Axonal localization of the fragile X family of RNA binding proteins is conserved across mammals

Spatial segregation of proteins to neuronal axons arises in part from local translation of mRNAs that are first transported into axons in ribonucleoprotein particles (RNPs), complexes containing mRNAs and RNA binding proteins. Understanding the importance of local translation for a particular circuit requires not only identifying axonal RNPs and their mRNA cargoes, but also whether these RNPs are broadly conserved or restricted to only a few species. Fragile X granules (FXGs) are axonal RNPs containing the fragile X related family of RNA binding proteins along with ribosomes and specific mRNAs. FXGs were previously identified in mouse, rat, and human brains in a conserved subset of neuronal circuits but with species-dependent developmental profiles. Here, we asked whether FXGs are a broadly conserved feature of the mammalian brain and sought to better understand the species-dependent developmental expression pattern. We found FXGs in a conserved subset of neurons and circuits in the brains of every examined species that together include mammalian taxa separated by up to 160 million years of divergent evolution. A developmental analysis of rodents revealed that FXG expression in frontal cortex and olfactory bulb followed consistent patterns in all species examined. In contrast, FXGs in hippocampal mossy fibers increased in abundance across development for most species but decreased across development in guinea pigs and members of the Mus genus, animals that navigate particularly small home ranges in the wild. The widespread conservation of FXGs suggests that axonal translation is an ancient, conserved mechanism for regulating the proteome of mammalian axons.     

The mental health exchange: An important function of a community Mental Health Center

A team of professional staff persons, including psychiatrists, psychologists, social workers, public health nurses, etc., accompanied by a group of volunteer women who have been trained as mental health aides, provides county residents with counseling and information regarding mental health problems. The Mental Health Exchange offers those in the community an open house, twice a week, to discuss their interests and concerns, not only with professionals, but with mental health aides who are perceived as neighbors and friends—just people like themselves who are interested in helping others who are not registered patients. The Exchange offers a unique procedure for learning and for giving a clinical type of service to a large number of people with minimum staff.The project was supported by Public Health Service Grant MH1134-4.     

Release of astroglial vimentin by extracellular vesicles: Modulation of binding and internalization of C3 transferase in astrocytes and neurons

Clostridium botulinum C3 transferase (C3bot) ADP-ribosylates rho proteins to change cellular functions in a variety of cell types including astrocytes and neurons. The intermediate filament protein vimentin as well as transmembrane integrins are involved in internalization of C3bot into cells. The exact contribution, however, of these proteins to binding of C3bot to the cell surface and subsequent cellular uptake remains to be unraveled. By comparing primary astrocyte cultures derived from wild-type with Vim^−/− mice, we demonstrate that astrocytes lacking vimentin exhibited a delayed ADP-ribosylation of rhoA concurrent with a blunted morphological response. This functional impairment was rescued by the extracellular excess of recombinant vimentin. Binding assays using C3bot harboring a mutated integrin-binding RGD motif (C3bot-G89I) revealed the involvement of integrins in astrocyte binding of C3bot. Axonotrophic effects of C3bot are vimentin dependent and postulate an underlying mechanism entertaining a molecular cross-talk between astrocytes and neurons. We present functional evidence for astrocytic release of vimentin by exosomes using an in vitro scratch wound model. Exosomal vimentin+ particles released from wild-type astrocytes promote the interaction of C3bot with neuronal membranes. This effect vanished when culturing Vim^−/− astrocytes. Specificity of these findings was confirmed by recombinant vimentin propagating enhanced binding of C3bot to synaptosomes from rat spinal cord and mouse brain. We hypothesize that vimentin+ exosomes released by reactive astrocytes provide a novel molecular mechanism constituting axonotrophic (neuroprotective) and plasticity augmenting effects of C3bot after spinal cord injury.     

Rat astroglial somatomedin/insulin-like growth factor binding proteins: characterization and evidence of biologic function

Specific binding proteins (BPs) to somatomedin/insulin-like growth factors (Sm/IGFs) have been identified in conditioned media from a variety of cells in culture. By affinity cross-linking using disuccinimidyl suberate, we have covalently cross-linked radiolabeled somatomedin-C/insulin-like growth factor I (Sm-C/IGF I), insulin-like growth factor II (IGF II) and insulin to BPs in conditioned medium (CM) from cultured astroglial cells derived from cerebral cortices of neonatal rats. Two species of radiolabeled Sm/IGF BP complexes of 40,000 Da (40K) and 45K were identified. Competition with unlabeled Sm-C/IGF I and IGF II demonstrated that the BPs in each complex have similar affinities for Sm-C/IGF I and IGF II. The BP in the 45K complex was about 5-fold more sensitive to competition with unlabeled Sm/IGFs than the BP in the 40K complex, suggesting that it either has a higher affinity for Sm/IGFs or is less abundant. Evidence that the BPs in each complex are distinct includes the following findings: (1) insulin competed with Sm/IGF for binding to the 45K complex, but not the 40K complex, and (2) the BP in the 40K complex, but not the 45K complex, was recognized by antibodies raised against a BP purified from CM of buffalo rat liver (BRL) 3A cells. Growth hormone did not affect the apparent secretion of either BP. The binding activity of both BPs was retained after mild heat treatment, changes to extremes of pH (2-10), and prolonged storage at -20 degrees C, but was destroyed after heating to higher temperatures (80 degrees C and greater), reduction, and proteolytic treatment.(ABSTRACT TRUNCATED AT 250 WORDS)     

The interaction of stem cells and vascularity in peripheral nerve regeneration

The degree of nerve regeneration after peripheral nerve injury can be altered by the microenvironment at the site of injury. Stem cells and vascularity are postulated to be a part of a complex pathway that enhances peripheral nerve regeneration; however, their interaction remains unexplored. This review aims to summarize current knowledge on this interaction, including various mechanisms through which trophic factors are promoted by stem cells and angiogenesis. Angiogenesis after nerve injury is stimulated by hypoxia, mediated by vascular endothelial growth factor, resulting in the growth of preexisting vessels into new areas. Modulation of distinct signaling pathways in stem cells can promote angiogenesis by the secretion of various angiogenic factors. Simultaneously, the importance of stem cells in peripheral nerve regeneration relies on their ability to promote myelin formation and their capacity to be influenced by the microenvironment to differentiate into Schwann-like cells. Stem cells can be acquired through various sources that correlate to their differentiation potential, including embryonic stem cells, neural stem cells, and mesenchymal stem cells. Each source of stem cells serves its particular differentiation potential and properties associated with the promotion of revascularization and nerve regeneration. Exosomes are a subtype of extracellular vesicles released from cell types and play an important role in cell-to-cell communication. Exosomes hold promise for future transplantation applications, as these vesicles contain fewer membrane-bound proteins, resulting in lower immunogenicity. This review presents pre-clinical and clinical studies that focus on selecting the ideal type of stem cell and optimizing stem cell delivery methods for potential translation to clinical practice. Future studies integrating stem cell-based therapies with the promotion of angiogenesis may elucidate the synergistic pathways and ultimately enhance nerve regeneration.     

The role of GTP binding proteins in ischemic brain damage: autoradiographic and histophatological study

Cerebral ischemia produces perturbation of signal transduction systems in neurons. In order to estimate the contribution of guanine nucleotide-binding protein (G-protein) to hippocampal neuronal death, the effect of pertussis toxin (PTX) on the CA1 pyramidal cell damage after transient forebrain ischemia in rats was examined. PTX was administered 3 days before 20 min of transient forebrain ischemia. PTX injection into the CA1 failed subfield to alter the number of ischemic-damaged CA1 pyramidal cells. In contrast, ventricular PTX injection exacerbated CA1 pyramidal cell damage. We also studied postischemic alteration of GTP binding sites in the hippocampal formation using quantitative in vitro autoradiography. Autoradiographic imaging demonstrated predominant distribution of GTP binding sites in synaptic areas in the hippocampus. No significant change of GTP binding activity was observed in the hippocampus until 2 days after recirculation. Seven days after ischemia, when the CA1 pyramidal cells were depleted, the GTP binding sites of the strata oriens and radiatum in the CA1 subfield had reduced by 32% and 31%, respectively. In contrast, GTP binding in the CA3 subfield and the dentate gyrus remained unaltered throughout the reperfusion period. These results suggest that the amount of G-proteins as estimated by GTP binding remained unaltered in the hippocampus during the early recirculation period, when the CA1 pyramidal cells were morphologically intact, and that signal transduction pathways mediated by G_i and G_o do not play a major role in delayed death of the CA1 pyramidal cells.     

The development and maintenance of sexual dysfunction: An explanation based on cognitive theory

The literature exploring the aetiology of sexual dysfunction is largely atheoretical. This situation stems primarily from the fact that most studies are clinical in their focus. The scientific literature on sexual function and dysfunction is fairly recent and, even here, most studies are confined to the examination of a single dysfunction or aspect of dysfunction. As a result there has been an insufficiently comprehensive database to allow for the development of a general model to explain the aetiology of sexual dysfunction. However, sufficient data have been gathered in the last few years to allow such a general model to be proposed. The model presented in this paper explains the development of sexual dysfunction by an individual in a relationship. The model would need to be slightly modified to explain sexual dysfunction in people not currently involved in relationships. Cognitive theory is used to explain the causes of sexual dysfunction in men and women. The aetiological factors contributing to dysfunction are reviewed and grouped into one of three categories: intrapsychic, individual and relationship causes. Cognitive theory is then used to explain the dynamics between these factors. Each of the causes is evaluated by both individuals in the relationship and, depending upon the evaluation that is made, the person reacts in particular ways. These reactions may then lead to the development of a sexual dysfunction. Implications from this model for the treatment of sexual dysfunction are discussed.     

The use of hydrogel-delivered extracellular vesicles in recovery of motor function in stroke: a testable experimental hypothesis for clinical translation including behavioral and neuroimaging assessment approaches

Neural tissue engineering, nanotechnology and neuroregeneration are diverse biomedical disciplines that have been working together in recent decades to solve the complex problems linked to central nervous system(CNS) repair. It is known that the CNS demonstrates a very limited regenerative capacity because of a microenvironment that impedes effective regenerative processes, making development of CNS therapeutics challenging. Given the high prevalence of CNS conditions such as stroke that damage the brain and place a severe burden on afflicted individuals and on society, it is of utmost significance to explore the optimum methodologies for finding treatments that could be applied to humans for restoration of function to pre-injury levels. Extracellular vesicles(EVs), also known as exosomes, when derived from mesenchymal stem cells, are one of the most promising approaches that have been attempted thus far, as EVs deliver factors that stimulate recovery by acting at the nanoscale level on intercellular communication while avoiding the risks linked to stem cell transplantation. At the same time, advances in tissue engineering and regenerative medicine have offered the potential of using hydrogels as bio-scaffolds in order to provide the stroma required for neural repair to occur, as well as the release of biomolecules facilitating or inducing the reparative processes. This review introduces a novel experimental hypothesis regarding the benefits that could be offered if EVs were to be combined with biocompatible injectable hydrogels. The rationale behind this hypothesis is presented, analyzing how a hydrogel might prolong the retention of EVs and maximize the localized benefit to the brain. This sustained delivery of EVs would be coupled with essential guidance cues and structural support from the hydrogel until neural tissue remodeling and regeneration occur. Finally, the importance of including nonhuman primate models in the clinical translation pipeline, as well as the added benefit of multi-modal neuroimaging analysis to establish non-invasive, in vivo, quantifiable imagingbased biomarkers for CNS repair are discussed, aiming for more effective and safe clinical translation of such regenerative therapies to humans.     

The interaction of perceived control and Gambler's fallacy in risky decision making: An fMRI study

Limited recent evidence implicates the anterior/posterior cingulate (ACC/PCC) and lateral prefrontal networks as the neural substrates of risky decision‐making biases such as illusions of control (IoC) and gambler's fallacy (GF). However, investigation is lacking on the dynamic interactive effect of those biases during decision making. Employing a card‐guessing game that independently manipulates trial‐by‐trial perceived control and gamble outcome among 29 healthy female participants, we observed both IoC‐ and GF‐type behaviors, as well as an interactive effect of previous control and previous outcome, with GF‐type behaviors only following computer‐selected, but not self‐selected, outcomes. Imaging results implicated the ACC and left dorsolateral prefrontal cortex (DLPFC) in agency processing, and the cerebellum and right DLPFC in previous outcome processing, in accordance with past literature. Critically, the right inferior parietal lobule (IPL) exhibited significant betting‐related activities to the interaction of previous control and previous outcome, showing more positive signals to previous computer‐selected winning versus losing outcomes but the reverse pattern following self‐selected outcomes, as well as responding to the interactive effect of control and outcome during feedback. Associations were also found between participants' behavioral sensitivity to the interactive effect of previous control and previous outcome, and right IPL signals, as well as its functional connectivity with neural networks implicated in agency and previous outcome processing. We propose that the right IPL provides the neural substrate for the interaction of perceived control and GF, through coordinating activities in the anterior and posterior cingulate cortices and working conjunctively with lateral PFC and other parietal networks. Hum Brain Mapp 37:1218–1234, 2016. © 2016 Wiley Periodicals, Inc .     

The effects of testosterone on sleep and sleep-disordered breathing in men: its bidirectional interaction with erectile function

As a major androgen with a key role in developing and maintaining male sexual characteristics, testosterone exerts a broad range of actions regulating several systems throughout human life. This article reviews data on the role of sleep in modulating endocrine release, as well as data on the effects of testosterone and androgen-replacement therapy on sleep architecture and breathing. This review also discusses the interaction of testosterone and sleep, with a particular emphasis on bilateral effects. Changes in nocturnal testosterone are sleep-related, with levels rising during sleep and falling on waking, whereas circadian effects are apparently marginal. Peak testosterone levels coincide with rapid-eye movement (REM) sleep onset. The decreasing sleep efficiency and numbers of REM sleep episodes with altered REM sleep latency observed in older men are associated with lower concentrations of circulating testosterone. The well-established male preponderance of sleep apnea suggests that sex hormones are involved in the pathogenesis of this breathing disorder. In addition, androgens are most certainly key players in the central and peripheral modulation of erectile function. Among other effects, sleep curtailment has been shown to lead to reduced levels of circulating androgens in healthy men and male rodents, and this highlights the biological significance of sleep homeostasis for endocrine regulation.     

The synaptic CT carbohydrate modulates binding and expression of extracellular matrix proteins in skeletal muscle: Partial dependence on utrophin

The CT carbohydrate, Neu5Ac/Neu5Gcα2,3[GalNAcβ1,4]Galβ1,4GlcNAcβ-, is specifically expressed at the neuromuscular junction in skeletal myofibers of adult vertebrates. When Galgt2, the glycosyltransferase that creates the synaptic β1,4GalNAc portion of this glycan, is overexpressed in extrasynaptic regions of the myofiber membrane, α dystroglycan becomes glycosylated with the CT carbohydrate and this coincides with the ectopic expression of synaptic dystroglycan-binding proteins, including laminin α4, laminin α5, and utrophin. Here we show that both synaptic and extrasynaptic forms of laminin and agrin have increased binding to the CT carbohydrate compared to sialyl-N-acetyllactosamine, its extrasynaptically expressed precursor. Muscle laminins also show increased binding to CT-glycosylated muscle α dystroglycan relative to its non-CT-containing glycoforms. Overexpression of Galgt2 in transgenic mouse skeletal muscle increased the mRNA expression of extracellular matrix (ECM) genes, including agrin and laminin α5, as well as utrophin, integrin α7, and neuregulin. Increased expression of ECM proteins in Galgt2 transgenic skeletal muscles was partially dependent on utrophin, but utrophin was not required for Galgt2-induced changes in muscle growth or neuromuscular development. These experiments demonstrate that overexpression of a synaptic carbohydrate can increase both ECM binding to α dystroglycan and ECM expression in skeletal muscle, and they suggest a mechanism by which Galgt2 overexpression may inhibit muscular dystrophy and affect neuromuscular development.     

Specific interaction between Sam68 and neuronal mRNAs: implication for the activity-dependent biosynthesis of elongation factor eEF1A

In cultured hippocampal neurons and in adult brain, the splicing regulatory protein Sam68 is partially relocated to the somatodendritic domain and associates with dendritic polysomes. Transfer to the dendrites is activity-dependent. We have investigated the repertoire of neuronal mRNAs to which Sam68 binds in vivo. By using coimmunoprecipitation and microarray screening techniques, Sam68 was found to associate with a number of plasticity-related mRNA species, including Eef1a1, an activity-responsive mRNA coding for translation elongation factor eEF1A. In cortical neuronal cultures, translation of the Eef1a1 mRNA was strongly induced by neuronal depolarisation and correlated with enhanced association of Sam68 with polysomal mRNAs. The possible function of Sam68 in Eef1a1 mRNA utilization was studied by expressing a dominant-negative, cytoplasmic Sam68 mutant (GFP-Sam68DeltaC) in cultured hippocampal neurons. The level of eEF1A was lower in neurons expressing GFP-Sam68DeltaC than in control neurons, supporting the proposal that endogenous Sam68 may contribute to the translational efficiency of the Eef1a1 mRNA. These findings are discussed in the light of the complex, potentially crucial regulation of eEF1A biosynthesis during long-term synaptic change.     

Expression of neurotrophins in skeletal muscle: Quantitative comparison and significance for motoneuron survival and maintenance of function

Neurotrophins play a crucial role in the regulation of survival and maintenance of specific functions of various populations of neurons. Brain-derived neurotrophic factor (BDNF), newrotrophin-3 (NT-3) and neurotrophin 4/5 (NT-4) have been shown to support motoneuron survival during embryonic development and, after birth, to protect motoneurons from degeneration after nerve lesion. We have compared the levels of these neurotrophins in skeletal muscle by quantitative Northern blot analysis, both during embryonic development and postnatally. We localized the sites of expression of these neurotrophins by in situ hybridisation and analysed the expression of trkB in the spinal cord by in situ hybridisation and immunohistochemistry. NT-3 is most abundantly expressed both during embryonic development and in the postnatal phase, followed by NT-4. The levels of BDNF are very low, in particular after birth. After nerve lesion, NT-3 mRNA essentially remained unchanged, whereas NT-4 mRNA rapidly decreased. The slow increase in BDNF expression seems to be essentially due to the expression in Schwann cells rather than skeletal muscle, demonstrated by in situ hybridisation. Our data indicate that motoneurons can receive trophic support from several members of the neurotrophin gene family during the period of naturally occurring cell death. Postnatally, the predominant ligand acting via trkB on motoneurons is NT-4, whereas BDNF expression seems to play a role mainly after nerve lesion. © 1995 Wiley-Liss, Inc.     

Epigenetics and gene expression profile in first-episode psychosis: The role of childhood trauma

Childhood Trauma (CT) mediation of the epigenome and its impact on gene expression profile could provide a mechanism for the gene-environment interaction underling psychosis. We reviewed the evidence concerning epigenetic and gene expression modifications associated with CT in both First-Episode Psychosis (FEP) and healthy subjects. In order to explore the relative role of psychosis itself in determining these modifications, evidence about FEP and epigenetics/gene expression was also summarized. We performed a systematic search on PubMed, last updated in December 2016. Out of 2966 potentially relevant records, only 41 studies were included. CT resulted associated: in FEP subjects, with global DNA hypo-methylation and reduced BDNF gene-expression; in healthy subjects, with hyper-methylation of SLC6A4, NR3C1, KITLG, and OXTR; hypo-methylation of FKBP5, IL-6, and BDNF; increased IL1B, IL8, and PTGS gene expression; and decreased SLC6A4 gene expression. FEP showed global DNA hypo-methylation; increased methylation and reduced gene expression of GCH1; hyper-expression of MPB, NDEL1, AKT1, and DICER1; and hypo-expression of DROSHA, COMT, and DISC1 in comparison with healthy controls.     

14-3-3和CLIC4蛋白在U251细胞自噬中的相互作用

目的通过饥饿诱导神经胶质瘤U251细胞发生自噬,探讨细胞CLIC4和14-3-3蛋白在饥饿条件下诱导自噬过程中的相互作用。方法通过Hoechst、14-3-3 epsilon、CLIC4染色于共聚焦显微镜下观察抑制CLIC4表达对于饥饿条件下,14-3-3 epsilon蛋白与CLIC4共定位的影响。通过Western Blot技术检测Beclin 1及14-3-3蛋白表达。免疫共沉淀技术检测14-3-3 epsilon蛋白与CLIC4蛋白的结合水平。结果共聚焦显微镜观察14-3-3 epsilon和CLIC4荧光染色结果显示,饥饿条件下,14-3-3 epsilon蛋白与CLIC4共定位显著增加,并广泛分布于胞浆及细胞核中。同时Western Blot结果表明抑制CLIC4表达能够引起14-3-3蛋白以及自噬相关蛋白Beclin1表达增加。饥饿条件下,14-3-3 epsilon蛋白与CLIC4共沉淀增强,而抑制CLIC4表达能够降低两者结合水平。结论 14-3-3epsilon蛋白与CLIC4的相互作用由于RNA干扰而减弱,促进了14-3-3蛋白水平上调,进而增强了14-3-3蛋白对Beclin1信号通路的调节,引起Beclin1表达增加,进一步激活饥饿条件下U251细胞自噬过程。