Small heat-shock proteins interact with a flanking domain to suppress polyglutamine aggregation

Small heat-shock proteins (sHsps) are molecular chaperones that play an important protective role against cellular protein misfolding by interacting with partially unfolded proteins on their off-folding pathway, preventing their aggregation. Polyglutamine (polyQ) repeat expansion leads to the formation of fibrillar protein aggregates and neuronal cell death in nine diseases, including Huntington disease and the spinocerebellar ataxias (SCAs). There is evidence that sHsps have a role in suppression of polyQ-induced neurodegeneration; for example, the sHsp alphaB-crystallin (αB-c) has been identified as a suppressor of SCA3 toxicity in a Drosophila model. However, the molecular mechanism for this suppression is unknown. In this study we tested the ability of αB-c to suppress the aggregation of a polyQ protein. We found that αB-c does not inhibit the formation of SDS-insoluble polyQ fibrils. We further tested the effect of αB-c on the aggregation of ataxin-3, a polyQ protein that aggregates via a two-stage aggregation mechanism. The first stage involves association of the N-terminal Josephin domain followed by polyQ-mediated interactions and the formation of SDS-resistant mature fibrils. Our data show that αB-c potently inhibits the first stage of ataxin-3 aggregation; however, the second polyQ-dependent stage can still proceed. By using NMR spectroscopy, we have determined that αB-c interacts with an extensive region on the surface of the Josephin domain. These data provide an example of a domain/region flanking an amyloidogenic sequence that has a critical role in modulating aggregation of a polypeptide and plays a role in the interaction with molecular chaperones to prevent this aggregation

Economic hardship associated with managing chronic illness: a qualitative inquiry

<p>Abstract</p> <p>Background</p> <p>Chronic illness and disability can have damaging, even catastrophic, socioeconomic effects on individuals and their households. We examined the experiences of people affected by chronic heart failure, complicated diabetes and chronic obstructive pulmonary disease to inform patient centred policy development. This paper provides a first level, qualitative understanding of the economic impact of chronic illness.</p> <p>Methods</p> <p>Interviews were conducted with patients aged between 45 and 85 years who had one or more of the index conditions and family carers from the Australian Capital Territory and Western Sydney, Australia (n = 66). Content analysis guided the interpretation of data.</p> <p>Results</p> <p>The affordability of medical treatments and care required to manage illness were identified as the key aspects of economic hardship, which compromised patients' capacity to proactively engage in self-management and risk reduction behaviours. Factors exacerbating hardship included ineligibility for government support, co-morbidity, health service flexibility, and health literacy. Participants who were on multiple medications, from culturally and linguistically diverse or Indigenous backgrounds, and/or not in paid employment, experienced economic hardship more harshly and their management of chronic illness was jeopardised as a consequence. Economic hardship was felt among not only those ineligible for government financial supports but also those receiving subsidies that were insufficient to meet the costs of managing long-term illness over and above necessary daily living expenses.</p> <p>Conclusion</p> <p>This research provides insights into the economic stressors associated with managing chronic illness, demonstrating that economic hardship requires households to make difficult decisions between care and basic living expenses. These decisions may cause less than optimal health outcomes and increased costs to the health system. The findings support the necessity of a critical analysis of health, social and welfare policies to identify cross-sectoral strategies to alleviate such hardship and improve the affordability of managing chronic conditions. In a climate of global economic instability, research into the economic impact of chronic illness on individuals' health and well-being and their disease management capacity, such as this study, provides timely evidence to inform policy development.</p

Food riots as representations of insecurity : examining the relationship between contentious politics and human security

The 2007–08 global food crisis saw the eruption of a wave of contentious action across the developing world, represented most clearly by the food riot. Food riots are sudden, unexpected events, presenting a challenge to the state that moves beyond simple demands for food. The upheaval caused by a food riot can lead to lasting instability and violence as social and political structures are challenged. The aims of the article are to: (1) identify the character of contemporary food riots in relation to traditional forms; (2) determine the extent to which food riots can be seen to represent broader human insecurity; and (3) demonstrate the utility of contentious actions in demonstrating insecurity. This article examines the causes of the 2007–08 wave of food riots in relation to earlier manifestations. The findings show that the contemporary food riots have similar origins to their historical counterparts. The article also shows that food riots are a clear sign of insecurity, demonstrating the benefit of examining contentious politics in this context

Ligand-enhanced expression and in-cell assay of human peroxisome proliferator-activated receptor alpha ligand binding domain

A human peroxisome proliferator-activated receptor alpha ligand binding domain (PPAR&alpha;LBD)-maltose binding protein fusion construct was expressed in Escherichia coli. A codon optimized DNA sequence encoding human PPAR&alpha;LBD (aa196&ndash;468) was synthesized and ligated into the pDEST17 E. coli expression vector downstream of a MBP solubility fusion tag and an intermittent TEV protease cleavage site. Following auto-induction at 28 &deg;C, PPAR&alpha;LBD protein was purified to electrophoretic homogeneity by a nickel affinity chromatographic step, on-column TEV protease cleavage followed by Sephacryl S200 size exclusion chromatography. The recombinant protein displayed cross-reactivity with goat anti-(human PPAR&alpha;) polyclonal antibody and was identified as human PPAR&alpha; by trypic peptide mass finger-printing. The addition of a PPAR&alpha; specific ligand (fenofibric acid, GW7647 or GW590735) to the growth media significantly stabilized the PPAR&alpha;LBD structure and enhanced the expression of soluble protein. In-cell ligand binding was examined by monitoring the enhancement of PPAR&alpha;LBD expression as a function of the concentration of ligand in the growth media. The efficient expression and in-cell assay of the reported PPAR&alpha;LBD construct make it amenable to high through-put screening assays in drug discovery programs.<br /

Small heat-shock proteins interact with a flanking domain to suppress polyglutamine aggregation

Small heat-shock proteins (sHsps) are molecular chaperones that play an important protective role against cellular protein misfolding by interacting with partially unfolded proteins on their off-folding pathway, preventing their aggregation. Polyglutamine (polyQ) repeat expansion leads to the formation of fibrillar protein aggregates and neuronal cell death in nine diseases, including Huntington disease and the spinocerebellar ataxias (SCAs). There is evidence that sHsps have a role in suppression of polyQ-induced neurodegeneration; for example, the sHsp alphaB-crystallin (αB-c) has been identified as a suppressor of SCA3 toxicity in a Drosophila model. However, the molecular mechanism for this suppression is unknown. In this study we tested the ability of αB-c to suppress the aggregation of a polyQ protein. We found that αB-c does not inhibit the formation of SDS-insoluble polyQ fibrils. We further tested the effect of αB-c on the aggregation of ataxin-3, a polyQ protein that aggregates via a two-stage aggregation mechanism. The first stage involves association of the N-terminal Josephin domain followed by polyQ-mediated interactions and the formation of SDS-resistant mature fibrils. Our data show that αB-c potently inhibits the first stage of ataxin-3 aggregation; however, the second polyQ-dependent stage can still proceed. By using NMR spectroscopy, we have determined that αB-c interacts with an extensive region on the surface of the Josephin domain. These data provide an example of a domain/region flanking an amyloidogenic sequence that has a critical role in modulating aggregation of a polypeptide and plays a role in the interaction with molecular chaperones to prevent this aggregation

Assignments of human integrin α1I domain in the apo and Mg 2+ bound states

The α1β1 integrin receptor binds to its main extracellular ligand, collagen, through an inserted domain in its α-subunit called the αI domain (αI). αI contains a metal binding site that allows collagen to coordinate to the domain through a divalent metal ion. Here we report the backbone assignments of the apo and Mg bound state of the isolated human α1I and the chemical shift changes resulting from metal coordination

Molecular dissection of an inhibitor targeting the HIV integrase dependent preintegration complex nuclear import

Human immunodeficiency virus (HIV) continues to be a major contributor to morbidity and mortality worldwide, particularly in developing nations where high cost and logistical issues severely limit the use of current HIV therapeutics. This, combined HIV's high propensity to develop resistance, means that new antiviral agents against novel targets are still urgently required. We previously identified novel anti-HIV agents directed against the nuclear import of the HIV integrase (IN) protein, which plays critical roles in the HIV lifecycle inside the cell nucleus, as well as in transporting the HIV preintegration complex (PIC) into the nucleus. Here we investigate the structure activity relationship of a series of these compounds for the first time, including a newly identified anti-IN compound, budesonide, showing that the extent of binding to the IN core domain correlates directly with the ability of the compound to inhibit IN nuclear transport in a permeabilised cell system. Importantly, compounds that inhibited the nuclear transport of IN were found to significantly decrease HIV viral replication, even in a dividing cell system. Significantly, budesonide or its analogue flunisolide, were able to effect a significant reduction in the presence of specific nuclear forms of the HIV DNA (2-LTR circles), suggesting that the inhibitors work though blocking IN, and potentially PIC, nuclear import. The work presented here represents a platform for further development of these specific inhibitors of HIV replication with therapeutic and prophylactic potential