In vitro aggregating β-lactamase-polyQ chimeras do not induce toxic effects in an in vivo <Emphasis Type="Italic">Caenorhabditis elegans</Emphasis> model

Background

A series of human diseases are caused by the misfolding and aggregation of specific proteins or peptides into amyloid fibrils; nine of these diseases, referred to as polyglutamine diseases, are associated with proteins carrying an expanded polyglutamine (polyQ) region. While the presence of this latter is thought to be the determinant factor for the development of polyQ diseases, the non-polyQ regions of the host proteins are thought to play a significant modulating role.

Method

In order to better understand the role of non-polyQ regions, the toxic effects of model proteins bearing different polyQ regions (containing up to 79 residues) embedded at two distinct locations within the β-lactamase (BlaP) host enzyme were evaluated in Caenorhabditis elegans. This small organism can be advantageous for the validation of in vitro findings, as it provides a multicellular context yet avoids the typical complexity of common studies relying on vertebrate models. Several phenotypic assays were performed in order to screen for potential toxic effects of the different BlaP-polyQ proteins.

Results

Despite the significant in vitro aggregation of BlaP-polyQ proteins with long polyQ regions, none of the BlaP-polyQ chimeras aggregated in the generated transgenic in vivo models.

Conclusion

The absence of a toxic effect of the expression of BlaP-polyQ chimeras may find its cause in biochemical mechanisms present in vivo to cope with protein aggregation (e.g. presence of chaperones) or in C. elegans’ limitations such as its short lifespan. It is plausible that the aggregation propensities of the different BlaP chimeras containing embedded polyQ sequences are too low in this in vivo environment to permit their aggregation. These experiments emphasize the need for several comparative and in vivo verification studies of biologically relevant in vitro findings, which reveal both the strengths and limitations of widely used model systems.

     

HnRNP A1 tethers KSRP to an exon splicing silencer that inhibits an erythroid-specific splicing event in PU.1-induced erythroleukemia

Exon 16 inclusion is a critical splicing event that triggers the production of a functional protein 4.1R in mature normal erythroblasts, and is obviated in PU.1-induced erythroleukemia cells. Exon 16 contains an exonic splicing silencer (ESS16) that interacts with hnRNP A/B in heterologous cell context. We here show that ESS16 promotes the recruitment of a protein complex containing hnRNP A1 and a 79-kDa protein in nuclear extracts from either proliferative erythroleukemia cells or cells induced to terminal differentiation. By using 2D gel fractionation and mass spectrometry, we unambiguously identified KSRP as the 79-kDa component interacting with ESS16. Furthermore, we show that KSRP slightly decreases in erythroleukemia cells induced to terminal erythroid differentiation. Yet, KSRP inducible knockdown, through stable transfection of small hairpin KSRP RNA, did not alter exon 16 splicing, suggesting that KSRP alone does not modulate the splicing event. Interestingly, absence of hnRNP A1 prevented KSRP from binding to ESS16. Reciprocally, KSRP interaction with ESS16 was recovered when hnRNP A1 expression is restored in hnRNP A1-null cells. Collectively, this study establishes that hnRNPA1 is part of a KSRP-containing RNP complex, and emphasizes that, aside from its function in AU-rich element-mediated mRNA decay and its role in microRNA biogenesis, KSRP associates with hnRNP A1 to bind an ESS. These findings further support the role of members of the KH-domain protein family in organizing large RNA-protein complex formation, rather than primarily in modulating specific splicing events.     

From efficacy to equity: Literature review of decision criteria for resource allocation and healthcare decisionmaking

ABSTRACT: Objectives: Resource allocation is a challenging issue faced by health policy decisionmakers requiring careful consideration of many factors. Objectives of this study were to identify decision criteria reported in the literature on healthcare decisionmaking. METHOD: An extensive literature search was performed in Medline and EMBASE to identify articles reporting healthcare decision criteria. Studies conducted with decisionmakers (e.g., focus groups, surveys, interviews), conceptual and review articles and articles describing tools were included. Criteria were extracted, organized using a classification system derived from the EVIDEM framework and applying multicriteria decision analysis (MCDA) principles, and the frequency of their occurrence was measured. RESULTS: Out of 3146 records identified, 2790 were excluded. Out of 356 articles assessed for eligibility, 39 were included in the study. Criteria were identified from studies performed in several regions of the world involving decisionmakers at micro, meso and macro levels of decision and from studies reporting on multicriteria tools. Large variations in terminology used to define criteria were observed and 338 different terms were identified. These were assigned to 58 criteria which were classified in 9 different categories including: health outcomes; types of benefit; disease impact; therapeutic context; economic impact; quality of evidence; implementation complexity; priority, fairness and ethics; and overall context. The most frequently mentioned criteria were: equity/fairness (33 times), efficacy/effectiveness (28), healthcare stakeholder interests and pressures (28), cost-effectiveness (24), strength of evidence (20), safety (19), mission and mandate of health system (18), need (16), organizational requirements and capacity (18) and patient-reported outcomes (16). CONCLUSION: This study highlights the importance of considering both normative and feasibility criteria for fair allocation of resources and optimized decisionmaking for coverage and use of healthcare interventions. This analysis provides a foundation to develop a questionnaire for an international survey of decisionmakers on criteria and their relative importance. The ultimate objective is to develop sound multicriteria approaches to enlighten healthcare decisionmaking and priority-setting.     

Breast cancer among women over 75 years: an important public health problem?

Women aged >75 years are not invited for mammographic screening; if diagnosed with breast cancer, due to their anticipated short-life expectancy, they are expected to die of other causes. To describe the breast cancer health problem in women aged >75 years, we estimated breast cancer incidence in this age group and the risk of breast cancer death in patients diagnosed after 75 years of age in Nijmegen, the Netherlands. Our findings demonstrate that in this age group, 3.3% of the women will be diagnosed with breast cancer, and that one in three of these incident cases die of this disease. These patients could have benefited from continued screening.     

Strengthening national laboratory health systems in the Caribbean Region

The President's Emergency Plan for AIDS Relief (PEPFAR) programme for the Caribbean Region was established in 2008 to address health system challenges, including fragile laboratory services and systems. The laboratory component of this programme consisted of several phases: assessment of laboratory needs of all 12 countries engaged in the programme; addressing gaps identified during the assessment; and monitoring and evaluation of the progress achieved. After one year of PEPFAR collaboration with national governments and other partners, laboratory services and systems greatly improved. Some of the milestones include: (1) the accreditation of a public laboratory; (2) improved access to HIV diagnosis with faster turnaround time; (3) establishment of capacity for platforms for DNA PCR, viral load and HIV drug resistance; (4) development of the laboratory workforce; and (5) establishment of a framework for implementation of sustainable quality management systems for laboratory accreditation. The progress recorded in strengthening laboratory health systems after one year of initiating this collaboration shows that with a rigorous initial assessment, programme design and intervention and strategic partnership, national laboratory health systems can be greatly enhanced to support programme implementation. Continued collaboration and country leadership is critical to create an integrated and sustainable laboratory network in the Caribbean.