A novel small-molecular CCR5 antagonist promotes neural repair after stroke

Chemokine receptor 5 (CCR5) is one of the main co-receptors of HIV-1, and has been found to be a potential therapeutic target for stroke. Maraviroc is a classic CCR5 antagonist, which is undergoing clinical trials against stroke. As maraviroc shows poor blood-brain barrier (BBB) permeability, it is of interest to find novel CCR5 antagonists suitable for neurological medication. In this study we characterized the therapeutic potential of a novel CCR5 antagonist A14 in treating ischemic stroke mice. A14 was discovered in screening millions compounds in the Chemdiv library based on the molecular docking diagram of CCR5 and maraviroc. We found that A14 dose-dependently inhibited the CCR5 activity with an IC50 value of 4.29 μM. Pharmacodynamic studies showed that A14 treatment exerted protective effects against neuronal ischemic injury both in vitro and vivo. In a SH-SY5Y cell line overexpressing CCR5, A14 (0.1, 1 μM) significantly alleviated OGD/R-induced cell injury. We found that the expression of CCR5 and its ligand CKLF1 was significantly upregulated during both acute and recovery period in focal cortical stroke mice; oral administration of A14 (20 mg·kg-1·d-1, for 1 week) produced sustained protective effect against motor impairment. A14 treatment had earlier onset time, lower onset dosage and much better BBB permeability compared to maraviroc. MRI analysis also showed that A14 treatment significantly reduced the infarction volume after 1 week of treatment. We further revealed that A14 treatment blocked the protein-protein interaction between CCR5 and CKLF1, increasing the activity of CREB signaling pathway in neurons, thereby improving axonal sprouting and synaptic density after stroke. In addition, A14 treatment remarkably inhibited the reactive proliferation of glial cells after stroke and reduced the infiltration of peripheral immune cells. These results demonstrate that A14 is a promising novel CCR5 antagonist for promoting neuronal repair after ischemic stroke. A14 blocked the protein-protein interaction between CKLF1 and CCR5 after stroke by binding with CCR5 stably, improved the infarct area and promoted motor recovery through reversing the CREB/pCREB signaling which was inhibited by activated CCR5 Gαi pathway, and benefited to the dendritic spines and axons sprouting.

A rabies virus-based toolkit for efficient retrograde labeling and monosynaptic tracing

Analyzing the structure and function of the brain's neural network is critical for identifying the working principles of the brain and the mechanisms of brain diseases. Recombinant rabies viral vectors allow for the retrograde labeling of projection neurons and cell type-specific trans-monosynaptic tracing, making these vectors powerful candidates for the dissection of synaptic inputs. Although several attenuated rabies viral vectors have been developed, their application in studies of functional networks is hindered by the long preparation cycle and low yield of these vectors. To overcome these limitations, we developed an improved production system for the rapid rescue and preparation of a high-titer CVS-N2c-ΔG virus. Our results showed that the new CVS-N2c-ΔG-based toolkit performed remarkably: (1) N2cG-coated CVS-N2c-ΔG allowed for efficient retrograde access to projection neurons that were unaddressed by rAAV9-Retro, and the efficiency was six times higher than that of rAAV9-Retro; (2) the trans-monosynaptic efficiency of oG-mediated CVS-N2c-ΔG was 2-3 times higher than that of oG-mediated SAD-B19-ΔG; (3) CVS-N2c-ΔG could delivery modified genes for neural activity monitoring, and the time window during which this was maintained was 3 weeks; and (4) CVS-N2c-ΔG could express sufficient recombinases for efficient transgene recombination. These findings demonstrate that new CVS-N2c-ΔG-based toolkit may serve as a versatile tool for structural and functional studies of neural circuits.

Observation of high-energy neutrinos from the Galactic plane

The origin of high-energy cosmic rays, atomic nuclei that continuously impact Earth's atmosphere, is unknown. Because of deflection by interstellar magnetic fields, cosmic rays produced within the Milky Way arrive at Earth from random directions. However, cosmic rays interact with matter near their sources and during propagation, which produces high-energy neutrinos. We searched for neutrino emission using machine learning techniques applied to 10 years of data from the IceCube Neutrino Observatory. By comparing diffuse emission models to a background-only hypothesis, we identified neutrino emission from the Galactic plane at the 4.5σ level of significance. The signal is consistent with diffuse emission of neutrinos from the Milky Way but could also arise from a population of unresolved point sources.

A breakdown of metabolic reprogramming in microglia induced by CKLF1 exacerbates immune tolerance in ischemic stroke

Ischemic stroke is characterized by the presence of reactive microglia. However, its precise involvement in stroke etiology is still unknown. We used metabolic profiling and showed that chemokine like factor 1 (CKLF1) causes acute microglial inflammation and metabolic reprogramming from oxidative phosphorylation to glycolysis, which was reliant on the AMP-activated protein kinase (AMPK)-mammalian target of rapamycin (mTOR)-hypoxia inducible factor 1α (HIF-1α) signaling pathway. Once activated, microglia enter a chronic tolerant state as a result of widespread energy metabolism abnormalities, which reduces immunological responses, including cytokine release and phagocytosis. Metabolically dysfunctional microglia were also found in mice using genome-wide RNA sequencing after chronic administration of CKLF1, and there was a decrease in the inflammatory response. Finally, we showed that the loss of CKLF1 reversed the defective immune response of microglia, as indicated by the maintenance its phagocytosis to neutrophils, thereby mitigating the long-term outcomes of ischemic stroke. Overall, CKLF1 plays a crucial role in the relationship between microglial metabolic status and immune function in stroke, which prepares a potential therapeutic strategy for ischemic stroke.

Search for Unstable Sterile Neutrinos with the IceCube Neutrino Observatory

We present a search for an unstable sterile neutrino by looking for a resonant signal in eight years of atmospheric ν_{μ} data collected from 2011 to 2019 at the IceCube Neutrino Observatory. Both the (stable) three-neutrino and the 3+1 sterile neutrino models are disfavored relative to the unstable sterile neutrino model, though with p values of 2.8% and 0.81%, respectively, we do not observe evidence for 3+1 neutrinos with neutrino decay. The best-fit parameters for the sterile neutrino with decay model from this study are Δm_{41}^{2}=6.7_{-2.5}^{+3.9}  eV^{2}, sin^{2}2θ_{24}=0.33_{-0.17}^{+0.20}, and g^{2}=2.5π±1.5π, where g is the decay-mediating coupling. The preferred regions of the 3+1+decay model from short-baseline oscillation searches are excluded at 90% C.L.

Strong Constraints on Neutrino Nonstandard Interactions from TeV-Scale ν_{μ} Disappearance at IceCube

We report a search for nonstandard neutrino interactions (NSI) using eight years of TeV-scale atmospheric muon neutrino data from the IceCube Neutrino Observatory. By reconstructing incident energies and zenith angles for atmospheric neutrino events, this analysis presents unified confidence intervals for the NSI parameter ε_{μτ}. The best-fit value is consistent with no NSI at a p value of 25.2%. With a 90% confidence interval of -0.0041≤ε_{μτ}≤0.0031 along the real axis and similar strength in the complex plane, this result is the strongest constraint on any NSI parameter from any oscillation channel to date.

The versatile role of TREM2 in regulating of microglia fate in the ischemic stroke

Microglia are the earliest activated and the longest lasting immune cells after stroke, and they participate in almost all the pathological reactions after stroke. However, their regulatory mechanism has not been fully elucidated. Triggering receptor expressed on myeloid cells-2 (TREM2) is a cell surface receptor that is mainly expressed in microglia of the central nervous system. The receptor plays an important role in regulating microglia energy metabolism and phenotypic transformation. At present, TREM2 has been developed as a potential target for AD, coronary atherosclerosis and other diseases. However, TREM2 does not provide a systematic summary of the functional transformation and intrinsic molecular mechanisms of microglia after stroke. In this paper, we have summarized the functional changes of TREM2 in microglia after stroke in recent years, and found that TREM2 has important effects on energy metabolism, phagocytosis and anti-inflammatory function of microglia after stroke, suggesting that TREM2 is a potential therapeutic target for the treatment of stroke.

Search for Relativistic Magnetic Monopoles with Eight Years of IceCube Data

We present an all-sky 90% confidence level upper limit on the cosmic flux of relativistic magnetic monopoles using 2886 days of IceCube data. The analysis was optimized for monopole speeds between 0.750c and 0.995c, without any explicit restriction on the monopole mass. We constrain the flux of relativistic cosmic magnetic monopoles to a level below 2.0×10^{-19}  cm^{-2} s^{-1} sr^{-1} over the majority of the targeted speed range. This result constitutes the most strict upper limit to date for magnetic monopoles with β≳0.8 and up to β∼0.995 and fills the gap between existing limits on the cosmic flux of nonrelativistic and ultrarelativistic magnetic monopoles.

The Role of AMPARs Composition and Trafficking in Synaptic Plasticity and Diseases

AMPA receptors are tetrameric ionic glutamate receptors, which mediate 90% fast excitatory synaptic transmission induced by excitatory glutamate in the mammalian central nervous system through the activation or inactivation of ion channels. The alternation of synaptic AMPA receptor number and subtype is thought to be one of the primary mechanisms that involve in synaptic plasticity regulation and affect the functions in learning, memory, and cognition. The increasing of surface AMPARs enhances synaptic strength during long-term potentiation, whereas the decreasing of AMPARs weakens synaptic strength during the long-term depression. It is closely related to the AMPA receptor as well as its subunits assembly, trafficking, and degradation. The dysfunction of any step in these precise regulatory processes is likely to induce the disorder of synaptic transmission and loss of neurons, or even cause neuropsychiatric diseases ultimately. Therefore, it is useful to understand how AMPARs regulate synaptic plasticity and its role in related neuropsychiatric diseases via comprehending architecture and trafficking of the receptors. Here, we reviewed the progress in structure, expression, trafficking, and relationship with synaptic plasticity of AMPA receptor, especially in anxiety, depression, neurodegenerative disorders, and cerebral ischemia.

[Advances of Akkermansia muciniphila in regulating host functions]

Akkermansia muciniphila, abbreviated as AKK and found in 2004, is an oval-shaped gram-negative bacterium isolated from a human feal. A. muciniphila is widely present in the intestinal tract of human. Its specialization in mucin degradation makes it a key organism at the mucosal interface between the lumen and host cells. More and more studies have shown that it can play the role of probiotics. Notably, declined levels of A. muciniphila have been observed in patients with diabetes, liver disease, cardiovascular disease, inflammatory bowel disease, neurodegenerative diseases, etc. In addition, A. muciniphila combined with traditional Chinese medicine, exhibited higher effect on regulating host functions, but the underlying mechanism was still unclear, requiring further in-depth research. Therefore, the aims of this review are to summarize the main effects of A. muciniphila on host health and its relationship with traditional Chinese medicine, summarize the main problems, and provide a reference for the further research of A. muciniphila and traditional Chinese medicine.

eV-Scale Sterile Neutrino Search Using Eight Years of Atmospheric Muon Neutrino Data from the IceCube Neutrino Observatory

The results of a 3+1 sterile neutrino search using eight years of data from the IceCube Neutrino Observatory are presented. A total of 305 735 muon neutrino events are analyzed in reconstructed energy-zenith space to test for signatures of a matter-enhanced oscillation that would occur given a sterile neutrino state with a mass-squared differences between 0.01 and 100  eV^{2}. The best-fit point is found to be at sin^{2}(2θ_{24})=0.10 and Δm_{41}^{2}=4.5  eV^{2}, which is consistent with the no sterile neutrino hypothesis with a p value of 8.0%.

Characteristics of the Diffuse Astrophysical Electron and Tau Neutrino Flux with Six Years of IceCube High Energy Cascade Data

We report on the first measurement of the astrophysical neutrino flux using particle showers (cascades) in IceCube data from 2010-2015. Assuming standard oscillations, the astrophysical neutrinos in this dedicated cascade sample are dominated (∼90%) by electron and tau flavors. The flux, observed in the sensitive energy range from 16 TeV to 2.6 PeV, is consistent with a single power-law model as expected from Fermi-type acceleration of high energy particles at astrophysical sources. We find the flux spectral index to be γ=2.53±0.07 and a flux normalization for each neutrino flavor of ϕ_{astro}=1.66_{-0.27}^{+0.25} at E_{0}=100  TeV, in agreement with IceCube's complementary muon neutrino results and with all-neutrino flavor fit results. In the measured energy range we reject spectral indices γ≤2.28 at ≥3σ significance level. Because of high neutrino energy resolution and low atmospheric neutrino backgrounds, this analysis provides the most detailed characterization of the neutrino flux at energies below ∼100  TeV compared to previous IceCube results. Results from fits assuming more complex neutrino flux models suggest a flux softening at high energies and a flux hardening at low energies (p value ≥0.06). The sizable and smooth flux measured below ∼100  TeV remains a puzzle. In order to not violate the isotropic diffuse gamma-ray background as measured by the Fermi Large Area Telescope, it suggests the existence of astrophysical neutrino sources characterized by dense environments which are opaque to gamma rays.

Time-Integrated Neutrino Source Searches with 10 Years of IceCube Data

This Letter presents the results from pointlike neutrino source searches using ten years of IceCube data collected between April 6, 2008 and July 10, 2018. We evaluate the significance of an astrophysical signal from a pointlike source looking for an excess of clustered neutrino events with energies typically above ∼1  TeV among the background of atmospheric muons and neutrinos. We perform a full-sky scan, a search within a selected source catalog, a catalog population study, and three stacked Galactic catalog searches. The most significant point in the northern hemisphere from scanning the sky is coincident with the Seyfert II galaxy NGC 1068, which was included in the source catalog search. The excess at the coordinates of NGC 1068 is inconsistent with background expectations at the level of 2.9σ after accounting for statistical trials from the entire catalog. The combination of this result along with excesses observed at the coordinates of three other sources, including TXS 0506+056, suggests that, collectively, correlations with sources in the northern catalog are inconsistent with background at 3.3σ significance. The southern catalog is consistent with background. These results, all based on searches for a cumulative neutrino signal integrated over the 10 years of available data, motivate further study of these and similar sources, including time-dependent analyses, multimessenger correlations, and the possibility of stronger evidence with coming upgrades to the detector.

[Application of three methods in occupational health risk assessment of automobile 4S shop]

Objective: To choose various occupational health risk assessment of the mature methods at home and abroad respectively occupational health risk assessment was carried out on the 4s stores, to explore different risk assessment methods on the 4 s shop the applicability of the occupational health risk assessment. Methods: Chemical was applied on the harmful factors of occupational health risk assessment technology guideline in the composite index method, quantitative cancer risk assessment method using the guidelines for the harmful factors of occupational health risk assessment of chemical technology of composite index method, quantitative cancer risk assessment method, international commission on mining and metals (ICMM) occupational health risk assessment quantitative method and the occupational-disease-inductive operation classification to evaluate chemical factors in 4S store, Combined with on-site occupational health investigation to compare with the result of risk assessment and analysis of international mining and metals (ICMM) committee occupational health risk assessment quantitative method and the occupational-disease-inductive operation classification of 4S store to evaluate chemical factors, combined with on-site occupational health investigation comparison and analysis the result of the risk assessment. Results: Except for 6 times, the results of ICMM matrix method and comprehensive index method were consistent, which were all higher than job classification. The other results were job classification of >of ICMM matrix method >comprehensive index method or job classification of >of ICMM matrix method. Conclusion: When the concentration of occupational-disease-inductive factors is lower than 1/2 limit, the risk assessment results tend to be ICMM quantitative >composite index method >operation classification. When the occupational-disease-inductive factors were involved with triphenyl, the quantitative non-carcinogenic risk assessment method was more likely to reach the conclusion that the occupational health risk was unacceptable.

Immediate effects of coloured overlays on the reading performance of preschool children with an autism spectrum disorder using eye tracking

BACKGROUND

Coloured overlays have often been used to improve reading performance in preschool children with an autism spectrum disorder (ASD), however, previous evidence shows conflicts in its application.

AIMS

To investigate the immediate effects of coloured overlays on reading performance using eye tracking in preschool children with ASD and their typical development (TD) counterparts closely matched by chronological age.

METHODS

Forty participants with ASD (n = 20) or TD (n = 20) were recruited by convenience sampling and asked to read aloud numbers randomly arranged on paper. Participants' ocular performance (fixation duration, fixation count, total visit duration), reading speed and number of errors were recorded by eye tracker and digital stopwatch respectively throughout testing with and without coloured overlays.

RESULTS

The findings show that coloured overlays had no significant immediate effect in improving ocular performance and reading speed of children with ASD or TD, although individual improvements were identified in some children with ASD.

CONCLUSIONS

Use of coloured overlays may not be useful to improve reading and ocular performance in children with ASD in one single occasion. The potential effect on reading ability of using coloured overlays repetitively for a longer period needs further investigation.

Search for CP Violation in Neutrino and Antineutrino Oscillations by the T2K Experiment with 2.2×10^{21} Protons on Target

The T2K experiment measures muon neutrino disappearance and electron neutrino appearance in accelerator-produced neutrino and antineutrino beams. With an exposure of 14.7(7.6)×10^{20} protons on target in the neutrino (antineutrino) mode, 89 ν_{e} candidates and seven anti-ν_{e} candidates are observed, while 67.5 and 9.0 are expected for δ_{CP}=0 and normal mass ordering. The obtained 2σ confidence interval for the CP-violating phase, δ_{CP}, does not include the CP-conserving cases (δ_{CP}=0, π). The best-fit values of other parameters are sin^{2}θ_{23}=0.526_{-0.036}^{+0.032} and Δm_{32}^{2}=2.463_{-0.070}^{+0.071}×10^{-3}  eV^{2}/c^{4}.

Search for Boosted Dark Matter Interacting with Electrons in Super-Kamiokande

A search for boosted dark matter using 161.9 kt yr of Super-Kamiokande IV data is presented. We search for an excess of elastically scattered electrons above the atmospheric neutrino background, with a visible energy between 100 MeV and 1 TeV, pointing back to the Galactic center or the Sun. No such excess is observed. Limits on boosted dark matter event rates in multiple angular cones around the Galactic center and Sun are calculated. Limits are also calculated for a baseline model of boosted dark matter produced from cold dark matter annihilation or decay. This is the first experimental search for boosted dark matter from the Galactic center or the Sun interacting in a terrestrial detector.

Combined Analysis of Neutrino and Antineutrino Oscillations at T2K

T2K reports its first results in the search for CP violation in neutrino oscillations using appearance and disappearance channels for neutrino- and antineutrino-mode beams. The data include all runs from January 2010 to May 2016 and comprise 7.482×10^{20} protons on target in neutrino mode, which yielded in the far detector 32 e-like and 135  μ-like events, and 7.471×10^{20} protons on target in antineutrino mode, which yielded 4 e-like and 66  μ-like events. Reactor measurements of sin^{2}2θ_{13} have been used as an additional constraint. The one-dimensional confidence interval at 90% for the phase δ_{CP} spans the range (-3.13, -0.39) for normal mass ordering. The CP conservation hypothesis (δ_{CP}=0, π) is excluded at 90% C.L.

Measurement of Coherent π^{+} Production in Low Energy Neutrino-Carbon Scattering

We report the first measurement of the flux-averaged cross section for charged current coherent π^{+} production on carbon for neutrino energies less than 1.5 GeV, and with a restriction on the final state phase space volume in the T2K near detector, ND280. Comparisons are made with predictions from the Rein-Sehgal coherent production model and the model by Alvarez-Ruso et al., the latter representing the first implementation of an instance of the new class of microscopic coherent models in a neutrino interaction Monte Carlo event generator. We observe a clear event excess above background, disagreeing with the null results reported by K2K and SciBooNE in a similar neutrino energy region. The measured flux-averaged cross sections are below those predicted by both the Rein-Sehgal and Alvarez-Ruso et al.

Measurement of Muon Antineutrino Oscillations with an Accelerator-Produced Off-Axis Beam

T2K reports its first measurements of the parameters governing the disappearance of ν[over ¯]_{μ} in an off-axis beam due to flavor change induced by neutrino oscillations. The quasimonochromatic ν[over ¯]_{μ} beam, produced with a peak energy of 0.6 GeV at J-PARC, is observed at the far detector Super-Kamiokande, 295 km away, where the ν[over ¯]_{μ} survival probability is expected to be minimal. Using a data set corresponding to 4.01×10^{20} protons on target, 34 fully contained μ-like events were observed. The best-fit oscillation parameters are sin^{2}(θ[over ¯]_{23})=0.45 and |Δm[over ¯]_{32}^{2}|=2.51×10^{-3}  eV^{2} with 68% confidence intervals of 0.38-0.64 and 2.26-2.80×10^{-3}  eV^{2}, respectively. These results are in agreement with existing antineutrino parameter measurements and also with the ν_{μ} disappearance parameters measured by T2K.

A new method for estimating the number of non-differentially expressed genes

Control of the false discovery rate is a statistical method that is widely used when identifying differentially expressed genes in high-throughput sequencing assays. It is often calculated using an adaptive linear step-up procedure in which the number of non-differentially expressed genes should be estimated accurately. In this paper, we discuss the estimation of this parameter and point out defects in the original estimation method. We also propose a new estimation method and provide the error estimation. We compared the estimation results from the two methods in a simulation study that produced a mean, standard deviation, range, and root mean square error. The results revealed that there was little difference in the mean between the two methods, but the standard deviation, range, and root mean square error obtained using the new method were much smaller than those produced by the original method, which indicates that the new method is more accurate and robust. Furthermore, we used real microarray data to verify the conclusion. Finally we provide a suggestion when analyzing differentially expressed genes using statistical methods.

Nerve growth factor regulates the expression of vascular endothelial growth factor in human HaCaT keratinocytes via PI3K/mTOR pathway

Decades of research have provided the data to confirm the hypothesis that there is bidirectional communication between the central nervous system and the immune system in psoriasis pathogenesis, but the contribution of the cutaneous neural system remains underexplored. In this study, we evaluated the molecular mechanisms by which nerve growth factor (NGF) regulates hypoxia-inducible factor-1α (HIF-1α) and vascular endothelial growth factor (VEGF) production. The mRNA and protein levels of VEGF secretion from HaCaT cells by NGF were increased in a concentration-dependent manner. In addition, the NGF- induced increase in VEGF is accompanied by an increase in HIF-1α, but not HIF-2α or HIF-1β. However, this increase is abrogated by pretreatment with a mammalian target of rapamycin (mTOR) inhibitor rapamycin. Pharmacologic inhibitors of the Trk tyrosine kinase, PI-3 kinase, and mTOR pathways prevent NGF-stimulated increases in HIF-1α and VEGF. Mutation of the siRNA-mediated silencing of HIF-1α expression blocks NGF-induced increases in VEGF transcription. Our study indicates that NGF regulates the expression of VEGF through the PI3K/mTOR signaling pathway in human HaCaT keratinocytes.

A method for simultaneously delineating multiple targets in 3D-FISH using limited channels, lasers, and fluorochromes

Many studies have suggested a link between the spatial organization of genomes and fundamental biological processes such as genome reprogramming, gene expression, and differentiation. Multicolor fluorescence in situ hybridization on three-dimensionally preserved nuclei (3D-FISH), in combination with confocal microscopy, has become an effective technique for analyzing 3D genome structure and spatial patterns of defined nucleus targets including entire chromosome territories and single gene loci. This technique usually requires the simultaneous visualization of numerous targets labeled with different colored fluorochromes. Thus, the number of channels and lasers must be sufficient for the commonly used labeling scheme of 3D-FISH, "one probe-one target". However, these channels and lasers are usually restricted by a given microscope system. This paper presents a method for simultaneously delineating multiple targets in 3D-FISH using limited channels, lasers, and fluorochromes. In contrast to other labeling schemes, this method is convenient and simple for multicolor 3D-FISH studies, which may result in widespread adoption of the technique. Lastly, as an application of the method, the nucleus locations of chromosome territory 18/21 and centromere 18/21/13 in normal human lymphocytes were analyzed, which might present evidence of a radial higher order chromatin arrangement.

5-Azacytidine induces early stage apoptosis and promotes in vitro maturation by changing chromosomal construction in murine oocytes

As an anticancer drug, 5-azacytidine (5-AzaC) has been widely used to treat various cancers. To investigate the effect of 5-AzaC on mouse oocytes cultured in vitro, we have performed morphological and molecular biology studies to examine the behavior of chromosomes and oocyte development. In 5-AzaC-treated oocytes, chromosomes were decondensed and unstable. The mRNA levels of Caspase3, Caspase8, and Caspase9 increased with the occurrence of early stage apoptosis in oocytes following 5-AzaC treatment. Furthermore, the mRNA levels of Gdf9 and Bmp15 also increased with the corresponding morphological changes in 5-AzaC-treated oocytes. In conclusion, 5-AzaC not only induced early apoptosis through both extrinsic and intrinsic pathways, but also had a positive effect on the developmental competence of mouse oocytes during in vitro maturation. These effects may be due to changes in chromosomal construction induced by DNA hypomethylation.

Three-dimensional quantitative analysis of chromosomes in the oocytes of aging mice during meiosis I in vitro

The mechanism of senescence is very complicated and can involve formation of chromosome abnormalities and a decline in female fertility. In this study, 3-D visualization of fluorescently labeled chromosomes in oocytes from aging and pubertal mice during in vitro maturation was done with a two-photon laser scanning microscope. Differences between aging and pubertal groups at various maturation stages were analyzed quantitatively in terms of chromosomal morphology, shape, and spatial arrangement. Compared with the pubertal group, the chromosomal morphology of oocytes from aging mice changed: both the mean volume and the mean surface area of chromosomes increased by approximately 20% (P < 0.05) at prometaphase and metaphase of meiosis I (considered to be the weakly condensed folded form of the chromosomes). Furthermore, at these stages, the shape of the chromosomal array became rounder (roundness factor increased by approximately 10%; P < 0.001) and the adhesion among chromosomes became more severe (P < 0.001) at approximately the same stages. Additionally, trends over time for both chromosomal morphology and shape were quite distinct between oocytes from aging and pubertal mice. Interestingly, trends for mean distance were similar; therefore, aging did not seem to influence chromosome movement toward the metaphase plate. These morphologic results should be useful to study age-related degradation of oocyte quality and to interpret results derived from molecular biology.

Inverse Correlation between Caveolin-1 Expression and Clinical Severity in Psoriasis Vulgaris

Objective:

This study investigated the clinical significance of expression of caveolin-1 - a plasma membrane protein involved in caveola formation, endocytosis, signal transduction and angiogenesis - inthe pathogenesis of psoriasis vulgaris.

Methods:

A total of 20 patients with psoriasis vulgaris and 20 healthy volunteers were recruited. The expressions of caveolin-1, Ki-67 (marker of cell proliferation) and CD34 (marker of angiogenesis) in skin biopsies were detected by immunohistochemistry, and the level of caveolin-1 protein was quantified by Western blotting. Clinical severity was assessed using the Psoriasis Area and Severity Index (PASI) score. Correlations between caveolin-1 expression and psoriasis severity, cell proliferation and angiogenesis were analysed using the Spearman rank correlation test.

Results:

Expression of caveolin-1 was significantly lower in psoriasis samples than in healthy skin samples. In psoriasis lesions, the level of caveolin-1 expression was inversely correlated with the severity of psoriasis, cell proliferation and angiogenesis.

Conclusions:

The level of caveolin-1 expression seems to be related to the clinical severity of psoriasis, and may play a role in the abnormal keratinocyte hyperplasia and angiogenesis seen in this condition.

A numerical investigation of the effect of vertex geometry on localized surface plasmon resonance of nanostructures

Advances in nanofabrication and nano-scale measurement methods now allow for fabrication of highly detailed nanometer-scale topographic features. As geometric features greatly impact the formation of an electromagnetic field in response to incident light, this in turn calls for the study of the effects of new features of nanostructures on their performance in applications such as localized surface plasmon resonance (LSPR) sensing. This paper studies the effects of vertex features of a single nanostructure on its LSPR properties. A general relationship between the LSPR spectra and the vertex features of a nanoparticle is established. The results of electrodynamics calculations show that a delta-star with a relatively small vertex angle exhibits a bigger resonant wavelength than one with a large vertex angle. Moreover, the sensing performance initially increases, and then decreases as angular size of the vertices increases, with a turning point of 30 degrees. It is also shown that for nanostars with different numbers of vertices, the resonant wavelength undergoes a blue shift and the sensing performance grows poorer as the number of vertices increases. A regular vertex angle of 30 degrees displays the greatest figure of merit (FOM) value for LSPR applications, approximately 9.5 RIU(-1).

Effects of vertex truncation of polyhedral nanostructures on localized surface plasmon resonance

Polyhedral nanostructures are widely used to enable localized surface plasmon resonance (LSPR). In practice, vertices of such structures are almost always truncated due to limitations of nanofabrication processes. This paper studies the effects of vertex truncation of polyhedral nanostructures on the characteristics of LSPR sensing. The optical properties and sensing performance of triangular nanoplates with truncated vertices are investigated using electrodynamics analysis and verified by experiment. The experimental results correlated with simulation analysis demonstrate that the fabricated triangular nanoplate array has a truncation ratio, defined as the length of truncation along an edge of the triangle over the edge length, of approximately 12.8%. This significantly influences optical properties of the nanostructures, resulting in poorer sensing performance. These insights can be used to guide the design and fabrication of nanostructures for high performance LSPR sensors.

Adhesiveness of dental resin-based restorative materials investigated with atomic force microscopy

This study aimed to show that the polymerization contraction of dental methacrylate-based materials, when used as adhesives on hard substrate, produces voids at the material-substrate interface. This phenomenology is closely related with the nanoleakage and the sealing ability of these materials. One prime/bond system, three restorative composite resins, and one orthodontic bonding system were cured by using mirror-like glass slides as a compliance-free reference substrate. The adhesive surface was analyzed by atomic force microscopy, and the polymerization contraction of bulk material was tested by laser beam-scanning method. Nanoperiodic structure of three-dimensional (3D) images, section analysis, and roughness characteristics (R(a) and R(z)) indicated that polymerization contraction produced voids at the interface. When the adhesive surface was exposed to oral simulating fluids (water, ethanol, and lactic acid solutions), hydrolytic degradation involved some hundreds of nanometers in depth. In visible light-cured (VLC) materials, the interface porosity decreased when an irradiation pause ( approximately 2 min) was carried out during gelation.

[Analysis on patial amino acid sequence of a novel glycoprotein binding to antiherpes simplex virus monoclonal antibody CHA9]

AIM

To acquire the characteristic amino acid sequence of a novel glycoprotein of herpes simplex virus (HSV), so as to localize gene encoding the novel glycoprotein accurately.

METHODS

A 12-mer phage peptide library was screened for 3 rounds by using biotinylated mAb CHA9 against new glycoprotein g30k of HSV-2. Positive phage clones were detected by ELISA. 10 positive clones were selected randomly for sequencing. Sequence alignment and hydrophobic cluster analysis were carried out.

RESULTS

Most of the sequences of 10 positive phage clones were highly homologous with a core-PH/KHXHXGS-. Phages containing this motif could react specifically with the mAb CHA9 and not cross-react with other IgG. Hydrophobic cluster analysis showed that the peptide was likely to form an epitope.

CONCLUSION

We obtained a characteristic short peptide which shows some characters of g30K amino acid sequence. It provides valuable clue for prediction of the open reading frame of g30K gene and will be useful to explore biological characteristics of the new glycoprotein.

[Expression of Japanese encephalitis virus E protein in methylotrophic yeast Pichia pastoris]

AIM

To express Japanese encephalitis virus (JEV) E protein in methylotrophic yeast Pichia pastoris.

METHODS

The gene coding for JEV E protein was sub-cloned into vector pPIC9k. The constructed plasmid was transformed into yeast SMD1168 by electroporation. The recombinant transformants with a high copy number of the plasmid were selected by using MD plate and G418. The expression of E protein in yeast was induced by the addition of methanol and analyzed by SDS-PAGE and Western blot.

RESULTS

The protein was produced at a yield of 50 mg per litre of culture. Owing to heterogeneous glycosylation, relative molecular mass (M(r)) of the expressed E protein was sized about 113 000 and 78 000.

CONCLUSION

JEV E protein was expressed successfully in yeast Pichia pastoris, which should be useful for the production of diagnostic reagents and genetically engineered vaccine of JEV.

Polymerization of dental composite resins using plasma light

Five visible light-cured composite resins used as restoration or adhesive materials in dentistry, were irradiated with high energy plasma light (1300 mW/cm2), and contraction, rate of contraction, irradiation-induced temperature were analysed. A comparison was carried out with the same materials irradiated with a conventional halogen light (400 mW/cm2). The exposure to the photoactivating lights was either continuously or sequentially in three or more intervals with 10 min between intervals. Comparing the lengths of exposure of both lights, which induced the same contraction in a given material, it was found that the exposure length to the plasma light was greatly reduced, when compared with the exposure length of the halogen light (1:10). Frequently, the final contraction of plasma-irradiated materials was lower, whereas the rate of contraction, as indicated by the linear dimensional variation curves obtained by laser beam scanning method, did not show significant differences between the two lights. The temperature increase induced by plasma light on the material did not exceed the temperature induced by conventional light.

Transactivation of the epidermal growth factor receptor is involved in 12-O-tetradecanoylphorbol-13-acetate-induced signal transduction

The mechanism of 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced tumor promotion is still not well understood even though it is thought to be related to the protein kinase C/mitogen-activated protein kinase/AP-1 pathway. Recently, TPA was also found to induce epidermal growth factor receptor (EGFR) activity. Here, we investigated whether the EGFR is a necessary component for TPA-induced signal transduction associated with tumor promotion. We demonstrated that potent inhibitors of the EGFR, PD153035 and AG1478, blocked TPA-induced phosphorylation of extracellular signal-regulated kinases (ERKs), AP-1 activity, and cell transformation. Egfr gene deficiency blocked TPA-induced ERK activity and AP-1 binding activity. The blocking of the ectodomain of the EGFR by a monoclonal antibody depressed TPA-induced ERK activity and AP-1 DNA binding activity. The use of a neutralizing antibody for heparin-binding EGF, one of the ligands of EGFR, blocked TPA-induced phosphorylation of ERKs. BB-94, a potent inhibitor of matrix metalloproteinases, which are activators of ectodomain shedding of EGFR ligands, also blocked TPA-induced ERK activity, AP-1 DNA binding, and cell transformation but had no effect on EGF-induced signal transduction. Anti-EGFR, anti-heparin-binding EGF, and BB-94 each blocked TPA-induced EGFR phosphorylation, but only anti-EGFR could block EGF-induced EGFR phosphorylation. Based on these results, we conclude that the EGFR is required for mediating TPA-induced signal transduction. EGFR transactivation induced by TPA is a mechanism by which the EGFR mediates TPA-induced tumor promotion-related signal transduction.

Inhibitory mechanisms of tea polyphenols on the ultraviolet B-activated phosphatidylinositol 3-kinase-dependent pathway

In this study, we investigated the effect of tea polyphenols, (-)-epigallocatechin-3-gallate or theaflavins, on UVB-induced phosphatidylinositol 3-kinase (PI3K) activation in mouse epidermal JB6 Cl 41 cells. Pretreatment of cells with these polyphenols inhibited UVB-induced PI3K activation. Furthermore, UVB-induced activation of Akt and ribosomal p70 S6 kinase (p70 S6-K), PI3K downstream effectors, were also attenuated by the polyphenols. In addition to LY294002, a PI3K inhibitor, pretreatment with a specific mitogen-activated protein/extracellular signal-regulated protein kinases (Erks) kinase 1 inhibitor, U0126, or a specific p38 kinase inhibitor, SB202190, blocked UVB-induced activation of both Akt and p70 S6-K. Pretreatment with LY294002 restrained UVB-induced phosphorylation of Erks, suggesting that in UVB signaling, the Erk pathway is mediated by PI3K. Moreover, pretreatment with rapamycin, an inhibitor of p70 S6-K, inhibited UVB-induced activation of p70 S6-K, but UVB-induced activation of Akt did not change. Interestingly, UVB-induced p70 S6-K activation was directly blocked by the addition of (-)-epigallocatechin-3-gallate or theaflavins, whereas these polyphenols showed only a weak inhibition on UVB-induced Akt activation. Because PI3K is an important factor in carcinogenesis, the inhibitory effect of these polyphenols on activation of PI3K and its downstream effects may further explain the anti-tumor promotion action of these tea constituents.

Induction of EGFR-dependent and EGFR-independent signaling pathways by ultraviolet A irradiation

Most of the signal pathways involved in ultraviolet (UV)-induced skin carcinogenesis are thought to originate at plasma membrane receptors. However, UVA-induced signal transduction to downstream ribosomal protein S6 kinases, p70(S6K) and p90(RSK), is not well understood. In this report, we show that UVA stimulation of the epidermal growth factor receptor (EGFR) may lead to activation of p70(S6K)/p90(RSK) through phosphatidyl isositol (PI)-3 kinase and extracellular receptor-activated kinases (ERKs). Evidence is provided that phosphorylation and activation of p70(S6K)/p90(RSK) induced by UVA were prevented in Egfr(-/-) cells and were also markedly inhibited by the EGFR-specific tyrosine kinase inhibitors AG1478 and PD153035. Furthermore, EGFR tyrosine kinase inhibitors and EGFR deficiency significantly suppressed activation of PI-3 kinase and ERKs in regulating activation of p90(RSK)/p70(S6K) but had no effect on activation of c-Jun NH(2)-terminal kinases (JNKs) and p38 kinase in response to UVA. Thus, our results suggest that UVA-induced EGFR signaling may be required for activation of p90(RSK)/p70(S6K), PI-3 kinase, and ERKs but not JNKs or p38 kinase.

Structure of dental glass-ionomer cements by confocal fluorescence microscopy and stereomicroscopy

The microstructure of four cements, setting by different mechanisms (acid-base, dual cure, triple cure), was studied. The porosity of unpolymerized materials was detected by stereomicroscopy. After polymerization and storage in water or lactic acid solution, the porosity, filler distribution and gel layer, which was formed at the filler/matrix interface of polymerized materials, were examined by confocal laser microscopy. For this purpose, the specimens were treated with fluorescent dye solution before the test. The results showed that hydrolytic degradation (pH 7) mainly involved the resin matrix, and the acid erosion (pH 3.5) involved the gel layer too. As regards the filler, materials with different setting mechanism released the glass particles in different times. The loss of the filler particles occurred quicker in acid-base setting cements, and slower in triple-cured material.

Inhibition of arsenite-induced apoptosis by aspirin

Arsenite exposure and subsequent arsenite-induced toxicity and carcinogenesis are common in many countries. Thus the study of chemopreventive compounds that inhibit arsenite-induced toxicity and carcinogenesis is very valuable. In the present work, we investigated the effect of aspirin on arsenite-induced apoptosis and signal transduction by means of luciferase activity, apoptosis analysis and Western blotting. Arsenite induced AP-1 transcriptional activity at the same concentration (20 microM) as was effective for inducing apoptosis. Arsenite-induced apoptosis and AP-1 transactivation in JB6 cells were blocked by aspirin and salicylate (SA). Both aspirin and SA inhibited arsenite-induced phosphorylation of Erks, but had no effect on phosphorylation of JNKs. SA inhibited arsenite-induced phosphorylation of p38 kinase, but aspirin did not. These results indicate that aspirin and SA inhibit arsenite-induced apoptosis through the inhibition of the Erks/AP-1 pathway.

Ultraviolet B-induced phosphorylation of histone H3 at serine 28 is mediated by MSK1

N-terminal tail phosphorylation of histone H3 plays an important role in gene expression, chromatin remodeling, and chromosome condensation. Phosphorylation of histone H3 at serine 10 was shown to be mediated by RSK2, mitogen- and stress-activated protein kinase-1 (MSK1), and mitogen-activated protein kinases depending on the specific stimulation or stress. Our previous study showed that mitogen-activated protein kinases MAP kinases are involved in ultraviolet B-induced phosphorylation of histone H3 at serine 28 (Zhong, S., Zhong, Z., Jansen, J., Goto, H., Inagaki, M., and Dong, Z., J. Biol. Chem. 276, 12932-12937). However, downstream effectors of MAP kinases remain to be identified. Here, we report that H89, a selective inhibitor of the nucleosomal response, totally inhibits ultraviolet B-induced phosphorylation of histone H3 at serine 28. H89 blocks MSK1 activity but does not inhibit ultraviolet B-induced activation of MAP kinases p70/85(S6K), p90(RSK), Akt, and protein kinase A. Furthermore, MSK1 markedly phosphorylated serine 28 of histone H3 and chromatin in vitro. Transfection experiments showed that an N-terminal mutant MSK1 or a C-terminal mutant MSK1 markedly blocked MSK1 activity. Compared with wild-type MSK1, cells transfected with N-terminal or C-terminal mutant MSK1 strongly blocked ultraviolet B-induced phosphorylation of histone H3 at serine 28 in vivo. These data illustrate that MSK1 mediates ultraviolet B-induced phosphorylation of histone H3 at serine 28.

Two novel glycosides from the fruits of Morinda citrifolia (noni) inhibit AP-1 transactivation and cell transformation in the mouse epidermal JB6 cell line

The fruit juice of Morinda citrifolia (noni), a plant originally grown in the Hawaiian and Tahitian islands, has long been used by islanders to treat diseases, including cancer. Two novel glycosides, 6-O-(beta-D-glucopyranosyl)-1-O-octanoyl-beta-D-glucopyranose and asperulosidic acid, extracted from the juice of noni fruits, were used to examine their effects on 12-O-tedtradecanoylphorbol-13-acetate (TPA)- and epidermal growth factor (EGF)-induced AP-1 transactivation and cell transformation in mouse epidermal JB6 cells. The results indicated that both compounds were effective in suppressing TPA- or EGF-induced cell transformation and associated AP-1 activity. TPA- or EGF-induced phosphorylation of c-Jun, but not extracellular signal-regulated kinases or p38 kinases, was also blocked by the compounds, indicating that c-Jun N-terminal kinases were critical in mediating TPA- or EGF-induced AP-1 activity and subsequent cell transformation in JB6 cells.

Expression of vascular endothelial growth factor and its role in oncogenesis of human gastric carcinoma

AIM

To establish the role of vascular endothelial growth factor (VEGF) in the oncogenesis of human gastric carcinoma more directly.

METHODS

The expression of VEGF and its receptor kinase-domain insert containing receptor (KDR) in human gastric cancer tissue were observed by immunohistochemical staining. VEGF levels were manipulated in human gastric cancer cell using eukaryotic expression constructs designed to express the complete VEGF(165) complimentary DNA in either the sense or antisense orientation. The biological changes of the cells were observed in which VEGF was up-regulated or down-regulated.

RESULTS

VEGF-positive rate was 50%, and VEGF was mainly localized in the cytoplasm and membrane of the tumor cells, while KDR was mainly located in the membrane of vascular endothelial cells in gastric cancer tissues and peri-cancerous tissue. In 2 cases of 50 specimens, the gastric cancer cells expressed KDR, localized in both the cytoplasm and membrane. Introduction of VEGF(165) antisense into human gastric cancer cells (SGC-7901, immunofluorescence intensity, 31.6%)) resulted in a significant reduction in VEGF-specific messenger RNA and total and cell surface VEGF protein (immunofluorescence intensity, 8.9%) (P<0.05). Conversely, stable integration of VEGF(165) in the sense orientation resulted in an increase in cellular and cell surface VEGF (immunofluorescence intensity, 75.4%) (P<0.05). Lowered VEGF levels were associated with a marked decrease in the growth of nude mouse xenografted tumor (at 33 days postimplantation, tumor volume: 345.40 +/- 136.31 mm3)(P<0.05 vs control SGC-7901 group: 1534.40 +/- 362.88 mm3), whereas up-regulation of VEGF resulted in increased xenografted tumor size (at 33 days postimplantation, tumor volume: 2350.50 +/- 637.70 mm3) (P<0.05 vs control SGC-7901 group).

CONCLUSION

This study provides direct evidence that VEGF plays an important role in the oncogenesis of human gastric cancer.

Inositol hexaphosphate inhibits ultraviolet B-induced signal transduction

Inositol hexaphosphate (InsP6) has an effective anticancer action in many experimental models in vivo and in vitro. Ultraviolet B (UVB) radiation is believed to be responsible for many of the carcinogenic effects related to sun exposure, and alteration in UVB-induced signal transduction is associated with UVB-induced carcinogenesis. Here we report the effects of InsP6 on UVB-induced signal transduction. InsP6 strongly blocked UVB-induced activator protein-1 (AP-1) and NF-kappaB transcriptional activities in a dose-dependent manner. InsP6 also suppressed UVB-induced AP-1 and nuclear factor kappaB (NF-kappaB) DNA binding activities and inhibited UVB-induced phosphorylation of extracellular signal-regulated protein kinases (Erks) and c-Jun NH2-terminal kinases (JNKs). Phosphorylation of p38 kinases was not affected. InsP6 also blocked UVB-induced phosphorylation of IkappaB-alpha, which is known to result in the inhibition of NF-kappaB transcriptional activity. InsP6 does not block UVB-induced phosphotidylinositol-3' (PI-3) kinase activity, suggesting that the inhibition of UVB-induced AP-1 and NF-kappaB activities by InsP6 is not mediated through PI-3 kinase. Because AP-1 and NF-kappaB are important nuclear transcription factors that are related to tumor promotion, our work suggests that InsP6 prevents UVB-induced carcinogenesis by inhibiting AP-1 and NF-kappaB transcription activities.

Omega 3 but not omega 6 fatty acids inhibit AP-1 activity and cell transformation in JB6 cells

Epidemiological and animal-based investigations have indicated that the development of skin cancer is in part associated with poor dietary practices. Lipid content and subsequently the derived fatty acid composition of the diet are believed to play a major role in the development of tumorigenesis. Omega 3 (omega3) fatty acids, including docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), can effectively reduce the risk of skin cancer whereas omega 6 (omega6) fatty acids such as arachidonic acid (AA) reportedly promote risk. To investigate the effects of fatty acids on tumorigenesis, we performed experiments to examine the effects of the omega3 fatty acids EPA and DHA and of the omega6 fatty acid AA on phorbol 12-tetradecanoate 13-acetate (TPA)-induced or epidermal growth factor (EGF)-induced transcription activator protein 1 (AP-1) transactivation and on the subsequent cellular transformation in a mouse epidermal JB6 cell model. DHA treatment resulted in marked inhibition of TPA- and EGF-induced cell transformation by inhibiting AP-1 transactivation. EPA treatment also inhibited TPA-induced AP-1 transactivation and cell transformation but had no effect on EGF-induced transformation. AA treatment had no effect on either TPA- or EGF-induced AP-1 transactivation or transformation, but did abrogate the inhibitory effects of DHA on TPA- or EGF-induced AP-1 transactivation and cell transformation in a dose-dependent manner. The results of this study demonstrate that the inhibitory effects of omega3 fatty acids on tumorigenesis are more significant for DHA than for EPA and are related to an inhibition of AP-1. Similarly, because AA abrogates the beneficial effects of DHA, the dietary ratio of omega6 to omega3 fatty acids may be a significant factor in mediating tumor development.

Suppression of skin tumorigenesis in c-Jun NH(2)-terminal kinase-2-deficient mice

Previous studies have shown that c-Jun NH(2)-terminal kinase (JNK) belongs to the mitogen-activated protein kinase (MAPK) family of signal transduction components that are rapidly initiated and activated by many extracellular stimuli. However, the potential role of JNK in mediating tumor promotion and carcinogenesis is unclear. We show here that in JNK2-deficient (Jnk2(-/-)) mice, the multiplicity of papillomas induced by 12-O-tetradecanoylphorbol-13-acetate (TPA) was lower than that in wild-type mice. Papillomas on wild-type mice grew rapidly and were well vascularized compared with Jnk2(-/-) mice. After the 12th week of TPA treatment, the mean number of tumors per mouse was 4.13-4.86 in wild-type mice but only 1.13-2.5 in Jnk2(-/-) mice. TPA induced phosphorylation of extracellular signal-regulated kinases and activator protein-1 DNA binding activity in wild-type mice, but the phosphorylation of extracellular signal-regulated kinases and activator protein-1 DNA binding were inhibited in Jnk2(-/-) mice. These data suggest that JNK2 is critical in the tumor promotion process.

Organ-specific activation of activator protein-1 in transgenic mice by 12-o-tetradecanoylphorbol-13-acetate with different administration methods

12-O-Tetradecanoylphorbol-13-acetate (TPA) is widely used as a tumor promoter with organotropy in skin and esophagus. TPA-induced, organ-specific tumor promotion is not correlated with the distribution of its receptor, protein kinase C (PKC). Using five administration methods (painting, drinking, gavage feeding, i.p. injection, and i.v. injection), we analyzed TPA-stimulated activator protein-1 (AP-1) activity in various organs (liver, kidney, brain, lung, spleen, heart, stomach, colon, esophagus, and skin) from transgenic mice expressing the AP-1 luciferase reporter gene. Topical application of TPA by painting the skin on the back of mice raised AP-1 activity 122.6-fold, and the highest peak of AP-1 activity was at 12 h after administration of TPA. Drinking water containing TPA caused a 25.8-fold induction of AP-1 activity in the skin, whereas gavage feeding with TPA caused a 34.2-fold induction of AP-1 in the skin. Intraperitoneal or i.v. injection of TPA induced a 49.56-fold or 20.4-fold increase in AP-1 activity in the skin, respectively. The highest peaks of AP-1 activity in the skin were at 12 h after drinking, feeding, or injection of TPA. More interesting, in the esophagus, i.p. injection of TPA raised AP-1 activity 13.9-fold, drinking TPA raised AP-1 activity 8.4-fold, and painting with TPA caused a 2.4-fold induction of AP-1 activity. In the colon, i.p. injection of TPA raised AP-1 activity 3.9-fold, drinking TPA induced a 1.2-fold increase in AP-1 activity, but painting with TPA had no effect. AP-1 activity in other organs was not detectable after administration of TPA by painting, drinking, or injection. Phosphorylation of extracellular signal-regulated kinases in the skin increased at 12 h after painting, drinking, or i.p. injection of TPA. In addition, phosphorylation of p38 kinase was raised slightly after TPA administration, but phosphorylation of c-Jun NH(2)-terminal kinases was not detected at any time point after TPA administration. Similar changes in MAP kinases were also seen in the esophagus after TPA administration. These results indicate that the skin is the most sensitive organ to TPA induction of AP-1 activity. The data suggest that the organ-specific, tumor-promoting effect of TPA may be through AP-1 activation and phosphorylation of ERKs and p38 kinase.

Mitogen- and stress-activated protein kinase 1 mediates activation of Akt by ultraviolet B irradiation

In this study, we investigated the mechanism by which UVB irradiation activates Akt (also known as protein kinase B (PKB)) in mouse epidermal JB6 cells. Treatment with a phosphatidylinositol 3-kinase inhibitor, LY 294002, or expression of a dominant negative mutant of p85 (regulatory component of phosphatidylinositol 3-kinase) inhibited UVB-induced Akt activation. Interestingly, Akt activation by UVB was attenuated by treatment with PD 98059, a specific mitogen-activated protein kinase/extracellular signal-regulated protein kinase (Erk) kinase 1 inhibitor, or SB 202190, a specific p38 kinase inhibitor. Furthermore, the expression of a dominant negative mutant of Erk2 or p38 kinase, but not that of c-Jun N-terminal kinase 1 (JNK1), blocked UVB-induced Akt activation. The expression of a dominant negative mutant of p85 or treatment with LY 294002 also inhibited UVB-induced Erk phosphorylation. The UVB-activated mitogen-activated protein kinase members, which were immunoprecipitated from cells exposed to UVB, did not phosphorylate Akt. Instead, Akt was phosphorylated at both threonine 308 and serine 473 and activated by UVB-activated mitogen- and stress-activated protein kinase 1 (Msk1). The expression of a Msk1 C-terminal kinase-dead mutant inhibited UVB-induced phosphorylation and activation of Akt. These data thus suggested that UVB-induced Akt activation was mediated through Msk1, which is a downstream kinase of the Erk and p38 kinase signaling pathways.

Involvement of the acid sphingomyelinase pathway in uva-induced apoptosis

The sphingomyelin-ceramide pathway is an evolutionarily conserved ubiquitous signal transduction system that regulates many cell functions including apoptosis. Sphingomyelin (SM) is hydrolyzed to ceramide by different sphingomyelinases. Ceramide serves as a second messenger in mediating cellular effects of cytokines and stress. In this study, we find that acid sphingomyelinase (SMase) activity was induced by UVA in normal JY lymphoblasts but was not detectable in MS1418 lymphoblasts from Niemann-Pick type D patients who have an inherited deficiency of acid SMase. We also provide evidence that UVA can induce apoptosis by activating acid SMase in normal JY cells. In contrast, UVA-induced apoptosis was inhibited in MS1418 cells. Exogenous SMase and its product, ceramide (10-40 micrometer), induced apoptosis in JY and MS1418 cells, but the substrate of SMase, SM (20-80 micrometer), induced apoptosis only in JY cells. These results suggest that UVA-induced apoptosis by SM is dependent on acid SMase activity. We also provide evidence that induction of apoptosis by UVA may occur through activation of JNKs via the acid SMase pathway.