Apoptosis signal-regulating kinase 1 regulates the expression of caspase-11

Caspase-11 is an inducible caspase involved in the regulation of cell death and inflammation. In the present study, we examined whether apoptosis signal-regulating kinase 1 (Ask1)-mediated signaling pathway is involved in the expression of caspase-11 induced by lipopolysaccharide (LPS). We found that the induction of caspase-11 was suppressed by the inhibitors of NADPH oxidase (Nox) or knockdown of Nox4 that acts downstream of toll-like receptor 4 and generates Ask1-activating reactive oxygen species. Overexpression of dominant negative tumor necrosis factor receptor associate factor 6 also suppressed the induction of caspase-11. Importantly, knockdown or dominant negative form of Ask1 suppressed the induction of caspase-11 following LPS stimulation. Taken together, our results show that Ask1 regulates the expression of caspase-11 following LPS stimulation.     

Plants,microorganisms, and soil temperatures contribute to a decrease in methane fluxes on a drained Arctic floodplain

As surface temperatures are expected to rise in the future, ice‐rich permafrost may thaw, altering soil topography and hydrology and creating a mosaic of wet and dry soil surfaces in the Arctic. Arctic wetlands are large sources of CH₄, and investigating effects of soil hydrology on CH₄ fluxes is of great importance for predicting ecosystem feedback in response to climate change. In this study, we investigate how a decade‐long drying manipulation on an Arctic floodplain influences CH₄‐associated microorganisms, soil thermal regimes, and plant communities. Moreover, we examine how these drainage‐induced changes may then modify CH₄ fluxes in the growing and nongrowing seasons. This study shows that drainage substantially lowered the abundance of methanogens along with methanotrophic bacteria, which may have reduced CH₄ cycling. Soil temperatures of the drained areas were lower in deep, anoxic soil layers (below 30 cm), but higher in oxic topsoil layers (0–15 cm) compared to the control wet areas. This pattern of soil temperatures may have reduced the rates of methanogenesis while elevating those of CH₄ oxidation, thereby decreasing net CH₄ fluxes. The abundance of Eriophorum angustifolium, an aerenchymatous plant species, diminished significantly in the drained areas. Due to this decrease, a higher fraction of CH₄ was alternatively emitted to the atmosphere by diffusion, possibly increasing the potential for CH₄ oxidation and leading to a decrease in net CH₄ fluxes compared to a control site. Drainage lowered CH₄ fluxes by a factor of 20 during the growing season, with postdrainage changes in microbial communities, soil temperatures, and plant communities also contributing to this reduction. In contrast, we observed CH₄ emissions increased by 10% in the drained areas during the nongrowing season, although this difference was insignificant given the small magnitudes of fluxes. This study showed that long‐term drainage considerably reduced CH₄ fluxes through modified ecosystem properties.     

Temperature range of thermodynamic stability for the native state of reversible two-state proteins

The difference between the heat (T(G)) and the cold (T(G)') denaturation temperatures defines the temperature range (T(Range)) over which the native state of a reversible two-state protein is thermodynamically stable. We have performed a correlation analysis for thermodynamic parameters in a selected data set of structurally nonhomologous single-domain reversible two-state proteins. We find that the temperature range is negatively correlated with the protein size and with the heat capacity change (DeltaC(p)) but is positively correlated with the maximal protein stability [DeltaG(T(S))]. The correlation between the temperature range and maximal protein stability becomes highly significant upon normalization of the maximal protein stability with protein size. The melting temperature (T(G)) also shows a negative correlation with protein size. Consistently, T(G) and T(G)' show opposite correlations with DeltaC(p), indicating a dependence of the T(Range) on the curvature of the protein stability curve. Substitution of proteins in our data set with their homologues and arbitrary addition or removal of a protein in the data set do not affect the outcome of our analysis. Simulations of the thermodynamic data further indicate that T(Range) is more sensitive to variations in curvature than to the slope of the protein stability curve. The hydrophobic effect in single domains is the principal reason for these observations. Our results imply that larger proteins may be stable over narrower temperature ranges and that smaller proteins may have higher melting temperatures, suggesting why protein structures often differentiate into multiple substructures with different hydrophobic cores. Our results have interesting implications for protein thermostability.     

The MHC class I-like IgG receptor controls perinatal IgG transport,IgG homeostasis,and fate of IgG-Fc-coupled drugs

Abs of the IgG isotype are efficiently transported from mother to neonate and have an extended serum t(1/2) compared with Abs of other isotypes. Circumstantial evidence suggests that the MHC class I-related protein, the neonatal FcR (FcRn), is the FcR responsible for both in vivo functions. To understand the phenotypes imposed by FcRn, we produced and analyzed mice with a defective FcRn gene. The results provide direct evidence that perinatal IgG transport and protection of IgG from catabolism are mediated by FcRn, and that the latter function is key to IgG homeostasis, essential for generating a potent IgG response to foreign Ags, and the basis of enhanced efficacy of Fc-IgG-based therapeutics. FcRn is therefore a promising therapeutic target for enhancing protective humoral immunity, treating autoimmune disease, and improving drug efficacy.     

Influence of Deglaciation on Microbial Communities in Marine Sediments Off the Coast of Svalbard,Arctic Circle

Increases in global temperatures have been shown to enhance glacier melting in the Arctic region. Here, we have evaluated the effects of meltwater runoff on the microbial communities of coastal marine sediment located along a transect of Temelfjorden, in Svalbard. As close to the glacier front, the sediment properties were clearly influenced by deglaciation. Denaturing gradient gel electrophoresis profiles showed that the sediment microbial communities of the stations of glacier front (stations 188–178) were distinguishable from that of outer fjord region (station 176). Canonical correspondence analysis indicated that total carbon and calcium carbonate in sediment and chlorophyll a in bottom water were key factors driving the change of microbial communities. Analysis of 16S rRNA gene clone libraries suggested that microbial diversity was higher within the glacier–proximal zone (station 188) directly affected by the runoffs than in the outer fjord region. While the crenarchaeotal group I.1a dominated at station 176 (62%), Marine Benthic Group-B and other Crenarchaeota groups were proportionally abundant. With regard to the bacterial community, alpha-Proteobacteria and Flavobacteria lineages prevailed (60%) at station 188, whereas delta-Proteobacteria (largely sulfate-reducers) predominated (32%) at station 176. Considering no clone sequences related to sulfate-reducers, station 188 may be more oxic compared to station 176. The distance-wise compositional variation in the microbial communities is attributable to their adaptations to the sediment environments which are differentially affected by melting glaciers.     

Targeting of polyplex to human hepatic cells by bio-nanocapsules, hepatitis B virus surface antigen L protein particles

We have previously demonstrated that lipoplex, a complex of cationic liposomes and DNA, could be targeted to human hepatic cells in vitro and in vivo by conjugation with bio-nanocapsules (BNCs) comprising hepatitis B virus (HBV) surface antigen L protein particles. Because the BNC-lipoplex complexes were endowed with the human hepatic cell-specific infection machinery from HBV, the complexes showed excellent specific transfection efficiency in human hepatic cells. In this study, we have found that polyplex (a complex of polyethyleneimine (PEI) and DNA) could form stable complexes with BNCs spontaneously. The diameter and ζ-potential of BNC-polyplex complexes are about 240 nm and +3.54 mV, respectively, which make them more suitable for in vivo use than polyplex alone. BNC-polyplex complexes with an N/P ratio (the molar ratio of the amine group of PEI to the phosphate group of DNA) of 40 showed excellent transfection efficiency in human hepatic cells. When acidification of endosomes was inhibited by bafilomycin A1, the complexes showed higher transfection efficiency than polyplex itself, strongly suggesting that the complexes escaped from endosomes by both fusogenic activity of BNCs and proton sponge activity of polyplex. Furthermore, the cytotoxicity is comparable to that of polyplex of the same N/P value. Thus, BNC-polyplex complexes would be a promising gene delivery carrier for human liver-specific gene therapy.     

Pain modality and spinal glia expression by streptozotocin induced diabetic peripheral neuropathy in rats

Pain symptoms are a common complication of diabetic peripheral neuropathy or an inflammatory condition. In the most experiments, only one or two evident pain modalities are observed at diabetic peripheral neuropathy according to experimental conditions. Following diabetic peripheral neuropathy or inflammation, spinal glial activation may be considered as an important mediator in the development of pain. For this reason, the present study was aimed to address the induction of pain modalities and spinal glial expression after streptozotocin injection as compared with that of zymosan inflammation in the rat. Evaluation of pain behavior by either thermal or mechanical stimuli was performed at 3 weeks or 5 hours after either intravenous streptozotocin or zymosan. Degrees of pain were divided into 4 groups: severe, moderate, mild, and non-pain induction. On the mechanical allodynia test, zymosan evoked predominantly a severe type of pain, whereas streptozotocin induced a weak degree of pain (severe+moderate: 57.1%). Although zymosan did not evoke cold allodynia, streptozotocin evoked stronger pain behavior, compared with zymosan (severe+moderate: 50.0%). On the other hand, the high incidence of thermal hyperalgesia (severe+moderate: 90.0%) and mechanical hyperalgesia (severe+moderate: 85.7%) by streptozotocin was observed, as similar to that of zymosan. In the spinal cord, the increase of microglia and astrocyte was evident by streptozotocin, only microglia was activated by zymosan. Therefore, it is recommended that the selection of mechanical and thermal hyperalgesia is suitable for the evaluation of streptozotocin induced diabetic peripheral neuropathy. Moreover, spinal glial activation may be considered an important factor.     

Progression of Parkinson's Disease Pathology Is Reproduced by Intragastric Administration of Rotenone in Mice

In patients with Parkinson''s disease (PD), the associated pathology follows a characteristic pattern involving inter alia the enteric nervous system (ENS), the dorsal motor nucleus of the vagus (DMV), the intermediolateral nucleus of the spinal cord and the substantia nigra, providing the basis for the neuropathological staging of the disease. Here we report that intragastrically administered rotenone, a commonly used pesticide that inhibits Complex I of the mitochondrial respiratory chain, is able to reproduce PD pathological staging as found in patients. Our results show that low doses of chronically and intragastrically administered rotenone induce alpha-synuclein accumulation in all the above-mentioned nervous system structures of wild-type mice. Moreover, we also observed inflammation and alpha-synuclein phosphorylation in the ENS and DMV. HPLC analysis showed no rotenone levels in the systemic blood or the central nervous system (detection limit [rotenone]<20 nM) and mitochondrial Complex I measurements showed no systemic Complex I inhibition after 1.5 months of treatment. These alterations are sequential, appearing only in synaptically connected nervous structures, treatment time-dependent and accompanied by inflammatory signs and motor dysfunctions. These results strongly suggest that the local effect of pesticides on the ENS might be sufficient to induce PD-like progression and to reproduce the neuroanatomical and neurochemical features of PD staging. It provides new insight into how environmental factors could trigger PD and suggests a transsynaptic mechanism by which PD might spread throughout the central nervous system.