PARTICLE - The RNA podium for genomic silencers.

Radiation exposure can evoke cellular stress responses. Emerging recognition that long non-coding RNAs (lncRNAs) act as regulators of gene expression has broadened the spectra of molecules controlling the genomic landscape upon alterations in environmental conditions. Knowledge of the mechanisms responding to low dose irradiation (LDR) exposure is very limited yet most likely involve subtle ancillary molecular pathways other than those protecting the cell from direct cellular damage. The discovery that transcription of the lncRNA PARTICLE (promoter of MAT2A- antisense radiation-induced circulating lncRNA; PARTICL) becomes dramatically instigated within a day after LDR exposure introduced a new gene regulator onto the biological landscape. PARTICLE affords an RNA binding platform for genomic silencers such as DNA methyltransferase 1 and histone tri-methyltransferases to reign in the expression of tumor suppressors such as its neighboring MAT2A in cis as well as WWOX in trans. In silico evidence offers scope to speculate that PARTICLE exploits the abundance of Hoogsten bonds that exist throughout mammalian genomes for triplex formation, presumably a vital feature within this RNA silencer. PARTICLE may provide a buffering riboswitch platform for S-adenosylmethionine. The correlation of PARTICLE triplex formation sites within tumor suppressor genes and their abundance throughout the genome at cancer-related hotspots offers an insight into potential avenues worth exploring in future therapeutic endeavors.

Synaptic vesicle cycle and amyloid ß: Biting the hand that feeds.

The synaptic vesicle cycle (SVC) holds center stage in the biology of presynaptic terminals. Through recurrent exocytosis and endocytosis, it facilitates a sequence of events enabling chemical neurotransmission between functionally related neurons. As a fundamental process that links the interior of nerve cells with their environment, the SVC is also critical for signaling and provides an entry route for a range of pathogens and toxins, enabling detrimental effects. In Alzheimer's disease, the SVC is both the prime site of amyloid ß production and toxicity. In this study, we discuss the emerging evidence for physiological and pathological effects of Aß on various stages of the SVC, from postfusion membrane recovery to trafficking, docking, and priming of vesicles for fusion and transmitter release. Understanding of the mechanisms of Aß interaction with the SVC within the unifying calcium hypothesis of aging and Alzheimer's disease should further elucidate the fundamental biology of the presynaptic terminal and reveal novel therapeutic targets for Alzheimer's disease and other age-related dementias.

Genome-wide analysis of somatic copy number alterations and chromosomal breakages in osteosarcoma.

Osteosarcoma (OS) is the most common primary malignant bone tumor in children and adolescents. It is characterized by highly complex karyotypes with structural and numerical chromosomal alterations. The observed OS-specific characteristics in localization and frequencies of chromosomal breakages strongly implicate a specific set of responsible driver genes or a specific mechanism of fragility induction. In this study, a comprehensive assessment of somatic copy number alterations (SCNAs) was performed in 160 OS samples using whole-genome CytoScan High Density arrays (Affymetrix, Santa Clara, CA). Genes or regions frequently targeted by SCNAs were identified. Breakage analysis revealed OS specific unstable regions in which well-known OS tumor suppressor genes, including TP53, RB1, WWOX, DLG2 and LSAMP are located. Certain genomic features, such as transposable elements and non-B DNA-forming motifs were found to be significantly enriched in the vicinity of chromosomal breakage sites. A complex breakage pattern-chromothripsis-has been suggested as a widespread phenomenon in OS. It was further demonstrated that hyperploidy and in particular chromothripsis were strongly correlated with OS patient clinical outcome. The revealed OS-specific fragility pattern provides novel clues for understanding the biology of OS.

Selective vulnerability of motor neuron types and functional groups to degeneration in amyotrophic lateral sclerosis: review of the neurobiological mechanisms and functional correlates.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative condition characterised by a progressive loss of motor neurons controlling voluntary muscle activity. The disease manifests through a variety of motor dysfunctions related to the extent of damage and loss of neurons at different anatomical locations. Despite extensive research, it remains unclear why some motor neurons are especially susceptible to the disease, while others are affected less or even spared. In this article, we review the neurobiological mechanisms, neurochemical profiles, and morpho-functional characteristics of various motor neuron groups and types of motor units implicated in their differential exposure to degeneration. We discuss specific cell-autonomous (intrinsic) and extrinsic factors influencing the vulnerability gradient of motor units and motor neuron types to ALS, with their impact on disease manifestation, course, and prognosis, as revealed in preclinical and clinical studies. We consider the outstanding challenges and emerging opportunities for interpreting the phenotypic and mechanistic variability of the disease to identify targets for clinical interventions.

Neurotoxin-Derived Optical Probes for Elucidating Molecular and Developmental Biology of Neurons and Synaptic Connections. Toxin-Derived Optical Probes for Neuroimaging.

Botulinum neurotoxins (BoNTs) and tetanus toxin (TeTX) are the deadliest biological substances that cause botulism and tetanus, respectively. Their astonishing potency and capacity to enter neurons and interfere with neurotransmitter release at presynaptic terminals have attracted much interest in experimental neurobiology and clinical research. Fused with reporter proteins or labelled with fluorophores, BoNTs and TeTX and their non-toxic fragments also offer remarkable opportunities to visualize cellular processes and functions in neurons and synaptic connections. This study presents the state-of-the-art optical probes derived from BoNTs and TeTX and discusses their applications in molecular and synaptic biology and neurodevelopmental research. It reviews the principles of the design and production of probes, revisits their applications with advantages and limitations and considers prospects for future improvements. The versatile characteristics of discussed probes and reporters make them an integral part of the expanding toolkit for molecular neuroimaging, promoting the discovery process in neurobiology and translational neurosciences.

A defined heteromeric KV1 channel stabilizes the intrinsic pacemaking and regulates the output of deep cerebellar nuclear neurons to thalamic targets.

The output of the cerebellum to the motor axis of the central nervous system is orchestrated mainly by synaptic inputs and intrinsic pacemaker activity of deep cerebellar nuclear (DCN) projection neurons. Herein, we demonstrate that the soma of these cells is enriched with K(V)1 channels produced by mandatory multi-merization of K(V)1.1, 1.2 α and KV ß2 subunits. Being constitutively active, the K(+) current (IK(V)1) mediated by these channels stabilizes the rate and regulates the temporal precision of self-sustained firing of these neurons. Placed strategically, IK(V)1 provides a powerful counter-balance to prolonged depolarizing inputs, attenuates the rebound excitation, and dampens the membrane potential bi-stability. Somatic location with low activation threshold render IK(V)1 instrumental in voltage-dependent de-coupling of the axon initial segment from the cell body of projection neurons, impeding invasion of back-propagating action potentials into the somato-dendritic compartment. The latter is also demonstrated to secure the dominance of clock-like somatic pacemaking in driving the regenerative firing activity of these neurons, to encode time variant inputs with high fidelity. Through the use of multi-compartmental modelling and retro-axonal labelling, the physiological significance of the described functions for processing and communication of information from the lateral DCN to thalamic relay nuclei is established.

Improved lentiviral transduction of ALS motoneurons in vivo via dual targeting.

Treatment of amyotrophic lateral sclerosis (ALS), a progressive neurodegenerative disease, is hampered by its complex etiology and lack of efficient means for targeted transfer of therapeutics into motoneurons. The objective of this research was engineering of a versatile motoneuron targeting adapter--a full-length atoxic tetanus toxin fused to core-streptavidin (CS-TeTIM)--for retro-axonal transduction of viral vectors; validation of the targeting efficiency of CS-TeTIM in vivo, by expression of green fluorescence protein (GFP) reporter in motoneurons of presymptomatic and symptomatic ALS-like SOD1(G93A) mice, and comparison with age-matched controls; and appraisal of lentiviral transduction with CS-TeTIM relative to (1) a HC binding fragment of tetanus toxin CS-TeTx(HC), (2) rabies glycoprotein (RG), and (3) a CS-TeTIM-RG dual targeting approach. CS-TeTIM and CS-TeTx(HC) were engineered using recombinant technology and site-directed mutagenesis. Biotinylated vectors, pseudotyped with vesicular stomatitis virus glycoprotein (VSV-G) or RG, were linked to these adaptors and injected intraperitoneally (ip) into presymptomatic (12 weeks old), symptomatic SOD1(G93A) (22 weeks old) or wild type control mice, followed by monitoring of GFP expression in the spinal cord and supraspinal motor structures with quantitative PCR and immuno-histochemistry. Transcripts were detected in the spinal cord and supraspinal motor structures of all mice 2 weeks after receiving a single ip injection, although in symptomatic SOD1(G93A) animals reporter RNA levels were lower compared to presymptomatic and wild-type controls irrespective of the targeting approach. GFP transduction with CS-TeTIM proved more efficient than CS-TeTx(HC) across all groups while CS-TeTIM-RG dual-targeted vectors yielded the highest transcript numbers. Importantly, in both wild-type and presymptomatic SOD1(G93A) mice strong colabeling of choline-acetyltransferase (ChAT) and GFP was visualized in neurons of the brain stem and spinal cord. CS-TeTIM, a versatile adaptor protein for targeted lentiviral transduction of motoneurons, has been engineered and its competence assessed relative to CS-TeTx(HC) and RG. Evidence has been provided that highlights the potential usefulness of this novel recombinant tool for basic research with implications for improved transfer of therapeutic candidates into motoneurons for the amelioration of ALS and related diseases.

Ageing perspective on cognitive outcomes from reproductive hormone adjustments.

In addition to primary reproductive functions, gonadal hormones play an important role in an array of neural mechanisms across the human lifespan. The ageing-related decline in their activity has been linked to the deterioration of cognitive functions in otherwise healthy women, associated with menopause transition, contributing to higher incidents of post-menopause dementia. Given the growing utility of gonadal steroids for birth control, as well as for compensatory treatment of menopause and oophorectomy symptoms, and adjuvant transgender therapy, their long-term effects on neural mechanisms warrant comprehensive assessment. In this article, we present an ageing perspective on the cognitive outcomes from contraceptive and replacement therapeutic use of gonadal hormones and discuss their effects on the risk of developing Alzheimer's and Parkinson's dementia. Despite rising data supporting the ameliorative effects of reproductive hormones on cognitive facilities, their impact varies depending on study design and type of intervention, thus, implying dynamic neuro-endocrine interactions with complex compensatory mechanisms. Elucidating differential effects of reproductive hormone adjustments on cognition with underlying mechanisms is expected not only to shed light on important aspects of brain ageing and dementia but to facilitate their use in personalized medicine with improved safety margins and therapeutic outcomes.

Molecular Biomarkers of Neuronal Injury in Epilepsy Shared with Neurodegenerative Diseases.

In neurodegenerative diseases, changes in neuronal proteins in the cerebrospinal fluid and blood are viewed as potential biomarkers of the primary pathology in the central nervous system (CNS). Recent reports suggest, however, that level of neuronal proteins in fluids also alters in several types of epilepsy in various age groups, including children. With increasing evidence supporting clinical and sub-clinical seizures in Alzheimer's disease, Lewy body dementia, Parkinson's disease, and in other less common neurodegenerative conditions, these findings call into question the specificity of neuronal protein response to neurodegenerative process and urge analysis of the effects of concomitant epilepsy and other comorbidities. In this article, we revisit the evidence for alterations in neuronal proteins in the blood and cerebrospinal fluid associated with epilepsy with and without neurodegenerative diseases. We discuss shared and distinctive characteristics of changes in neuronal markers, review their neurobiological mechanisms, and consider the emerging opportunities and challenges for their future research and diagnostic use.

Evaluation of common genetic variants in 82 candidate genes as risk factors for neural tube defects.

BACKGROUND: Neural tube defects (NTDs) are common birth defects (~1 in 1000 pregnancies in the US and Europe) that have complex origins, including environmental and genetic factors. A low level of maternal folate is one well-established risk factor, with maternal periconceptional folic acid supplementation reducing the occurrence of NTD pregnancies by 50-70%. Gene variants in the folate metabolic pathway (e.g., MTHFR rs1801133 (677 C > T) and MTHFD1 rs2236225 (R653Q)) have been found to increase NTD risk. We hypothesized that variants in additional folate/B12 pathway genes contribute to NTD risk. METHODS: A tagSNP approach was used to screen common variation in 82 candidate genes selected from the folate/B12 pathway and NTD mouse models. We initially genotyped polymorphisms in 320 Irish triads (NTD cases and their parents), including 301 cases and 341 Irish controls to perform case-control and family based association tests. Significantly associated polymorphisms were genotyped in a secondary set of 250 families that included 229 cases and 658 controls. The combined results for 1441 SNPs were used in a joint analysis to test for case and maternal effects. RESULTS: Nearly 70 SNPs in 30 genes were found to be associated with NTDs at the p < 0.01 level. The ten strongest association signals (p-value range: 0.0003-0.0023) were found in nine genes (MFTC, CDKN2A, ADA, PEMT, CUBN, GART, DNMT3A, MTHFD1 and T (Brachyury)) and included the known NTD risk factor MTHFD1 R653Q (rs2236225). The single strongest signal was observed in a new candidate, MFTC rs17803441 (OR = 1.61 [1.23-2.08], p = 0.0003 for the minor allele). Though nominally significant, these associations did not remain significant after correction for multiple hypothesis testing. CONCLUSIONS: To our knowledge, with respect to sample size and scope of evaluation of candidate polymorphisms, this is the largest NTD genetic association study reported to date. The scale of the study and the stringency of correction are likely to have contributed to real associations failing to survive correction. We have produced a ranked list of variants with the strongest association signals. Variants in the highest rank of associations are likely to include true associations and should be high priority candidates for further study of NTD risk.

Adult Neurogenesis in the Gut, Homeostatic Autoimmunity and Neurodegenerative Disease Biomarkers.

Autoantibodies to neuronal antigens are viewed as potential biomarkers for neurodegenerative diseases. Increasing evidence, however, suggests a dissociation of the neurodegenerative process in the central nervous system and dynamics of neuronal proteins in peripheral circulation with the prevalence of a wide variety of immunoglobulins reactive to neuronal antigens reported also in the blood of healthy subjects, including children. Recently discovered physiological turnover of neurons in enteric nervous system with release of neuronal proteins in peripheral circulation may account for this conundrum and provide a new perspective on molecular biomarkers of neurodegenerative diseases and immunotherapy.

Integrated phylogeny of the human brain and pathobiology of Alzheimer's disease: A unifying hypothesis.

The disproportionate evolutionary expansion of the human cerebral cortex with reinforcement of cholinergic innervations warranted a major rise in the functional and metabolic load of the conserved basal forebrain (BF) cholinergic system. Given that acetylcholine (ACh) regulates properties of the microtubule-associated protein (MAP) tau and promotes non-amyloidogenic processing of amyloid precursor protein (APP), growing neocortex predicts higher demands for ACh, while the emerging role of BF cholinergic projections in Aß clearance infers greater exposure of source neurons and their innervation fields to amyloid pathology. The higher exposure of evolutionary most recent cortical areas to the amyloid pathology of Alzheimer's disease (AD) with synaptic impairments and atrophy, therefore, might involve attenuated homeostatic effects of BF cholinergic projections, in addition to fall-outs of inherent processes of expanding association areas. This unifying model, thus, views amyloid pathology and loss of cholinergic cells as a quid pro quo of the allometric evolution of the human brain, which in combination with increase in life expectancy overwhelm the fine homeostatic balance and trigger the disease process.

The Ups and Downs of BACE1: Walking a Fine Line between Neurocognitive and Other Psychiatric Symptoms of Alzheimer's Disease.

Although neurocognitive deficit is the best-recognized indicator of Alzheimer's disease (AD), psychotic and other noncognitive symptoms are the prime cause of institutionalization. BACE1 is the rate-limiting enzyme in the production of Aß of AD, and one of the promising therapeutic targets in countering cognitive decline and amyloid pathology. Changes in BACE1 activity have also emerged to cause significant noncognitive neuropsychiatric symptoms and impairments of circadian rhythms, as evident from clinical trials and reports in transgenic models. In this study, we consider key characteristics of BACE1 with its contribution to neurocognitive deficit and other psychiatric symptoms of AD. We argue that a growing list of noncognitive mental impairments related to pharmacological modulation of BACE1 might present a major obstacle in clinical translation of emerging therapeutic leads targeting this protease. The adverse effects of BACE1 inhibition on mental health call for a revision of treatment strategies that assume indiscriminate inhibition of this key protease, and stress the need for further mechanistic and translational studies.

Mainstream psychiatry reinstates therapeutic ventures of the remote past.

The reinstatement and revision of abandoned therapeutic ventures of the past has been an integral part of medical research and advancement. In psychiatry, much interest was generated recently by emerging data on the use of faecal supplements for restoring the neurochemical balance in the brain, and on the ingestion of placenta to stabilize neural circuits disrupted by childbirth-related hormonal changes. Herein, we consider the emerging scientific evidence and socio-cultural prerequisites favouring the re-entry of these heterodox customs, which are reminiscent of widespread instinctive behaviours in wildlife, into modern healthcare. We explore their evolutionary background and adaptive significance, and consider mechanisms of therapeutic benefits. Finally, we reflect on emerging opportunities and challenges, which present clues towards better prevention and treatment of major neuropsychiatric disorders.

Revisiting Brain Tuberous Sclerosis Complex in Rat and Human: Shared Molecular and Cellular Pathology Leads to Distinct Neurophysiological and Behavioral Phenotypes.

Tuberous sclerosis complex (TSC) is a dominant autosomal genetic disorder caused by loss-of-function mutations in TSC1 and TSC2, which lead to constitutive activation of the mammalian target of rapamycin C1 (mTORC1) with its decoupling from regulatory inputs. Because mTORC1 integrates an array of molecular signals controlling protein synthesis and energy metabolism, its unrestrained activation inflates cell growth and division, resulting in the development of benign tumors in the brain and other organs. In humans, brain malformations typically manifest through a range of neuropsychiatric symptoms, among which mental retardation, intellectual disabilities with signs of autism, and refractory seizures, which are the most prominent. TSC in the rat brain presents the first-rate approximation of cellular and molecular pathology of the human brain, showing many instructive characteristics. Nevertheless, the developmental profile and distribution of lesions in the rat brain, with neurophysiological and behavioral manifestation, deviate considerably from humans, raising numerous research and translational questions. In this study, we revisit brain TSC in human and Eker rats to relate their histopathological, electrophysiological, and neurobehavioral characteristics. We discuss shared and distinct aspects of the pathology and consider factors contributing to phenotypic discrepancies. Given the shared genetic cause and molecular pathology, phenotypic deviations suggest an incomplete understanding of the disease. Narrowing the knowledge gap in the future should not only improve the characterization of the TSC rat model but also explain considerable variability in the clinical manifestation of the disease in humans.

Evolutionary origins of chemical synapses.

Synaptic transmission is a fundamental neurobiological process by which neurons interact with each other and non-neuronal cells. It involves release of active substances from the presynaptic neuron onto receptive elements of postsynaptic cells, inducing waves of spreading electrochemical response. While much has been learned about the cellular and molecular mechanisms driving and governing transmitter release and sensing, the evolutionary origin of synaptic connections remains obscure. Herein, we review emerging evidence and concepts suggesting that key components of chemical synapse arose independently from neurons, in different functional and biological contexts, before the rise of multicellular living forms. We argue that throughout evolution, distinct synaptic constituents have been co-opted from ancestral forms for a new role in early metazoan, leading to the rise of chemical synapses and neurotransmission. Such a mosaic model of the origin of chemical synapses agrees with and supports the pluralistic hypothesis of evolutionary change.

Amyloid Plaques of Alzheimer's Disease as Hotspots of Glutamatergic Activity.

Deposition of amyloid plaques in limbic and associative cortices is amongst the most recognized histopathologic hallmarks of Alzheimer's disease. Despite decades of research, there is a lack of consensus over the impact of plaques on neuronal function, with their role in cognitive decline and memory loss undecided. Evidence has emerged suggesting complex and localized axonal pathology around amyloid plaques, with a significant fraction of swellings and dystrophies becoming enriched with putative synaptic vesicles and presynaptic proteins normally colocalized at hotspots of transmitter release. In the absence of hallmark active zone proteins and postsynaptic receptive elements, the axonal swellings surrounding amyloid plaques have been suggested as sites for ectopic release of glutamate, which under reduced clearance can lead to elevated local excitatory drive. Throughout this review, we consider the emerging data suggestive of amyloid plaques as hotspots of compulsive glutamatergic activity. Evidence for local and long-range effects of nonsynaptic glutamate is discussed in the context of circuit dysfunctions and neurodegenerative changes of Alzheimer's disease.

Neurobiology and therapeutic utility of neurotoxins targeting postsynaptic mechanisms of neuromuscular transmission.

The neuromuscular junction (NMJ) is the principal site for the translation of motor neurochemical signals to muscle activity. Therefore, the release and sensing machinery of acetylcholine (ACh) along with muscle contraction are two of the main targets of natural toxins and pathogens, causing paralysis. Given pharmacology and medical advances, the active ingredients of toxins that target postsynaptic mechanisms have become of major interest, showing promise as drug leads. Herein, we review key facets of prevalent toxins modulating the mechanisms of ACh sensing and generation of the postsynaptic response, with muscle contraction. We consider the correlation between their outstanding selectivity and potency plus effects on motor function, and discuss emerging data advocating their usage for the development of therapies alleviating neuromuscular dysfunction.

Neurobiology and therapeutic applications of neurotoxins targeting transmitter release.

Synaptic transmission is a fundamental neurobiological process enabling exchange of signals between neurons as well as neurons and their non-neuronal effectors. The complex molecular machinery of the synaptic vesicle cycle and transmitter release has emerged and developed in the course of the evolutionary race, to ensure adaptive gain and survival of the fittest. In parallel, a generous arsenal of biomolecules and neuroactive peptides have co-evolved, which selectively target the transmitter release machinery, with the aim of subduing natural rivals or neutralizing prey. With advances in neuropharmacology and quantitative biology, neurotoxins targeting presynaptic mechanisms have attracted major interest, revealing considerable potential as carriers of molecular cargo and probes for meddling synaptic transmission mechanisms for research and medical benefit. In this review, we investigate and discuss key facets employed by the most prominent bacterial and animal toxins targeting the presynaptic secretory machinery. We explore the cellular basis and molecular grounds for their tremendous potency and selectivity, with effects on a wide range of neural functions. Finally, we consider the emerging preclinical and clinical data advocating the use of active ingredients of neurotoxins for the advancement of molecular medicine and development of restorative therapies.

Spatial and Spectral Mapping and Decomposition of Neural Dynamics and Organization of the Mouse Brain with Multispectral Optoacoustic Tomography.

In traditional optical imaging, limited light penetration constrains high-resolution interrogation to tissue surfaces. Optoacoustic imaging combines the superb contrast of optical imaging with deep penetration of ultrasound, enabling a range of new applications. We used multispectral optoacoustic tomography (MSOT) for functional and structural neuroimaging in mice at resolution, depth, and specificity unattainable by other neuroimaging modalities. Based on multispectral readouts, we computed hemoglobin gradient and oxygen saturation changes related to processing of somatosensory signals in different structures along the entire subcortical-cortical axis. Using temporal correlation analysis and seed-based maps, we reveal the connectivity between cortical, thalamic, and sub-thalamic formations. With the same modality, high-resolution structural tomography of intact mouse brain was achieved based on endogenous contrasts, demonstrating near-perfect matches with anatomical features revealed by histology. These results extend the limits of noninvasive observations beyond the reach of standard high-resolution neuroimaging, verifying the suitability of MSOT for small-animal studies.