Engineering a single ubiquitin ligase for the selective degradation of all activated ErbB receptor tyrosine kinases

Interrogating specific cellular activities often entails the dissection of posttranslational modifications or functional redundancy conferred by protein families, which demands more sophisticated research tools than simply eliminating a specific gene product by gene targeting or RNA interference. We have developed a novel methodology that involves engineering a single SCF(βTrCP)-based ubiquitin ligase that is capable of not only simultaneously targeting the entire family of ErbB receptor tyrosine kinases for ubiquitination and degradation, but also selectively recruiting only activated ErbBs. The engineered SCF(βTrCP) ubiquitin ligase effectively blocked ErbB signaling and attenuated oncogenicity in breast cancer cells, yet had little effect on the survival and growth of non-cancerous breast epithelial cells. Therefore, engineering ubiquitin ligases offers a simple research tool to dissect the specific traits of tumorigenic protein families, and provides a rapid and feasible means to expand the dimensionality of drug discovery by assessing protein families or posttranslational modifications as potential drug targets.

Serum N-terminal pro-brain natriuretic peptide level is a significant prognostic factor in patients with severe sepsis among Southwest Chinese population

BACKGROUND

This study aimed to determine the predictive value of elevated N-terminal pro-brain natriuretic peptide (NTproBNP) for mortality in patients with severe sepsis.

PATIENTS AND METHODS

This was a retrospective study in Emergency Department of Sichuan Provincial People's Hospital, and patients were screened between January 1, 2009 and December 31, 2011. Demographic and clinical data as well as Acute Physiology And Chronic Health Evaluation II (APACHE II) and Sepsis Organ Failure Assessment (SOFA) scores were collected within the first day of admission. Survival was determined to establish its association with the NT-proBNP using logistic regression and receiver operating characteristic (ROC) curve.

RESULTS

A total of 171 patients with severe sepsis were analyzed. The median APACHE IIⅡ and SOFA scores were 11 (IQR, 7-16) and 3 (IQR, 1-5), respectively. The median C-reactive protein (CRP), procalcitonin (PCT) and NT-proBNP was 10.3 mg/dL (IQR, 3.4-21.4 mg/dL), 0.4 ng/mL (IQR, 0.2-3.6 ng/mL), and 954 (321-1576) pg/mL, respectively. The median NT-proBNP in survivors was 584 pg/mL (IQR, 321-875 pg/mL) versus 1271 (IQR, 851-1576 pg/mL) in nonsurvivors (p < 0.001). In the ROC curves, the area value was 0.89 for serum NT-proBNP, and its potent cutoff value was 1500 pg/mL. After multivariate regression analysis, NT-proBNP was significantly correlated with the mortality of severe sepsis (OR = 1.58, 95% CI 1.36-1.77).

CONCLUSIONS

Serum NT-proBNP is frequently increased in severe sepsis patients, and non-survivors have higher levels than survivors. High levels of admission NT-proBNP are associated with mortality.

The Cul4A-DDB1 E3 ubiquitin ligase complex represses p73 transcriptional activity

The Cullin4A (cul4A)-dependent ligase (CDL4A) E3 has been implicated in a variety of biological processes, including cell cycle progression and DNA damage response. Remarkably, CDL4A exerts its function through both proteolytic and non-proteolytic events. Here, we show that the p53 family member p73 is able to interact with the CDL4A complex through its direct binding to the receptor subunit DNA-binding protein 1 (DDB1). As a result, the CDL4A complex is able to monoubiquitylate p73. Modification of p73 by CDL4A-mediated ubiquitylation does not affect p73 protein stability, but negatively regulates p73-dependent transcriptional activity. Indeed, genetic or RNA interference-mediated depletion of DDB1 induces the expression of several p73 target genes in a p53-independent manner. In addition, by exploiting a bioinformatic approach, we found that elevated expression of Cul4A in human breast carcinomas is associated with repression of p73 target genes. In conclusion, our findings add a novel insight into the regulation of p73 by the CDL4A complex, through the inhibition of its transcriptional function.

[A study on immunity enhancement of frozen human lung cancer cells in vitro.]

BACKGROUND

To investigate the mechanisms of cryo-immunotherapeutic effect.

METHODS

After the mixed culture of human lung cancer cells and autologous lymphocytes was conducted in vitro ,lymphocyte transformation rate (LTR) , soluble interleukin-2 receptor (SIL-2R) and interleukin-6 ( IL-6) in the supernatants of the frozen lung cancer cells and the control were detected. Meanwhile , the effects of the supernatants of the culture of frozen lung cancer cells and the control on the proliferation of autologous lung cancer cells were also determined with FCM measurement.

RESULTS

(1)The levels of SIL-2R , IL-6 and LTR in the group of frozen lung cancer cells were all highly significant higher than those in the group of the control ( P < 0. 01) . (2)The supernatant of the culture of the frozen lung cancer cells could remarkably inhibit the proliferation of the autologous lung cancer cells ( P < 0. 01) .

CONCLUSIONS

(1)Frozen lung cancer cells may improve the immune function of lymphocytes through promoting their activation , proliferation and secretion of cytokines. (2)The activation of immune competent cells by freezing can remarkably inhibit the proliferation of lung cancer cells. Therefore , freezing can irritate the body's anti-tumor immunity.

Dendritic cell-derived tumor necrosis factor α modifies airway epithelial cell responses

Mucosal dendritic cells (DC) are intimately associated with the airway epithelium and thus are ideally situated to be first responders to pathogens. We hypothesize that DC drive innate immune responses through early release of tumor necrosis factor (TNF) α, which drives airway epithelial cell responses. In a mouse model, TNFα release was significantly increased following a single exposure to German cockroach (GC) frass, an event independent of neutrophil recruitment into the airways. While lung epithelial cells and alveolar macrophages failed to release TNFα following GC frass exposure, bone marrow-derived DC (BMDC) produced substantial amounts of TNFα suggesting their importance as early responding cells. This was confirmed by flow cytometry of pulmonary myeloid DC. Addition of GC frass-pulsed BMDC or conditioned media from GC frass-pulsed BMDC to primary mouse tracheal epithelial cells (MTEC) or MLE-15 cells induced chemokine (C-C) motif ligand (CCL) 20 and granulocyte macrophage (GM) colony-stimulating factor (CSF), both of which are important for DC recruitment, survival and differentiation. Importantly, DC do not produce CCL20 or GM-CSF following allergen exposure. Blocking TNFα receptor 1 (TNFR1) completely abolished chemokine production, suggesting that BMDC-derived TNFα induced airway epithelial cell activation and enhancement of the innate immune response. Lastly, blocking TNFR1 in vivo resulted in significantly decreased CCL20 and GM-CSF production in the lungs of mice. Together, our data strongly suggest that DC-derived TNFα plays a crucial role in the initiation of innate immune responses through the modification of airway epithelial cell responses.

Mechanisms generating bistability and oscillations in microRNA-mediated motifs

The importance of post-transcriptional regulation by microRNAs (miRNAs) has recently been recognized in almost all cellular processes. When participating in cellular processes, miRNAs mainly mediate mRNA degradation or translational repression. Recently computational and experimental studies have identified an abundance of motifs involving miRNAs and transcriptional factors (TFs). The simplest motif is a two-node miRNA-mediated feedback loop (MFL) in which a TF regulates an miRNA and the TF itself is negatively regulated by the miRNA. In this paper we present a general computational model for the MFL based on biochemical regulations and explore its dynamics by using bifurcation analysis. Our results show that the MFL can behave either as switches or as oscillators, depending on the TF as a repressor or an activator. These functional features are consistent with the widespread appearance of miRNAs in fate decisions such as proliferation, differentiation, and apoptosis during development. We found that under the interplay of a TF and an miRNA, the MFL model can behave as switches for wide ranges of parameters even without cooperative binding of the TF. In addition, oscillations induced by the miRNA in the MFL model require neither an additional positive feedback loop, nor self-activation of the gene, nor cooperative binding of the TF, nor saturated degradation. Therefore, the MFL may provide a general network structure to induce bistability or oscillations. It is hoped that the results presented here will provide a new view on how gene expression is regulated by miRNAs and further guidance for experiments. Moreover, the insight gained from this study is also expected to provide a basis for the investigation of more complex networks assembled by simple building blocks.

Hypoglycemic effect and mechanism of a proteoglycan from ganoderma lucidum on streptozotocin-induced type 2 diabetic rats

BACKGROUND AND OBJECTIVES

Diabetes mellitus inducing a leading cause of morbidity are widespread in the entire globe. The present study was to investigate the antidiabetic potency and mechanism of a proteoglycan extract, named FYGL (Fudan-Yueyang-G. lucidum), from the fruiting bodies of Ganoderma Lucidum as published recently, using streptozotocin-induced type 2 diabetic mellitus (T2DM) rats.

MATERIAL AND METHODS

The T2DM model rats were treated with FYGL as well as metformin and rosiglitazone. The levels of plasma glucose and insulin were measured, and the expression and activity of the protein tyrosine phosphatase 1B (PTP1B) and the tyrosine phosphorylation level of the insulin receptor (IR) 3-subunit in the livers and skeletal muscles of the T2DM rats were analyzed by immunoprecipitation and Western blotting methods. In addition, the levels of free fatty acid and serum lipid profile were measured using commercial kits for those trailed rats.

RESULTS

The decrease in fasting plasma glucose and the increase in insulin concentration dose- and time-dependently in the T2DM rats treated by FYGL, comparable with that by the clinical drugs, metformin and rosiglitazone. The levels of the PTP1B expression and activity were decreased, and the tyrosine phosphorylation level of the IR 1-subunit was increased in the skeletal muscles of the T2DM rats. Furthermore, FYGL significantly decreased the levels of free fatty acid, triglyceride, total cholesterol and low density lipoprotein-cholesterol as well as increased the level of high density lipoprotein-cholesterol.

DISCUSSION

It is suggested that the hypoglycemic mechanisms of FYGL are caused by inhibition of the PTP1B expression and activity, consequently, regulation of the tyrosine phosphorylation level of the IR 13-subunit. As those results, FYGL also controlled the plasma biochemistry indexes relative to the type 2 diabetes-accompanied metabolic disorders. This is possibly the first report on the underlying mechanisms responsible for the antidiabetic effect of Ganoderma lucidum.

The association between bacterial colonization and inflammatory pattern in Chinese chronic rhinosinusitis patients with nasal polyps

BACKGROUND

Chronic rhinosinusitis with nasal polyps (CRSwNP) can be subdivided according to the mucosal inflammatory patterns. In mainland China, apart from interleukin (IL)-5-positive and IL-17-positive polyps, a large group of patients with IL-5/IL-17/interferon-gamma (IFNγ)-negative nasal polyps (referred to as key cytokine-negative (KCN) polyps) can be found.

OBJECTIVE

To further study the KCN polyps and evaluate the associations between bacterial colonization and mucosal inflammatory pattern in KCN vs IL-5-positive nasal polyps.

METHODS

Nasal polyp or nasal turbinate tissue was obtained from 89 Chinese CRSwNP patients and 36 nonatopic control subjects during surgery. Samples without and after SEB exposure were processed for the assessment of pro-inflammatory cytokines and mediators by immunoassay. Prior to surgery, nasal swabs were taken from each patient for microbiological evaluation.

RESULTS

Overall, 80% polyp tissue did not express IL-5, with about 70% (49/71) of these being KCN. Key cytokine-negative nasal polyps were characterized by the synthesis of mediators promoting neutrophilic inflammation (myeloperoxidase (MPO), IL-1β, IL-6 and IL-8), whereas IL-5-positive nasal polyps were characterized by the synthesis of mediators promoting eosinophilic inflammation (IL-5, ECP, total IgE and SE-IgE). Key cytokine-negative nasal polyps were associated with greater Gram-negative bacterial load compared with controls, while IL-5-positive nasal polyps were associated with greater Gram-positive bacterial colonization vs controls and KCN polyps.

CONCLUSION

Our findings suggest that the bacteria colonizing nasal polyps of CRSwNP patients may impact on or be determined by the presence/absence of IL-5.

Search for CP violation in τ±→K(S)0π±ντ decays at Belle

We report on a search for CP violation in τ(±)→K(S)(0)π(±)ν(τ) decays using a data sample of 699 fb(-1) collected by the Belle experiment at the KEKB electron-positron asymmetric-energy collider. The CP asymmetry is measured in four bins of the invariant mass of the K(S)(0)π(±) system and found to be compatible with zero with a precision of O(10(-3)) in each mass bin. Limits for the CP violation parameter Im(η(S)) are given at the 90% confidence level. These limits are |Im(η(S))| < 0.026 or better, depending on the parametrization used to describe the hadronic form factors, and improve upon previous limits by 1 order of magnitude.

Observation of X(3872)→J/ψγ and search for X(3872)→ψ'γ in B decays

We report a study of B→(J/ψγ)K and B→(ψ'γ)K decay modes using 772×10⁶ B ̅B events collected at the Υ(4S) resonance with the Belle detector at the KEKB energy-asymmetric e(+)e(-) collider. We observe X(3872)→J/ψγ and report the first evidence for χ(c2)→J/ψγ in B→(X_{c ̅cγ)K decays, while in a search for X(3872)→ψ'γ no significant signal is found. We measure the branching fractions, B(B(±)→X(3872)K(±))B(X(3872)→J/ψγ)=(1.78(-0.44)(+0.48)±0.12)×10(-6), B(B(±)→χ(c2)K(±))=(1.11(-0.34)(+0.36)±0.09)×10(-5), B(B(±)→X(3872)K(±))B(X(3872)→ψ'γ)<3.45×10⁶ (upper limit at 90% C.L.), and also provide upper limits for other searches.

Observation of transverse polarization asymmetries of charged pion pairs in e+e- annihilation near √s = 10.58 GeV

The interference fragmentation function translates the fragmentation of a quark with a transverse projection of the spin into an azimuthal asymmetry of two final-state hadrons. In e(+)e(-) annihilation the product of two interference fragmentation functions is measured. We report nonzero asymmetries for pairs of charge-ordered π(+)π(-) pairs, which indicate a significant interference fragmentation function in this channel. The results are obtained from a 672 fb(-1) data sample that contains 711 × 10(6) π(+)π(-) pairs and was collected at and near the Υ(4S) resonance, with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider.

Observation of the h(c)(1P) Using e+ e- collisions above the DD threshold

Using 586  pb(-1) of e+ e- collision data at E(c.m.) = 4170  MeV, produced at the Cornell Electron Storage Ring collider and collected with the CLEO-c detector, we observe the process e+ e- → π+ π- h(c)(1P). We measure its cross section to be 15.6±2.3±1.9±3.0  pb, where the third error is due to the external uncertainty on the branching fraction of ψ(2S) → π0 h(c)(1P), which we use for normalization. We also find evidence for e+ e- → ηh(c)(1P) at 4170 MeV at the 3σ level and see hints of a rise in the e+ e- → π+ π- h(c)(1P) cross section at 4260 MeV.

Numerical simulation of microneedles' insertion into skin

Microneedles have recently received much attention as a novel way for transdermal drug delivery. In this paper, a numerical simulation of the insertion process of the microneedle into human skin is reported using the finite element method. A multilayer skin model consisting of the stratum corneum, dermis and underlying hypodermis has been developed. The effective stress failure criterion has been coupled with the element deletion technique to predict the complete insertion process. The numerical results show a good agreement with the reported experimental data for the deformation and failure of the skin and the insertion force. The influences of the mechanical properties of the skin and the microneedle geometry (e.g. tip area, wall angle and wall thickness) on the insertion force are discussed. The numerical results are helpful for the optimum design of the microneedles for the transdermal drug delivery system.

Ursolic acid promotes robust tolerance to cardiac allografts in mice

Nuclear factor (NF)-κB is an important molecule in T cell activation. Our previous work has found that T cell-restricted NF-κB super-repressor (IκBαΔN-Tg) mice, expressing an inhibitor of NF-κB restricted to the T cell compartment, can permanently accept fully allogeneic cardiac grafts and secondary donor skin grafts. In this study, we explore if transient NF-κB inhibition by a small molecular inhibitor could induce permanent graft survival. Ursolic acid, a small molecular compound, dose-dependently inhibited T cell receptor (TCR)-triggered NF-κB nuclear translocation and T cell activation in vitro. In vivo, ursolic acid monotherapy prolonged significantly the survival of cardiac allograft in mice. Assisted with donor-specific transfusion (DST) on day 0, ursolic acid promoted 84·6% of first cardiac grafts to survive for more than 150 days. While the mice with long-term surviving grafts (LTS) did not reject the second donor strain hearts for more than 100 days without any treatment, they all promptly rejected the third-party strain hearts within 14 days. Interestingly, this protocol did not result in an increased proportion of CD4(+) CD25(+) forkhead box P3(+) regulatory T cells in splenocytes. That adoptive transfer experiments also did not support regulation was the main mechanism in this model. Splenocytes from LTS showed reduced alloreactivity to donor antigen. However, depletion of CD4(+) CD25(+) regulatory T cells did not alter the donor-reactivity of LTS splenocytes. These data suggest that depletion of donor-reactive T cells may play an important role in this protocol.