PRSS50-mediated inhibition of MKP3/ERK signaling is crucial for meiotic progression and sperm quality.

Serine protease 50 (PRSS50/TSP50) is highly expressed in spermatocytes. Our study investigated its role in testicular development and spermatogenesis. Initially, PRSS50 knockdown was observed to impair DNA synthesis in spermatocytes. To further explore this, we generated PRSS50 knockout ( Prss50 -/- ) mice ( Mus musculus), which exhibited abnormal spermatid nuclear compression and reduced male fertility. Furthermore, dysplastic seminiferous tubules and decreased sex hormones were observed in 4-week-old Prss50 -/- mice, accompanied by meiotic progression defects and increased apoptosis of spermatogenic cells. Mechanistic analysis indicated that PRSS50 deletion resulted in increased phosphorylation of extracellular signal-regulated protein kinases 1 and 2 (ERK1/2) and elevated levels of MAP kinase phosphatase 3 (MKP3), a specific ERK antagonist, potentially accounting for testicular dysplasia in adolescent Prss50 -/- mice. Taken together, these findings suggest that PRSS50 plays an important role in testicular development and spermatogenesis, with the MKP3/ERK signaling pathway playing a significant role in this process.

Structural characterization and immunoregulatory activity of a neutral polysaccharide from the roots of Apocynum venetum L.

The structural characteristics and immunoregulatory activities of neutral heteropolysaccharide (AVRP-N) separated from the roots of Apocynum venetum L. were extensively investigated. The results showed that the weight average molecular mass (Mw) of AVRP-N was 6.430 × 103 Da. Moreover, the backbone is composed of natural acetylated (1 â†’ 4)-ß-D-Man and (1 â†’ 5)-α-L-Ara domains. The mannan is composed of →4)-ß-D-Manp-(1→, →4)-ß-D-Glcp-(1→, and the terminal group α-D-Galp-(1→ attached to →4,6)-ß-D-Manp-(1→ at O-6. Araban is composed of →5)-α-L-Araf-(1→; the terminal group α-L-Araf-(1→attached to→2,3,5)-α-L-Araf-(1→ at O-2, O-3 and →3,5)-α-L-Araf-(1→ at O-3. In addition, the senior structure shows that AVRP-N has a triple-helix conformation. Furthermore, AVRP-N exhibited immunomodulatory effects, which could significantly regulate the proliferation of mouse splenic lymphocytes by enhancing the secretion of the cytokines (IFN-γ, IL-2, IL-4, and IL-10). Our results provide new structural and immunoregulatory information for natural polysaccharides derived from Apocynum venetum L.

Immunomodulatory effects of flazin from Crassostrea sikamea on splenic lymphocytes of Sprague-Dawley rats.

Crassostrea sikamea (C.sikamea) is an important edible and medicinal seafood in China. In the present study, a compound named flazin was separated and identified from the ethyl acetate extract of C.sikamea (EAECs) for the first time. In addition, the 3-(4, 5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetra zolium (MTS) assay revealed that EAECs and flazin inhibited the transformation of splenic lymphocytes in vitro. Moreover, flazin (20 µg·mL-1) altered the populations of splenic lymphocyte subtypes. Real-time quantitative PCR (RT-qPCR) analysis and enzyme-linked immunosorbent assay (ELISA) showed that flazin suppressed the mRNA expression and secretion of TNF-α and IL-2, and reversed Concanavalin A (ConA)-induced mRNA up-regulation and protein secretion of TNF-α and IL-2. Western blot results showed that flazin reversed ConA-induced increases in p-ERK1/2 and p-p38 in splenocytes. In conclusion, flazin exhibits effective immunomodulatory function and may be useful for treating immune-related disorders, which indicates the application potential of C.sikamea as a functional food or immunomodulator.

Tectorigenin enhances PDX1 expression and protects pancreatic ß-cells by activating ERK and reducing ER stress.

Pancreas/duodenum homeobox protein 1 (PDX1) is an important transcription factor that regulates islet ß-cell proliferation, differentiation, and function. Reduced expression of PDX1 is thought to contribute to ß-cell loss and dysfunction in diabetes. Thus, promoting PDX1 expression can be an effective strategy to preserve ß-cell mass and function. Previously, we established a PDX1 promoter-dependent luciferase system to screen agents that can promote PDX1 expression. Natural compound tectorigenin (TG) was identified as a promising candidate that could enhance the activity of the promoter for the PDX1 gene. In this study, we first demonstrated that TG could promote the expression of PDX1 in ß-cells via activating extracellular signal-related kinase (ERK), as indicated by increased phosphorylation of ERK; this effect was observed under either normal or glucotoxic/lipotoxic conditions. We then found that TG could suppress induced apoptosis and improved the viability of ß-cells under glucotoxicity and lipotoxicity by activation of ERK and reduction of reactive oxygen species and endoplasmic reticulum (ER) stress. These effects held true in vivo as well: prophylactic or therapeutic use of TG could obviously inhibit ER stress and decrease islet ß-cell apoptosis in the pancreas of mice given a high-fat/high-sucrose diet (HFHSD), thus dramatically maintaining or restoring ß-cell mass and islet size, respectively. Accordingly, both prophylactic and therapeutic use of TG improved HFHSD-impaired glucose metabolism in mice, as evidenced by ameliorating hyperglycemia and glucose intolerance. Taken together, TG, as an agent promoting PDX1 expression exhibits strong protective effects on islet ß-cells both in vitro and in vivo.

Convallatoxin induces HaCaT cell necroptosis and ameliorates skin lesions in psoriasis-like mouse models.

Psoriasis is considered an immune-mediated inflammatory skin disorder that affects the quality of life of nearly four percent of the world population. Considering the side effects of existing therapeutic drugs and the urgent need for new drug development, we screened more than 250 traditional Chinese medicine compounds to identify drugs that significantly reduced the viability of human HaCaT keratinocytes, a psoriasis-related model cell line. Convallatoxin (CNT) was found to be a highly effective inhibitor of HaCaT cell viability. Subsequent mechanistic studies revealed that CNT induced HaCaT cell death by necroptosis rather than by apoptosis. CNT destroyed the membrane integrity of HaCaT cells, as detected by nuclear propidium iodide (PI) staining and lactate dehydrogenase (LDH) release. Additionally, the intercellular levels of adenosine triphosphate (ATP) were lower in HaCaT cells treated with CNT than in control HaCaT cells, and typical necroptosis-associated characteristics were observed by electron microscopy in cells treated with CNT. Furthermore, compared with control HaCaT cells, CNT-treated HaCaT cells produced more reactive oxygen species (ROS), but this effect was inhibited by the antioxidants N-acetyl-cysteine (NAC), diphenyleneiodonium chloride (DPI), and apocynin and the necroptosis inhibitor Nec-1. In addition, antioxidant treatment attenuated necroptotic cell death, suggesting that CNT-induced HaCaT necroptosis is mediated by oxidative stress. More importantly, CNT ameliorated skin lesions and inflammation in imiquimod (IMQ)- and 12-O-tetradecanoyl-phorbol-13-acetate (TPA)-induced psoriasis-like mouse models. In conclusion, our results demonstrate that CNT is cytotoxic against HaCaT cells in vitro and exerts antipsoriatic activities in two mouse models of psoriasis in vivo, making CNT a potential promising candidate drug for future research.

Nitidine chloride induces S phase cell cycle arrest and mitochondria-dependent apoptosis in HaCaT cells and ameliorates skin lesions in psoriasis-like mouse models.

Psoriasis is a common dermatosis causing considerable inconvenience to 4% of the general population. Traditional psoriasis treatments often cause side effects, drug resistance and complications, necessitating development of safer and more effective treatments. In this study, we screened over 600 natural compounds to identify viability inhibitors of human HaCaT keratinocytes cultured in vitro. The results showed that nitidine chloride was a highly effective inhibitor. Further studies revealed that nitidine chloride inhibited HaCaT proliferation and induced S phase cell cycle arrest; these effects were associated with reduced DNA synthesis, decreased Ki67, cyclin A, and cyclin D1 levels, and increased p53 protein expression. Nitidine chloride also significantly downregulated bcl-2 and upregulated bax, cleaved caspase-9 and cleaved caspase-3. Mechanistic studies revealed that nitidine chloride-induced apoptosis involved the c-Jun N-terminal kinase (JNK) pathway. More importantly, in 12-O-tetradecanoyl-phorbol-13-acetate (TPA)- and imiquimod (IMQ)-induced epidermal hyperplasia and inflammation models, nitidine chloride inhibited topical edema in mouse ear and back skin, substantially reducing tissue thickness and weight. In some cases, nitidine chloride also ameliorated conditions caused by TPA and IMQ, such as angiogenesis and infiltration of large numbers of inflammatory cells around blood vessels. Additionally, nitidine chloride inhibited the expression of various proinflammatory cytokines in the two animal models. In conclusion, our results are the first to demonstrate that nitidine chloride inhibits the proliferation of HaCaT cells, induces apoptosis partly via the JNK signaling pathway in vitro and ameliorates skin lesions and inflammation in vivo, making it an appropriate candidate for psoriasis treatment.

Expression and effects of TSP50 in mouse embryo and cardiac myocyte development.

TSP50, a testis-specific gene encoding a serine protease-like protein, was specifically expressed in the spermatocytes of testes but abnormally activated and expressed in many different kinds of cancers. Here, we aimed to analyze the expression of TSP50 in mouse embryo and its function in early embryonic development. Firstly, the distribution of TSP50 in oocytes and embryonic development was characterized by immunofluorescence, RT-PCR and western blotting, and the results showed that TSP50 was detected at all studied stages with a dynamic expression pattern. When overexpressed TSP50 in zygotes by microinjection, the zygotes development was highly accelerated. On the contrary, knocking down TSP50 expression by RNA interference greatly retarded the zygote development. Furthermore, TSP50 expression at embryonic day 6.5 (E6.5), day 8.5 (E8.5) and day 10.5 (E10.5) were increasingly enhanced, However, the expression of TSP50 decreased gradually in the development and differentiation of cardiac myocyte from E12.5 to postnatal (P0). Additionally, we found that TSP50 expression was decreased during cardiac myocyte differentiation of P19 cells. Overexpression of TSP50 could decrease the expression of GATA-4, and knockdown of TSP50 markedly increase the expression of GATA-4. Taken together, our data indicate that TSP50 may play an important role during the process of mouse embryonic development as well as myocardial cell differentiation.

20(S)-25-methoxyl-dammarane-3ß, 12ß, 20-triol negatively regulates activation of STAT3 and ERK pathways and exhibits anti-cancer effects in HepG2 cells.

The pro-inflammatory cytokine interleukin 6 (IL-6), via activating its downstream JAK/STAT3 and Ras/ERK signaling pathways, is involved in cell growth, proliferation and anti-apoptotic activities in various malignancies. To screen inhibitors of IL-6 signaling, we constructed a STAT3 and ERK dual-pathway responsive luciferase reporter vector (Co.RE). Among several candidates, the natural compound 20(S)-25-methoxyl-dammarane-3ß, 12ß, 20-triol (25-OCH3-PPD, GS25) was identified to clearly inhibit the luciferase activity of Co.RE. GS25 was confirmed to indeed inhibit activation of both STAT3 and ERK pathways and expression of downstream target genes of IL-6, and to predominantly decrease the viability of HepG2 cells via induction of cell cycle arrest and apoptosis. Interestingly, GS25 showed preferential inhibition of HepG2 cell viability relative to normal liver L02 cells. Further investigation showed that GS25 could not induce apoptosis and block activation of STAT3 and ERK pathways in L02 cells as efficiently as in HepG2 cells, which may result in differential effects of GS25 on malignant and normal liver cells. In addition, GS25 was found to potently suppress the expression of endogenous STAT3 at a higher concentration and dramatically induce p38 phosphorylation in HepG2 cells, which could mediate its anti-cancer effects. Finally, we demonstrated that GS25 also inhibited tumor growth in HepG2 xenograft mice. Taken together, these findings indicate that GS25 elicits its anti-cancer effects on HepG2 cells through multiple mechanisms and has the potential to be used as an inhibitor of IL-6 signaling. Thus, GS25 may be developed as a treatment for hepatocarcinoma with low toxicity on normal liver tissues as well as other inflammation-associated diseases.

Virtual screening and experimental validation of novel histone deacetylase inhibitors.

BACKGROUND: Histone deacetylases (HDACs) are promising therapeutic targets for the treatment of cancer, diabetes and other human diseases. HDAC inhibitors, as a new class of potential therapeutic agents, have attracted a great deal of interest for both research and clinical applications. Increasing efforts have been focused on the discovery of HDAC inhibitors and some HDAC inhibitors have been approved for use in cancer therapy. However, most HDAC inhibitors, including the clinically approved agents, do not selectively inhibit the deacetylase activity of class I and II HDAC isforms, and many suffer from metabolic instability. This study aims to identify new HDAC inhibitors by using a high-throughput virtual screening approach. METHODS: An integration of in silico virtual screening and in vitro experimental validation was used to identify novel HDAC inhibitors from a chemical database. RESULTS: A virtual screening workflow for HDAC inhibitors were created by integrating ligand- and receptor- based virtual screening methods. Using the virtual screening workflow, 22 hit compounds were selected and further tested via in vitro assays. Enzyme inhibition assays showed that three of the 22 compounds had HDAC inhibitory properties. Among these three compounds, ZINC12555961 significantly inhibited HDAC activity. Further in vitro experiments indicated that ZINC12555961 can selectively inhibit proliferation and promote apoptosis of cancer cells. CONCLUSIONS: In summary, our study presents three new and potent HDAC inhibitors and one of these HDAC inhibitors shows anti-proliferative and apoptosis-inducing activity against various cancer cell lines. These results suggest that the developed virtual screening workflow can provide a useful source of information for the screening and validation of new HDAC inhibitors. The new-found HDAC inhibitors are worthy to further and more comprehensive investigations.

Paclitaxel inhibits selenoprotein S expression and attenuates endoplasmic reticulum stress.

The primary effect of the endoplasmic reticulum (ER) stress response or unfolded protein response (UPR) is to reduce the load of unfolded protein and promote survival. However, prolonged and severe ER stress leads to tissue injury and serious diseases. Thus, it is important to identify drugs that can attenuate ER stress for the treatment of diseases. Natural products continue to provide lead compounds for drug discovery and front­line pharmacotherapy for people worldwide. Previous studies have indicated that selenoprotein S (SelS) is a sensitive and ideal maker of ER stress. In the present study, a firefly luciferase reporter driven by the SelS gene promoter was used to screen for natural compounds capable of attenuating ER stress. From this, paclitaxel (PTX) was identified to efficiently inhibit the promoter activity of the SelS gene, and further results revealed that PTX significantly inhibited the tunicamycin­induced upregulation of SelS at the mRNA and protein levels in HepG2 and HEK293T cells. In addition, PTX was able to efficiently inhibit the expression of the ER stress marker, glucose­regulated protein 78, in ER stress, indicating that PTX may reverse ER stress. Taken together, these results suggest that PTX is able to inhibit SelS expression during ER stress and attenuate ER stress.

Cardamonin inhibited cell viability and tumorigenesis partially through blockade of testes-specific protease 50-mediated nuclear factor-kappaB signaling pathway activation.

Previous studies have shown that testes-specific protease 50 (TSP50), a pro-oncogene overexpressed in many types of tumors, could promote cell proliferation, invasion, tumorigenesis, and tumor metastasis, suggesting that it is a potential cancer therapeutic target in drug discovery. Here, a luciferase assay system driven by the TSP50 gene promoter was used to screen the inhibitor of expression of TSP50. The study found that cardamonin, a flavone compound, could efficiently inhibit the expression of TSP50 in both mRNA and protein levels. Further results revealed that cardamonin also efficiently inhibited the viability of TSP50 high-expressing cancer cells by inducing G2/M-phase arrest and mitochondrial-dependent apoptosis. Surprisingly, knocking down the expression of TSP50 gene had the same effects as treatment with cardamonin. Moreover, it has been found that cardamonin had an inhibitory potency on TSP50 high-expressing tumor growth in vivo. In contrast, overexpression of TSP50 greatly decreased the cell sensitivity to the inhibitory effect of cardamonin and reversed the decreased tumor-inhibitory effect of cardamonin. Additionally, both TSP50 interference and treatment with cardamonin could suppress p65 nuclear translocation, and overexpression of TSP50 reversed the suppressive effect of cardamonin on p65 nuclear translocation. Taken together, these results suggest that cardamonin inhibited cell viability and tumorigenesis at least partially via blocking the activation of TSP50-mediated nuclear factor-kappaB signaling pathway, and cardamonin may be a promising anticancer drug candidate in the development of a novel agent for TSP50 high-expressing cancer cells.

Periplogenin induces necroptotic cell death through oxidative stress in HaCaT cells and ameliorates skin lesions in the TPA- and IMQ-induced psoriasis-like mouse models.

Psoriasis is a multifactorial skin disease that inconveniences many patients. Considering the side effects and drug resistance of the current therapy, it is urgent to discover more effective and safer anti-psoriatic drugs. In the present study, we screened over 250 traditional Chinese medicine compounds for their ability to inhibit the cell viability of cultured human HaCaT keratinocytes, a psoriasis-relevant in vitro model, and found that periplogenin was highly effective. Mechanistic studies revealed that apoptosis and autophagy were not induced by periplogenin in HaCaT cells. However, periplogenin caused PI to permeate into cells, increased lactate LDH release and rapidly increased the number of necrotic cells. Additionally, the typical characteristics of necrosis were observed in the periplogenin-treated HaCaT cells. Notably, the necroptosis inhibitor Nec-1 and NSA were able to rescue the cells from necrotic cell death, supporting that necroptosis was involved in periplogenin-induced cell death. Furthermore, the ROS levels were elevated in the periplogenin-treated cells, NAC (an antioxidant) and Nec-1 could inhibit the ROS levels, and NAC could attenuate necroptotic cell death, indicating that the periplogenin-induced necroptotic cell death was mediated by oxidative stress. More importantly, in the murine models of TPA-induced epidermal hyperplasia and IMQ-induced skin inflammation, topical administration of periplogenin ameliorated skin lesions and inflammation. In sum, our results indicate, for the first time, that periplogenin is a naturally occurring compound with potent anti-psoriatic effects in vitro and in vivo, making it a promising candidate for future drug research.

JA, a new type of polyunsaturated fatty acid isolated from Juglans mandshurica Maxim, limits the survival and induces apoptosis of heptocarcinoma cells.

Juglans mandshurica Maxim (Juglandaceae) is a famous folk medicine for cancer treatment and some natural compounds isolated from it have been studied extensively. Previously we isolated a type of ω-9 polyunsaturated fatty acid (JA) from the bark of J. mandshurica, however little is known about its activity and the underlying mechanisms. In this study, we studied anti-tumor activity of JA on several human cancer cell lines. Results showed that JA is cytotoxic to HepG2, MDA-MB-231, SGC-7901, A549 and Huh7 cells at a concentration exerting minimal toxic effects on L02 cells. The selective toxicity of JA was better than other classical anti-cancer drugs. Further investigation indicated that JA could induce cell apoptosis, characterized by chromatin condensation, DNA fragmentation and activation of the apoptosis-associated proteins such as Caspase-3 and PARP-1. Moreover, we investigated the cellular apoptosis pathway involved in the apoptosis process in HepG2 cells. We found that proteins involved in mitochondrion (cleaved-Caspase-9, Apaf-1, HtrA2/Omi, Bax, and Mitochondrial Bax) and endocytoplasmic reticulum (XBP-1s, GRP78, cleaved-Caspase-7 and cleaved-Caspase-12) apoptotic pathways were up-regulated when cells were treated by JA. In addition, a morphological change in the mitochondrion was detected. Furthermore, we found that JA could inhibit DNA synthesis and induce G2/M cell cycle arrest. The expression of G2-to-M transition related proteins, such as CyclinB1 and phosphorylated-CDK1, were reduced. In contrast, the G2-to-M inhibitor p21 was increased in JA-treated cells. Overall, our results suggest that JA can induce mitochondrion- and endocytoplasmic reticulum-mediated apoptosis, and G2/M phase arrest in HepG2 cells, making it a promising therapeutic agent against hepatoma.

Cripto-1 modulates macrophage cytokine secretion and phagocytic activity via NF-κB signaling.

Cripto-1 is an oncogenic protein belonging to the epidermal growth factor­Cripto-1/FRL-1/Cryptic family. It has important roles in tumor formation and metastasis, but its effects on the immune system are unclear. In the present study, we investigated the effects of Cripto-1 overexpression on macrophage activities and examined the underlying mechanisms. A cell line stably overexpressing Cripto-1 was developed. The culture supernatant from this cell line was collected and used to condition macrophages (RAW264.7, THP-1, and primary mouse macrophages) for various times. Exposure to this supernatant significantly increased the mRNA and protein expression levels of the anti-inflammatory cytokine interleukin (IL)-10 and of three pro-inflammatory cytokines (tumor necrosis factor-α, IL-6, and IL-1ß), but did not affect the expression of transforming growth factor-ß, another anti-inflammatory cytokine. Exposure to this supernatant also enhanced macrophage phagocytosis of chicken erythrocytes and yeast cells. Similar effects were observed in macrophages stimulated with purified Cripto-1 protein. Mechanistic experiments revealed that Cripto-1 activated nuclear factor (NF)-κB signaling by inducing IκB kinase phosphorylation and p65 nuclear translocation. Pretreatment with ammonium pyrrolidine dithiocarbamate, a specific NF-κB inhibitor, inhibited Cripto-1-induced cytokine secretion and phagocytosis of macrophages. Taken together, our present findings suggest that Cripto-1 enhances macrophage phagocytic activity and upregulates the production of anti- and pro-inflammatory cytokines via the NF-κB signaling pathway.

Juglanthraquinone C Induces Intracellular ROS Increase and Apoptosis by Activating the Akt/Foxo Signal Pathway in HCC Cells.

Juglanthraquinone C (JC), a naturally occurring anthraquinone extracted from Juglans mandshurica, could induce apoptosis of cancer cells. This study aims to investigate the detailed cytotoxicity mechanism of JC in HepG2 and BEL-7402 cells. The Affymetrix HG-U133 Plus 2.0 arrays were first used to analyze the mRNA expression exposed to JC or DMSO in HepG2 cells. Consistent with the previous results, the data indicated that JC could induce apoptosis and hyperactivated Akt. The Western blot analysis further revealed that Akt, a well-known survival protein, was strongly activated in HepG2 and BEL-7402 cells. Furthermore, an obvious inhibitory effect on JC-induced apoptosis was observed when the Akt levels were decreased, while the overexpression of constitutively active mutant Akt greatly accelerated JC-induced apoptosis. The subsequent results suggested that JC treatment suppressed nuclear localization and increased phosphorylated levels of Foxo3a, and the overexpression of Foxo3a abrogated JC-induced apoptosis. Most importantly, the inactivation of Foxo3a induced by JC further led to an increase of intracellular ROS levels by suppressing ROS scavenging enzymes, and the antioxidant N-acetyl-L-cysteine and catalase successfully decreased JC-induced apoptosis. Collectively, this study demonstrated that JC induced the apoptosis of hepatocellular carcinoma (HCC) cells by activating Akt/Foxo signaling pathway and increasing intracellular ROS levels.

Protumoral TSP50 Regulates Macrophage Activities and Polarization via Production of TNF-α and IL-1ß, and Activation of the NF-κB Signaling Pathway.

Testes-specific protease 50 (TSP50) is abnormally overexpressed in many kinds of cancers and promotes cell proliferation and migration. However, whether TSP50 can influence the tumor microenvironment, especially the function of immune cells in the microenvironment, remains largely unknown. We demonstrated that exposure to the conditioned medium from TSP50-overexpressing cells, or co-culture with TSP50-overexpressing cells, enhanced the cytokine production and phagocytic activities of macrophages, and induced M2b polarization. Further investigation showed that production of TNF-α and IL-1ß was strongly induced by TSP50 in TSP50-overexpressing cells. TSP50-induced TNF-α and IL-1ß were main factors that mediated the effects of TSP50-overexpressing cells on macrophages. The NF-κB pathway could be activated in macrophages upon the treatment of conditioned medium of TSP50-overexpressing cells and its activation is necessary for the observed effects on macrophages. Taken together, our results suggested that oncogenic TSP50 expressed in cells could activate surrounding macrophages and induce M2b polarization, partly through inducing TNF-α/ IL-1ß secretion and subsequent NF-κB pathway activation. This implies a potential mechanism by which oncogene TSP50 regulates tumor microenvironment to support tumor development.

Modelling coupled oscillations in the Notch, Wnt, and FGF signaling pathways during somitogenesis: a comprehensive mathematical model.

Somite formation in the early stage of vertebrate embryonic development is controlled by a complicated gene network named segmentation clock, which is defined by the periodic expression of genes related to the Notch, Wnt, and the fibroblast growth factor (FGF) pathways. Although in recent years some findings about crosstalk among the Notch, Wnt, and FGF pathways in somitogenesis have been reported, the investigation of their crosstalk mechanisms from a systematic point of view is still lacking. In this study, a more comprehensive mathematical model was proposed to simulate the dynamics of the Notch, Wnt, and FGF pathways in the segmentation clock. Simulations and bifurcation analyses of this model suggested that the concentration gradients of both Wnt, and FGF signals along the presomitic mesoderm (PSM) are corresponding to the whole process from start to stop of the segmentation clock. A number of highly sensitive parameters to the segmentation clock's oscillatory pattern were identified. By further bifurcation analyses for these sensitive parameters, and several complementary mechanisms in respect of the maintenance of the stable oscillation of the segmentation clock were revealed.

Systematic analysis of time-series gene expression data on tumor cell-selective apoptotic responses to HDAC inhibitors.

SAHA (suberoylanilide hydroxamic acid or vorinostat) is the first nonselective histone deacetylase (HDAC) inhibitor approved by the US Food and Drug Administration (FDA). SAHA affects histone acetylation in chromatin and a variety of nonhistone substrates, thus influencing many cellular processes. In particularly, SAHA induces selective apoptosis of tumor cells, although the mechanism is not well understood. A series of microarray experiments was recently conducted to investigate tumor cell-selective proapoptotic transcriptional responses induced by SAHA. Based on that gene expression time series, we propose a novel framework for detailed analysis of the mechanism of tumor cell apoptosis selectively induced by SAHA. Our analyses indicated that SAHA selectively disrupted the DNA damage response, cell cycle, p53 expression, and mitochondrial integrity of tumor samples to induce selective tumor cell apoptosis. Our results suggest a possible regulation network. Our research extends the existing research.

Three new compounds from the stem bark of Juglans mandshurica.

Three new compounds, 3,6-dihydroxy-4,5-dimethoxy-1,8-naphalic anhydride (1), 3,4,5,6-tetrahydroxy-1,8-naphalic anhydride (2), and methyl (7E,9E)-6,11-dioxononadeca-7,9-dienoate (3), were isolated from the stem bark of Juglans mandshurica. Their structures were elucidated on the basis of spectroscopic evidence, including 1D and 2D NMR, HR-TOF-MS, and by comparison with the literature data.

The catalytic triad of testes-specific protease 50 (TSP50) is essential for its function in cell proliferation.

Testes-specific protease 50 (TSP50) is a novelly identified pro-oncogene and it shares a similar enzymatic structure with many serine proteases. Our previous results suggested that TSP50 could promote tumorigenesis through degradation of IκBα protein and activating NF-κB signaling, and the threonine mutation in its catalytic triad could depress TSP50-mediated cell proliferation. However, whether the two other residues in the catalytic triad of TSP50 play a role in maintaining protease activity and tumorigenesis, and the mechanisms involved in this process remain unclear. Here, we constructed and characterized three catalytic triad mutants of TSP50 and found that all the mutants could significantly depress TSP50-induced cell proliferation and colony formation in vitro and tumor formation in vivo, and the aspartic acid at position 206 in the catalytic triad played a more crucial role than threonine and histidine in this process. Mechanistic studies revealed that the mutants in the catalytic triad abolished the enzyme activity of TSP50, but did not change the cellular localization. Furthermore, our data indicated that all the three mutants suppressed activation of NF-κB signal by preventing the interaction between TSP50 and the NF-κB:IκBα complex. Most importantly, we demonstrated that TSP50 could interact with IκBα protein and cleave it directly as a new protease in vitro.