DnaJ/Hsc70 chaperone complexes control the extracellular release of neurodegenerative‐associated proteins

It is now known that proteins associated with neurodegenerative disease can spread throughout the brain in a prionlike manner. However, the mechanisms regulating the trans‐synaptic spread propagation, including the neuronal release of these proteins, remain unknown. The interaction of neurodegenerative disease‐associated proteins with the molecular chaperone Hsc70 is well known, and we hypothesized that much like disaggregation, refolding, degradation, and even normal function, Hsc70 may dictate the extracellular fate of these proteins. Here, we show that several proteins, including TDP‐43, α‐synuclein, and the microtubule‐associated protein tau, can be driven out of the cell by an Hsc70 co‐chaperone, DnaJC5. In fact, DnaJC5 overexpression induced tau release in cells, neurons, and brain tissue, but only when activity of the chaperone Hsc70 was intact and when tau was able to associate with this chaperone. Moreover, release of tau from neurons was reduced in mice lacking the DnaJC5 gene and when the complement of DnaJs in the cell was altered. These results demonstrate that the dynamics of DnaJ/Hsc70 complexes are critically involved in the release of neurodegenerative disease proteins.     

Reasons for Missing Antiretroviral Therapy: Results from a Multi-Country Study in Tanzania,Uganda, and Zambia

Objectives

To identify the reasons patients miss taking their antiretroviral therapy (ART) and the proportion who miss their ART because of symptoms; and to explore the association between symptoms and incomplete adherence.

Methods

Secondary analysis of data collected during a cross-sectional study that examined ART adherence among adults from 18 purposefully selected sites in Tanzania, Uganda, and Zambia. We interviewed 250 systematically selected patients per facility (≥18 years) on reasons for missing ART and symptoms they had experienced (using the HIV Symptom Index). We abstracted clinical data from the patients’ medical, pharmacy, and laboratory records. Incomplete adherence was defined as having missed ART for at least 48 consecutive hours during the past 3 months.

Results

Twenty-nine percent of participants reported at least one reason for having ever missed ART (1278/4425). The most frequent reason was simply forgetting (681/1278 or 53%), followed by ART-related hunger or not having enough food (30%), and symptoms (12%). The median number of symptoms reported by participants was 4 (IQR: 2–7). Every additional symptom increased the odds of incomplete adherence by 12% (OR: 1.1, 95% CI: 1.1–1.2). Female participants and participants initiated on a regimen containing stavudine were more likely to report greater numbers of symptoms.

Conclusions

Symptoms were a common reason for missing ART, together with simply forgetting and food insecurity. A combination of ART regimens with fewer side effects, use of mobile phone text message reminders, and integration of food supplementation and livelihood programmes into HIV programmes, have the potential to decrease missed ART and hence to improve adherence and the outcomes of ART programmes.     

Evolutionary history predicts high‐impact invasions by herbivorous insects

相似文献   

Deoxyhypusine synthase haploinsufficiency attenuates acute cytokine signaling

Deoxyhypusine synthase (DHS) catalyzes the post-translational formation of the amino acid hypusine. Hypusine is unique to the eukaryotic translational initiation factor 5A (eIF5A), and is required for its functions in mRNA shuttling, translational elongation and stress granule formation. In recent studies, we showed that DHS promotes cytokine and ER stress signaling in the islet β cell and thereby contributes to its dysfunction in the setting of diabetes mellitus. Here, we review the evidence supporting a role for DHS (and hypusinated eIF5A) in cellular stress responses, and provide new data on the phenotype of DHS knockout mice. We show that homozygous knockout mice are embryonic lethal, but heterozygous knockout mice appear normal with no evidence of growth or metabolic deficiencies. Mouse embryonic fibroblasts from heterozygous knockout mice attenuate acute cytokine signaling, as evidenced by reduced production of inducible nitric oxide synthase, but show no statistically significant defects in proliferation or cell cycle progression. Our data are discussed with respect to the utility of sub- maximal inhibition of DHS in the setting of inflammatory states, such as diabetes mellitus.Key words: inflammation, post-translational modification, cytokine, diabetes, mRNA translation, hypusine     

Sexual dimorphism in the developmental regulation of brain aromatase

Steroid sex hormones have an organizational role in gender-specific brain development. Aromatase (cytochrome P450_AR), converting testosterone (T) to estradiol-17β (E₂) is a key enzyme in brain development and the regulation of aromatase determines the availability of E₂ effective for neural differentiation. Gender differences in brain development and behaviour are likely to be influenced by E₂ acting during sensitive periods. This differentiating action has been demonstrated in rodent and avian species, but also probably occurs in primates including humans. In rodents, E₂ is formed in various hypothalamic areas of the brain during fetal and postnatal development. The question considered here is whether hypothalamic aromatase activity is gender-specific during sensitive phases of behavioural and brain development, and when these sensitive phases occur. In vitro preoptic and limbic aromatase activity has been measured in two strains of wild mice, genetically selected for behavioural aggression based on attack latency, and in the BALB/c mouse. Short attack latency males show a different developmental pattern of aromatase activity in hypothalamus and amygdala to long attack latency males. Using primary brain cell cultures of the BALB/c mouse, sex differences in hypothalamic aromatase activity during both early embryonic and later perinatal development can be demonstrated, with higher E₂ formation in males. The sex dimorphisms are brain region specific, since no differences between male and female are detectable in cultured cortical cells. Immunoreactive staining with a polyclonal aromatase antibody identifies a neuronal rather than an astroglial localization of the enzyme. T increases fetal brain aromatase activity and numbers of aromatase-immunoreactive hypothalamic neuronal cell bodies. T appears to influence the growth of hypothalamic neurons containing aromatase. Differentiation of sexually dimorphic brain mechanisms may involve maturation of a gender-specific network of estrogen-forming neurons which are steroid-sensitive in early development.     

The good,the bad and the ugly: science,aesthetics and environmental assessment

The question is raised, whether there are peculiarly scientific values which can be applied in environmental assessment. The use of the expression scientific interest is traced from its 19th century origins to modern British statutes. It is argued that attempts to replace expert judgements by objective scientific criteria (e.g., indices of biodiversity) can never be completely successful. In particular, interest is an aesthetic atribute particularly valued by scientists but incapable of precise measurement. While science provides the best framework for informed judgements on conservation issues, the judgements of scientists are inevitably distinct from their experimental results. Judgements rest on ethical and aesthetic values such as importance and interest, which are essential constituents of the scientific sub-culture, but which are not uniquely scientific.     

Synthesis of cathepsin B by cells derived from the HL60 promyelocytic leukaemia cell line

Cells of the human promyelocytic HL60 line were induced to differentiate into granulocyte-like cells with dimethylsulphoxide (DMSO) or macrophage-like cells with 12-0-tetradecanoylphorbol-13-acetate (TPA). The synthesis of Cathepsin B by these cells was studied by immunoperoxidase staining and assay of cell lysates using the fluorimetric substrate benzoyloxycarbonyl-phenylanalyl-arginine-4-methyl-7-coumarylamide. Only 2–5% of the uninduced HL60 cells and DMSO-induced cells were immunohistochemically positive for Cathepsin B, compared with over 80% of the TPA-induced cells. Cathepsin B activity was lowest in the lysates of uninduced HL60s. DMSO-induced cells contained 1.5–2-fold the enzyme activity of HL60s and TPA-induced cell lysates demonstrated 5–14-fold the activity of uninduced HL60s. Induction of Cathepsin B synthesis was therefore associated with differentiation of the promyelocytes into cells of the monocyte/macrophage type, but not granulocyte-like cells. Cathepsin B was located immunohistochemically in human palatine tonsils. The enzyme was only demonstrated within macrophages in these tissues. Cathepsin B may therefore be a useful immunohistochemical marker for malignant and nonmalignant cells of the monocyte/macrophage lineage.     

Shading and texture: separate information channels with a common adaptation mechanism?

We outline a scheme for the way in which early vision may handle information about shading (luminance modulation, LM) and texture (contrast modulation, CM). Previous work on the detection of gratings has found no sub-threshold summation, and no cross-adaptation, between LM and CM patterns. This strongly implied separate channels for the detection of LM and CM structure. However, we now report experiments in which adapting to LM (or CM) gratings creates tilt aftereffects of similar magnitude on both LM and CM test gratings, and reduces the perceived strength (modulation depth) of LM and CM gratings to a similar extent. This transfer of aftereffects between LM and CM might suggest a second stage of processing at which LM and CM information is integrated. The nature of this integration, however, is unclear and several simple predictions are not fulfilled. Firstly, one might expect the integration stage to lose identity information about whether the pattern was LM or CM. We show instead that the identity of barely detectable LM and CM patterns is not lost. Secondly, when LM and CM gratings are combined in-phase or out-of-phase we find no evidence for cancellation, nor for 'phase-blindness'. These results suggest that information about LM and CM is not pooled or merged--shading is not confused with texture variation. We suggest that LM and CM signals are carried by separate channels, but they share a common adaptation mechanism that accounts for the almost complete transfer of perceptual aftereffects.     

Geniculo-Cortical Projection Diversity Revealed within the Mouse Visual Thalamus

The mouse dorsal lateral geniculate nucleus (dLGN) is an intermediary between retina and primary visual cortex (V1). Recent investigations are beginning to reveal regional complexity in mouse dLGN. Using local injections of retrograde tracers into V1 of adult and neonatal mice, we examined the developing organisation of geniculate projection columns: the population of dLGN-V1 projection neurons that converge in cortex. Serial sectioning of the dLGN enabled the distribution of labelled projection neurons to be reconstructed and collated within a common standardised space. This enabled us to determine: the organisation of cells within the dLGN-V1 projection columns; their internal organisation (topology); and their order relative to V1 (topography). Here, we report parameters of projection columns that are highly variable in young animals and refined in the adult, exhibiting profiles consistent with shell and core zones of the dLGN. Additionally, such profiles are disrupted in adult animals with reduced correlated spontaneous activity during development. Assessing the variability between groups with partial least squares regression suggests that 4–6 cryptic lamina may exist along the length of the projection column. Our findings further spotlight the diversity of the mouse dLGN–an increasingly important model system for understanding the pre-cortical organisation and processing of visual information. Furthermore, our approach of using standardised spaces and pooling information across many animals will enhance future functional studies of the dLGN.     

A Proteomic Investigation of Hepatic Resistance to Ascaris in a Murine Model

The helminth Ascaris causes ascariasis in both humans and pigs. Humans, especially children, experience significant morbidity including respiratory complications, growth deficits and intestinal obstruction. Given that 800 million people worldwide are infected by Ascaris, this represents a significant global public health concern. The severity of the symptoms and associated morbidity are related to the parasite burden and not all hosts are infected equally. While the pathology of the disease has been extensively examined, our understanding of the molecular mechanisms underlying resistance and susceptibility to this nematode infection is poor. In order to investigate host differences associated with heavy and light parasite burden, an experimental murine model was developed utilising Ascaris-susceptible and -resistant mice strains, C57BL/6J and CBA/Ca, respectively, which experience differential burdens of migratory Ascaris larvae in the host lungs. Previous studies identified the liver as the site where this difference in susceptibility occurs. Using a label free quantitative proteomic approach, we analysed the hepatic proteomes of day four post infection C57BL/6J and CBA/Ca mice with and without Ascaris infection to identify proteins changes potentially linked to both resistance and susceptibility amongst the two strains, respectively. Over 3000 proteins were identified in total and clear intrinsic differences were elucidated between the two strains. These included a higher abundance of mitochondrial proteins, particularly those associated with the oxidative phosphorylation pathway and reactive oxygen species (ROS) production in the relatively resistant CBA/Ca mice. We hypothesise that the increased ROS levels associated with higher levels of mitochondrial activity results in a highly oxidative cellular environment that has a dramatic effect on the nematode’s ability to successfully sustain a parasitic association with its resistant host. Under infection, both strains had increased abundances in proteins associated with the oxidative phosphorylation pathway, as well as the tricarboxylic acid cycle, with respect to their controls, indicating a general stress response to Ascaris infection. Despite the early stage of infection, some immune-associated proteins were identified to be differentially abundant, providing a novel insight into the host response to Ascaris. In general, the susceptible C57BL/6J mice displayed higher abundances in immune-associated proteins, most likely signifying a more active nematode cohort with respect to their CBA/Ca counterparts. The complement component C8a and S100 proteins, S100a8 and S100a9, were highly differentially abundant in both infected strains, signifying a potential innate immune response and the importance of the complement pathway in defence against macroparasite infection. In addition, the signatures of an early adaptive immune response were observed through the presence of proteins, such as plastin-2 and dipeptidyl peptidase 1. A marked decrease in proteins associated with translation was also observed in both C57BL/6J and CBA/Ca mice under infection, indicative of either a general response to Ascaris or a modulatory effect by the nematode itself. Our research provides novel insights into the in vivo host-Ascaris relationship on the molecular level and provides new research perspectives in the development of Ascaris control and treatment strategies.