Dihydroartemisinin eliminates senescent cells by promoting autophagy-dependent ferroptosis via AMPK/mTOR signaling pathway.

Cellular senescence is an irreversible cell-cycle arrest in response to a variety of cellular stresses, which contribute to the pathogenesis of a variety of age-related degenerative diseases. However, effective antisenescence strategies are still lacking. Drugs that selectively target senescent cells represent an intriguing therapeutic strategy to delay aging and age-related diseases. Thus, we thought to investigate the effects of dihydroartemisinin (DHA) on senescent cells and elucidated its mechanisms underlying aging. Stress-induced premature senescence (SIPS) model was built in NIH3T3 cells using H2O2 and evaluated by ß-galactosidase staining. Cells were exposed to DHA and subjected to cellular activity assays including viability, ferroptosis, and autophagy. The number of microtubule-associated protein light-chain 3 puncta was detected by immunofluorescence staining. The iron content was assessed by spectrophotometer and intracellular reactive oxygen species (ROS) was measured by fluorescent probe dichlorodihydrofluorescein diacetate. We found that DHA triggered senescent cell death via ferroptosis. DHA accelerated ferritin degradation via promoting autophagy, increasing the iron contents, promoting ROS accumulation, thus leading to ferroptotic cell death in SIPS cells. In addition, autophagy inhibitor BafA1 preconditioning inhibited ferroptosis induced by DHA. Moreover, Atg5 silencing and autophagy inhibitor BafA1 preconditioning inhibited ferroptosis induced by DHA. We also revealed that the expression of p-AMP-activated protein kinase (AMPK) and p-mammalian target of rapamycin (mTOR) in senescent cells was downregulated. These results suggested that DHA may be a promising drug candidate for clearing senescent cells by inducing autophagy-dependent ferroptosis via AMPK/mTOR signaling pathway.

Cordycepin inhibits cell senescence by ameliorating lysosomal dysfunction and inducing autophagy through the AMPK and mTOR-p70S6K pathway.

Cell senescence is closely related to autophagy. In this article, we identified a natural nucleoside analogue, cordycepin, that has the ability to significantly improve lysosomal function, enhance the activity of the lysosomal representative protease cathepsin B (CTSB), and promote the expression of the functional protein lysosomal-associated membrane protein 2 (LAMP2) on the lysosomal membrane. Cordycepin then restores the damaged autophagy level of aging cells by activating the classic AMPK and mTOR-p70S6K signaling pathways, thus inhibiting cell senescence in an H2 O2 -induced stress-induced premature senescence (SIPS) cell model. This study provides new theoretical support for the further development of cordycepin and clinical antiaging drugs to inhibit cell senescence and suggests that the regulatory mechanisms of lysosomes in senescent cells should be considered when treating age-related diseases.

PAX6 contributes to the activation and proliferation of hepatic stellate cells via activating Hedgehog/GLI1 pathway.

Aberrant activation of Hedgehog signaling is considered as the key player in hepatic stellate cell (HSC) activation involved in liver fibrosis (LF). The glioma-associated protein gene (GLI) has a predicted paired box 6 (PAX6)-binding site within its transcribed region. Therefore, this study aimed to investigate the relationship between PAX6 and GLI and their contribution to HSC activation and proliferation. PAX6 expression was upregulated in platelet-derived growth factor-BB (PDGF-BB)-induced LX-2 cells. The activation and proliferation of HSC were inhibited by interference of PAX6 with short hairpin RNA (shPAX6) via curbing Hedgehog signaling. Notably, PAX6 directly bound to the promoter sequence of GLI1 independent of the PTCH/SMO axis. Therefore, we propose that PAX6 upregulation induces HSC activation and proliferation through crosstalk with GLI1 signaling. Thus, these novel mechanistic insights involving the PAX6-mediated regulation of the activation and proliferation of HSC may provide a new therapeutic target for LF.

Autophagy inhibition via Becn1 downregulation improves the mesenchymal stem cells antifibrotic potential in experimental liver fibrosis.

Liver fibrosis (LF) is the result of a vicious cycle between inflammation-induced chronic hepatocyte injury and persistent activation of hepatic stellate cells (HSCs). Mesenchymal stem cell (MSC)-based therapy may represent a potential remedy for treatment of LF. However, the fate of transplanted MSCs in LF remains largely unknown. In the present study, the fate and antifibrotic effect of MSCs were explored in a LF model induced by CCl4 in mouse. Additionally, MSCs were stimulated in vitro with LF-associated factors, tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ), and transforming growth factor-ß1 (TGF-ß1), to mimic the LF microenvironment. We unveiled that MSCs exhibited autophagy in response to the LF microenvironment through Becn1 upregulation both in vivo and in vitro. However, autophagy suppression induced by Becn1 knockdown in MSCs resulted in enhanced antifibrotic effects on LF. The improved antifibrotic potential of MSCs may be attributable to their inhibitory effects on T lymphocyte infiltration, HSCs proliferation, as well as production of TNF-α, IFN-γ, and TGF-ß1, which may be partially mediated by elevated paracrine secretion of PTGS2/PGE2 . Thus, autophagy manipulation in MSCs may be a novel strategy to promote their antifibrotic efficacy.

[Effect of Human Adipose Mesenchymal Stem Cells on Phenotype Polarization of Mice Microglia via TLR3/TRIF Signal Pathway].

OBJECTIVE: To explore the effect and mechanism of human adipose-derived mesenchymal stem cells (hADMSCs) on phenotypic polarization of microglia. METHODS: BV-2 microglia of C57/BL6 mice were co-cultured with hADMSCs+lipopolysaccharide (LPS), or cultured with LPS alone. Cell morphology was observed under an inverted microscope. The effect of hADMSCs on microglial proliferation was evaluated by CCK-8 assay. The impact of hADMSCs on microglia M1/M2 phenotype markers were detected using quantitative real-time PCR (RT-qPCR). The affect of hADMSCs on the proteins expression levels of Toll-like receptor 4 (TLR4)-TIR domain containing adaptor protein inducing interferon ß (TRIF) signaling pathway in BV-2 microglia was detected by using Western blot analysis. RESULTS: As compared with the LPS treatment, hADMSCs treatment had no obvious effect on microglia morphology, whereas showed significant inhibition on microglial proliferation activity (P<0.05). Simultaneously, hADMSCs treatment reduced expression of microglia M1 phenotype markers (P<0.05), and increased microglia M1 phenotype markers in gene levels (P<0.05). At the same time, protein expression levels of TRIF, TLR4, phosphorylated interferon regulatory factor 3 (P-IRF3) and interferon regulatory factor 3 (IRF3) in BV-2 microglia were decreased after hADMSCs treatment. CONCLUSION: hADMSCs can blockade the LPS-induced pro-inflammatory microglia M1 phenotype, whereas induces protective microglial M2 phenotype, which may be related to inhibition of the TLR4-TRIF signaling pathway.

[Establishing Glioma-associated Oncogene Homolog 1 Genetic Lineage-tracing Mice for Studies on Hepatic Fibrosis].

OBJECTIVE: To establish Gli1-CreERt2; tdTomato genetic lineage-tracing mice for studies on hepatic fibrosis. METHODS: Offspring of ROSA26 td Tomato (tdTomato) mice and Gli1-CreERt2 mice (Gli1 mice) were obtained, with Gli1-CreERt2; tdTomato genotype being identified by PCR. The mice model of hepatic fibrosis was induced with CCl4. Their liver samples were taken. The formalin-fixed and paraffin-embedded samples were prepared for HE staining and Masson staining. The expression of tdTomato was observed under immunofluorescent microscope. RESULTS: An ideal number of Gli1-CreERt2; tdTomato genetic lineage-tracing mice were harvested. The differences in fertility between the parental and the offspring mice were not significant (P>0.05). Pseudolobular formation occurred in the CCl4-induced hepatic fibrosis model mice. Enhanced red fluoresce was observed in the model mice. CONCLUSION: Gli1-CreERt2; tdTomato genetic lineage-tracing mice can be used to monitor the cell source of fibrous tissues, its transition as well as the underlying mechanism of pathogenesis of hepatic fibrosis.

Differentiation of rat adipose-derived mesenchymal stem cells into corneal-like epithelial cells driven by PAX6.

Corneal integrity, transparency and vision acuity are maintained by corneal epithelial cells (CECs), which are continuously renewed by corneal limbal stem cells (LSCs). Deficiency of CECs and/or LSCs is associated with numerous ocular diseases. Paired box (PAX)6 is an eye development-associated transcription factor that is necessary for cell fate determination and differentiation of LSCs and CECs. In the present study, the PAX6 gene was introduced into adipose-derived rat mesenchymal stem cells (ADMSCs) to investigate whether PAX6-transfected cells were able to transdifferentiate into corneal-like epithelial cells and to further verify whether the cells were suitable as a cell source for corneal transplantation. The ADMSCs were isolated from the bilateral inguinal region of healthy Sprague Dawley rats. The characteristics of ADMSCs were identified using flow cytometric analysis. After subculture, ADMSCs underwent transfection with recombinant plasmid containing either PAX6-enhanced green fluorescent protein (EGFP) complementary (c)DNA or EGFP cDNA (blank plasmid group), followed by selection with G418 and determination of the transfection efficiency. Subsequently, the morphology of the ADMSCs and the expression profiles of corneal-specific markers CK3/12 and epithelial-specific adhesion protein were determined. E-cadherin was detected using immunofluorescence staining and western blot analysis at 21 days following transfection. An MTT cell proliferation and a colony formation assay were performed to assess the proliferative activity and clonogenicity of PAX6-transfected ADMSCs. Finally, the PAX6-expressing ADMSCs were transplanted onto the cornea of a rabbits with limbal stem cell deficiency (LSCD). At 21 days after transfection, the ADMSCs with PAX6 transfection exhibited a characteristic flagstone-like appearance with assembled corneal-like epithelial cells, and concomitant prominent expression of the corneal-specific markers cytokeratin 3/12 and E-cadherin. Furthermore, the proliferation and colony formation ability of PAX6-overexpressing ADMSCs was significantly retarded. The transplantation experiment indicated that PAX6-reprogramed ADMSCs attached to and replenished the damaged cornea via formation of stratified corneal epithelium. Taken together, these results suggested that conversion of ADMSCs into corneal-like epithelium may be driven by PAX6 transfection, which makes ADMSCs a promising cell candidate for the treatment of LSCD.

Ectopic expression of specific GA2 oxidase mutants promotes yield and stress tolerance in rice.

A major challenge of modern agricultural biotechnology is the optimization of plant architecture for enhanced productivity, stress tolerance and water use efficiency (WUE). To optimize plant height and tillering that directly link to grain yield in cereals and are known to be tightly regulated by gibberellins (GAs), we attenuated the endogenous levels of GAs in rice via its degradation. GA 2-oxidase (GA2ox) is a key enzyme that inactivates endogenous GAs and their precursors. We identified three conserved domains in a unique class of C20 GA2ox, GA2ox6, which is known to regulate the architecture and function of rice plants. We mutated nine specific amino acids in these conserved domains and observed a gradient of effects on plant height. Ectopic expression of some of these GA2ox6 mutants moderately lowered GA levels and reprogrammed transcriptional networks, leading to reduced plant height, more productive tillers, expanded root system, higher WUE and photosynthesis rate, and elevated abiotic and biotic stress tolerance in transgenic rice. Combinations of these beneficial traits conferred not only drought and disease tolerance but also increased grain yield by 10-30% in field trials. Our studies hold the promise of manipulating GA levels to substantially improve plant architecture, stress tolerance and grain yield in rice and possibly in other major crops.

Genetic resources offer efficient tools for rice functional genomics research.

Rice is an important crop and major model plant for monocot functional genomics studies. With the establishment of various genetic resources for rice genomics, the next challenge is to systematically assign functions to predicted genes in the rice genome. Compared with the robustness of genome sequencing and bioinformatics techniques, progress in understanding the function of rice genes has lagged, hampering the utilization of rice genes for cereal crop improvement. The use of transfer DNA (T-DNA) insertional mutagenesis offers the advantage of uniform distribution throughout the rice genome, but preferentially in gene-rich regions, resulting in direct gene knockout or activation of genes within 20-30 kb up- and downstream of the T-DNA insertion site and high gene tagging efficiency. Here, we summarize the recent progress in functional genomics using the T-DNA-tagged rice mutant population. We also discuss important features of T-DNA activation- and knockout-tagging and promoter-trapping of the rice genome in relation to mutant and candidate gene characterizations and how to more efficiently utilize rice mutant populations and datasets for high-throughput functional genomics and phenomics studies by forward and reverse genetics approaches. These studies may facilitate the translation of rice functional genomics research to improvements of rice and other cereal crops.

RIPK1 regulates survival of human melanoma cells upon endoplasmic reticulum stress through autophagy.

Although RIPK1 (receptor [TNFRSF]-interacting protein kinase 1) is emerging as a critical determinant of cell fate in response to cellular stress resulting from activation of death receptors and DNA damage, its potential role in cell response to endoplasmic reticulum (ER) stress remains undefined. Here we report that RIPK1 functions as an important prosurvival mechanism in melanoma cells undergoing pharmacological ER stress induced by tunicamycin (TM) or thapsigargin (TG) through activation of autophagy. While treatment with TM or TG upregulated RIPK1 and triggered autophagy in melanoma cells, knockdown of RIPK1 inhibited autophagy and rendered the cells sensitive to killing by TM or TG, recapitulating the effect of inhibition of autophagy. Consistently, overexpression of RIPK1 enhanced induction of autophagy and conferred resistance of melanoma cells to TM- or TG-induced cell death. Activation of MAPK8/JNK1 or MAPK9/JNK2, which phosphorylated BCL2L11/BIM leading to its dissociation from BECN1/Beclin 1, was involved in TM- or TG-induced, RIPK1-mediated activation of autophagy; whereas, activation of the transcription factor HSF1 (heat shock factor protein 1) downstream of the ERN1/IRE1-XBP1 axis of the unfolded protein response was responsible for the increase in RIPK1 in melanoma cells undergoing pharmacological ER stress. Collectively, these results identify upregulation of RIPK1 as an important resistance mechanism of melanoma cells to TM- or TG-induced ER stress by protecting against cell death through activation of autophagy, and suggest that targeting the autophagy-activating mechanism of RIPK1 may be a useful strategy to enhance sensitivity of melanoma cells to therapeutic agents that induce ER stress.

The Role of Computer Simulation in Nanoporous Metals-A Review.

Nanoporous metals (NPMs) have proven to be all-round candidates in versatile and diverse applications. In this decade, interest has grown in the fabrication, characterization and applications of these intriguing materials. Most existing reviews focus on the experimental and theoretical works rather than the numerical simulation. Actually, with numerous experiments and theory analysis, studies based on computer simulation, which may model complex microstructure in more realistic ways, play a key role in understanding and predicting the behaviors of NPMs. In this review, we present a comprehensive overview of the computer simulations of NPMs, which are prepared through chemical dealloying. Firstly, we summarize the various simulation approaches to preparation, processing, and the basic physical and chemical properties of NPMs. In this part, the emphasis is attached to works involving dealloying, coarsening and mechanical properties. Then, we conclude with the latest progress as well as the future challenges in simulation studies. We believe that highlighting the importance of simulations will help to better understand the properties of novel materials and help with new scientific research on these materials.

Mesenchymal stem cell-mediated suppression of hypertrophic scarring is p53 dependent in a rabbit ear model.

INTRODUCTION: Mesenchymal stem cells (MSCs) are considered to play important roles in wound repair and tissue remodeling. Hypertrophic scar (HTS) is a cutaneous condition characterized by deposits of excessive amount of collagen after an acute skin injury. However, currently there is little knowledge about the direct relationship between MSCs and HTS. METHODS: The hypertrophic scar model was established on rabbit ears. MSCs were isolated from rabbit femur bone marrow and transplanted through ear artery injection. Hypertrophic scar formation was examined using frozen-section analysis, hematoxylin and eosin (HE) staining, Masson's trichrome staining, and scar elevation index. The role of p53 in the MSCs-mediated anti-scarring effect was examined by gene knockdown using p53 shRNA. RESULTS: In this study, MSCs engraftment through ear artery injection significantly inhibited the hypertrophic scarring in a rabbit ear hypertrophic scar model, while this anti-scarring function could be abrogated by p53 gene knockdown in MSCs. Additionally, we found that MSCs down-regulated the expression of TGF-ß receptor I (TßRI) and alpha-smooth muscle actin (α-SMA) at both mRNA and protein levels in a paracrine manner, and this down-regulation was rescued by p53 gene knockdown. Moreover, our results showed that MSCs with p53 gene knockdown promoted the proliferation of fibroblasts through increasing nitric oxide (NO) production. CONCLUSIONS: These results suggest that MSCs inhibit the formation of HTS in a p53 dependent manner through at least two mechanisms: inhibition of the transformation of HTS fibroblast to myofibroblast; and inhibition of the proliferation of fibroblasts through inhibition of NO production.

Noxa upregulation by oncogenic activation of MEK/ERK through CREB promotes autophagy in human melanoma cells.

Reduction in the expression of the anti-survival BH3-only proteins PUMA and Bim is associated with the pathogenesis of melanoma. However, we have found that the expression of the other BH3-only protein Noxa is commonly upregulated in melanoma cells, and that this is driven by oncogenic activation of MEK/ERK. Immunohistochemistry studies showed that Noxa was expressed at higher levels in melanomas than nevi. Moreover, the expression of Noxa was increased in metastatic compared to primary melanomas, and in thick primaries compared to thin primaries. Inhibition of oncogenic BRAFV600E or MEK downregulated Noxa, whereas activation of MEK/ERK caused its upregulation. In addition, introduction of BRAFV600E increased Noxa expression in melanocytes. Upregulation of Noxa was due to a transcriptional increase mediated by cAMP responsive element binding protein, activation of which was also increased by MEK/ERK signaling in melanoma cells. Significantly, Noxa appeared necessary for constitutive activation of autophagy, albeit at low levels, by MEK/ERK in melanoma cells. Furthermore, it was required for autophagy activation that delayed apoptosis in melanoma cells undergoing nutrient deprivation. These results reveal that oncogenic activation of MEK/ERK drives Noxa expression to promote autophagy, and suggest that Noxa has an indirect anti-apoptosis role in melanoma cells under nutrient starvation conditions.

Effect of pomegranate peel polyphenol gel on cutaneous wound healing in alloxan-induced diabetic rats.

BACKGROUND: Pomegranate (punica granatum) belongs to the family Punicaceae, and its peel has been used as a traditional Chinese medicine because of its efficacy in restraining intestine, promoting hemostasis, and killing parasites. Pomegranate peel has been reported to possess wound-healing properties which are mainly attributed to its polyphenol extracts. The purpose of this study was to investigate the effect of pomegranate peel polyphenols (PPP) gel on cutaneous wound healing in diabetic rats. METHODS: Alloxan-induced diabetic rats were given incisional wounds on each side of the mid-back and then treated daily with PPP gel (polyphenol mass fraction = 30%) post-wounding. Rats were sacrificed on days 4, 7, 14, and 21 post-wounding to assess the rates of wound closure, histological characteristics; and to detect the contents of hydroxyproline, production of nitric oxide (NO), and activities of NO synthase (NOS), as well as the expressions of transforming growth factor-ß1 (TGF-ß1), vascular endothelial growth factor (VEGF), and epidermal growth factor (EGF) in wound tissue. RESULTS: Wound closure was significantly shortened when PPP gel was applied to the wounds of diabetic rats. Histological examination showed the ability of PPP gel to increase fibroblast infiltration, collagen regeneration, vascularization, and epithelialization in the wound area of diabetic rats. In addition, PPP gel-treated diabetic rats showed increased contents of hydroxyproline, production of NO, and activities of NOS and increased expressions of TGF-ß1, VEGF, and EGF in wound tissues. CONCLUSION: PPP gel may be a beneficial method for treating wound disorders associated with diabetes.

A graphite nanoeraser.

We present here a method for cleaning intermediate-size (up to 50 nm) contamination from highly oriented pyrolytic graphite and graphene. Electron-beam-induced deposition of carbonaceous material on graphene and graphite surfaces inside a scanning electron microscope, which is difficult to remove by conventional techniques, can be removed by direct mechanical wiping using a graphite nanoeraser, thus drastically reducing the amount of contamination. We discuss potential applications of this cleaning procedure.

Constitutive expression of a fungal glucose oxidase gene in transgenic tobacco confers chilling tolerance through the activation of antioxidative defence system.

Scientific evidences in the literature have shown that plants treated exogenously with micromole concentration of hydrogen peroxide (H(2)O(2)) acquire abiotic stress tolerance potential, without substantial disturbances in the endogenous H(2)O(2) pool. In this study, we enhanced the endogenous H(2)O(2) content of tobacco (Nicotiana tabaccum L. cv. SR1) plants by the constitutive expression of a glucose oxidase (GO; EC 1.1.3.4) gene of Aspergillus niger and studied their cold tolerance level. Stable integration and expression of GO gene in the transgenic (T(0)-T(2)) tobacco lines were ascertained by molecular and biochemical tests. Production of functionally competent GO in transgenic plants was confirmed by the elevated levels of H(2)O(2) in the transformed tissues. When three homozygous transgenic lines were exposed to different chilling temperatures for 12 h, the electrolyte conductivity was significantly lower in GO-expressing tobacco plants than the control plants; in particular, chilling protection was more prominent at -1 degree C. In addition, most transgenic lines recovered within a week when returned to normal culture conditions after -1 degree C-12 h cold stress. However, control plants displayed symptoms of chilling injuries such as necrosis of shoot tip, shoots and leaves, consequently plant death. The protective effect realized in the transgenic plants was comparable to cold-acclimatized wild tobacco. The chilling tolerance of transgenic lines was found associated, at least in part, with elevated levels of total antioxidant content, CAT and APX activities. Based on our findings, we predict that the transgenic expression of GO may be deployed to improve cold tolerance potential of higher plants.

[Preparation of polyclonal antibody of human endothelial-overexpressed lipopolysaccharide-associated factor 1].

OBJECTIVE: To prepare the polyclonal antibody of human endothelial-overexpressed lipopolysaccharide-associated factor 1 (EOLA1), and to determine the expression of EOLA1 in human umbilical vein endothelial cell (HUVEC). METHODS: The protein samples (sample 1 and 2) expressing EOLA1 were purified and renatured. The protein concentrations were determined with bicinchoninic acid assay. The protein samples were identified with peptide mass fingerprinting (PMF) analysis. Protein sample with higher coincidence rate of amino acid sequence with theoretic protein was used to inoculate 4 mice; another 4 mice inoculated with adjuvant were used as control. Serum was isolated from collected mice blood. Polyclonal antibody of EOLA1 was purified with saturated ammonium sulfate precipitation, and was determined with ELISA for the titer (data were denoted by absorbance value). The expression of EOLA1 in HUVEC was determined with Western blot. RESULTS: The concentration of protein sample 1 and 2 was respectively 0.124 16 mg/mL and 0.132 15 mg/mL. According to PMF analysis, the coincidence rate of amino acid sequence between protein samples and theoretic protein were 32% (protein sample 1) and 24% (protein sample 2). The polyclonal antibody of EOLA1 with titer more than 1:10 000 was obtained from mice inoculated with protein sample 1. The expression of EOLA1 protein in HUVEC was determined with polyclonal antibody of EOLA1. CONCLUSIONS: The polyclonal antibody of EOLA1 can be prepared by inoculating mice with EOLA1 prokaryotic expressing protein, which can be used for determination of EOLA1 protein.

Antigenic diversity of Neisseria meningitidis isolated in Taiwan between 1995 and 2002.

The geographic distribution of N. meningitidis is diverse. Information on the antigenic variation of N. meningitidis is important for the development of an outer membrane protein-based vaccine. As a first step towards vaccine development, serological typing was performed to determine the antigenic properties of 127 invasive N. meningitidis isolates collected in Taiwan between 1995 and 2002. With 31.5% non-serotypeable and 32.3% non-serosubtypeable, the 127 isolates fell into 51 phenotypes, with W135:NT:P1.5,2:L3,7,9, Y:14P1.5,2, and B:1:NST:L3,7,9 being the 3 most prevalent. Among the 37 serogroup B isolates, 15 serosubtypes were found, with P1.5,2 and P1.12,13 being the most prevalent. The high diversity of Por A among serogroup B isolates circulating in Taiwan poses a great challenge for the development of a PorA-based vaccine. Because 85% of the serogroup B isolates had the L3,7,9 immunotype, inclusion of L3,7,9 lipooligosaccharides in a PorA-based vaccine may be a promising approach. In addition, based on the phenotypic characterization, we suggest that both serogroup B and W135 isolates were endemic and that serogroup A, C, and Y isolates were imported, which may reflect increased international travel.