ERK signaling is triggered by hepatitis C virus E2 protein through DC-SIGN

Dendritic cell-specific intercellular adhesion molecule-3-grabbing nonintegrin (DC-SIGN) is a binding receptor for hepatitis C virus (HCV). Binding of HCV envelope protein E2 to target cells is a prerequisite to DC-SIGN-mediated signaling. Using cell lines with stable or transient expression of DC-SIGN, we investigated effects of soluble HCV E2 protein on ERK pathway. MEK and ERK are activated by the E2 in NIH3T3 cells stably expressing DC-SIGN. Treatment of the cells with antibody to DC-SIGN results in inhibition of the E2 binding as well as the E2-induced MEK and ERK activation. In HEK293T cells transiently expressing DC-SIGN, activation of MEK and ERK is also induced by the E2. Activation of ERK pathway by HCV E2 through DC-SIGN provides useful information for understanding cellular receptor-mediated signaling.     

hPNAS-4 inhibits proliferation through S phase arrest and apoptosis: underlying action mechanism in ovarian cancer cells

PNAS-4, a novel pro-apoptotic gene, was activated during the early response to DNA damage. Previous studies have shown that hPNAS-4 can inhibit tumor growth when over-expressed in ovarian cancer cells. However, the underlying action mechanism remains elusive. In this work, we found that hPNAS-4 expression was significantly increased in SKOV3 cells when exposed to cisplatin, methyl methanesulfonate or mitomycin C, and that its overexpression could induce proliferation inhibition, S phase arrest and apoptosis in A2780s and SKOV3 ovarian cancer cells. The S phase arrest caused by hPNAS-4 was associated with up-regulation of p21. p21 is p53-dispensable and correlates with activation of ERK, and activation of the Cdc25A-Cdk2-Cyclin E/Cyclin A pathway, while the pro-apoptotic effects of hPNAS-4 were mediated by activation of caspase-9 and -3 other than caspase-8, and accompanied by release of AIF, Smac and cytochrome c into the cytosol. Taken together, these data suggest a new mechanism by which hPNAS-4 inhibits proliferation of ovarian cancer cells by inducing S phase arrest and apoptosis via activation of Cdc25A-Cdk2-Cyclin E/Cyclin A axis and mitochondrial dysfunction-mediated caspase-dependent and -independent apoptotic pathways. To our knowledge, we provide the first molecular evidence for the potential application of hPNAS-4 as a novel target in ovarian cancer gene therapy.     

Alantolactone induces apoptosis in chronic myelogenous leukemia sensitive or resistant to imatinib through NF-κB inhibition and Bcr/Abl protein deletion

Alantolactone, an allergenic sesquiterpene lactone, has recently been found to have significant antitumor effects on malignant tumor cells. Here, we investigated the potential effect of alantolactone on Bcr/Abl⁺ imatinib-sensitive and -resistant cells. Alantolactone treatment resulted in obvious apoptosis in both imatinib-sensitive and -resistant K562 cells, as shown by the increase in Annexin V-positive cells, caspase-3 activation, poly(ADP-ribose) polymerase-1 (PARP-1) cleavage and mitochondrial membrane potential collapse. Alantolactone significantly inhibited NF-κB-dependent reporter gene activity, decreased the DNA-binding activity of NF-ОκB, and blocked TNF-α-induced IκBα phosphorylation. Of interest, the oncogenic Bcr/Abl fusion protein but not its mRNA levels were quickly reduced upon alantolactone exposure in imatinib-sensitive and -resistant K562 cells. Bcr/Abl knockdown enhanced the apoptosis driven by alantolactone. Bcr/Abl protein reduction could not be reversed by the addition of proteasome or caspase-3 inhibitors. The overexpression of p65 inhibited alantolactone-induced apoptosis, whereas p65 or Bcr/Abl silencing enhanced its apoptotic-inducing effect. Furthermore, Bcr/Abl-transfected 32D cells showed more sensitivity to alantolactone than vector-transfected control cells, and the Bcr/Abl protein was depleted, as observed in K562 cells. Finally, alantolactone-induced apoptosis was also observed in primary CD34⁺ CML leukemic cells. Collectively, these findings suggest that alantolactone is a promising potent agent to fight against CML cells via the inhibition of the NF-κB signaling pathway and depletion of the Bcr/Abl protein.     

The role of IL-6 in bone marrow (BM)-derived mesenchymal stem cells (MSCs) proliferation and chondrogenesis

Rheumatoid arthritis (RA) is the most common degenerative arthritic cartilage and represents a disease where the prospect of stem cell therapy offers considerable hope. Currently, bone marrow (BM) represents the major source of mesenchymal stem cells (MSCs) for cell therapy. In the pathology of RA, the pro-inflammatory cytokines, such as interleukin 6 (IL-6) play a pivotal role. To investigate the direct role of IL-6 in the chondrogenic differentiation of murine MSCs (mMSCs), we isolate MSCs from the murine bone marrow, and induce MSCs chondrogenesis with different concentrations of IL-6 in vitro. Through detecting the histological and histochemical qualities of the aggregates, we demonstrate that IL-6 inhibited the differentiation of MSCs into chondrocytes in the dose-dependence manner. These findings suggest that possible strategies for improving the clinical outcome of cartilage repair procedures.     

The impacts of climate change and human activities on biogeochemical cycles on the Qinghai‐Tibetan Plateau

With a pace of about twice the observed rate of global warming, the temperature on the Qinghai‐Tibetan Plateau (Earth's ‘third pole’) has increased by 0.2 °C per decade over the past 50 years, which results in significant permafrost thawing and glacier retreat. Our review suggested that warming enhanced net primary production and soil respiration, decreased methane (CH₄) emissions from wetlands and increased CH₄ consumption of meadows, but might increase CH₄ emissions from lakes. Warming‐induced permafrost thawing and glaciers melting would also result in substantial emission of old carbon dioxide (CO₂) and CH₄. Nitrous oxide (N₂O) emission was not stimulated by warming itself, but might be slightly enhanced by wetting. However, there are many uncertainties in such biogeochemical cycles under climate change. Human activities (e.g. grazing, land cover changes) further modified the biogeochemical cycles and amplified such uncertainties on the plateau. If the projected warming and wetting continues, the future biogeochemical cycles will be more complicated. So facing research in this field is an ongoing challenge of integrating field observations with process‐based ecosystem models to predict the impacts of future climate change and human activities at various temporal and spatial scales. To reduce the uncertainties and to improve the precision of the predictions of the impacts of climate change and human activities on biogeochemical cycles, efforts should focus on conducting more field observation studies, integrating data within improved models, and developing new knowledge about coupling among carbon, nitrogen, and phosphorus biogeochemical cycles as well as about the role of microbes in these cycles.     

A comparative study of the atp9 gene between a cytoplasmic male sterile line and its maintainer line and further development of a molecular marker specific for male sterile cytoplasm in kenaf (Hibiscus cannabinus L.)

mtDNA was isolated from cytoplasmic male sterility (CMS) line P3A and its maintainer P3B of kenaf (Hibiscus cannabinus L.). The atp9 gene and its two flanking sequences were obtained using homology cloning and high-efficiency thermal asymmetric interlaced PCR methods. The coding sequences showed only two base pairs difference between the CMS and its maintainer, and shared a homology of over 87 % with atp9 genes from other species in GenBank. However, when comparing the flanking sequences, a 47-bp deletion was characterized at the 3′ flanking sequence of atp9 in the CMS line. Quantitative PCR analysis indicated that the expression level of atp9 in the CMS line was 0.937-fold that of its maintainer. Furthermore, the respiratory rate of anthers in the CMS line was markedly lower than that of its maintainer. The results indicated that the 47-bp deletion at the 3′ flanking sequence of atp9 and/or down-regulated expression of the atp9 gene in the CMS line might be closely related to CMS in kenaf. To confirm whether the 47-bp deletion was specific to cytoplasm of male sterile lines, another 21 varieties were used for further analysis. The results showed that the 47-bp deletion was specific to male sterile cytoplasm (MSC) of kenaf. Based on these, a specific molecular marker was developed to distinguish the MSC from male fertile cytoplasm of kenaf.     

Efficient and fine mapping of RMES1 conferring resistance to sorghum aphid Melanaphis sacchari

Melanaphis sacchari causes serious damage to sorghum (Sorghum bicolor (L.) Moench) growth, development and productivity in many countries. A dominant gene (RMES1) conferring resistance to M. sacchari has been found in the grain sorghum variety Henong 16 (HN16), but fine mapping of the RMES1 locus remains to be reported. In this study, genetic populations segregating for RMES1 were prepared with HN16 and BTx623 as parental lines. The latter had been used for sorghum genome sequencing but was found to be susceptible to M. sacchari in this work. A total of 11 molecular markers were mapped to the short arm of chromosome 6 harboring RMES1. The closest markers flanking the RMES1 locus were Sb6m2650 and Sb6rj2776, which delimited a chromosomal region of about 126 kb containing five predicted genes. The utility of the newly identified DNA markers for tagging RMES1 in molecular breeding of M. sacchari resistance, and further efforts in cloning RMES1, are discussed.     

Genetic and physical fine mapping of a multilocular gene Bjln1 in Brassica juncea to a 208-kb region

Most of the germplasm resources in Brassica juncea produce silique with only two locules, whereas a few varieties can produce silique with three or four locules. The increase in locule number in B. juncea has been shown to cause an increase in the number of seeds per silique, resulting in an increase in the yield per plant. Thus, the development of high-locule-number varieties may be an effective way of improving the yield of B. juncea. Duoshi, a B. juncea landrace originating from the Qinghai–Tibetan plateau, produces silique with 3–4 locules. Genetic analysis has shown that the high-locule-number trait in Duoshi is determined by two recessive genes, tentatively designated as Bjln1 and Bjln2. For fine mapping of the Bjln1 gene, a BC3 population was developed from the cross between Duoshi (multilocular parent) and Xinjie (bilocular parent). Using a combination of amplified fragment length polymorphism (AFLP) and bulked segregant analysis, only two AFLP markers linked to Bjln1 were identified. Preliminary linkage analysis showed that the two AFLP markers were located on the same side of Bjln1. Blast analysis revealed that the sequences of the two AFLP markers had homologues on Scaffold000019 at the bottom of B. rapa A7. Using the results of linkage analysis and BlastN searches, simple sequence repeat (SSR) markers were subsequently developed based on the sequence information from B. rapa A7. Seven SSR markers were eventually identified, of which ln 8 was co-segregated with Bjln1. ln 7 and ln 9, the closest flanking markers, were mapped at 2.0 and 0.4 cM distant from the Bjln1 gene, respectively. The SSR markers were cloned, sequenced and mapped on A7 of B. rapa (corresponding to J7 in the A genome of B. juncea). The two closest flanking markers, ln 7 and ln 9, were mapped within a 208-kb genomic region on B. rapa A7, in which the Bjln1 gene might be included. The present study may facilitate cloning of the Bjln1 gene as well as the selection process for developing multilocular varieties in B. juncea by marker-assisted selection and genetic engineering.