UBE2T mediates the stemness properties of breast cancer cells through the mTOR signaling pathway

Objectives:This study aimed to reveal the role and possible mechanism of the ubiquitin-conjugating enzyme 2T(UBE2T)in the biological activities of breast cancer stem cells(BCSCs).Methods:The specific protein and gene expression were quantified by Western blotting and quantitative real-time polymerase chain reaction,the proportion of BCSCs was examined by flow cytometry,and the self-renewal and proliferation of BCSCs were verified by serial sphere formation and soft agar.Results:Increasing expression of UBE2T was drastically found in breast cancer than that in adjacent tissues.Furthermore,UBE2T overexpression significantly increased the proportion of BCSCs in breast cancer cells and promoted their self-renewal and proliferation.Silent UBE2T exhibited the opposite functions.UBE2T increased the levels of the mammalian target of rapamycin and the phosphorylated mammalian target of rapamycin.Mammalian target of rapamycin(mTOR)inhibitor rapamycin inhibited the function of UBE2T in BCSCs.Conclusion:UBE2T plays a role in BCSCs through mTOR pathway and may suggest a novel therapeutic strategy for breast cancer.

CUL4B orchestrates mesenchymal stem cell commitment by epigenetically repressing KLF4 and C/EBPδ

Dysregulated lineage commitment of mesenchymal stem cells(MSCs)contributes to impaired bone formation and an imbalance between adipogenesis and osteogenesis during skeletal aging and osteoporosis.The intrinsic cellular mechanism that regulates MSC commitment remains unclear.Here,we identified Cullin 4B(CUL4B)as a critical regulator of MSC commitment.CUL4B is expressed in bone marrow MSCs(BMSCs)and downregulated with aging in mice and humans.Conditional knockout of Cul4b in MSCs resulted in impaired postnatal skeletal development with low bone mass and reduced bone formation.Moreover,depletion of CUL4B in MSCs aggravated bone loss and marrow adipose accumulation during natural aging or after ovariectomy.In addition,CUL4B deficiency in MSCs reduced bone strength.Mechanistically,CUL4B promoted osteogenesis and inhibited adipogenesis of MSCs by repressing KLF4 and C/EBPδexpression,respectively.The CUL4B complex directly bound to Klf4 and Cebpd and epigenetically repressed their transcription.Collectively,this study reveals CUL4B-mediated epigenetic regulation of the osteogenic or adipogenic commitment of MSCs,which has therapeutic implications in osteoporosis.

Unveiling the time-temperature dependence of metastability of supercooled liquid using nano-calorimetry

There is a lack of understanding of both the conversion of an unstable glass into a metastable supercooled liquid(MSL) upon heating and the metastability of MSLs. In this study, we investigated the time-and temperature-dependent metastability of an MSL using an advanced nano-calorimetric technique. The chosen Au-based metallic glass(Au MG) allowed adequate probing of its MSL in a temperature range between 10 and 70 K above the standard glass transition temperature. We found that the survival time of the MSL state is a quadratic function of temperature. Beyond this duration threshold, the sample undergoes fast crystallization even if it is below the crystallization temperature that is measured using differential scanning calorimetry.Employing transmission electron microscopy, we observed the formation of clusters with a partially ordered lattice structure during relaxation in the Au MG sample fabricated using a nano-calorimeter. The atomic ordering within the clusters was enhanced by increasing time and temperature in the MSL region. Once the as-produced glass entered the MSL stage upon heating followed by a quenching stage at a given rate, the mechanical properties of the quenched glass remained the same regardless of its holding temperature and duration within the MSL region. This work provides insights into the glass-MSL-crystal transformation and offers guidance for designing standard metallic glasses for property characterizations.

RECQL4 regulates DNA damage response and redox homeostasis in esophageal cancer

Objective:RECQL4(a member of the RECQ helicase family)upregulation has been reported to be associated with tumor progression in several malignancies.However,whether RECQL4 sustains esophageal squamous cell carcinoma(ESCC)has not been elucidated.In this study,we determined the functional role for RECQL4 in ESCC progression.Methods:RECQL4 expression in clinical samples of ESCC was examined by immunohistochemistry.Cell proliferation,cellular senescence,the epithelial-mesenchymal transition(EMT),DNA damage,and reactive oxygen species in ESCC cell lines with RECQL4 depletion or overexpression were analyzed.The levels of proteins involved in the DNA damage response(DDR),cell cycle progression,survival,and the EMT were determined by Western blot analyses.Results:RECQL4 was highly expressed in tumor tissues when compared to adjacent non-tumor tissues in ESCC(P<0.001)and positively correlated with poor differentiation(P=0.011),enhanced invasion(P=0.033),and metastasis(P=0.048).RECQL4 was positively associated with proliferation and migration in ESCC cells.Depletion of RECQL4 also inhibited growth of tumor xenografts in vivo.RECQL4 depletion induced G0/G1 phase arrest and cellular senescence.Importantly,the levels of DNA damage and reactive oxygen species were increased when RECQL4 was depleted.DDR,as measured by the activation of ATM,ATR,CHK1,and CHK2,was impaired.RECQL4 was also shown to promote the activation of AKT,ERK,and NF-k B in ESCC cells.Conclusions:The results indicated that RECQL4 was highly expressed in ESCC and played critical roles in the regulation of DDR,redox homeostasis,and cell survival.

CUL4B facilitates HBV replication by promoting HBx stabilization

Objective:Hepatitis B virus(HBV)infection is a major public health problem worldwide.However,the regulatory mechanisms underlying HBV replication remain unclear.Cullin 4 B-RING ubiquitin E3 ligase(CRL4 B)is involved in regulating diverse physiological and pathophysiological processes.In our study,we aimed to explain the role of CUL4 B in HBV infection.Methods:Cul4 b transgenic mice or conditional knockout mice,as well as liver cell lines with CUL4 B overexpression or knockdown,were used to assess the role of CUL4 B in HBV replication.Immunoprecipitation assays and immunofluorescence staining were performed to study the interaction between CUL4 B and HBx.Cycloheximide chase assays and in vivo ubiquitination assays were performed to evaluate the half-life and the ubiquitination status of HBx.Results:The hydrodynamics-based hepatitis B model in Cul4 b transgenic or conditional knockout mice indicated that CUL4 B promoted HBV replication(P<0.05).Moreover,the overexpression or knockdown system in human liver cell lines validated that CUL4 B increased HBV replication in an HBx-dependent manner.Importantly,immunoprecipitation assays and immunofluorescence staining showed an interaction between CUL4 B and HBx.Furthermore,CUL4 B upregulated HBx protein levels by inhibiting HBx ubiquitination and proteasomal degradation(P<0.05).Finally,a positive correlation between CUL4 B expression and HBV pg RNA level was observed in liver tissues from HBV-positive patients and HBV transgenic mice.Conclusions:CUL4 B enhances HBV replication by interacting with HBx and disrupting its ubiquitin-dependent proteasomal degradation.CUL4 B may therefore be a potential target for anti-HBV therapy.

Gut-on-a-chip for exploring the transport mechanism of Hg(II)

Animal models and static cultures of intestinal epithelial cells are commonly used platforms for exploring mercury ion(Hg(II))transport.However,they cannot reliably simulate the human intestinal microenvironment and monitor cellular physiology in situ;thus,the mechanism of Hg(II)transport in the human intestine is still unclear.Here,a gut-on-a-chip integrated with transepithelial electrical resistance(TEER)sensors and electrochemical sensors is proposed for dynamically simulating the formation of the physical intestinal barrier and monitoring the transport and absorption of Hg(II)in situ.The cellular microenvironment was recreated by applying fluid shear stress(0.02 dyne/cm^(2))and cyclic mechanical strain(1%,0.15 Hz).Hg(II)absorption and physical damage to cells were simultaneously monitored by electrochemical and TEER sensors when intestinal epithelial cells were exposed to different concentrations of Hg(II)mixed in culture medium.Hg(II)absorption increased by 23.59%when tensile strain increased from 1%to 5%,and the corresponding expression of Piezo1 and DMT1 on the cell surface was upregulated.

Regulation and function of histone acetyltransferase MOF

The mammalian MOF （male absent on the first）, a member of the MYST （MOZ, YBF2, SAS2, and Tip60） family of histone acetyltransferases （HATs）, is the major enzyme that catalyzes the acetylation of histone H4 on lysine 16. Acetylation of K16 is a prevalent mark associated with chromatin decondensation. MOF has recently been shown to play an essential role in maintaining normal cell functions. In this study, we discuss the important roles of MOF in DNA damage repair, apoptosis, and tumorigenesis. We also analyze the role of MOF as a key regulator of the core transcriptional network of embryonic stem cells.

Characterization of the immune defense related tissues,cells,and genes in amphioxus

Amphioxus is an important animal model for phylogenetic analysis,including comparative immunology.Exploring the immune system in amphioxus contributes to our understanding of the origin and evolution of the vertebrate immune system.We investigated the amphioxus immune system using ultrastructural examination and in situ hybridization.The expression patterns of TLR1(toll-like receptor 1),C1Q(complement component 1,q subcomponent),ECSIT(evolutionarily conserved signaling intermediate in Toll pathways),SoxC,DDAHa(Dimethylarginine dimethylaminohydrolase a),and NOS(nitric oxide synthase) show that these genes play key roles in amphioxus immunity.Our results suggest that the epidermis and alimentary canal epithelium may play important roles in immune defense,while macrophages located in the coelom and so-called lymph spaces may also be crucial immune cells.

HIV-1B gp120 genes from one patient with AIDS dementia complex can affect the secretion of tumor necrosis factor and interleukin lp in glial cells

Background HIV-1 infected and immune-activated macrophages and microglia secrete neurotoxins, such as tumor necrosis factor-a （TNF-a） and interleukin-113 （IL-113）, which play major role in the neuronal death. It has been shown that different HIV-1 variants have varying abilities to elicit secretion of TNF-a by peripheral blood mononuclear cell （PBMC）; however, whether the difference of gp120 gene could affect the secretion of TNF-a and IL-113 by glial cells is unknown. The aim of this study was to explore the association between gene diversity and induction of neurotoxic cytokines. Methods In this study, we constructed retroviral vectors MSCV-IRES-GFP/gp120 using HIV-1 gp120 genes isolated from four different tissues of one patient who died of AIDS dementia complex （ADC）. Recombinant retroviruses produced by cotransfection of MSCV-IRES-GFP/gp120, pCMV-VSV-G and pUMVC into 293T cells were collected and added into U87 glial cells. Concentrations of TNF-α and IL-1β secreted by transduced U87 cells were assayed with ELISA separately. Results The four HIV-1 gp120 were in the different branch of the neighbor-joining tree. Compared to the pMIG retrovirus （gp120-negative） or U87 cells, all the gp120-positive recombinant retroviruses induced more TNF-a （P 〈0.01） and IL-113 （P 〈0.01）. In addition, compared with the L/MIG retrovirus, all the three brain gp120-positive recombinant retroviruses induced less TNF-α （P 〈0.01） and IL-1β （P 〈0.01）. Conclusions HIV-1 gp120 could induce U87 cells secret more TNF-α and IL-1β again. The more important is that difference of HIV-1 gp120, especially cell-tropism may account for the different ability in eliciting secretion of TNF-α and IL-1 β, which might supply a novel idea helping understand the pathogenesis of ADC.

The histone acetyltransferase MOF is required for the cellular stress response

When exposing to environmental stress or internal damage,such as genotoxic stress,oxidative stress,and heat stress,cells produce a series of adaptive responses called cellular stress responses[1].The major proteins involved in cellular stress are heat shock proteins(HSPs).HSPs remain in a low expression level and display a diffused distribution in the nucleoplasm and cytoplasm under basal conditions.In response to various stress conditions。

Cullin 4B-RING E3 ligase complex in immune cell differentiation and function

CUL4B,which encodes the scaffold protein in the CRL4B complex,is a commonly mutated gene in X-linked intellectual disability[10,11].In addition to intellectual disability,patients with CUL4B mutations present with an elevated number of monocytes in peripheral blood[10],implying a role for CUL4B in regulating monocytes/macrophages.Monocytes/macrophages are critical players in innate immunity.Hung et al.found that depletion of CUL4B in myeloid cells aggravated lipopolysaccharide(LPS)-induced acute peritonitis[3].They further showed that after LPS stimulation,Cul4b-deficient macrophages secreted more chemokines than control macrophages,which might have accounted for the elevated infiltration of immune cells into the peritoneum[3].Our previous work demonstrated that myeloid-specific Cul4b-knockout mice exhibited reduced survival after LPS injection or Salmonella typhimurium infection compared to control mice[6].In contrast to work from Hung et al.,which showed that Cul4b-deficient macrophages secreted less TNFαand IL-6 after LPS stimulation[3],our works showed that deletion of CUL4B in macrophages increased the production of proinflammatory cytokines and decreased the expression of the anti-inflammatory cytokine IL-10 in response to the activation of Toll-like receptor(TLR).CUL4B regulation of macrophages relies on the ubiquitination activity of the CRL4B complex.The CRL4B complex catalyzes monoubiquitination of H2AK119 at the promoter of Pten,resulting in the repression of Pten transcription and subsequent activation of AKT and AKT-dependent inhibition of GSK3β,which suppresses TLR-triggered proinflammatory responses(Fig.1B)[6].

Mendelian randomization studies on atherosclerotic cardiovascular disease: evidence and limitations

Epidemiological research has revealed a galaxy of biomarkers, such as genes, molecules or traits, which are associated with increased risk of atherosclerotic cardiovascular diseases(ASCVD). However, the etiological basis remains poorly characterized.Mendelian randomization(MR) involves the use of observational genetic data to ascertain the roles of disease-associated risk factors and, in particular, differentiate those reflecting the presence or severity of a disease from those contributing causally to a disease. Over the past decade, MR has evolved into a fruitful approach to clarifying the causal relation of a biomarker with ASCVD and to verifying potential therapeutic targets for ASCVD. In this review, we selected high-quality MR studies on ASCVD, examined the causal relationship of a series of biomarkers with ASCVD, and elucidated the role of MR in validating biomarkers as a therapeutic target by comparing the results from MR studies and randomized clinical trials(RCTs) for the treatment of ASCVD. The good agreement between the results derived by MR and RCTs suggests that MR could be performed as a screening process before novel drug development. However, when designing and interpreting a MR study, the assumptions and limitations inherent in this approach should be taken into account. Novel methodological developments, such as sensitivity analysis, will help to strengthen the validity of MR studies.

CUL4B negatively regulates Toll-like receptor-triggered proinflammatory responses by repressing Pten transcription

Toll-like receptors (TLRs) play critical roles in innate immunity and inflammation. The molecular mechanisms by which TLR signaling is fine-tuned remain to be completely elucidated. Cullin 4B (CUL4B), which assembles the CUL4B-RING E3 ligase complex (CRL4B), has been shown to regulate diverse developmental and physiological processes by catalyzing monoubiquitination for histone modification or polyubiquitination for proteasomal degradation. Here, we identified the role of CUL4B as an intrinsic negative regulator of the TLR-triggered inflammatory response. Deletion of CUL4B in macrophages increased the production of proinflammatory cytokines and decreased anti-inflammatory cytokine IL-10 production in response to pathogens that activate TLR3, TLR4, or TLR2. Myeloid cell-specific Cul4b knockout mice were more susceptible to septic shock when challenged with lipopolysaccharide, polyinosinic-polycytidylic acid or Salmonella typhimurium infection. We further demonstrated that enhanced TLR-induced inflammatory responses in the absence of CUL4B were mediated by increased GSK3β activity. Suppression of GSK3β activity efficiently blocked the TLR-triggered increase in proinflammatory cytokine production and attenuated TLR-triggered death in Cul4b mutant mice. Mechanistically, CUL4B was found to negatively regulate TLR-triggered signaling by epigenetically repressing the transcription of Pten, thus maintaining the anti-inflammatory PI3K-AKT-GSK3β pathway. The upregulation of PTEN caused by CUL4B deletion led to uncontrolled GSK3β activity and excessive inflammatory immune responses. Thus, our findings indicate that CUL4B functions to restrict TLR-triggered inflammatory responses through regulating the AKT-GSK3β pathway.

A benzoxazine derivative specifically inhibits cell cycle progression in p53-wild type pulmonary adenocarcinoma cells

A fundamental aspect of cancer development is cancer cell proliferation.Seeking for chemical agents that can interfere with cancer cell growth has been of great interest over the years.In our study,we found that a benzoxazine derivative,(6-tert-butyl-3,4-dihydro-2Hbenzo[b][1,4]oxazin-3-yl)methanol(TBM),could inhibit cell growth and caused significant cell cycle arrest in pulmonary adenocarcinoma A549 and H460 cells with wild-type p53,while not affecting the cell cycle distribution in p53-deleted H1299 lung adenocarcinoma cells.Since P53 plays an important role in regulating cell cycle progression,we analyzed the protein level of p53 by Western blot,and detected a significant elevation of p53 level after TBM treatment in A549 and H460 cells.The data suggested that TBM might specifically inhibit the proliferation of p53 wild-type lung adenocarcinoma cells through a p53-dependent cell cycle control pathway.More interestingly,results indicated that TBM might serve as a useful tool for studying the molecular mechanisms of lung cancer cell growth and cell cycle control,especially for the biologic process regulated by P53.