The dimeric structure of the Cpn60.2 chaperonin of Mycobacterium tuberculosis at 2.8 Å reveals possible modes of function

Mycobacterium tuberculosis expresses two proteins (Cpn60.1 and Cpn60.2) that belong to the chaperonin (Cpn) family of heat shock proteins. Studies have shown that the two proteins have different functional roles in the bacterial life cycle and that Cpn60.2 is essential for cell viability and may be involved in M. tuberculosis pathogenicity. Cpn60.2 does not form a tetradecameric double ring, which is typical of other Cpns. We have determined the crystal structure of recombinant Cpn60.2 to 2.8 Å resolution by molecular replacement; the asymmetric unit (AU) contains a dimer, which is consistent with size-exclusion high-performance liquid chromatography and dynamic light-scattering measurements of the soluble recombinant protein. However, we suggest that the actual Cpn60.2 dimer may be different from that identified within the AU on the basis of surface contact stability, solvation free-energy gain, and functional aspects. Unlike the dimer found in the AU, which is formed through apical domain interactions, the dimeric form we propose here provides a free apical domain that is required for normal chaperone activity and may be involved in M. tuberculosis association with macrophages and arthrosclerosis plaque formation. Here we describe in detail the structural aspects that lead to Cpn60.2 dimer formation and prevent the formation of heptameric rings and tetradecameric double rings.     

The neurexin superfamily of Caenorhabditis elegans

The neurexin superfamily is a group of transmembrane molecules mediating cell-cell contacts and generating specialized membranous domains in polarized epithelial and nerves cells. We describe here the domain organization and expression of the entire, core neurexin superfamily in the nematode Caenorhabditis elegans, which is composed of three family members. One of the superfamily members, nrx-1, is an ortholog of vertebrate neurexin, the other two, itx-1 and nlr-1, are orthologs of the Caspr subfamily of neurexin-like genes. Based on reporter gene analysis, we find that nrx-1 is exclusively expressed in most if not all cells of the nervous system and localizes to presynaptic specializations. itx-1 and nrx-1 reporter genes are expressed in non-overlapping patterns within and outside the nervous system. ITX-1 protein co-localizes with β-G-spectrin to a subapical domain within intestinal cells. These studies provide a starting point for further functional analysis of this family of proteins.     

Health Perceptions,Self and Body Image,Physical Activity and Nutrition among Undergraduate Students in Israel

Purpose

This study examines health perceptions, self and body image, physical exercise and nutrition among undergraduate students.

Methods

A structured, self-reported questionnaire was administered to more than 1500 students at a large academic institute in Israel. The study population was heterogenic in both gender and fields of academic study.

Results

High correlations between health perceptions, appropriate nutrition, and positive self and body image were found. The relationships between these variables differed between the subpopulation in the sample and the different genders. Engagement in physical exercise contributed to positive body image and positive health perceptions more than engagement in healthy nutrition. Nutrition students reported higher frequencies of positive health perceptions, positive self and body image and higher engagement in physical exercise in comparison to all other students in the sample.

Conclusions

This study suggests, as have many before, that successful health promotion policy should reflect a collectivist rather than an individualist ethos by providing health prerequisites through a public policy of health-promotion, where the academic settings support a healthy lifestyle policy, by increasing availability of a healthy, nutritious and varied menu in the cafeterias, and offering students various activities that enhance healthy eating and exercise.

Implications and contribution

This study examined health perceptions, self-image, physical exercise and nutrition among undergraduate students and found high correlations between these topics. Nutrition students reported higher frequencies of positive health perceptions, and positive self and body image and engaged more in physical exercise when compared with all other students in the sample.     

Blood Vessels Pattern Heparan Sulfate Gradients between Their Apical and Basolateral Aspects

A hallmark of immune cell trafficking is directional guidance via gradients of soluble or surface bound chemokines. Vascular endothelial cells produce, transport and deposit either their own chemokines or chemokines produced by the underlying stroma. Endothelial heparan sulfate (HS) was suggested to be a critical scaffold for these chemokine pools, but it is unclear how steep chemokine gradients are sustained between the lumenal and ablumenal aspects of blood vessels. Addressing this question by semi-quantitative immunostaining of HS moieties around blood vessels with a pan anti-HS IgM mAb, we found a striking HS enrichment in the basal lamina of resting and inflamed post capillary skin venules, as well as in high endothelial venules (HEVs) of lymph nodes. Staining of skin vessels with a glycocalyx probe further suggested that their lumenal glycocalyx contains much lower HS density than their basolateral extracellular matrix (ECM). This polarized HS pattern was observed also in isolated resting and inflamed microvascular dermal cells. Notably, progressive skin inflammation resulted in massive ECM deposition and in further HS enrichment around skin post capillary venules and their associated pericytes. Inflammation-dependent HS enrichment was not compromised in mice deficient in the main HS degrading enzyme, heparanase. Our results suggest that the blood vasculature patterns steep gradients of HS scaffolds between their lumenal and basolateral endothelial aspects, and that inflammatory processes can further enrich the HS content nearby inflamed vessels. We propose that chemokine gradients between the lumenal and ablumenal sides of vessels could be favored by these sharp HS scaffold gradients.     

Attention Enhances the Retrieval and Stability of Visuospatial and Olfactory Representations in the Dorsal Hippocampus

A key question in the analysis of hippocampal memory relates to how attention modulates the encoding and long-term retrieval of spatial and nonspatial representations in this region. To address this question, we recorded from single cells over a period of 5 days in the CA1 region of the dorsal hippocampus while mice acquired one of two goal-oriented tasks. These tasks required the animals to find a hidden food reward by attending to either the visuospatial environment or a particular odor presented in shifting spatial locations. Attention to the visuospatial environment increased the stability of visuospatial representations and phase locking to gamma oscillations—a form of neuronal synchronization thought to underlie the attentional mechanism necessary for processing task-relevant information. Attention to a spatially shifting olfactory cue compromised the stability of place fields and increased the stability of reward-associated odor representations, which were most consistently retrieved during periods of sniffing and digging when animals were restricted to the cup locations. Together, these results suggest that attention selectively modulates the encoding and retrieval of hippocampal representations by enhancing physiological responses to task-relevant information.     

EHDS are serine phosphoproteins: EHD1 phosphorylation is enhanced by serum stimulation

Endocytic processes are mediated by multiple protein-protein interacting modules and regulated by phosphorylation and dephosphorylation. The Eps15 homology domain containing protein 1 (EHD1) has been implicated in regulating recycling of proteins, internalized both in clathrin-dependent and clathrin-independent endocytic pathways, from the recycling compartment to the plasma membrane. EHD1 was found in a complex with clathrin, adaptor protein complex-2 (AP-2) and insulin-like growth factor-1 receptor (IGF-1R), and was shown to interact with Rabenosyn-5, SNAP29, EHBP1 (EH domain binding protein 1) and syndapin I and II. In this study, we show that EHD1, like the other human EHDs, undergoes serine-phosphorylation. Our results also indicate that EHD1 is a serum-inducible serine-phosphoprotein and that PKC (protein kinase C) is one of its kinases. In addition, we show that inhibitors of clathrin-mediated endocytosis decrease EHD1 phosphorylation, while inhibitors of caveolinmediated endocytosis do not affect EHD1 phosphorylation. The results of experiments in which inhibitors of endocytosis were employed strongly suggest that EHD1 phosphorylation occurs between early endosomes and the endocytic recycling compartment.     

Expeditious chemical synthesis of ubiquitinated peptides employing orthogonal protection and native chemical ligation

Ubiquitination-the attachment of ubiquitin to a protein target-is involved in a wide range of cellular processes in eukaryotes. This dynamic posttranslational modification utilizes three enzymes to link, through an isopeptide bond, the C-terminal Gly of ubiquitin to the lysine side chain from a protein target. Progress in the field aiming at deciphering the role of ubiquitination in biological processes has been very dependent on the discovery of the enzymatic machinery, which is known to be very specific to each protein target. Chemical approaches offer a complementary route to the biochemical methods to construct these conjugates in vitro in order to assist in unraveling the role of ubiquitination on protein function. Herein is presented a novel method for the rapid synthesis of ubiquitinated peptides employing solid-phase peptide to generate the critical isopeptide linkage. Using these tools, several ubiquitinated peptides derived from known ubiquitinated proteins were prepared. Among them is the ubiquitinated C-terminal fragment of H2B, which can be used in the synthesis of monoubiquitinated H2B. For the first time, we systematically assessed the effect of the length of the ubiquitinated peptides on the UCH-L3 activity and found that peptides of up to ～20 residues are preferred substrates.     

IFN-gamma acts on T cells to induce NK cell mobilization and accumulation in target organs

The mechanism(s) that regulates NK cell mobilization and the significance of this process to NK cell activity are unknown. After Con A-induced hepatitis, NK cells are mobilized from the spleen and bone marrow into the periphery in an IFN-gamma-dependent fashion. Intraperitoneal administration of IFN-gamma stimulates the mobilization of NK cells into the circulation, but not their cell death or proliferation. Increased number of circulating NK cells was coupled with their accumulation in the peritoneum, liver, and tumor-bearing lung tissue. Furthermore, increased number of NK cells in the lung reduced metastasis of Lewis lung carcinoma cells (3LL cell line) resulting in significantly extended NK-dependent survival. Mobilization of NK cells was specific and required the presence of T cells. Moreover, mobilization and migration of spleen NK cells in response to IFN-gamma treatment is dependent on the chemokine receptor CXCR3. Mechanistic insights regarding the role of IFN-gamma in the regulation of NK cell mobilization and their accumulation at sites of tumor metastasis may lead to the development of novel immunotherapy for cancer.     

Are infertility treatments a potential risk factor for cancer development? Perspective of 30 years of follow-up

The aim of the present study was to evaluate the possible risk for cancer development in infertile women with over 30 years of follow-up. Cancer development was assessed through linkage with the National Cancer Registry updated to 31 December 2005 in a cohort of 2431 women who were treated for infertility at the Sheba Medical Center in Israel during the period 1964-1974 and contributed more than 84,000 women years of follow-up. Standardized incidence ratios (SIR) were calculated between the observed cancer cases and the expected cancer rates in the general population. The mean age at the end of follow-up was 62.7 years. Eighteen cases of ovarian cancer were observed as compared to 18.1 expected (SIR = 1.0; 95% CI = 0.59-1.57). For breast cancer, 153 cases were observed as compared to 131.9 expected (SIR = 1.16; 95% CI = 0.98-1.36), and for endometrial cancer, 30 cases were observed as compared to 17.8 expected cases (SIR = 1.69; 95% CI = 1.14-2.41). No excess risk associated with exposure to gonadotropins was observed. Infertility was found to be associated with significant increased risk for endometrial cancer and borderline increased risk for breast cancer. Ovarian cancer risk was not found to be elevated. No significant excess risk was associated with treatment with ovulation induction.