Effect of influenza A virus non-structural protein 1(NS1) on a mouse model of diabetes mellitus induced by Streptozotocin

Type 1 diabetes (T1D) is a chronic autoimmune disease caused by proinflammatory autoreactive T cells that mediate the selective destruction of insulin-producing β cells via both direct and indirect mechanisms. Many immune cells and proinflammatory cytokines are involved in the pathogenesis of autoimmune diabetes. Immune intervention is effective for the prevention and treatment of T1D by blocking the autoimmune assault to β cells. The non-structural protein 1(NS1) of influenza A viruses is a non-essential virulence factor encoded on segment 8 that has multiple accessory functions, including suppression of innate immunity and adaptive immunity, inhibition of apoptosis and activation of phosphoinositide 3-kinase (PI3K). This research investigated whether the expression of NS1 can prevent and treat diabetes mellitus induced by Streptozotocin (STZ). The NS1 expressing plasmid pEGFP-C2/NS1 was constructed and injected intramuscularly to both thighs of mice. Its effect on mice was observed. Intramuscular delivery of pEGFP-C2/NS1 resulted in reduction in hyperglycemia and diabetes incidence, with an increase in insulin. pEGFP-C2/NS1 could also increase glycogen and regulated serum cytokine levels. In addition, by comparison to the mice treated with empty vector pEGFP-C2, ameliorative insulitis was observed in the mice treated with recombinant plasmid pEGFP-C2/NS1. This result suggests that the expression of NS1 is effective for the prevention and treatment of diabetes mellitus induced by STZ in a mouse model.     

Activated CD69+ T cells foster immune privilege by regulating IDO expression in tumor-associated macrophages

Substantial evidence indicates that immune activation at stroma can be rerouted in a tumor-promoting direction. CD69 is an immunoregulatory molecule expressed by early-activated leukocytes at sites of chronic inflammation, and CD69(+) T cells have been found to promote human tumor progression. In this study, we showed that, upon encountering autologous CD69(+) T cells, tumor macrophages (MΦs) acquired the ability to produce much greater amounts of IDO protein in cancer nests. The T cells isolated from the hepatocellular carcinoma tissues expressed significantly more CD69 molecules than did those on paired circulating and nontumor-infiltrating T cells; these tumor-derived CD69(+) T cells could induce considerable IDO in monocytes. Interestingly, the tumor-associated monocytes/MΦs isolated from hepatocellular carcinoma tissues or generated by in vitro culture effectively activated circulating T cells to express CD69. IL-12 derived from tumor MΦs was required for early T cell activation and subsequent IDO expression. Moreover, we found that conditioned medium from IDO(+) MΦs effectively suppressed T cell responses in vitro, an effect that could be reversed by adding extrinsic IDO substrate tryptophan or by pretreating MΦs with an IDO inhibitor 1-methyl-DL-tryptophan. These data revealed a fine-tuned collaborative action between different types of immune cells to counteract T cell responses in tumor microenvironment. Such an active induction of immune tolerance should be considered for the rational design of effective immune-based anticancer therapies.     

Protection of exenatide for retinal ganglion cells with different glucose concentrations

Exendin-4 is a peptide resembling glucagon-like peptide-1 (GLP-1), which has protective effects on nerve cells. However, the effects of Exendin-4 on retinal ganglion cells (RGC) are still under clear. The purpose of the present study is to demonstrate that exenatide prevents high- or low-glucose-induced retinal ganglion cell impairment. We observed the expression of GLP-1R in RGC-5 cells by immunofluorescence and Western blot. To investigate the effect of exenatide on RGC-5 cells incubated different glucose concentrations, CCK-8 measured the survival rates and electron microscopy detected cellular injury. The expression levels of Bcl-2 and Bax were analyzed by immunocytochemistry and Western blot. Exenatide protects RGC-5 from high- or low-glucose-induced cellular injury and the optimum concentration was 0.5μg/ml. Exenatide can inhibit high- or low-glucose-induced mitochondrial changes. Exenatide protects RGC-5 from high- or low-glucose-induced Bax increased and Bcl-2 decreased. Furthermore, the protective effect of exenatide could be inhibited by Exendin (9-39). These findings indicate that exenatide shows a neuroprotective effect for different glucose concentrations-induced RGC-5 cells injury. Exenatide could protect RGC-5 cells from degeneration or death, which may protect retinal function and have a potential value for patients with diabetic retinopathy.     

Exenatide prevents high-glucose-induced damage of retinal ganglion cells through a mitochondrial mechanism

Exenatide (exendin-4 analogue) is widely used in clinics and shows a neuroprotective effect. The main objectives of the present study were to prove that retinal ganglion cells (RGC-5) express GLP-1R, to ascertain whether exenatide prevents a high-glucose-induced RGC-5 impairment, to determine the appropriate concentration of exenatide to protect RGC-5 cells, and to explore the neuroprotective mechanisms of exenatide. Immunofluorescence and Western blot analyses demonstrated that RGC-5 cells express GLP-1R. We incubated RGC-5 cells with 25 mM glucose prior to incubation with either 25 mM glucose, 55 mM glucose (high), high glucose plus exenatide or high glucose plus a GLP-1R antagonist. The survival rates of the cells were measured by CCK-8, and cellular injury was detected by electron microscopy. There were statistical differences between the high-glucose group and the control group (P<0.05). Exenatide improved the survival rate of the cells and suppressed changes in the mitochondrial morphology. The optimum concentration of exenatide to protect the RGC-5 cells from high-glucose-induced RGC injury was 0.5 μg/ml, and this protective effect could be inhibited by exendin (9-39). To further study the mechanism underlying the beneficial effects of exenatide, the expression levels of cytochrome c, Bcl-2, Bax and caspase-3 were analysed by Western blot. The present study showed that treatment with exenatide significantly inhibited cytochrome c release and decreased the intracellular expression levels of Bax and caspase-3, whereas Bcl-2 was increased (P<0.05). These results suggested that GLP-1R activation can inhibit the cellular damage that is induced by high glucose. A mitochondrial mechanism might play a key role in the protective effect of exenatide on the RGC-5 cells, and exenatide might be beneficial for patients with diabetic retinopathy.     

Plk1 phosphorylates sgt1 at the kinetochores to promote timely kinetochore-microtubule attachment

Accurate chromosome segregation during cell division maintains genomic integrity and requires the proper establishment of kinetochore-microtubule attachment in mitosis. As a key regulator of mitosis, Polo-like kinase 1 (Plk1) is essential for this attachment process, but the molecular mechanism remains elusive. Here we identify Sgt1, a cochaperone for Hsp90, as a novel Plk1 substrate during mitosis. We show that Sgt1 dynamically localizes at the kinetochores, which lack microtubule attachments during prometaphase. Plk1 is required for the kinetochore localization of Sgt1 and phosphorylates serine 331 of Sgt1 at the kinetochores. This phosphorylation event enhances the association of the Hsp90-Sgt1 chaperone with the MIS12 complex to stabilize this complex at the kinetochores and thus coordinates the recruitment of the NDC80 complex to form efficient microtubule-binding sites. Disruption of Sgt1 phosphorylation reduces the MIS12 and NDC80 complexes at the kinetochores, impairs stable microtubule attachment, and eventually results in chromosome misalignment to delay the anaphase onset. Our results demonstrate a mechanism for Plk1 in promoting kinetochore-microtubule attachment to ensure chromosome stability.     

Design, synthesis and biological evaluation of novel acrylamide analogues as inhibitors of BCR-ABL kinase

A series of acrylamide analogues were designed and synthesized from Imatinib and Nilotinib as novel BCR-ABL inhibitors by application of the principle of nonclassical electronic isostere. All new compounds were evaluated for their inhibitory effects on the activity of BCR-ABL kinase and the proliferation of K562 leukemia cancer cells in vitro. The acrylamide analogues in which the substituent in C ring was trifluoromethyl group were identified as highly potent BCR-ABL kinase inhibitors. Compound 13f exhibited an IC(50) value as low as 20.6nM in ABL kinase inhibition and an IC(50) value of 32.3nM for antiproliferative activity, about 10.5-fold and 12-fold lower than those of Imatinib respectively. These results suggest that compound 13f is a promising candidate as a novel BCR-ABL kinase inhibitor for further development.     

Temporal encoding of spatial information during active visual fixation

Humans and other species continually perform microscopic eye movements, even when attending to a single point. These movements, which include drifts and microsaccades, are under oculomotor control, elicit strong neural responses, and have been thought to serve important functions. The influence of these fixational eye movements on the acquisition and neural processing of visual information remains unclear. Here, we show that during viewing of natural scenes, microscopic eye movements carry out a crucial information-processing step: they remove predictable correlations in natural scenes by equalizing the spatial power of the retinal image within the frequency range of ganglion cells' peak sensitivity. This transformation, which had been attributed to center-surround receptive field organization, occurs prior to any neural processing and reveals a form of matching between the statistics of natural images and those of normal eye movements. We further show that the combined effect of microscopic eye movements and retinal receptive field organization is to convert spatial luminance discontinuities into synchronous firing events, beginning the process of edge detection. Thus, microscopic eye movements are fundamental to two goals of early visual processing: redundancy reduction and feature extraction.     

U–Pb SHRIMP age for the Tuchengzi Formation,northern China,and its implications for biotic evolution during the Jurassic–Cretaceous transition

The Late Jurassic–Early Cretaceous Tuchengzi Formation is widespread in North China. Its clastic deposits indicate a tropical, dry, and hot paleoclimate, different from the subtropical, humid, and seasonal climate in the early Middle Jurassic. The sudden environmental change from the Middle to Late Jurassic resulted in a rapid disappearance of the Yanliao/Daohugou Biota, with more than 90% of the species of the Yanliao/Daohugou Biota dying out and replaced by the Early Cretaceous Jehol Biota. Eolian sandstones with large-scale cross-bedding occur within the uppermost part of the Tuchengzi Formation in North China. The sandstones are stratigraphically higher than the tuff previously dated as 139 Ma. We obtained two SHRIMP zircon U/Pb ages from the tuff beds. One sample was collected from the tuff in the basal Tuchengzi Formation in northern Hebei and the other from the tuff intercalated in the eolian cross-bedded sandstones in the uppermost Tuchengzi Formation in western Liaoning. Our results show that 154 Ma is the oldest age constraint for the Tuchengzi Formation and 137 Ma is the youngest age estimate of the formation, providing an age constraint for the transition from the Yanliao Biota to the Jehol Biota.