A Ras GTPase associated protein is involved in the phototropic and circadian photobiology responses in fungi

Light is an environmental signal perceived by most eukaryotic organisms and that can have major impacts on their growth and development. The MadC protein in the fungus Phycomyces blakesleeanus (Mucoromycotina) has been postulated to form part of the photosensory input for phototropism of the fruiting body sporangiophores, but the madC gene has remained unidentified since the 1960s when madC mutants were first isolated. In this study the madC gene was identified by positional cloning. All madC mutant strains contain loss-of-function point mutations within a gene predicted to encode a GTPase activating protein (GAP) for Ras. The madC gene complements the Saccharomyces cerevisiae Ras-GAP ira1 mutant and the encoded MadC protein interacts with P. blakesleeanus Ras homologs in yeast two-hybrid assays, indicating that MadC is a regulator of Ras signaling. Deletion of the homolog in the filamentous ascomycete Neurospora crassa affects the circadian clock output, yielding a pattern of asexual conidiation similar to a ras-1 mutant that is used in circadian studies in N. crassa. Thus, MadC is unlikely to be a photosensor, yet is a fundamental link in the photoresponses from blue light perceived by the conserved White Collar complex with Ras signaling in two distantly-related filamentous fungal species

Prevalência e determinantes sociais da ideação suicida entre estudantes brasileiros em escolas públicas do ensino médio

Background and Aim: Recent studies have shown an increase in suicidal ideation and behaviors among youths, highlighting solid associations between being poor, being female, being LGBT (lesbian, gay, bisexual, or transgender), and suffering discrimination at school and on the internet. Although the social determinants of suicidal ideation are widely debated worldwide, there is a lack of data on these topics concerning young Brazilians. The present study aimed to contribute to filling this gap. Method: The cross-sectional study used a convenience sample of 475 senior high school students (16–17 y-old) from nine public schools in São Paulo, Brazil. Results: Of the total interviewed, 224 reported lifetime suicidal ideation, an unexpectedly high prevalence (47.2%). In the multiple analysis with an estimated adjusted prevalence ratio (PR), same-sex or bisexual attraction (PR = 1.87; 95%CI: 1.5–2.3), studying in night schools (PR = 1.36; 95%CI: 1.1–1.6) — indicative of lower economic status — and being discriminated against at school (PR = 1.22; 95%CI: 1.0–1.5) and on the internet (PR = 1.48; 95%CI: 1.2–1.8) were positively associated with lifetime suicidal ideation. The students' self-defined race/ethnicity and gender were not. Conclusions: The results indicate the need to consider the social determinants of mental health in the public debate and intervention programs aimed at youth in Brazil and elsewhere. Enhancing mental health promotion while considering the sociopolitical determinants of health should be a strategic and political priority. It is crucial to have a comprehensive intersectional perspective that reflects on the various forms of domination and how these connect with mental distress and its consequences.Contexto e Objetivo: Estudos recentes mostram um aumento de ideação e comportamentos suicidas entre jovens, havendo fortes associações com ser pobre, ser mulher, ser LGBT (lésbica, gay, bissexual ou transgénero) e sofrer discriminação na escola e/ou na internet. Embora os determinantes sociais da ideação suicida sejam amplamente debatidos em todo o mundo, há uma lacuna sobre esses temas em relação aos jovens brasileiros, o que o presente estudo pretende contribuir para preencher. Métodos: O estudo transversal utilizou uma amostra de conveniência de 475 alunos do ensino médio (16–17 anos) de nove escolas públicas do estado de São Paulo, Brasil. Resultados: Do total de entrevistados, 224 deles relataram ideação suicida ao longo da vida, uma prevalência inesperadamente alta (47,2%). Na análise múltipla com estimativa da razão de prevalência (RP) ajustada, atração por pessoas do mesmo sexo ou bissexual (RP = 1,87; IC95%: 1,5–2,3), estudar em escolas noturnas (RP = 1,36; IC95%: 1,1–1,6) — indicativo de menor condição econômica — e ser discriminado em escola (RP = 1,22; IC95%: 1,0–1,5) e na internet (RP = 1,48; IC95%: 1,2–1,8) foram associados positivamente à ideação suicida ao longo da vida. Raça/etnia e gênero dos alunos não foram associados. Conclusões: Os resultados apontam para a necessidade de consideração dos determinantes sociais da saúde mental no debate público e nos programas de intervenção voltados à juventude no Brasil e em outros lugares. O aprimoramento da promoção da saúde mental, levando-se em conta os determinantes sociopolíticos da saúde, deve ser uma prioridade estratégica e política. É crucial uma perspectiva interseccional abrangente que reflita sobre as várias formas de dominação e como estas se conectam com o sofrimento mental e suas consequências

IGF-1 receptor antagonism inhibits autophagy

Inhibition of the insulin/insulin-like growth factor signalling pathway increases lifespan and protects against neurodegeneration in model organisms, and has been considered as a potential therapeutic target. This pathway is upstream of mTORC1, a negative regulator of autophagy. Thus, we expected autophagy to be activated by insulin-like growth factor-1 (IGF-1) inhibition, which could account for many of its beneficial effects. Paradoxically, we found that IGF-1 inhibition attenuates autophagosome formation. The reduced amount of autophagosomes present in IGF-1R depleted cells can be, at least in part, explained by a reduced formation of autophagosomal precursors at the plasma membrane. In particular, IGF-1R depletion inhibits mTORC2, which, in turn, reduces the activity of protein kinase C (PKCa/b). This perturbs the actin cytoskeleton dynamics and decreases the rate of clathrin-dependent endocytosis, which impacts autophagosome precursor formation. Finally, with important implications for human diseases, we demonstrate that pharmacological inhibition of the IGF-1R signalling cascade reduces autophagy also in zebrafish and mice models. The novel link we describe here has important consequences for the interpretation of genetic experiments in mammalian systems and for evaluating the potential of targeting the IGF-1R receptor or modulating its signalling through the downstream pathway for therapeutic purposes under clinically relevant conditions, such as neurodegenerative diseases, where autophagy stimulation is considered beneficial.This is the version of the manuscript that was first published on line. The final version can be found published in Human Molecular Genetics by OUP here: http://hmg.oxfordjournals.org/content/22/22/4528.full.pdf+html

Deficiency of the zinc finger protein ZFP106 causes motor and sensory neurodegeneration

Acknowledgements We are indebted to Jim Humphries, JennyCorrigan, LizDarley, Elizabeth Joynson, Natalie Walters, Sara Wells and the whole necropsy, histology, genotyping and MLC ward 6 teams at MRC Harwell for excellent technical assistance. We thank the staff of the WTSI Illumina Bespoke Team for the RNA-seq data, the Sanger Mouse Genetics Project for the initial mouse characterization and Dr David Adams for critical reading of the manuscript. We also thank KOMP for the mouse embryonic stem cells carrying the knockout first promoter-less allele (tm1a(KOMP)Wtsi) within Zfp016. Conflict of Interest statement. None declared. Funding This work was funded by the UK Medical Research Council (MRC) to A.A.-A. and a Motor Neurone Disease Association (MNDA) project grant to A.A.-A. and EMCF. D.L.H.B. is a Wellcome Trust Senior Clinical Scientist Fellow and P.F. is a MRC/MNDA Lady Edith Wolfson Clinician Scientist Fellow. Funding to pay the Open Access publication charges for this article was provided by the MRC grant number: MC_UP_A390_1106.Peer reviewedPublisher PD

A Ras GTPase associated protein is involved in the phototropic and circadian photobiology responses in fungi

[EN] Light is an environmental signal perceived by most eukaryotic organisms and that can have major impacts on their growth and development. The MadC protein in the fungus Phycomyces blakesleeanus (Mucoromycotina) has been postulated to form part of the photosensory input for phototropism of the fruiting body sporangiophores, but the madC gene has remained unidentified since the 1960s when madC mutants were first isolated. In this study the madC gene was identified by positional cloning. All madC mutant strains contain loss-of-function point mutations within a gene predicted to encode a GTPase activating protein (GAP) for Ras. The madC gene complements the Saccharomyces cerevisiae Ras-GAP ira1 mutant and the encoded MadC protein interacts with P. blakesleeanus Ras homologs in yeast two-hybrid assays, indicating that MadC is a regulator of Ras signaling. Deletion of the homolog in the filamentous ascomycete Neurospora crassa affects the circadian clock output, yielding a pattern of asexual conidiation similar to a ras-1 mutant that is used in circadian studies in N. crassa. Thus, MadC is unlikely to be a photosensor, yet is a fundamental link in the photoresponses from blue light perceived by the conserved White Collar complex with Ras signaling in two distantly-related filamentous fungal species

A genetic modifier suggests that endurance exercise exacerbates Huntington's disease.

Polyglutamine expansions in the huntingtin gene cause Huntington's disease (HD). Huntingtin is ubiquitously expressed, leading to pathological alterations also in peripheral organs. Variations in the length of the polyglutamine tract explain up to 70% of the age-at-onset variance, with the rest of the variance attributed to genetic and environmental modifiers. To identify novel disease modifiers, we performed an unbiased mutagenesis screen on an HD mouse model, identifying a mutation in the skeletal muscle voltage-gated sodium channel (Scn4a, termed 'draggen' mutation) as a novel disease enhancer. Double mutant mice (HD; Scn4aDgn/+) had decreased survival, weight loss and muscle atrophy. Expression patterns show that the main tissue affected is skeletal muscle. Intriguingly, muscles from HD; Scn4aDgn/+ mice showed adaptive changes similar to those found in endurance exercise, including AMPK activation, fibre type switching and upregulation of mitochondrial biogenesis. Therefore, we evaluated the effects of endurance training on HD mice. Crucially, this training regime also led to detrimental effects on HD mice. Overall, these results reveal a novel role for skeletal muscle in modulating systemic HD pathogenesis, suggesting that some forms of physical exercise could be deleterious in neurodegeneration

The Ncoa7 locus regulates V-ATPase formation and function, neurodevelopment and behaviour

Members of the Tre2/Bub2/Cdc16 (TBC), lysin motif (LysM), domain catalytic (TLDc) protein family are associated with multiple neurodevelopmental disorders, although their exact roles in disease remain unclear. For example, nuclear receptor coactivator 7 (NCOA7) has been associated with autism, although almost nothing is known regarding the mode-of-action of this TLDc protein in the nervous system. Here we investigated the molecular function of NCOA7 in neurons and generated a novel mouse model to determine the consequences of deleting this locus in vivo. We show that NCOA7 interacts with the cytoplasmic domain of the vacuolar (V)-ATPase in the brain and demonstrate that this protein is required for normal assembly and activity of this critical proton pump. Neurons lacking Ncoa7 exhibit altered development alongside defective lysosomal formation and function; accordingly, Ncoa7 deletion animals exhibited abnormal neuronal patterning defects and a reduced expression of lysosomal markers. Furthermore, behavioural assessment revealed anxiety and social defects in mice lacking Ncoa7. In summary, we demonstrate that NCOA7 is an important V-ATPase regulatory protein in the brain, modulating lysosomal function, neuronal connectivity and behaviour; thus our study reveals a molecular mechanism controlling endolysosomal homeostasis that is essential for neurodevelopment

Mutation in the FUS nuclear localisation signal domain causes neurodevelopmental and systemic metabolic alterations

Variants in the ubiquitously expressed DNA/RNA-binding protein FUS cause aggressive juvenile forms of amyotrophic lateral sclerosis (ALS). Most FUS mutation studies have focused on motor neuron degeneration; little is known about wider systemic or developmental effects. We studied pleiotropic phenotypes in a physiological knock-in mouse model carrying the pathogenic FUSDelta14 mutation in homozygosity. RNA sequencing of multiple organs aimed to identify pathways altered by the mutant protein in the systemic transcriptome, including metabolic tissues, given the link between ALS-frontotemporal dementia and altered metabolism. Few genes were commonly altered across all tissues, and most genes and pathways affected were generally tissue specific. Phenotypic assessment of mice revealed systemic metabolic alterations related to the pathway changes identified. Magnetic resonance imaging brain scans and histological characterisation revealed that homozygous FUSDelta14 brains were smaller than heterozygous and wild-type brains and displayed significant morphological alterations, including a thinner cortex, reduced neuronal number and increased gliosis, which correlated with early cognitive impairment and fatal seizures. These findings show that the disease aetiology of FUS variants can include both neurodevelopmental and systemic alterations

Proinsulin attenuates the loss of vision and delays apoptosis of photoreceptors in a mouse model of retinitis pigmentosa.

34 p. 8 fig. 2 supl. fig.purpose. Retinitis pigmentosa (RP) is a heterogeneous group of inherited conditions that lead to blindness and for which there is no effective therapy. Apoptosis of photoreceptors is a common feature in animal models of the disease. Thus, the authors studied the therapeutic potential of proinsulin, an antiapoptotic molecule active during retinal development. methods. Transgenic mice expressing human proinsulin (hPi) in the skeletal muscle were generated in a mixed C57BL/6:SJL background and were back-crossed to a C57BL/6 background. Two independent lineages of transgenic mice were established in which hPi production in muscle was constitutive and not regulated by glucose levels. hPi levels in serum, muscle, and retina were determined with a commercial ELISA kit, visual function was evaluated by electroretinographic (ERG) recording, and programmed cell death was assessed by TUNEL. Immunohistochemistry was used to evaluate retinal structure preservation and oxidative damage. results. Transgenic expression of hPi in the rd10 retinal degeneration mouse model led to prolonged vision, as determined by ERG recording, in a manner that was related to the level of transgene expression. This attenuation of visual deterioration was correlated with a delay in photoreceptor apoptosis and with the preservation of retinal cytoarchitecture, particularly that of the cones. conclusions. These results provide a new basis for possible therapies to counteract retinitis pigmentosa and a new tool to characterize the mechanisms involved in the progress of retinal neurodegenerationSupported by Spanish Ministerio de Educación y Ciencia Grants SAF2001-1038, SAF2004-05870, and SAF2007-66175 (EJdlR, PdlV); BFU2004-02352 (FdP); SAF2005-01262 (FB); Spanish Ministerio de Sanidad y Consumo Grant RETIC RD-06 (FdP, FB); Comunidad de Madrid Grants 8.5-0019.1/2001 (EJdlR) and 08.5-0049/2003 and CCG06-UAH/BIO-0711 (PdlV); Fundación Médica Mutua Madrileña (EJdlR); and Fundaluce (PdlV). SC and NR-M were supported by postgraduate fellowships from the Ministerio de Educación y Ciencia, PB by a Ramón y Cajal contract from the Ministerio de Educación y Ciencia, AIA by a postdoctoral contract from the Fondo de Investigaciones Sanitarias, and VG-V by an I3P postdoctoral contract from the European Social FundPeer reviewe

Novel mutations in human and mouse SCN4A implicate AMPK in myotonia and periodic paralysis

Mutations in the skeletal muscle channel (SCN4A), encoding the Nav1.4 voltage-gated sodium channel, are causative of a variety of muscle channelopathies, including non-dystrophic myotonias and periodic paralysis. The effects of many of these mutations on channel function have been characterized both in vitro and in vivo. However, little is known about the consequences of SCN4A mutations downstream from their impact on the electrophysiology of the Nav1.4 channel. Here we report the discovery of a novel SCN4A mutation (c.1762A>G; p.I588V) in a patient with myotonia and periodic paralysis, located within the S1 segment of the second domain of the Nav1.4 channel. Using N-ethyl-N-nitrosourea mutagenesis, we generated and characterized a mouse model (named draggen), carrying the equivalent point mutation (c.1744A>G; p.I582V) to that found in the patient with periodic paralysis and myotonia. Draggen mice have myotonia and suffer from intermittent hind-limb immobility attacks. In-depth characterization of draggen mice uncovered novel systemic metabolic abnormalities in Scn4a mouse models and provided novel insights into disease mechanisms. We discovered metabolic alterations leading to lean mice, as well as abnormal AMP-activated protein kinase activation, which were associated with the immobility attacks and may provide a novel potential therapeutic target