Structural Determinants of the Mechanical Stability of α-Catenin

α-Catenin plays a crucial role in cadherin-mediated adhesion by binding to β-catenin, F-actin, and vinculin, and its dysfunction is linked to a variety of cancers and developmental disorders. As a mechanotransducer in the cadherin complex at intercellular adhesions, mechanical and force-sensing properties of α-catenin are critical to its proper function. Biochemical data suggest that α-catenin adopts an autoinhibitory conformation, in the absence of junctional tension, and biophysical studies have shown that α-catenin is activated in a tension-dependent manner that in turn results in the recruitment of vinculin to strengthen the cadherin complex/F-actin linkage. However, the molecular switch mechanism from autoinhibited to the activated state remains unknown for α-catenin. Here, based on the results of an aggregate of 3 μs of molecular dynamics simulations, we have identified a dynamic salt-bridge network within the core M region of α-catenin that may be the structural determinant of the stability of the autoinhibitory conformation. According to our constant-force steered molecular dynamics simulations, the reorientation of the MII/MIII subdomains under force may constitute an initial step along the transition pathway. The simulations also suggest that the vinculin-binding domain (subdomain MI) is intrinsically much less stable than the other two subdomains in the M region (MII and MIII). Our findings reveal several key insights toward a complete understanding of the multistaged, force-induced conformational transition of α-catenin to the activated conformation.     

Monocyte and T-cell responses to exercise training in elderly subjects

The purpose of this study was to examine the effects of exercise training on age-related impairment of immune parameters related to T-cell activation in elderly individuals. Twenty-four elderly subjects were assigned to an exercise training group (EXC: 3 men, 9 women; age 61-76 years) or a nonexercise control group (CON: 4 men, 8 women; age 62-79 years). Subjects in EXC participated in exercise sessions 2 d·wk(-1) for 12 weeks. The training session included stretching and endurance exercise (10 minutes), resistance training comprised leg extension, leg press, hip abduction, and hip adduction using exercise machine and each subject's body weight. Subjects in CON maintained their normal physical activity levels during the study period. Blood samples were collected before and after the training period. Samples were measured for the numbers of leukocytes, lymphocytes, and monocytes, and for CD3(+), CD4(+), CD8(+), CD28(+)CD4(+), CD28(+)CD8(+), TRL-4(+)CD14(+), and CD80(+)CD14(+) cells. The number of leukocytes, lymphocytes, monocytes, CD3(+), CD4(+), and CD8(+) cells did not change after 12 weeks in either EXC or CON. The number of CD28(+)CD8(+) cells increased significantly after training in EXC (p ≤ 0.05), although CON showed no significant change. In the EXC group, CD80(+)CD14(+) cell counts were significantly higher after training (p ≤ 0.05), but the TLR-4(+)CD14(+) cell counts were unchanged. In the CON group, no significant alteration existed in TLR-4(+)CD14(+) and CD80(+)CD14(+) cell numbers. In conclusion, exercise training in elderly people is associated with increased CD28-expressing Tc cells and CD80-expressing monocytes. Therefore, exercise training might upregulate monocyte and T-cell-mediated immunity in elderly people.     

Serological characterizations of tandem repeat proteins for detection of African trypanosome infection in cattle

Serological diagnosis is a useful method to detect African trypanosome infection in livestock animals. Currently available serological tests utilize whole parasites or crude antigens, and recombinant antigens may improve reproducibility/standardization and reduce production costs. With a goal of identifying such recombinant proteins, we computationally identified proteins with tandem repeat (TR) domain from the parasite proteomes and evaluated their potential for serological diagnosis of African trypanosome infections in cattle. Among those tested, Tbg4 demonstrated the best performance with 92% sensitivity, followed by TbbGM6 (85%), TcoGM6 (85%), Tbg2 (65%) and Tbg5 (65%). Although further evaluations such as investigating cross-reactivity to other infections are needed, our data indicate the potential of these antigens for detection of African trypanosome infection in cattle.     

Crohn disease: A current perspective on genetics,autophagy and immunity

Crohn disease (CD) is a chronic and debilitating inflammatory condition of the gastrointestinal tract.¹ Prevalence in western populations is 100–150/100,000 and somewhat higher in Ashkenazi Jews. Peak incidence is in early adult life, although any age can be affected and a majority of affected individuals progress to relapsing and chronic disease. Medical treatments rely significantly on empirical corticosteroid therapy and immunosuppression, and intestinal resectional surgery is frequently required. Thus, 80% of patients with CD come to surgery for refractory disease or complications. It is hoped that an improved understanding of pathogenic mechanisms, for example by studying the genetic basis of CD and other forms of inflammatory bowel diseases (IBD), will lead to improved therapies and possibly preventative strategies in individuals identified as being at risk.Key words: Atg16L1, dendritic cells, gastrointestinal, genome-wide association, gut microbiota, inflammatory bowel diseases, IRGM, Paneth cell, ulcerative colitis     

Lercanidipine Rescues Hippocampus Pyramidal Neurons from Mild Ischemia-Induced Delayed Neuronal Death in SHRSP

Stroke-prone spontaneously hypertensive rats (SHRSPs) are vulnerable to ischemia and delayed neuronal death (DND) of hippocampus pyramidal cells when bilateral carotid arteries are occluded for only 10 min. Since this occlusion induces just mild ischemia, the resulting DND may be an appropriate animal model for dementia in patient with essential hypertension exposed to small ischemic insults. This study was designed to compare the effects of the antihypertensive drugs lercanidipine, nicardipine, lisinopril, valsartan, and hydralazine on occlusion-induced DND in SHRSPs. Drugs were administered for 2 weeks, from 15 to 17 weeks of age. 0.1% Nicardipine and 0.01 or 0.03% lercanidipine were administered in the SP diet (about 61.3, 5.7, and 18.8 mg/kg/day, respectively), and the remaining drugs were administered at 10 mg/kg/day using the mini-osmotic pump. The animals were operated on at 16 weeks of age, and DND was analyzed by histological examination 1 week later. Systolic blood pressure was measured at 15, 16, and 17 weeks of age. For chronic treatment, Calcium-channel blockers were administered from 8 to 17 weeks of age. All antihypertensive drugs significantly lowered systolic blood pressure at 16 weeks of age. Hydralazine and lisinopril were associated with the greatest reduction; however, lercanidipine, nicardipine, and valsartan effectively reduced systolic blood pressure to within a medium range. DND was significantly inhibited only by 0.03% lercanidipine. Chronic treatment with 0.03% lercanidipine also protected pyramidal neurons. The results of this study demonstrate that the long-acting, lipophilic Calcium-channel blocker lercanidipine inhibits occlusion-induced DND in SHRSPs and that lercanidipine may effectively reduce dementia induced by small ischemic insults in patients with essential hypertension.     

An artificial neural network approach for glomerular activity pattern prediction using the graph kernel method and the gaussian mixture functions

This paper proposes a neural network model for prediction of olfactory glomerular activity aimed at future application to the evaluation of odor qualities. The model's input is the structure of an odorant molecule expressed as a labeled graph, and it employs the graph kernel method to quantify structural similarities between odorants and the function of olfactory receptor neurons. An artificial neural network then converts odorant molecules into glomerular activity expressed in Gaussian mixture functions. The authors also propose a learning algorithm that allows adjustment of the parameters included in the model using a learning data set composed of pairs of odorants and measured glomerular activity patterns. We observed that the defined similarity between odorant structure has correlation of 0.3-0.9 with that of glomerular activity. Glomerular activity prediction simulation showed a certain level of prediction ability where the predicted glomerular activity patterns also correlate the measured ones with middle to high correlation in average for data sets containing 363 odorants.     

Structural characterization and epitope mapping of the glutamic acid/alanine-rich protein from Trypanosoma congolense: defining assembly on the parasite cell surface

Trypanosoma congolense is an African trypanosome that causes serious disease in cattle in Sub-Saharan Africa. The four major life cycle stages of T. congolense can be grown in vitro, which has led to the identification of several cell-surface molecules expressed on the parasite during its transit through the tsetse vector. One of these, glutamic acid/alanine-rich protein (GARP), is the first expressed on procyclic forms in the tsetse midgut and is of particular interest because it replaces the major surface coat molecule of bloodstream forms, the variant surface glycoprotein (VSG) that protects the parasite membrane, and is involved in antigenic variation. Unlike VSG, however, the function of GARP is not known, which necessarily limits our understanding of parasite survival in the tsetse. Toward establishing the function of GARP, we report its three-dimensional structure solved by iodide phasing to a resolution of 1.65 Å. An extended helical bundle structure displays an unexpected and significant degree of homology to the core structure of VSG, the only other major surface molecule of trypanosomes to be structurally characterized. Immunofluorescence microscopy and immunoaffinity-tandem mass spectrometry were used in conjunction with monoclonal antibodies to map both non-surface-disposed and surface epitopes. Collectively, these studies enabled us to derive a model describing the orientation and assembly of GARP on the surface of trypanosomes. The data presented here suggest the possible structure-function relationships involved in replacement of the bloodstream form VSG by GARP as trypanosomes differentiate in the tsetse vector after a blood meal.     

Photodynamic therapy for American cutaneous leishmaniasis: the efficacy of methylene blue in hamsters experimentally infected with Leishmania (Leishmania) amazonensis

The aim of this study was to investigate the effectiveness of Photodynamic Therapy (PDT) using Methylene Blue (MB) as the photosensitizing compound and a Light-Emitting Diode (LED) in American cutaneous leishmaniasis (ACL). Hamsters were experimentally infected with Leishmania (Leishmania) amazonensis. After the development of the lesions in the footpad, the animals were treated with MB three times a week for 3 months. Ten minutes after each application of MB, the lesions were irradiated with LED for 1 h. The lesions were evaluated weekly by the measurement of the hamster footpad thickness. At the end of the treatment the parasitic load was quantified in the regional lymph node of the hamsters. The treatment promoted a decrease in the thickness of infected footpad (P = 0.0001) and reduction in the parasitic load in the regional lymph node (P = 0.0007) of the animals from group treated with MB + LED. PDT using MB + LED in ACL caused by L. amazonensis shows a strong photodynamic effect. This therapy is very promising, once it is an inexpensive system and the own patient can apply it in their wound and in their house without the need of technical assistance.