Agonistic antibody to the α1-adrenergic receptor mobilizes intracellular calcium and induces phosphorylation of a cardiac 15-kDa protein

Hypertension is a major cause for hypertrophic remodelling of the myocardium. Agonistic autoantibodies to extracellular loops of the α₁-adrenergic receptor (α₁-AR) have been identified in patients with arterial hypertension. However, intracellular reactions elicited by these agonistic antibodies remain elusive. An anti-peptide antibody (anti-α₁) was generated against the second extracellular loop of the α₁-AR that bound to its peptide epitope with high affinity (K _D ~50 nM). We studied anti-α₁ effects on intracellular calcium (Ca_i), a key factor in cellular remodelling, and receptor-mediated cardiac protein phosphorylation. Anti-α₁ induced pronounced but transient increases in Ca_i in CHO cells expressing the human α₁-AR (CHO-α₁) and in neonatal cardiomyocytes. Preincubation experiments failed to demonstrate a tonic effect of anti-α₁ on Ca_i. However, preincubation with the antibody attenuated the effect of the α₁-AR antagonist prazosin. In neonatal cardiomyocytes anti-α₁ induced a robust phosphorylation of a 15-kDa protein that is involved in α₁-AR signalling. Our data support the notion that elevation of Ca_i is a general feature of agonistic antibodies’ action and constitute an important pathogenic component of hypertension-associated autoantibodies. Furthermore, we suggest that agonistic antibodies to the α₁-AR contribute to hypertrophic remodelling of cardiac myocytes, and that the cardiac 15-kDa protein is a relevant downstream target of their action.     

Systematics and evolution of Iolania (Hemiptera: Fulgoromorpha: Cixiidae) from Hawai'i

Abstract.  Within the planthopper taxon Cixiidae, which is distributed worldwide, only two lineages have colonized the Hawaiian Islands: Iolania Kirkaldy, 1902, and Oliarus Stål, 1862 , and subsequently given rise to endemic species. Neither radiation has been studied in depth hitherto. Here the degree of speciation within Iolania is assessed and a taxonomic revision including a key to the species based on the male genitalic characters is provided. Six endemic species are recognized: I. perkinsi Kirkaldy, I. koolauensis Giffard, I. oahuensis Giffard, I. lanaiensis Giffard, I. mauiensis Giffard and I. kraussohana sp.n. A lectotype is designated for the type-species I. perkinsi Kirkaldy, and I. perkinsi notata Kirkaldy is interpreted as an invalid name. Morphological arguments for the monophyly of Iolania and phylogenetic relationships among the species are discussed. A plausible scenario for the sequence of speciation events and history of colonization within the Hawaiian Islands is attempted. Combined information from taxon- and area-cladograms suggests progressive inter-island dispersal from older to younger islands in the Hawaiian chain as the major pattern of colonization and speciation.     

Die Beurteilung des Einflusses qualitativer Prüffaktoren (Infektionstermine,Sorten) auf den Befall mit Hilfe der Kontingenztafelanalyse

Mycelial growth of some wood‐rotting fungi was studied on a solid modified medium MS (Murashige and Skoog, 1962) with indole‐3‐acetic acid at concentrations of 10^‐6 to 10^‐3 M. The IAA concentrations of 10^‐6 M and 10^‐5 M inhibited mycelial growth of the fungus Phaeolus schweinitzii, Laetiporus sulphureus and Pleurotus ostreatus while the same concentrations stimulated mycelial growth of the fungus Stereum rugosum. The IAA concentrations of 10^‐6 M stimulated mycelial growth in Piptoporus betulinus and temporarily stimulated mycelial growth in Heterobasidion annosum. The IAA concentration of 10^‐4 M appeared critical for wood‐rotting fungi. The IAA concentration of 10^‐3 M inhibited mycelial growth in all the fungi under study.     

Arbuscular mycorrhizas in phosphate-polluted soil: interrelations between root colonization and nitrogen

To investigate whether arbuscular mycorrhizal fungi (AMF) – abundant in a phosphate-polluted but nitrogen-poor field site – improve plant N nutrition, we carried out a two-factorial experiment, including N fertilization and fungicide treatment. Percentage of root length colonized (% RLC) by AMF and tissue element concentrations were determined for four resident plant species. Furthermore, soil nutrient levels and N effects on aboveground biomass of individual species were measured. Nitrogen fertilization lowered % RLC by AMF of Artemisia vulgaris L., Picris hieracioides L. and Poa compressa L., but not of Bromus japonicus Thunb. This – together with positive N addition effects on N status, N:P-ratio and aboveground biomass of most species – suggested that plants are mycorrhizal because of N deficiency. Fungicide treatment, which reduced % RLC in all species, resulted in lower N concentrations in A. vulgaris and P. hieracioides, a higher N concentration in P. compressa, and did not consistently affect N status of B. japonicus. Evidently, AMF had an influence on the N nutrition of plants in this P-rich soil; however – potentially due to differences in their mycorrhizal responsiveness – not all species seemed to benefit from a mycorrhiza-mediated N uptake and accordingly, N distribution.     

Role of Rho/ROCK signaling in the interaction of melanoma cells with the blood–brain barrier

We have investigated the role of the Rho/ROCK signaling pathway in the interaction of metastatic melanoma cells with the brain endothelium. ROCK inhibition induced a shift of melanoma cells to the mesenchymal phenotype, increased the number of melanoma cells attached to the brain endothelium, and strengthened the adhesion force between melanoma and endothelial cells. Inhibition of ROCK raised the number of melanoma cells migrating through the brain endothelial monolayer and promoted the formation of parenchymal brain metastases in vivo. We have shown that inhibition of the Rho/ROCK pathway in melanoma, but not in brain endothelial cells, is responsible for this phenomenon. Our results indicate that the mesenchymal type of tumor cell movement is primordial in the transmigration of melanoma cells through the blood–brain barrier.     

A glutathione peroxidase, intracellular peptidases and the TOR complexes regulate peptide transporter PEPT-1 in C. elegans

The intestinal peptide transporter PEPT-1 in Caenorhabditis elegans is a rheogenic H(+)-dependent carrier responsible for the absorption of di- and tripeptides. Transporter-deficient pept-1(lg601) worms are characterized by impairments in growth, development and reproduction and develop a severe obesity like phenotype. The transport function of PEPT-1 as well as the influx of free fatty acids was shown to be dependent on the membrane potential and on the intracellular pH homeostasis, both of which are regulated by the sodium-proton exchanger NHX-2. Since many membrane proteins commonly function as complexes, there could be proteins that possibly modulate PEPT-1 expression and function. A systematic RNAi screening of 162 genes that are exclusively expressed in the intestine combined with a functional transport assay revealed four genes with homologues existing in mammals as predicted PEPT-1 modulators. While silencing of a glutathione peroxidase surprisingly caused an increase in PEPT-1 transport function, silencing of the ER to Golgi cargo transport protein and of two cytosolic peptidases reduced PEPT-1 transport activity and this even corresponded with lower PEPT-1 protein levels. These modifications of PEPT-1 function by gene silencing of homologous genes were also found to be conserved in the human epithelial cell line Caco-2/TC7 cells. Peptidase inhibition, amino acid supplementation and RNAi silencing of targets of rapamycin (TOR) components in C. elegans supports evidence that intracellular peptide hydrolysis and amino acid concentration are a part of a sensing system that controls PEPT-1 expression and function and that involves the TOR complexes TORC1 and TORC2.     

Blood pressure and lipid management fall far short in persons with type 2 diabetes: results from the DIAB-CORE Consortium including six German population-based studies

Background

Although most deaths among patients with type 2 diabetes (T2D) are attributable to cardiovascular disease, modifiable cardiovascular risk factors appear to be inadequately treated in medical practice. The aim of this study was to describe hypertension, dyslipidemia and medical treatment of these conditions in a large population-based sample.

Methods

The present analysis was based on the DIAB-CORE project, in which data from five regional population-based studies and one nationwide German study were pooled. All studies were conducted between 1997 and 2006. We assessed the frequencies of risk factors and co-morbidities, especially hypertension and dyslipidemia, in participants with and without T2D. The odds of no or insufficient treatment and the odds of pharmacotherapy were computed using multivariable logistic regression models. Types of medication regimens were described.

Results

The pooled data set comprised individual data of 15, 071 participants aged 45?C74?years, including 1287 (8.5%) participants with T2D. Subjects with T2D were significantly more likely to have untreated or insufficiently treated hypertension, i.e. blood pressure of?>?= 140/90?mmHg (OR?=?1.43, 95% CI 1.26-1.61) and dyslipidemia i.e. a total cholesterol/HDL-cholesterol ratio?>?= 5 (OR?=?1.80, 95% CI 1.59-2.04) than participants without T2D. Untreated or insufficiently treated blood pressure was observed in 48.9% of participants without T2D and in 63.6% of participants with T2D. In this latter group, 28.0% did not receive anti-hypertensive medication and 72.0% were insufficiently treated. In non-T2D participants, 28.8% had untreated or insufficiently treated dyslipidemia. Of all participants with T2D 42.5% had currently elevated lipids, 80.3% of these were untreated and 19.7% were insufficiently treated.

Conclusions

Blood pressure and lipid management fall short especially in persons with T2D across Germany. The importance of sufficient risk factor control besides blood glucose monitoring in diabetes care needs to be emphasized in order to prevent cardiovascular sequelae and premature death.     

The hinge region of the scaffolding protein of cell contacts, zonula occludens protein 1, regulates interacting with various signaling proteins

Zonula occludens protein 1 (ZO-1) is a ubiquitous scaffolding protein, but it is unknown why it functions in very different cellular contacts. We hypothesized that a specific segment, the unique hinge region, can be bound by very different regulatory proteins. Using surface plasmon resonance spectroscopy and binding assays to peptide libraries, we show, for the first time, that the hinge region directly interacts with disparate signal elements such as G-proteins alpha 12 and alpha i2, the regulator of G-protein signaling 5, multifunctional signaling protein ahnak1, and L-type Ca2+-channel beta-2-subunit. The novel binding proteins specifically bound to a coiled coil-helix predicted in the hinge region of ZO-. The interactions were modulated by phosphorylation in the hinge helix. Activation of the G-proteins influenced their association to ZO-1. In colon cells, G alpha i2 and ZO-1 were associated, as shown by coimmunoprecipitation. After cotransfection in kidney cells, G alpha i2 barely colocalized with ZO-1; the colocalization coefficient was significantly increased when epinephrine activated G-protein signaling. In conclusion, proteins with different regulatory potential adhere to and influence cellular functions of ZO-proteins, and the interactions can be modulated via its hinge region and/or the binding proteins.     

Acetatifactor muris gen. nov., sp. nov., a novel bacterium isolated from the intestine of an obese mouse

We used selective agar media for culturing bacteria from the caecum of mice fed a high calorie diet. In addition to the isolation of Enterobacteriaceae growing on a medium containing cholesterol and bile salts, we focused on the characterization of strain CT-m2^T, which, based on 16S rDNA analysis, did not appear to correspond to any currently described organisms. The isolate belongs to the Clostridium cluster XIV and is most closely related to members of the Lachnospiraceae, including the genera Anaerostipes, Blautia, Butyrivibrio, Clostridium, Coprococcus, Eubacterium, Robinsoniella, Roseburia, Ruminococcus and Syntrophococcus (≤90?% similarity). Strain CT-m2^T is a non-motile Gram-positive rod that does not form spores and has a G?+?C content of DNA of 48.5?%. Cells grow under strictly anoxic conditions (100?% N₂) and produce acetate and butyrate after growth in reduced WCA broth. In contrast to related species, the new bacterium does not metabolize glucose and is positive for phenylalanine arylamidase, and its major cellular fatty acid is C_14:0. Based on phylogenetic and phenotypic studies, the isolate merits recognition as a member of a novel genus and species, for which the name Acetatifactor muris is proposed. The type strain is CT-m2^T (=?DSM 23669^T?=?ATCC BAA-2170^T).     

Erythropoietin attenuates neurological and histological consequences of toxic demyelination in mice

Erythropoietin (EPO) reduces symptoms of experimental autoimmune encephalomyelitis in rodents and shows neuroregenerative effects in chronic progressive multiple sclerosis. The mechanisms of action of EPO in these conditions with shared immunological etiology are still unclear. Therefore, we used a model of toxic demyelination allowing exclusion of T cell-mediated inflammation. In a double-blind (for food/injections), placebo-controlled, longitudinal four-arm design, 8-wk-old C57BL/6 mice (n = 26/group) were assigned to cuprizone-containing (0.2%) or regular food (ground chow) for 6 wks. After 3 wks, mice were injected every other day with placebo or EPO (5,000 IU/kg intraperitoneally) until the end of cuprizone feeding. Half of the mice were exposed to behavioral testing, magnetic resonance imaging (MRI) and histology immediately after treatment cessation, whereas the other half were allowed a 3-wk treatment-free recovery. Immediately after termination of cuprizone feeding, all toxin-exposed mice were compromised regarding vestibulomotor function/coordination, with EPO-treated animals performing better than placebo. Likewise, ventricular enlargement after cuprizone, as documented by MRI, was less pronounced upon EPO. After a 3-wk recovery, remarkable spontaneous improvement was observed in all mice with no measurable further benefit in the EPO group ("ceiling effect"). Histological analysis of the corpus callosum revealed attenuation by EPO of the cuprizone-induced increase in microglial numbers and amyloid precursor protein accumulations as a readout of inflammation and axonal degeneration. To conclude, EPO ameliorates neurological symptoms in the cuprizone model of demyelination, possibly by reduction of inflammation-associated axonal degeneration in white matter tracts. These findings underscore the value of future therapeutic strategies for multiple sclerosis based on EPO or EPO variants.