The hypothesis of the main role of H2S in coupled sulphide-nitroso signalling pathway

As a part of the nitroso signalling pathway, nitroso-compounds serve as stores and carriers of NO; as part of the sulphide signalling pathway, bound sulfane-sulphur compounds serve as stores and carriers of H2S. Here we hypothesise a coupled sulphide-nitroso signalling pathway, in which H2S plays a main role. H2S releases NO from the endogenous S-nitroso-compounds nitroso-cysteine, nitroso-acetylcysteine and nitroso-albumin. Relaxation of noradrenaline-precontracted aortic rings by H2S is also enhanced in the presence of nitroso-albumin, which may implicate the involvement of the nitroso signalling pathway. Pretreatment of albumin, cysteine, N-acetylcysteine and lipids with H2S results in binding of sulphur to these compounds creating thus new-modified sulphur compounds that release NO from nitroso-compounds directly and/or through released H2S, which suggests sulphide-nitroso signalling pathway participation. This hypothesis is supported by the observation that the pretreatment of noradrenaline-precontracted aortic rings with H2S significantly enhanced relaxation induced by nitroso-glutathione in the absence of H2S. We assume that the NO release from nitroso-compounds directly by H2S or indirectly by the H2S-induced sulphur-bound compounds represents coupled sulphide-nitroso signalling, which may explain some of the numerous biological effects of H2S that are shared with NO.     

TGF-β1 suppresses IL-6-induced STAT3 activation through regulation of Jak2 expression in prostate epithelial cells

Chronic inflammation plays an important role in the initiation and progression of various human diseases including benign prostatic hyperplasia or prostate cancer. Here we show that the proinflammatory cytokine interleukin-6 (IL-6) has prosurvival effects and chronically activates the Jak2/STAT3 signalling pathway in a model of benign prostatic hyperplasia (BPH-1). We demonstrate that the antiinflammatory cytokine transforming growth factor-β1 (TGF-β1), which also permanently activates its canonical signalling pathway through SMAD proteins in BPH-1 cells, modifies the effects of IL-6 on cell proliferation. Importantly, TGF-β1 inhibits IL-6 signal transduction by decreasing the phosphorylation levels of STAT3. This effect is associated with decreased expression of Jak2 at both mRNA and protein levels. Moreover, we showed that TGF-β1 inhibits IL-6-induced expression of the cancer-associated gene MUC1. These observations demonstrated a novel interaction between TGF-β1 and IL-6 signalling and suggested another mechanism of how defects in TGF-β signalling, frequently associated with prostate pathologies, can contribute to the disruption of tissue homeostasis.     

Genetic diversity and its effect on fitness in an endangered plant species, <Emphasis Type="Italic">Dracocephalum austriacum</Emphasis> L.

The aim of this study was to estimate genetic diversity and assess its importance for plant fitness in a species belonging to the most endangered species in Europe, Dracocephalum austriacum L., and to select the most valuable populations for conservation of genetic diversity within the species in the studied regions. We analyzed allozyme variation of 12 populations in three distinct regions (Czech Karst, Moravia and Slovak Karst) in Central Europe. The results showed high genetic diversity within populations (80.14%) and relatively low differentiation among populations within regions (9.42%) and between regions (10.45%). Seed production was significantly higher in larger, genetically more diverse and less inbred populations. The results suggest that genetic diversity has important effect on seed production in this species and thus can be expected to have strong direct consequences for plant fitness and vitality of the whole populations. They also show large variation in genetic diversity between populations and indicate which populations should get a priority in attempts to conserve all the genetic diversity within the region.     

Phosphorylation pattern of the NDUFS4 subunit of complex I of the mammalian respiratory chain

The NDUFS4 subunit of complex I of the mammalian respiratory chain has a fully conserved carboxy-terminus with a canonical RVSTK phosphorylation site. Immunochemical analysis with specific antibodies shows that the serine in this site of the protein is natively present in complex I in both the phosphorylated and non-phosphorylated state. Two-dimensional IEF/SDS–PAGE electrophoresis, ³²P labelling and immunodetection show that “in vitro” PKA phosphorylates the serine in the C-terminus of the NDUFS4 subunit in isolated bovine complex I. ³²P labelling and TLC phosphoaminoacid mapping show that PKA phosphorylates serine and threonine residues in the purified heterologous human NDUFS4 protein.     

4Pi microscopy reveals an impaired three-dimensional mitochondrial network of pancreatic islet β-cells,an experimental model of type-2 diabetes

Insulin production in pancreatic β-cells is critically linked to mitochondrial oxidative phosphorylation. Increased ATP production triggered by blood glucose represents the β-cells' glucose sensor. Type-2 diabetes mellitus results from insulin resistance in peripheral tissues and impaired insulin secretion. Pathology of diabetic β-cells might be reflected by the altered morphology of mitochondrial network. Its characterization is however hampered by the complexity and density of the three-dimensional (3D) mitochondrial tubular networks in these cell types. Conventional confocal microscopy does not provide sufficient axial resolution to reveal the required details; electron tomography reconstruction of these dense networks is still difficult and time consuming. However, mitochondrial network morphology in fixed cells can also be studied by 4Pi microscopy, a laser scanning microscopy technique which provides an ～ 7-fold improved axial resolution (～ 100 nm) over conventional confocal microscopy. Here we present a quantitative study of these networks in insulinoma INS-1E cells and primary β-cells in Langerhans islets. The former were a stably-transfected cell line while the latter were transfected with lentivirus, both expressing mitochondrial matrix targeted redox-sensitive GFP. The mitochondrial networks and their partial disintegration and fragmentation are revealed by carefully created iso-surface plots and their quantitative analysis. We demonstrate that β-cells within the Langerhans islets from diabetic Goto Kakizaki rats exhibited a more disintegrated mitochondrial network compared to those from control Wistar rats and model insulinoma INS-1E cells. Standardization of these patterns may lead to development of morphological diagnostics for Langerhans islets, for the assessment of β-cell condition, before their transplantations.     

Ploidy-specific interactions of three host plants with arbuscular mycorrhizal fungi: Does genome copy number matter?

? Premise of the study: Polyploidy has been shown to affect different plant traits and modulate interactions between plants and other organisms, such as pollinators and herbivores. However, no information is available on whether it can also shape the functioning of mycorrhizal symbiosis. ? Methods: The mycorrhizal growth response was assessed for three angiosperms with intraspecific ploidy variation. Different cytotypes of Aster amellus, Campanula gentilis, and Pimpinella saxifraga were either left uninoculated or were inoculated with arbuscular mycorrhizal (AM) fungi in a pot experiment. After 3 mo of cultivation in a greenhouse, plant growth, phosphorus concentration in the shoot biomass, and development of the AM symbiosis were evaluated. ? Key results: No significant ploidy-specific differences in AM development were recorded. The inoculation led to consistently greater phosphorus uptake; however, the effect on plant growth differed considerably among plant species, populations, ploidy levels, and AM species. A salient ploidy-specific response was observed in A. amellus. Whereas diploid plants benefited from AM inoculation, the hexaploids consistently showed negative or no-growth responses (depending on the AM species). In contrast to A. amellus, no interactions between inoculation and ploidy were observed in C. gentilis and P. saxifraga. ? Conclusions: The first evidence is provided of a ploidy-specific response of a mycotrophic plant to AM fungi. Our results demonstrate the complexity of interaction between plants and associated AM fungi, with the ploidy level of the host plant being one component that may modulate the functioning of the symbiosis.     

<Emphasis Type="Italic">TRAF1/C5</Emphasis>polymorphism is not associated with increased mortality in rheumatoid arthritis: two large longitudinal studies

Introduction  

Recently an association between a genetic variation in TRAF1/C5 and mortality from sepsis or cancer was found in rheumatoid arthritis (RA). The most prevalent cause of death, cardiovascular disease, may have been missed in that study, since patients were enrolled at an advanced disease stage. Therefore, we used an inception cohort of RA patients to investigate the association between TRAF1/C5 and cardiovascular mortality, and replicate the findings on all-cause mortality. As TRAF1/C5 associated mortality may not be restricted to RA, we also studied a large cohort of non-RA patients.     

Inhibition of anion channels derived from mitochondrial membranes of the rat heart by stilbene disulfonate—DIDS

The objective of this work was to characterize in more detail the inhibition effect of diisothiocyanatostilbene-2′,2-disulfonic acid (DIDS) on anion channels isolated from the rat heart mitochondria. The channels reconstituted into a planar lipid membrane displayed limited powers of discrimination between anions and cations and the ion conductance measured under asymmetric (250/50 mM KCl, cis/trans) and symmetric (150 mM KCl) conditions was ∼100 pS. DIDS caused a dramatic decrease in the channel activity (IC₅₀ = 11.7 ± 3.1 μM) only when it was added to the cis side of a planar lipid membrane. The inhibition was accompanied by the significant prolongation of closings and the shortening of openings within the burst as well as gaps between bursts were prolonged and durations of bursts were reduced. The blockade was complete and irreversible when concentration of DIDS was increased up to 200 μM. Our data indicate that DIDS is an allosteric blocker of mitochondrial anion channels and this specific effect could be used as a tool for reliable identification of anion channels on the functional level.