Membrane-bound LERK2 ligand can signal through three different Eph-related receptor tyrosine kinases.

The Eph-related family of receptor tyrosine kinases consists of at least 13 members, several of which display distinctive expression patterns in the developing and adult nervous system. Recently, a small family of ligands, structurally related to the B61 protein, was identified. Binding of these ligands to Eph-related receptors did not, however, elicit measurable biological signals in cultured cells. In order to study functional interactions between B61-related ligands and Eph-related receptors, we constructed chimeric receptors, containing an Eph-related ectodomain and the cytoplasmic domain of the TrkB neurotrophin receptor. Expression and activation of such chimeric receptors in NIH 3T3 cells induced transformation in focus formation assays. Membrane-bound LERK2 ligand is shown to signal through three different Eph-related receptors, namely Cek5, Cek10 and Elk. LERK2, however, fails to interact functionally with the Cek9 receptor. Quantitative analysis including binding assays indicates that Cek10 is the preferred LERK2 receptor. Preliminary mutagenesis of the LERK2 protein suggests a negative regulatory role for its cytoplasmic domain in LERK2 signaling.     

Combined control of Lasioderma serricorne (F.) and Ephestia elutella (Hbn.) in a tobacco processing facility by attracticide method

Results on application of attracticide method in the combined control of cigarette beetle, Lasioderma serricorne and tobacco moth, Ephestia elutella, infesting a tobacco processing facility are reported. Experimental devices with cross-panel stripes treated with microencapsulated permethrin at 6% (a.i.) and baited at same time with (4,6-dimethyl-7-hydroxynonan-3-one) serricornin and (Z,E)-9,12-tetradecadien-1 ol acetate (TDA) were used for 2 years (2017 and 2018) in an Italian tobacco processing facility. The experiment demonstrated that the presence of both serricornin and TDA dispensers on cross-panel striped devices had no affect on the numbers of L. serricorne and E. elutella male adults caught. After 2 years, the densities of adult males were clearly suppressed in room treated with attracticide compared to control room. Thus, the 2017–2018 experiment suggests that attracticide devices with two pheromone lures and microencapsulated permethrin at 6% (a.i.) can be effective suppression tools for managing combined pest populations of L. serricorne and E. elutella in tobacco facilities. The reduction of male infestation by L. serricorne ranged from 36% to 87%, and in E. elutella, the reduction of infestation ranged from 63% to 91%.     

Three paradigms of airway smooth muscle hyperresponsiveness in young guinea pigs

Evidence for contributions of airway smooth muscle (ASM) to the hyperresponsiveness of newborn and juvenile airways continues to accumulate. In our laboratory, 3 novel paradigms of hyperresponsiveness of newborn and young ASM have recently emerged using a guinea pig model of maturation in 3 age groups: 1 week (newborn), 3 weeks (juvenile), and 2-3 months (adult). The first paradigm includes evidence for a natural decline after newborn and juvenile life of the velocity of ASM shortening associated with a decrease in regulatory myosin light chain phosphorylation and a parallel decline in the content of myosin light chain kinase. Associated with the decrease in ASM shortening with age is an increase in the internal resistance to shortening. Dynamic stiffness is shown to relate inversely to the expression of myosin light chain kinase. This suggests that developmental changes in shortening relate inversely to the stiffness of the ASM early in shortening, suggesting a dynamic role for the cytoskeleton in facilitating and opposing ASM shortening. This relationship can be approximated as (dP/dt)max approximately (dP/dL)passive x (dL/dt)max (the maximal rate of increase of active stress generation approximately to the passive stiffness x the maximal shortening velocity). The second paradigm demonstrates that newborn ASM, unlike that in adults, does not relax during prolonged electric field stimulation. The impaired relaxation is related to changes in prostanoid synthesis and acetylcholinesterase function. The third paradigm demonstrates that, whereas oscillatory strain serves to transiently relax adult ASM, in newborns it induces (after the initial relaxation) a sustained potentiation of active stress. This is related to developmental changes in the prostanoid release. Together, these paradigms demonstrate that ASM contributes by multiple mechanisms to the natural hyperresponsiveness of newborn and juvenile airways. Future studies will elaborate the mechanisms and extend these paradigms to ASM hyperresponsiveness following sensitization in early life.     

Eph receptors in the adult brain

The Eph receptors are a large family of receptor tyrosine kinases with important roles in the establishment of neuronal and vascular networks during embryonic development. The functions of Eph receptors in the adult brain have only recently been investigated, and the results are forcing us to amend the conventional view that these molecules function predominantly in a developmental context. This review summarizes this rapidly expanding new area of research, which has shown that the Eph receptors regulate the structure and physiological function of excitatory synapses through multiple mechanisms, and might thus play a significant role in higher brain functions.     

Excision dynamics of <Emphasis Type="Italic">Vibrio</Emphasis> pathogenicity island-2 from <Emphasis Type="Italic">Vibrio cholerae:</Emphasis> role of a recombination directionality factor VefA

Background  

Vibrio Pathogenicity Island-2 (VPI-2) is a 57 kb region present in choleragenic V. cholerae isolates that is required for growth on sialic acid as a sole carbon source. V. cholerae non-O1/O139 pathogenic strains also contain VPI-2, which in addition to sialic acid catabolism genes also encodes a type 3 secretion system in these strains. VPI-2 integrates into chromosome 1 at a tRNA-serine site and encodes an integrase intV2 (VC1758) that belongs to the tyrosine recombinase family. IntV2 is required for VPI-2 excision from chromosome 1, which occurs at very low levels, and formation of a non-replicative circular intermediate.     

Geographic differences in genetic susceptibility to IgA nephropathy: GWAS replication study and geospatial risk analysis

IgA nephropathy (IgAN), major cause of kidney failure worldwide, is common in Asians, moderately prevalent in Europeans, and rare in Africans. It is not known if these differences represent variation in genes, environment, or ascertainment. In a recent GWAS, we localized five IgAN susceptibility loci on Chr.6p21 (HLA-DQB1/DRB1, PSMB9/TAP1, and DPA1/DPB2 loci), Chr.1q32 (CFHR3/R1 locus), and Chr.22q12 (HORMAD2 locus). These IgAN loci are associated with risk of other immune-mediated disorders such as type I diabetes, multiple sclerosis, or inflammatory bowel disease. We tested association of these loci in eight new independent cohorts of Asian, European, and African-American ancestry (N = 4,789), followed by meta-analysis with risk-score modeling in 12 cohorts (N = 10,755) and geospatial analysis in 85 world populations. Four susceptibility loci robustly replicated and all five loci were genome-wide significant in the combined cohort (P = 5×10⁻³²–3×10⁻¹⁰), with heterogeneity detected only at the PSMB9/TAP1 locus (I² = 0.60). Conditional analyses identified two new independent risk alleles within the HLA-DQB1/DRB1 locus, defining multiple risk and protective haplotypes within this interval. We also detected a significant genetic interaction, whereby the odds ratio for the HORMAD2 protective allele was reversed in homozygotes for a CFHR3/R1 deletion (P = 2.5×10⁻⁴). A seven–SNP genetic risk score, which explained 4.7% of overall IgAN risk, increased sharply with Eastward and Northward distance from Africa (r = 0.30, P = 3×10⁻¹²⁸). This model paralleled the known East–West gradient in disease risk. Moreover, the prediction of a South–North axis was confirmed by registry data showing that the prevalence of IgAN–attributable kidney failure is increased in Northern Europe, similar to multiple sclerosis and type I diabetes. Variation at IgAN susceptibility loci correlates with differences in disease prevalence among world populations. These findings inform genetic, biological, and epidemiological investigations of IgAN and permit cross-comparison with other complex traits that share genetic risk loci and geographic patterns with IgAN.     

Nimodipine confers clinical improvement in two models of experimental autoimmune encephalomyelitis

Multiple sclerosis is characterised by inflammatory neurodegeneration, with axonal injury and neuronal cell death occurring in parallel to demyelination. Regarding the molecular mechanisms responsible for demyelination and axonopathy, energy failure, aberrant expression of ion channels and excitotoxicity have been suggested to lead to Ca²⁺ overload and subsequent activation of calcium‐dependent damage pathways. Thus, the inhibition of Ca²⁺ influx by pharmacological modulation of Ca²⁺ channels may represent a novel neuroprotective strategy in the treatment of secondary axonopathy. We therefore investigated the effects of the L‐type voltage‐gated calcium channel blocker nimodipine in two different models of mouse experimental autoimmune encephalomyelitis (EAE ), an established experimental paradigm for multiple sclerosis. We show that preventive application of nimodipine (10 mg/kg per day) starting on the day of induction had ameliorating effects on EAE in SJL /J mice immunised with encephalitic myelin peptide PLP _139–151, specifically in late‐stage disease. Furthermore, supporting these data, administration of nimodipine to MOG _35–55‐immunised C57BL /6 mice starting at the peak of pre‐established disease, also led to a significant decrease in disease score, indicating a protective effect on secondary CNS damage. Histological analysis confirmed that nimodipine attenuated demyelination, axonal loss and pathological axonal β‐amyloid precursor protein accumulation in the cerebellum and spinal cord in the chronic phase of disease. Of note, we observed no effects of nimodipine on the peripheral immune response in EAE mice with regard to distribution, antigen‐specific proliferation or activation patterns of lymphocytes. Taken together, our data suggest a CNS ‐specific effect of L‐type voltage‐gated calcium channel blockade to inflammation‐induced neurodegeneration.

     

Novel Gut-Based Pharmacology of Metformin in Patients with Type 2 Diabetes Mellitus

Metformin, a biguanide derivate, has pleiotropic effects beyond glucose reduction, including improvement of lipid profiles and lowering microvascular and macrovascular complications associated with type 2 diabetes mellitus (T2DM). These effects have been ascribed to adenosine monophosphate-activated protein kinase (AMPK) activation in the liver and skeletal muscle. However, metformin effects are not attenuated when AMPK is knocked out and intravenous metformin is less effective than oral medication, raising the possibility of important gut pharmacology. We hypothesized that the pharmacology of metformin includes alteration of bile acid recirculation and gut microbiota resulting in enhanced enteroendocrine hormone secretion. In this study we evaluated T2DM subjects on and off metformin monotherapy to characterize the gut-based mechanisms of metformin. Subjects were studied at 4 time points: (i) at baseline on metformin, (ii) 7 days after stopping metformin, (iii) when fasting blood glucose (FBG) had risen by 25% after stopping metformin, and (iv) when FBG returned to baseline levels after restarting the metformin. At these timepoints we profiled glucose, insulin, gut hormones (glucagon-like peptide-1 (GLP-1), peptide tyrosine-tyrosine (PYY) and glucose-dependent insulinotropic peptide (GIP) and bile acids in blood, as well as duodenal and faecal bile acids and gut microbiota. We found that metformin withdrawal was associated with a reduction of active and total GLP-1 and elevation of serum bile acids, especially cholic acid and its conjugates. These effects reversed when metformin was restarted. Effects on circulating PYY were more modest, while GIP changes were negligible. Microbiota abundance of the phylum Firmicutes was positively correlated with changes in cholic acid and conjugates, while Bacteroidetes abundance was negatively correlated. Firmicutes and Bacteroidetes representation were also correlated with levels of serum PYY. Our study suggests that metformin has complex effects due to gut-based pharmacology which might provide insights into novel therapeutic approaches to treat T2DM and associated metabolic diseases.

Trial Registration:

www.ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT01357876","term_id":"NCT01357876"}}NCT01357876