The haematopoietic stem cell niche:new insights into the mechanisms regulating haematopoietic stem cell behaviour

The concept of the haematopoietic stem cell (HSC) niche was formulated by Schofield in the 1970s, as a region within the bone marrow containing functional cell types that can maintain HSC potency throughout life. Since then, ongoing research has identified numerous cell types and a plethora of signals that not only maintain HSCs, but also dictate their behaviour with respect to homeostatic requirements and exogenous stresses. It has been proposed that there are endosteal and vascular niches within the bone marrow, which are thought to regulate different HSC populations. However, recent data depicts a more complicated picture, with functional crosstalk between cells in these two regions. In this review, recent research into the endosteal/vascular cell types and signals regulating HSC behaviour are considered, together with the possibility of a single subcompartmentalised niche.

The role of tissue transglutaminase (TG2) in regulating the tumour progression of the mouse colon carcinoma CT26

The multifunctional enzyme tissue transglutaminase (TG2) is reported to both mediate and inhibit tumour progression. To elucidate these different roles of TG2, we established a series of stable-transfected mouse colon carcinoma CT26 cells expressing a catalytically active (wild type) and a transamidating-inactive TG2 (Cys277Ser) mutant. Comparison of the TG2-transfected cells with the empty vector control indicated no differences in cell proliferation, apoptosis and susceptibility to doxorubicin, which correlated with no detectable changes in the activation of the transcription factor NF-?B. TG2-transfected cells showed increased expression of integrin ß3, and were more adherent and less migratory on fibronectin than control cells. Direct interaction of TG2 with ß3 integrins was demonstrated by immunoprecipitation, suggesting that TG2 acts as a coreceptor for fibronectin with ß3 integrins. All cells expressed the same level of TGFß receptors I and II, but only cells transfected with active TG2 had increased levels of TGFß1 and matrix-deposited fibronectin, which could be inhibited by TG2 site-directed inhibitors. Moreover, only cells transfected with active TG2 were capable of inhibiting tumour growth when compared to the empty vector controls. We conclude that in this colon carcinoma model increased levels of active TG2 are unfavourable to tumour growth due to their role in activation of TGFß1 and increased matrix deposition, which in turn favours increased cell adhesion and a lowered migratory and invasive behaviour.

The Audit Commission:guiding, steering and regulating local government

How does the non-executant state ensure that its agents are fulfilling their obligations to deliver nationally determined policies? In the case of elected local government in England and Wales, this function is carried out by the Audit Commission (AC) for Local Authorities and the Health Service for England and Wales. Since being established in 1983, it is the means by which local authorities are held to account by central government, both for its own purposes and on behalf of other interested stakeholders. Although the primary function of the AC is to ensure that local authorities are fulfilling their obligations, it does so by using different methods. By acting as a regulator, an independent expert, an opinion former and a mediator, the AC steers local authorities to ensure that they are compliant with the regulatory regime and are implementing legislation properly.

The role of TG2 in regulating S100A4-mediated mammary tumour cell migration

The importance of S100A4, a Ca2+-binding protein, in mediating tumour cell migration, both intracellularly and extracellularly, is well documented. Tissue transglutaminase (TG2) a Ca2+-dependent protein crosslinking enzyme, has also been shown to enhance cell migration. Here by using the well characterised non-metastatic rat mammary R37 cells (transfected with empty vector) and highly metastatic KP1 cells (R37 cells transfected with S100A4), we demonstrate that inhibition of TG2 either by TG2 inhibitors or transfection of cells with TG2 shRNA block S100A4-accelerated cell migration in the KP1cells and in R37 cells treated with exogenous S100A4. Cell migration was also blocked by the treatment with the non-cell permeabilizing TG2 inhibitor R294, in the human breast cancer cell line MDA-MB-231 (Clone 16, which has a high level of TG2 expression). Inhibition was paralleled by a decrease in S100A4 polymer formation. co-immunoprecipitation and Far Western blotting assays and cross-linking assays showed not only the direct interaction between TG2 and S100A4, but also confirmed S100A4 as a substrate for TG2. Using specific functional blocking antibodies, a targeting peptide and a recombinant protein as a competitive treatment, we revealed the involvement of syndecan-4 and a5ß1 integrin co-signalling pathways linked by activation of PKCa in this TG2 and S100A4-mediated cell migration. We propose a mechanism for TG2-regulated S100A4-related mediated cell migration, which is dependent on TG2 crosslinking.

Regulating audit beyond the crisis:a critical discussion of the EU green paper

With the European Commission making global leadership claims in the field of audit regulation, the content of its 2010 Green Paper on ‘Audit Policy: Lessons from the Crisis’ warrants careful scrutiny. Important issues raised in the Green Paper include regulatory oversight, competition in the audit market, the dangers of having very few firms with the capacity to audit global transnational corporations, professional judgement, innovative audit practices and, last but not least, social responsibility. This article analyses the principal perspectives and assumptions underpinning the construction of the Green Paper. The aims are threefold: to enhance understanding of the contemporary regulatory mindset of the European Commission, contribute to policy debate and inspire future research.

Regulating the expression of eEF1A to decipher its non canonical functions in eukaryotic cells

The canonical function of eEF1A is delivery of the aminoacylated tRNA to the A site of the ribosome during protein translation, however, it is also known to be an actin binding protein. As well as this actin binding function, eEF1A has been shown to be involved in other cellular processes such as cell proliferation and apoptosis. It has long been thought that the actin cytoskeleton and protein synthesis are linked and eEF1A has been suggested to be a candidate protein to form this link, though very little is understood about the relationship between its two functions. Overexpression of eEF1A has also been shown to be implicated in many different types of cancers, especially cancers that are metastatic, therefore it is important to further understand how eEF1A can affect both translation and the organisation of the actin cytoskeleton. To this end, we aimed to determine the effects of reduced expression of eEF1A on both translation and its non canonical functions in CHO cells. We have shown that reduced expression of eEF1A in this cell system results in no change in protein synthesis, however results in an increased number of actin stress fibres and other proteins associated with these fibres such as myosin IIA, paxillin and vinculin. Cell motility and attachment are also affected by this reduction in eEF1A protein expression. The organisational and motility phenotypes were found to be specific to eEF1A by transforming the cells with plasmids containing either human eEF1A1 or eEF1A2. Though the mechanisms by which these effects are regulated have not yet been established, this data provides evidence to show that the translation and actin binding functions of eEF1A are independent of each other as well as being suggestive of a role for eEF1A in cell motility as supported by the observation that overexpression of eEF1A protein tends to be associated with the cancer cells that are metastatic.

The handedness-associated PCSK6 locus spans an intronic promoter regulating novel transcripts

We recently reported the association of the PCSK6 gene with handedness through a quantitative genome-wide association study (GWAS; P < 0.5 × 10(-8)) for a relative hand skill measure in individuals with dyslexia. PCSK6 activates Nodal, a morphogen involved in regulating left-right body axis determination. Therefore, the GWAS data suggest that the biology underlying the patterning of structural asymmetries may also contribute to behavioural laterality, e.g. handedness. The association is further supported by an independent study reporting a variable number tandem repeat (VNTR) within the same PCSK6 locus to be associated with degree of handedness in a general population cohort. Here, we have conducted a functional analysis of the PCSK6 locus combining further genetic analysis, in silico predictions and molecular assays. We have shown that the previous GWAS signal was not tagging a VNTR effect, suggesting that the two markers have independent effects. We demonstrated experimentally that one of the top GWAS-associated markers, rs11855145, directly alters the binding site for a nuclear factor. Furthermore, we have shown that the predicted regulatory region adjacent to rs11855415 acts as a bidirectional promoter controlling the expression of novel RNA transcripts. These include both an antisense long non-coding RNA (lncRNA) and a short PCSK6 isoform predicted to be coding. This is the first molecular characterization of a handedness-associated locus that supports the role of common variants in non-coding sequences in influencing complex phenotypes through gene expression regulation.

The promotion of children's health and wellbeing:the contributions of England's charity sector

Background. Sports and arts based services for children have positive impacts on their mental and physical health. The charity sector provides such services, often set up in response to local communities expressing a need. The present study maps resilience promoting services provided by children's charities in England. Specifically, the prominence of sports and arts activities, and types of mental health provisions including telephone help-lines, are investigated. Findings. The study was a cross-sectional web-based survey of chief executives, senior mangers, directors and chairs of charities providing services for children under the age of 16. The aims, objectives and activities of participating children's charities and those providing mental health services were described overall. In total 167 chief executives, senior managers, directors and chairs of charities in England agreed to complete the survey. From our sample of charities, arts activities were the most frequently provided services (58/167, 35%), followed by counselling (55/167, 33%) and sports activities (36/167, 22%). Only 13% (22/167) of charities expected their work to contribute to the health legacy of the 2012 London Olympics. Telephone help lines were provided by 16% of the charities that promote mental health. Conclusions. Counselling and arts activities were relatively common. Sports activities were limited despite the evidence base that sport and physical activity are effective interventions for well-being and health gain. Few of the charities we surveyed expected a health legacy from the 2012 London Olympics. © 2010 Bhui et al; licensee BioMed Central Ltd.