Lamin Mutations Cause Increased YAP Nuclear Entry in Muscle Stem Cells

Mutations in the LMNA gene, encoding the nuclear envelope A-type lamins, are responsible for muscular dystrophies, the most severe form being the LMNA-related congenital muscular dystrophy (L-CMD), with severe defects in myonucleus integrity. We previously reported that L-CMD mutations compromise the ability of muscle stem cells to modulate the yes-associated protein (YAP), a pivotal factor in mechanotransduction and myogenesis. Here, we investigated the intrinsic mechanisms by which lamins influence YAP subcellular distribution, by analyzing different conditions affecting the balance between nuclear import and export of YAP. In contrast to wild type (WT) cells, LMNADK32 mutations failed to exclude YAP from the nucleus and to inactivate its transcriptional activity at high cell density, despite activation of the Hippo pathway. Inhibiting nuclear pore import abolished YAP nuclear accumulation in confluent mutant cells, thus showing persistent nuclear import of YAP at cell confluence. YAP deregulation was also present in congenital myopathy related to nesprin-1KASH mutation, but not in cells expressing the LMNAH222P mutation, the adult form of lamin-related muscle dystrophy with reduced nuclear deformability. In conclusion, our data showed that L-CMD mutations increased YAP nuclear localization via an increased nuclear import and implicated YAP as a pathogenic contributor in muscle dystrophies caused by nuclear envelop defects

The lymphocyte secretome from young adults enhances skeletal muscle proliferation and migration, but effects are attenuated in the secretome of older adults.

Older people experience skeletal muscle wasting, in part due to impaired proliferative capacity of quiescent skeletal muscle satellite cells which can be reversed by exposure to young blood. To investigate the role of immune cells in muscle regeneration, we isolated lymphocytes from whole blood of young and older healthy volunteers and cultured them with, or without, anti-CD3/CD28 activators to induce release of cytokines, interleukins, and growth factors into the media. The secreted proteins were collected to prepare a conditioned media, which was subsequently used to culture C2C12 myoblasts. The conditioned media from the activated young lymphocytes increased the rate of proliferation of myoblasts by around threefold (P < 0.005) and caused an approximate fourfold (P < 0.005) increase in migration compared with nonactivated lymphocyte control media. These responses were characterized by minimal myotube formation (2%), low fusion index (5%), low myosin heavy chain content, and substantial migration. In contrast, myoblasts treated with conditioned media from activated old lymphocytes exhibited a high degree of differentiation, and multi-nucleated myotube formation that was comparable to control conditions, thus showing no effect on proliferation or migration of myoblasts. These results indicate that secreted proteins from lymphocytes of young people enhance the muscle cell proliferation and migration, whereas secreted proteins from lymphocytes of older people may contribute to the attenuated skeletal muscle satellite cell proliferation and migration

The validity and reliability of the exposure index as a metric for estimating the radiation dose to the patient

Introduction With the introduction of digital radiography, the feedback between image quality and over-exposure has been partly lost which in some cases has led to a steady increase in dose. Over the years the introduction of exposure index (EI) has been used to resolve this phenomenon referred to as ‘dose creep’. Even though EI is often vendor specific it is always a related of the radiation exposure to the detector. Due to the nature of this relationship EI can also be used as a patient dose indicator, however this is not widely investigated in literature. Methods A total of 420 dose-area-product (DAP) and EI measurements were taken whilst varying kVp, mAs and body habitus on two different anthropomorphic phantoms (pelvis and chest). Using linear regression, the correlation between EI and DAP were examined. Additionally, two separate region of interest (ROI) placements/per phantom where examined in order to research any effect on EI. Results When dividing the data into subsets, a strong correlation between EI and DAP was shown with all R-squared values > 0.987. Comparison between the ROI placements showed a significant difference between EIs for both placements. Conclusion This research shows a clear relationship between EI and radiation dose which is dependent on a wide variety of factors such as ROI placement, body habitus. In addition, pathology and manufacturer specific EI’s are likely to be of influence as well. Implications for practice The combination of DAP and EI might be used as a patient dose indicator. However, the influencing factors as mentioned in the conclusion should be considered and examined before implementation

Cryoultramicrotomy and Immunocytochemistry in the Analysis of Muscle Fine Structure

Cryoultramicrotomy, which avoids the use of harsh fixation procedures, deleterious dehydration and plastic embedding can be combined with immunocytochemis try to determine the ultra-structural localization of cellular proteins. Our attempts to use the cryosectioning technique in combination with immunolabelling to bridge the gap between light and electron microscopic analysis of muscle morphology have enabled us to obtain new information on fibre typing at the ultrastructural level. Furthermore, we have obtained a marked improvement in the resolution of myofibrillar structures by using semithin cryosections for fluorescence microscopy. Data are also presented on correlated light and electron microscope immunocytochemistry of myocardial intermediate filaments confirming the presence of longitudinally oriented intermediate filaments of desmin in the region of the intercalated discs of mammalian cardiac myocytes, whereas elsewhere in the myocyte the bulk of intermediate filaments of desmin is concentrated in the intermyofibrillar space at the level of the Z disc

Towards transnational feminist queer methodologies

This article introduces the possibilities of transnational feminist queer research as seeking to conceptualise the transnational as a methodology composed of a series of flows that can augment feminist and queer research. Transnational feminist queer methodologies can contest long-standing configurations of power between researcher and researched, subject and object, academics and activists across places, typically those which are embedded in the hierarchies of the Global North/Global South. Beginning with charting our roots in, and routes through, the diverse arenas of transnational, feminist, participatory and queer methodologies, the article uses a transcribed and edited conversation between members of the Liveable Lives research team in Kolkata and Brighton, to start an exploration of transnational feminist queer methodologies. Understanding the difficult, yet constructive moments of collaborative work and dialogue, we argue for engagements with the multiplicities of ‘many-many' lives that recognise local specificities, and the complexities of lives within transnational research, avoiding creating a currency of comparison between places. We seek to work toward methodologies that take seriously the politics of place, namely by creating research that answers the same question in different places, using methods that are created in context and may not be ‘comparable'. Using a dialogue across the boundaries of activism/academia, as well as across geographical locations, the article contends that there are potentials, as well as challenges, in thinking ourselves through transnational research praxis. This seeks complexities and spatial nuances within as well as between places

Lamin-Related Congenital Muscular Dystrophy Alters Mechanical Signaling and Skeletal Muscle Growth

Laminopathies are a clinically heterogeneous group of disorders caused by mutations in the LMNA gene, which encodes the nuclear envelope proteins lamins A and C. The most frequent diseases associated with LMNA mutations are characterized by skeletal and cardiac involvement, and include autosomal dominant Emery–Dreifuss muscular dystrophy (EDMD), limb-girdle muscular dystrophy type 1B, and LMNA-related congenital muscular dystrophy (LMNA-CMD). Although the exact pathophysiological mechanisms responsible for LMNA-CMD are not yet understood, severe contracture and muscle atrophy suggest that mutations may impair skeletal muscle growth. Using human muscle stem cells (MuSCs) carrying LMNA-CMD mutations, we observe impaired myogenic fusion with disorganized cadherin/β catenin adhesion complexes. We show that skeletal muscle from Lmna-CMD mice is unable to hypertrophy in response to functional overload, due to defective fusion of activated MuSCs, defective protein synthesis and defective remodeling of the neuromuscular junction. Moreover, stretched myotubes and overloaded muscle fibers with LMNA-CMD mutations display aberrant mechanical regulation of the yes-associated protein (YAP). We also observe defects in MuSC activation and YAP signaling in muscle biopsies from LMNA-CMD patients. These phenotypes are not recapitulated in closely related but less severe EDMD models. In conclusion, combining studies in vitro, in vivo, and patient samples, we find that LMNA-CMD mutations interfere with mechanosignaling pathways in skeletal muscle, implicating A-type lamins in the regulation of skeletal muscle growth

Gay male academics in UK business and management schools: negotiating heteronormativities in everyday work life

This paper contributes to a neglected topic area about lesbian, gay, bisexual and trans people’s employment experiences in UK business and management schools. Drawing on queer theory to problematize essentialist notions of sexuality, we explore how gay male academics negotiate and challenge discourses of heteronormativity within different work contexts. Using in-depth interview data, the paper shows that gay male academics are continually constrained by heteronormativity in constructing viable subject positions as ‘normal’, often having to reproduce heteronormative values that squeeze opportunities for generating non-heteronormative ‘queer’ sexualities, identities and selves. Constructing a presence as an openly gay academic can invoke another binary through which identities are (re)constructed: as either ‘gay’ (a cleaned up version of gay male sexuality that sustains a heteronormative moral order) or ‘queer’ (cast as radical, disruptive and sexually promiscuous). Data also reveal how gay men challenge organizational heteronormativities through teaching and research activities, producing reverse discourses and creating alternative knowledge/power regimes, despite institutional barriers and risks of perpetuating heteronormative binaries and constructs. Study findings call for pedagogical and research practices that ‘queer’ (rupture, destabilize, disrupt) management knowledge and the heterosexual/homosexual binary, enabling non-heteronormative voices, perspectives, identities and ways of relating to emerge in queer(er) business and management schools

Coexistence of 'alpha+ 208Pb' cluster structures and single-particle excitations in 212Po

Excited states in 212Po have been populated by alpha transfer using the 208Pb(18O,14C) reaction at 85MeV beam energy and studied with the EUROBALL IV gamma multidetector array. The level scheme has been extended up to ~ 3.2 MeV excitation energy from the triple gamma coincidence data. Spin and parity values of most of the observed states have been assigned from the gamma angular distributions and gamma -gamma angular correlations. Several gamma lines with E(gamma) < 1 MeV have been found to be shifted by the Doppler effect, allowing for the measurements of the associated lifetimes by the DSAM method. The values, found in the range [0.1-0.6] ps, lead to very enhanced E1 transitions. All the emitting states, which have non-natural parity values, are discussed in terms of alpha-208Pb structure. They are in the same excitation-energy range as the states issued from shell-model configurations.Comment: 21 pages, 19 figures, corrected typos, revised arguments in Sect. III

Circulating levels of dickkopf-1, osteoprotegerin and sclerostin are higher in old compared with young men and women and positively associated with whole-body bone mineral density in older adults

Summary: Bone mineral density declines with increasing older age. We examined the levels of circulating factors known to regulate bone metabolism in healthy young and older adults. The circulating levels of dickkopf-1, osteocalcin, osteoprotegerin and sclerostin were positively associated with WBMD in older adults, despite the average WBMD being lower and circulating dickkopf-1, osteoprotegerin and sclerostin being higher in old than young. Purpose: To investigate the relationship between whole-body bone mineral density (WBMD) and levels of circulating factors with known roles in bone remodelling during 'healthy' ageing. Methods: WBMD and fasting plasma concentrations of dickkopf-1, fibroblast growth factor-23, osteocalcin, osteoprotegerin, osteopontin and sclerostin were measured in 272 older subjects (69 to 81 years; 52% female) and 171 younger subjects (18-30 years; 53% female). Results: WBMD was lower in old than young. Circulating osteocalcin was lower in old compared with young, while dickkopf-1, osteoprotegerin and sclerostin were higher in old compared with young. These circulating factors were each positively associated with WBMD in the older adults and the relationships remained after adjustment for covariates (r-values ranging from 0.174 to 0.254, all p<0.01). In multivariate regression, the body mass index, circulating sclerostin and whole-body lean mass together accounted for 13.8% of the variation with WBMD in the older adults. In young adults, dickkopf-1 and body mass index together accounted for 7.7% of variation in WBMD. Conclusion: Circulating levels of dickkopf-1, osteocalcin, osteoprotegerin and sclerostin are positively associated with WBMD in community-dwelling older adults, despite the average WBMD being lower and circulating dickkopf-1, osteoprotegerin and sclerostin being higher in old than young