The Key Role of the Amygdala in Stress

Several data highlighted that stress exposure is strongly associated with several psychiatric disorders. The amygdala, an area of the brain that contributes to emotional processing, has a pivotal role in psychiatric disorders and it has been demonstrated to be highly responsive to stressful events. Here we will review evidences indicating how the amygdala changes its functionality following exposure to stress and how this contributes to the onset of anxiety disorders

eEF1Bγ binds the Che-1 and TP53 gene promoters and their transcripts

Background: We have previously shown that the eukaryotic elongation factor subunit 1B gamma (eEF1Bγ) interacts with the RNA polymerase II (pol II) alpha-like subunit “C” (POLR2C), alone or complexed, in the pol II enzyme. Moreover, we demonstrated that eEF1Bγ binds the promoter region and the 3’ UTR mRNA of the vimentin gene. These events contribute to localize the vimentin transcript and consequentially its translation, promoting a proper mitochondrial network. Methods: With the intent of identifying additional transcripts that complex with the eEF1Bγ protein, we performed a series of ribonucleoprotein immunoprecipitation (RIP) assays using a mitochondria-enriched heavy membrane (HM) fraction. Results: Among the eEF1Bγ complexed transcripts, we found the mRNA encoding the Che-1/AATF multifunctional protein. As reported by other research groups, we found the tumor suppressor p53 transcript complexed with the eEF1Bγ protein. Here, we show for the first time that eEF1Bγ binds not only Che-1 and p53 transcripts but also their promoters. Remarkably, we demonstrate that both the Che-1 transcript and its translated product localize also to the mitochondria and that eEF1Bγ depletion strongly perturbs the mitochondrial network and the correct localization of Che-1. In a doxorubicin (Dox)-induced DNA damage assay we show that eEF1Bγ depletion significantly decreases p53 protein accumulation and slightly impacts on Che-1 accumulation. Importantly, Che-1 and p53 proteins are components of the DNA damage response machinery that maintains genome integrity and prevents tumorigenesis. Conclusions: Our data support the notion that eEF1Bγ, besides its canonical role in translation, is an RNA-binding protein and a key player in cellular stress responses. We suggest for eEF1Bγ a role as primordial transcription/translation factor that links fundamental steps from transcription control to local translatio

Correction to: MicroRNA-34 Contributes to the Stress-related Behavior and Affects 5-HT Prefrontal/GABA Amygdalar System through Regulation of Corticotropin-releasing Factor Receptor 1

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transient upregulation of translational efficiency in prodromal and early symptomatic tg2576 mice contributes to aβ pathology

Abstract Tg2576 mice show high levels of human APP protein with Swedish Mutation during prodromal and early symptomatic stages. Interestingly, this is strictly associated with unbalanced expression of its two RNA binding proteins (RBPs) regulators, the Fragile-X Mental Retardation Protein (FMRP) and the heteronuclear Ribonucleoprotein C (hnRNP C). Whether an augmentation in overall translational efficiency also contributes to the elevation of APP levels at those early developmental stages is currently unknown. We investigated this possibility by performing a longitudinal polyribosome profiling analysis of APP mRNA and protein in total hippocampal extracts from Tg2576 mice. Results showed that protein polysomal signals were exclusively detected in pre-symptomatic (1 months) and early symptomatic (3 months) mutant mice. Differently, hAPP mRNA polysomal signals were detected at any age, but a peak of expression was found when mice were 3-month old. Consistent with an early but transient rise of translational efficiency, the phosphorylated form of the initial translation factor eIF2α (p-eIF2α) was reduced at pre-symptomatic and early symptomatic stages, whereas it was increased at the fully symptomatic stage. Pharmacological downregulation of overall translation in early symptomatic mutants was then found to reduce hippocampal levels of full length APP, Aβ species, BACE1 and Caspase-3, to rescue predominant LTD at hippocampal synapses, to revert dendritic spine loss and memory alterations, and to reinstate memory-induced c-fos activation. Altogether, our findings demonstrate that overall translation is upregulated in prodromal and early symptomatic Tg2576 mice, and that restoring proper translational control at the onset of AD-like symptoms blocks the emergence of the AD-like phenotype

NGF-Dependent Changes in Ubiquitin Homeostasis Trigger Early Cholinergic Degeneration in Cellular and Animal AD-Model

Basal forebrain cholinergic neurons (BFCNs) depend on nerve growth factor (NGF) for their survival/differentiation and innervate cortical and hippocampal regions involved in memory/learning processes. Cholinergic hypofunction and/or degeneration early occurs at prodromal stages of Alzheimer’s disease (AD) neuropathology in correlation with synaptic damages, cognitive decline and behavioral disability. Alteration(s) in ubiquitin-proteasome system (UPS) is also a pivotal AD hallmark but whether it plays a causative, or only a secondary role, in early synaptic failure associated with disease onset remains unclear. We previously reported that impairment of NGF/TrkA signaling pathway in cholinergic-enriched septo-hippocampal primary neurons triggers “dying-back” degenerative processes which occur prior to cell death in concomitance with loss of specific vesicle trafficking proteins, including synapsin I, SNAP-25 and α-synuclein, and with deficit in presynaptic excitatory neurotransmission. Here, we show that in this in vitro neuronal model: (i) UPS stimulation early occurs following neurotrophin starvation (-1 h up to -6 h); (ii) NGF controls the steady-state levels of these three presynaptic proteins by acting on coordinate mechanism(s) of dynamic ubiquitin-C-terminal hydrolase 1 (UCHL-1)-dependent (mono)ubiquitin turnover and UPS-mediated protein degradation. Importantly, changes in miniature excitatory post-synaptic currents (mEPSCs) frequency detected in -6 h NGF-deprived primary neurons are strongly reverted by acute inhibition of UPS and UCHL-1, indicating that NGF tightly controls in vitro the presynaptic efficacy via ubiquitination-mediated pathway(s). Finally, changes in synaptic ubiquitin and selective reduction of presynaptic markers are also found in vivo in cholinergic nerve terminals from hippocampi of transgenic Tg2576 AD mice, even from presymptomatic stages of neuropathology (1-month-old). By demonstrating a crucial role of UPS in the dysregulation of NGF/TrkA signaling on properties of cholinergic synapses, these findings from two well-established cellular and animal AD models provide novel therapeutic targets to contrast early cognitive and synaptic dysfunction associated to selective degeneration of BFCNs occurring in incipient early/middle-stage of disease

Passive immunotherapy for N-truncated tau ameliorates the cognitive deficits in two mouse Alzheimer's disease models

Abstract Clinical and neuropathological studies have shown that tau pathology better correlates with the severity of dementia than amyloid plaque burden, making tau an attractive target for the cure of Alzheimer's disease. We have explored whether passive immunization with the 12A12 monoclonal antibody (26–36aa of tau protein) could improve the Alzheimer's disease phenotype of two well-established mouse models, Tg2576 and 3xTg mice. 12A12 is a cleavage-specific monoclonal antibody which selectively binds the pathologically relevant neurotoxic NH226-230 fragment (i.e. NH2htau) of tau protein without cross-reacting with its full-length physiological form(s). We found out that intravenous administration of 12A12 monoclonal antibody into symptomatic (6 months old) animals: (i) reaches the hippocampus in its biologically active (antigen-binding competent) form and successfully neutralizes its target; (ii) reduces both pathological tau and amyloid precursor protein/amyloidβ metabolisms involved in early disease-associated synaptic deterioration; (iii) improves episodic-like type of learning/memory skills in hippocampal-based novel object recognition and object place recognition behavioural tasks; (iv) restores the specific up-regulation of the activity-regulated cytoskeleton-associated protein involved in consolidation of experience-dependent synaptic plasticity; (v) relieves the loss of dendritic spine connectivity in pyramidal hippocampal CA1 neurons; (vi) rescues the Alzheimer's disease-related electrophysiological deficits in hippocampal long-term potentiation at the CA3-CA1 synapses; and (vii) mitigates the neuroinflammatory response (reactive gliosis). These findings indicate that the 20–22 kDa NH2-terminal tau fragment is crucial target for Alzheimer's disease therapy and prospect immunotherapy with 12A12 monoclonal antibody as safe (normal tau-preserving), beneficial approach in contrasting the early Amyloidβ-dependent and independent neuropathological and cognitive alterations in affected subjects

Studio clinico e molecolare di forme autosomiche recessive di paraparesi spastica ereditaria

Le paraparesi spastiche ereditarie (HSP) sono un gruppo di disordini neurodegenerativi clinicamente e geneticamente eterogeneo, che hanno come fattore comune il danneggiamento dei motoneuroni superiori e delle loro proiezioni assonali. Sulla base del meccanismo di trasmissione genetica le HSP possono essere classificate in autosomiche dominanti (ADHSP), autosomiche recessive (ARHSP) o X-linked. Dal punto di vista clinico, invece, le HSP possono essere suddivise in forme pure e complicate in base alla presenza o meno di sintomi neurologici o non neurologici associati alla spasticità. Il progetto di ricerca svolto prevede tra gli obiettivi l’analisi genetico-molecolare di famiglie affette da una forma complicata di ARHSP con assottigliamento del corpo calloso (ARHSPTCC); famiglie affette da una forma pura di ARHSP e casi apparentemente sporadici puri e complicati. Il gene più frequentemente mutato nei casi di ARHSP-TCC è SPG11 che codifica per la spatacsina, mentre i due geni più comunemente studiati per le forme ARHSP pure e complicate sono SPG5A e SPG7. Lo studio dei casi ARHSP con TCC è stato condotto mediante analisi di linkage. Il successivo screening genetico-molecolare delle famiglie in linkage con il locus SPG11 è stato messo a punto con l’ausilio dell’ High Resolution Melting (HRM), la Conformation Sensitive Capillary Elettrophoresis (CSCE) e del sequenziamento diretto. L’utilizzo di queste tecniche è stato richiesto anche per lo screening genetico-molecolare delle forme pure e complicate di famiglie e casi sporadici ARHSP. Pertanto, è stato condotto uno studio di linkage su 14 famiglie ARHSP-TCC al fine di identificare un’eventuale associazione tra la malattia e il locus SPG11. L’ analisi ha evidenziato 5 famiglie in linkage per SPG11. Il successivo screening dei 40 esoni del gene sui probandi di tali famiglie ha rivelato 5 di mutazioni nel DNA dei pazienti di cui tre riportate in letteratura. In seguito, le restanti famiglie ARHSP e i casi apparentemente sporadici sono stati analizzati per i geni SPG7 e SPG5A. I probandi di due famiglie ARHSP, di cui uno complicato da TCC, sono risultati positivi allo screening mutazionale del gene SPG5A; le due mutazioni identificate ad oggi non sono ancora riportate in letteratura. Contrariamente, l’indagine per il gene SPG7 non ha evidenziato mutazioni patogenetiche, ma solo polimorfismi gia’ noti in letteratura. I risultati di questa tesi confermano dati di letteratura secondo i quali il gene SPG7 risulta poco frequente come causa di ARHSP; mentre, il gene SPG5A ed SPG11 mostrano una frequenza mutazionale più elevata rispettivamente per le forme ARHSP (pure e complicate) e per le ARHSP-TCC (7% e 28%).Hereditary spastic paraplegias (HSP) are a clinically and genetically heterogeneous group of neurodegenative disorders. The predominant symptom of HSP is the degeneration of upper motoneurons and their corticospinal tract axons. They are classified genetically into autosomal dominant (ADHSP), autosomal recessive (ARHSP), and X-linked HSP forms. The clinical classification may distinguish between pure and complicated forms of HSP based on the presence of neurological or non neurological symptoms associated to spasticity. This study aims at genetic-molecular investigation of families affected by a complicated form of ARHSP with thin corpus callosum (ARHSP-TCC), families affected by a pure form of ARHSP, and apparently sporadic cases. The study of the ARHSP cases with TCC was carried out by linkage analysis. The next geneticmolecular screening of families in linkage with SPG11 locus was based on HRM, CSCE, and direct sequencing techniques. These techniques was also used for the screening of pure and complicated forms and apparently sporadic cases of HSP. In particular we performed a linkage study on 14 ARHSP-TCC families to identify a probably association between HSP and the SPG11 locus. The analysis revealed 5 pedigrees in linkage with SPG11. The next screening of 40 exons of the SPG11 gene on probands of the families revealed 5 mutations; three of these mutations were just reported in literature. After that, the remaining families with ARHSP and the apparently sporadic cases were analyzed for SPG7 and SPG5A genes. Two probands of the families, one of which complicated by TCC, were positive to mutational screening of the gene SPG5A; two identified mutations were novel. On the other hand, the SPG7 analysis has not revealed patogenetic mutations, but only polymorphisms reported in literature. These results confirm data observed in literature according to which the SPG7 gene is not a frequent cause of ARHSP while the SPG5A and SPG11 genes show an high mutational frequency in ARHSP and ARHSP-TCC (respectively 7% and 28%)

FMRP-Driven Neuropathology in Autistic Spectrum Disorder and Alzheimer’s disease: A Losing Game

International audienceFragile X mental retardation protein (FMRP) is an RNA binding protein (RBP) whose absence is essentially associated to Fragile X Syndrome (FXS). As an RNA Binding Protein (RBP), FMRP is able to bind and recognize different RNA structures and the control of specific mRNAs is important for neuronal synaptic plasticity. Perturbations of this pathway have been associated with the autistic spectrum. One of the FMRP partners is the APP mRNA, the main protagonist of Alzheimer’s disease (AD), thereby regulating its protein level and metabolism. Therefore FMRP is associated to two neurodevelopmental and age-related degenerative conditions, respectively FXS and AD. Although these pathologies are characterized by different features, they have been reported to share a number of common molecular and cellular players. The aim of this review is to describe the double-edged sword of FMRP in autism and AD, possibly allowing the elucidation of key shared underlying mechanisms and neuronal circuits. As an RBP, FMRP is able to regulate APP expression promoting the production of amyloid β fragments. Indeed, FXS patients show an increase of amyloid β load, typical of other neurological disorders, such as AD, Down syndrome, Parkinson’s Disease, etc. Beyond APP dysmetabolism, the two neurodegenerative conditions share molecular targets, brain circuits and related cognitive deficits. In this review, we will point out the potential common neuropathological pattern which needs to be addressed and we will hopefully contribute to clarifying the complex phenotype of these two neurorological disorders, in order to pave the way for a novel, common disease-modifying therapy