients and the controls (P=0.021).</p><p><b>CONCLUSION</b>The 4 SNPs (rs2241769, rs11857513, rs7174015 and rs3743044) of USP8 gene may not be associated with male infertility in ethnic Hans from Sichuan. While the haplotype CAAG may be a down-regulating factor for the risk of NOA.</p>

Association of NEDD4 gene polymorphisms with schizophrenia and its clinical characteristics in Chinese Han population / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To assess the association of neural precursor cell expressed developmentally down-regulated 4 (NEDD4) with schizophrenia.</p><p><b>METHODS</b>Five single nucleotide polymorphisms (SNPs) of the NEDD4 gene were genotyped by TaqMan SNP genotyping assay in an independent sample of 464 individuals with schizophrenia and 487 healthy controls from eastern Han Chinese population. Clinical data were collected with a general information questionnaire and Positive and Negative Syndrome Scale (PANSS).</p><p><b>RESULTS</b>Frequencies of rs3088077 (allelic: χ2=18.024, P=0.000; genotypic: χ2=16.634, P=0.000), rs7162435 (allelic: χ2=6.771, P=0.009; genotypic: χ2=7.352, P=0.025) and rs2303579 (allelic: χ2=11.253, P=0.001; genotypic: χ2=12.248, P=0.002) were found to be significant different between the two groups. Moreover, TT of rs7162435 was significantly correlated with scores of factors of excitement and hostility (14.53±3.925, F=3.551, P=0.029).</p><p><b>CONCLUSION</b>rs3088077, rs7162435 and rs2303579 of the NEDD4 gene may be associated with schizophrenia. Moreover, the TT genotype of rs7162435 may increase the severity of excitement and hostility. Our results may provide a clue for delineating the connection between the glutamate hypothesis of schizophrenia and ubiquitination.</p>

Extraction and identification of exosomes from drug-resistant breast cancer cells and their potential role in cell-to-cell drug-resistance transfer / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To 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.</p><p><b>METHODS</b>Exosomes 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.</p><p><b>RESULTS</b>Similar 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).</p><p><b>CONCLUSION</b>Our results suggest that drug-resistance can be transferred between breast cancer cells, and exosomes are probably the transporter of the drug resistance.</p>

Application of methylation-specific multiplex ligation-dependent probe amplification for the study of DNA methylation in placenta tissues / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To study the feasibility of using methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA) for the detection of DNA methylation in placenta tissue.</p><p><b>METHODS</b>For 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.</p><p><b>RESULTS</b>The 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.</p><p><b>CONCLUSION</b>MS-MLPA is an effective alternative to bisulfite sequencing for the assessment of methylation ratios in placental tissues.</p>

Exosomes: mediators of communication in eukaryotes

In addition to the established mechanisms of intercellular signaling, a new way of communication has gained much attention in the last decade: communication mediated by exosomes. Exosomes are nanovesicles (with a diameter of 40-120 nm) secreted into the extracellular space by the multivesicular endosome after its outer membrane fuses with the plasma membrane. Once released, exosomes modulate the response of the recipient cells that recognize them. This indicates that exosomes operate in a specific manner and participate in the regulation of the target cell. Remarkably, exosomes occur from unicellular organisms to mammals, suggesting an evolutionarily conserved mechanism of communication. In this review we describe the cascade of exosome formation, intracellular traffic, secretion, and internalization by recipient cells, and review their most relevant effects. We also highlight important steps that are still poorly understood.

Upregulation of SIRT1 by 17β-estradiol depends on ubiquitin-proteasome degradation of PPAR-γ mediated by NEDD4-1

17β-estradiol (E2) treatment of cells results in an upregulation of SIRT1 and a down-regulation of PPARγ. The decrease in PPARγ expression is mediated by increased degradation of PPARγ. Here we report that PPARγ is ubiquitinated by HECT E3 ubiquitin ligase NEDD4-1 and degraded, along with PPARγ, in response to E2 stimulation. The PPARγ interacts with ubiquitin ligase NEDD4-1 through a conserved PPXY-WW binding motif. The WW3 domain in NEDD4-1 is critical for binding to PPARΓ. NEDD4-1 overexpression leads to PPARγ ubiquitination and reduced expression of PPARγ. Conversely, knockdown of NEDD4-1 by specific siRNAs abolishes PPARΓ ubiquitination. These data indicate that NEDD4-1 is the E3 ubiquitin ligase responsible for PPARγ ubiquitination. Here, we show that NEDD4-1 delays cellular senescence by degrading PPARΓ expression. Taken together, our data show that E2 could upregulate SIRT1 expression via promoting the PPARΓ ubiquitination-proteasome degradation pathway to delay the process of cell senescence.

TGF-α increases neuroendocrine differentiation and strengthens chemoresistance in prostate cancer DU145 cells / 中南大学学报(医学版)

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.

Cellular ESCRT complex and its roles in enveloped viruses budding / 生物工程学报

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.

Identification of Nedd4 as a novel regulator in Hedgehog signaling / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Hedgehog (Hh) signaling plays an important role in both embryonic development and postnatal tissue homeostasis. Aberrant Hh activation results in a large variety of cancers. This study was designed to discover novel modulators in Hh signaling pathway.</p><p><b>METHODS</b>We performed yeast-two-hybrid screening and immunoprecipitation to identify the interaction of Nedd4 and Smo. To verify whether Nedd4 is involved in the regulation of Hh signaling, we monitored the activation of Gli-luciferase reporter by overexpressing Nedd4 together with Gli-luciferase reporter. In order to examine the role of endogenous Nedd4 in regulating Hh signaling, we used a short hairpin RNA (shRNA) interference strategy to silence the Nedd4 expression, and then perform dual-luciferase reporter assay. Statistical comparisons were performed by Student's t tests.</p><p><b>RESULTS</b>We showed that Nedd4 binds to Smo in the transfected HEK293 cells. Overexpression of Nedd4 alone did not significantly activate the Gli reporter compared to pcDNA3 control (Nedd4 group: dimethyl sulfoxide (DMSO), relative luciferase unit (RLU) 1.87 ± 0.41). However, Smo agonist (SAG)-stimulated activation of Gli-luciferase reporter was markedly potentiated in Nedd4 transfected cells (Nedd4 group: SAG, RLU 13.49 ± 1.04, P < 0.05), indicating that overexpression of Nedd4 increases Gli luciferase reporter activity and Nedd4-induced activation of Hh signaling is activity dependent. In Nedd4 knockdown NIH 3T3 cells, the luciferase reporter activity was measured basally and after SAG treatment. In scrambled cells, compared to DMSO, SAG could activate reporter activity by (4.16 ± 0.84)-fold. In Nedd4 knockdown cells, the luciferase reporter activation by SAG was significantly inhibited (SAG, RLU 1.72 ± 0.24, P < 0.05); knockdown of Nedd4 did not change the basal activity of luciferase activity (DMSO, RLU 0.86 ± 0.11), suggesting that the loss of Nedd4 expression diminishes Gli-dependent activity in the Hh pathway and the regulation of Nedd4 in the Hh signaling pathway is activity-dependent.</p><p><b>CONCLUSION</b>Nedd4 positively regulates the Hh pathway and provides a potential target for inhibiting Hh signaling in cancer therapy.</p>

Inhibition of HBV replication by VPS4B and its dominant negative mutant VPS4B-K180Q in vivo / 华中科技大学学报（医学）（英德文版）

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.

Neuronal Functions of ESCRTs

The endosomal sorting complexes required for transport (ESCRTs) regulate protein trafficking from endosomes to lysosomes. Recent studies have shown that ESCRTs are involved in various cellular processes, including membrane scission, microRNA function, viral budding, and the autophagy pathway in many tissues, including the nervous system. Indeed, dysfunctional ESCRTs are associated with neurodegeneration. However, it remains largely elusive how ESCRTs act in post-mitotic neurons, a highly specialized cell type that requires dynamic changes in neuronal structures and signaling for proper function. This review focuses on our current understandings of the functions of ESCRTs in neuronal morphology, synaptic plasticity, and neurodegenerative diseases.

Hrs inhibits citron kinase-mediated HIV-1 budding via its FYVE domain

Hepatocyte growth factor-regulated tyrosine kinase substrate (Hrs) is a key component of the endosomal sorting complexes required for transport and has been demonstrated to play a regulatory role in endocytosis/exocytosis and the accumulation of internal vesicles in multivesicular bodies. Citron kinase is a Ser/The kinase that we previously reported to enhance human immunodeficiency virus type 1 (HIV-1) virion production. However, the relationship between Hrs and citron kinase in HIV-1 production remains elusive. Here, we report that Hrs interacts with citron kinase via its FYVE domain. Overexpression of Hrs or the FYVE domain resulted in a significant decrease in HIV-1 virion production. Depletion of Hrs by RNA interference in HEK293T cells increased HIV-1 virion production and enhanced the activity of citron kinase. These data suggest that Hrs inhibits HIV-1 production by inhibiting citron kinase-mediated exocytosis.

Relationship between rs3865418 polymorphism of neural precursor cell expressed developmentally downregulated 4-like gene and obesity in Kazakh general population / 中国医学科学院学报

<p><b>OBJECTIVE</b>To investigate the relationships between rs3865418 polymorphism of neural precursor cell expressed developmentally downregulated 4-like gene and obesity in Kazakh general population.</p><p><b>METHODS</b>Based on a cross-sectional epidemiological study in a Kazakh general population, a case-control study was conducted. The rs3865418 polymorphism in a Kazakh general population (856 subjects, including 364 males and 492 females; 478 in obesity group and 378 in normal control group) was genotyped by TaqMan polymerase chain reaction, and the relationship between rs3865418 polymorphism and obesity was analyzed.</p><p><b>RESULTS</b>The rs3865418 polymorphism was successfully genotyped in 851 Kazakh subjects. The distribution of the genotypes and alleles of rs3865418 polymorphism did not differ significantly between the obesity group and normal control group in terms of general populations, males, and females (all P > 0.05). The waist circumference showed a tendency of C/C > C/T > T/T in males and C/C < C/T < T/T in females, but without statistical significance (P > 0.05).</p><p><b>CONCLUSIONS</b>The rs3865418 polymorphism of neural precursor cell expressed developmentally downregulated 4-like gene may not be associated with obesity in Kazakh general population. In other words, it is not a predisposing factor for obesity in Kazakh.</p>

HIV-1 infection affects the expression of host cell factor TSG101 and Alix / 病毒学报

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.