Synaptic and transcriptomic features of cortical and amygdala pyramidal neurons predict inefficient fear extinction

Fear-related disorders arise from inefficient fear extinction and have immeasurable social and economic costs. Here, we characterize mouse phenotypes that spontaneously show fear-independent behavioral traits predicting adaptive or maladaptive fear extinction. We find that, already before fear conditioning, specific morphological, electrophysiological, and transcriptomic patterns of cortical and amygdala pyramidal neurons predispose to fear-related disorders. Finally, by using an optogenetic approach, we show the possibility to rescue inefficient fear extinction by activating infralimbic pyramidal neurons and to impair fear extinction by activating prelimbic pyramidal neurons.

Optogenetic Stimulation of Prelimbic Pyramidal Neurons Maintains Fear Memories and Modulates Amygdala Pyramidal Neuron Transcriptome

Fear extinction requires coordinated neural activity within the amygdala and medial prefrontal cortex (mPFC). Any behavior has a transcriptomic signature that is modified by environmental experiences, and specific genes are involved in functional plasticity and synaptic wiring during fear extinction. Here, we investigated the effects of optogenetic manipulations of prelimbic (PrL) pyramidal neurons and amygdala gene expression to analyze the specific transcriptional pathways associated to adaptive and maladaptive fear extinction. To this aim, transgenic mice were (or not) fear-conditioned and during the extinction phase they received optogenetic (or sham) stimulations over photo-activable PrL pyramidal neurons. At the end of behavioral testing, electrophysiological (neural cellular excitability and Excitatory Post-Synaptic Currents) and morphological (spinogenesis) correlates were evaluated in the PrL pyramidal neurons. Furthermore, transcriptomic cell-specific RNA-analyses (differential gene expression profiling and functional enrichment analyses) were performed in amygdala pyramidal neurons. Our results show that the optogenetic activation of PrL pyramidal neurons in fear-conditioned mice induces fear extinction deficits, reflected in an increase of cellular excitability, excitatory neurotransmission, and spinogenesis of PrL pyramidal neurons, and associated to strong modifications of the transcriptome of amygdala pyramidal neurons. Understanding the electrophysiological, morphological, and transcriptomic architecture of fear extinction may facilitate the comprehension of fear-related disorders.

Ring Finger Protein 11 acts on ligand-activated EGFR via the direct interaction with the UIM region of ANKRD13 protein family

RING finger protein 11 (RNF11) is an evolutionary conserved Really Interesting New Gene E3 ligase that is overexpressed in several human tumours. Although several reports have highlighted its involvement in crucial cellular processes, the mechanistic details underlying its function are still poorly understood. Utilizing stable isotope labelling by amino acids in culture (SILAC)-based proteomics analysis, we identified 51 proteins that co-immunoprecipitate with wild-type RNF11 and/or with its catalytically inactive mutant. We focused our attention on the interaction of RNF11 with Ankyrin repeat domain-containing protein 13 (ANKRD13)s family. Members of the ANKRD13 family contain ubiquitin-interacting motifs (UIM) that recognize the Lys-63-linked ubiquitin (Ub) chains appended to Epidermal growth factor receptor (EGFR) soon after ligand binding. We show that ANKRD13A, ANKRD13B and ANKRD13D form a complex with RNF11 in vivo and that the UIMs are required for complex formation. However, at odds with the conventional UIM binding mode, Ub modification of RNF11 is not required for the interaction with ANKRD13 proteins. We also show that the interaction between ANKRD13A and RNF11 is modulated by the EGF stimulus and that a complex formed by ANKRD13A, RNF11 and activated EGFR is transiently assembled in the early phases of receptor endocytosis. Moreover, loss of function of the E3 ligases Itchy E3 ubiquitin-protein ligase (ITCH) or RNF11, respectively, abrogates or increases the ubiquitination of endogenous ANKRD13A, affecting its ability to bind activated EGFR. We propose a model whereby the ANKRD13 proteins act as molecular scaffolds that promote the transient formation of a complex between the activated EGFR and the E3 ligases ITCH and RNF11. By regulating the ubiquitination status of ANKRD13A and consequently its endocytic adaptor function, RNF11 promotes sorting of the activated EGFR for lysosomal degradation.

CoCUN, a Novel Ubiquitin Binding Domain Identified in N4BP1

Ubiquitin binding domains (UBDs) are modular elements that bind non-covalently to ubiquitin and act as downstream effectors and amplifiers of the ubiquitination signal. With few exceptions, UBDs recognize the hydrophobic path centered on Ile44, including residues Leu8, Ile44, His68, and Val70. A variety of different orientations, which can be attributed to specific contacts between each UBD and surface residues surrounding the hydrophobic patch, specify how each class of UBD specifically contacts ubiquitin. Here, we describe the structural model of a novel ubiquitin-binding domain that we identified in NEDD4 binding protein 1 (N4BP1). By performing protein sequence analysis, mutagenesis, and nuclear magnetic resonance (NMR) spectroscopy of the ¹⁵N isotopically labeled protein, we demonstrate that a Phe-Pro motif in N4BP1 recognizes the canonical hydrophobic patch of ubiquitin. This recognition mode resembles the molecular mechanism evolved in the coupling of ubiquitin conjugation to endoplasmic-reticulum (ER) degradation (CUE) domain family, where an invariant proline, usually following a phenylalanine, is required for ubiquitin binding. Interestingly, this novel UBD, which is not evolutionary related to CUE domains, shares a 40% identity and 47% similarity with cullin binding domain associating with NEDD8 (CUBAN), a protein module that also recognizes the ubiquitin-like NEDD8. Based on these features, we dubbed the region spanning the C-terminal 50 residues of N4BP1 the CoCUN domain, for Cousin of CUBAN. By performing circular dichroism and ¹⁵N NMR chemical shift perturbation of N4BP1 in complex with ubiquitin, we demonstrate that the CoCUN domain lacks the NEDD8 binding properties observed in CUBAN. We also show that, in addition to mediating the interaction with ubiquitin and ubiquitinated substrates, both CUBAN and CoCUN are poly-ubiquitinated in cells. The structural and the functional characterization of this novel UBD can contribute to a deeper understanding of the molecular mechanisms governing N4BP1 function, providing at the same time a valuable tool for clarifying how the discrimination between ubiquitin and the highly related NEDD8 is achieved.

Selectivity of the CUBAN domain in the recognition of ubiquitin and NEDD8

Among the members of the ubiquitin-like (Ubl) protein family, neural precursor cell expressed developmentally down-regulated protein 8 (NEDD8) is the closest in sequence to ubiquitin (57% identity). The two modification mechanisms and their functions, however, are highly distinct and the two Ubls are not interchangeable. A complex network of interactions between modifying enzymes and adaptors, most of which are specific while others are promiscuous, ensures selectivity. Many domains that bind the ubiquitin hydrophobic patch also bind NEDD8 while no domain that specifically binds NEDD8 has yet been described. Here, we report an unbiased selection of domains that bind ubiquitin and/or NEDD8 and we characterize their specificity/promiscuity. Many ubiquitin-binding domains bind ubiquitin preferentially and, to a lesser extent, NEDD8. In a few cases, the affinity of these domains for NEDD8 can be increased by substituting the alanine at position 72 with arginine, as in ubiquitin. We have also identified a unique domain, mapping to the carboxyl end of the protein KHNYN, which has a stark preference for NEDD8. Given its ability to bind neddylated cullins, we have named this domain CUBAN (Cullin-Binding domain Associating with NEDD8). We present here the solution structure of the CUBAN domain both in the isolated form and in complex with NEDD8. The results contribute to the understanding of the discrimination mechanism between ubiquitin and the Ubl. They also provide new insights on the biological role of a ill-defined protein, whose function is hitherto only predicted.

SIGNOR: a database of causal relationships between biological entities

Assembly of large biochemical networks can be achieved by confronting new cell-specific experimental data with an interaction subspace constrained by prior literature evidence. The SIGnaling Network Open Resource, SIGNOR (available on line at http://signor.uniroma2.it), was developed to support such a strategy by providing a scaffold of prior experimental evidence of causal relationships between biological entities. The core of SIGNOR is a collection of approximately 12,000 manually-annotated causal relationships between over 2800 human proteins participating in signal transduction. Other entities annotated in SIGNOR are complexes, chemicals, phenotypes and stimuli. The information captured in SIGNOR can be represented as a signed directed graph illustrating the activation/inactivation relationships between signalling entities. Each entry is associated to the post-translational modifications that cause the activation/inactivation of the target proteins. More than 4900 modified residues causing a change in protein concentration or activity have been curated and linked to the modifying enzymes (about 351 human kinases and 94 phosphatases). Additional modifications such as ubiquitinations, sumoylations, acetylations and their effect on the modified target proteins are also annotated. This wealth of structured information can support experimental approaches based on multi-parametric analysis of cell systems after physiological or pathological perturbations and to assemble large logic models.

Production of brain-derived neurotrophic factor by mononuclear cells of patients with multiple sclerosis treated with glatiramer acetate, interferon-beta 1a, and high doses of immunoglobulins

Sixty, relapsing remitting (RR) multiple sclerosis (MS) patients, who underwent treatment with glatiramer acetate (GA), interferon (IFN)-beta 1a, and immunoglobulins (Igs) (20 per treatment group), were assessed for levels of brain-derived neurotrophic factor (BDNF) in the supernatants of unstimulated and stimulated peripheral blood mononuclear cells (PBMCs) in the first year of treatment. Phytohemagglutinin (PHA), anti-OKT3 antibody, myelin basic protein (MPB) and GA were used as stimuli. Cytokine responses by ELISPOT and lymphoproliferative responses were also assessed. The GA-treated MS patient group showed a progressive increase in BDNF levels, from baseline to month three; thereafter, the levels remained stable and significantly greater compared with baseline and controls (ANOVA=P<0.001). IFN-beta 1a had no effect on BDNF production, whereas Igs induced a slight decrease (ANOVA=P<0.04). ELISPOT analysis revealed a significant decrease of IFN-gamma, an increase of interleukin (IL)-4 and IL-5 in GA-treated MS patients, and an increase of IL-10 in patients treated with IFN-beta 1a and GA. No significant correlation was found between BDNF secretion in the supernatants of PBMCs and cytokine response, lesional load, and measures of atrophy. Increased BDNF production related to GA treatment can have implications for understanding the mechanism of action of this immunomodulatory agent, in light of evidence suggesting its effects in promoting neuroprotective immunity in MS patients; however, a clinically measurable effect, especially in terms of an impact on actual disease progression, remains to be established.

Delayed loss of residual hearing in Clarion® cochlear implant users

Hearing threshold has been measured in a group of patients following cochlear implantation with a Clarion® device for the last eight years. The patients had received either a pre-curved carrier or the Hi-Focus I plus Electrode Positioner System (EPS). The assessment was carried out within the first post-operative week as well as at a later stage, between six and 87 months, post-operatively. Residual hearing thresholds were still measurable early after surgery in 24.5 per cent of the patients, without differences between the two different Clarion® models. However, the number of subjects with measurable hearing dropped to 16.3 per cent as observed when hearing was measured at a later stage, with an equal distribution between the two groups of patients. From this study it has been possible to observe that only a limited number of patients maintain residual hearing after Clarion® cochlear implantation, and that this tends to decrease further over time. Nevertheless, the performance of these patients for speech tests did not appear to be affected by deterioration of the pure-tone auditory threshold.

The role of neuroimaging in the diagnosis of headache in childhood and adolescence: a multicentre study

Following the diagnostic indications of the Guidelines for the diagnosis and therapy of juvenile headache, we present the results of a prospective, multicentre study of headache patients aimed at evaluating the utility of neuroradiologic testing in the diagnosis of headache. A total of 6535 subjects up to age 18 were studied, and 1485 underwent neuroimaging testing based on the indications of the diagnostic Flow-Chart. Abnormal results were observed in 273 (18.5%) subjects. Incidental findings were observed in 138 (9.3%) subjects, not correlated with the headache pathology, whereas alterations that led to the diagnosis of secondary headache were observed in 135 (9.1%) subjects. In conclusion, our data support a greater incidence of positive neuroimaging examinations among patients who underwent testing based on suspicion of a secondary headache pathology when compared with the low percentages observed in study populations.

[Ethical problems in dialysis in elderly patients]

The incidence and prevalence of elderly patients are progressively increasing in most dialysis facilities with consequent medical assistance difficulties and the need to find a suitable care unit. Particularly in this age group, the clinical assessment is often difficult and the selection criteria vary widely, not only from country to country, but also from one dialysis unit to another unit in the same area. The authors discuss some of the more complex arguments for and against dialysis in elderly patients. For some of the more difficult cases, Kantian deontology and its three ethical principles of beneficence, non-maleficence and autonomy can facilitate the decision-making process regarding the acceptance or refusal of the therapy. The central role of the patients themselves, the involvement of the family, the discussion of the individual case within the dialysis team, and the good performance of the pre-dialysis program are particularly important. In certain cases it is possible to actually discontinue the treatment, or not initiate it, by using different arguments in competent or incompetent patients. In conclusion, the difficult choice of whether to treat or turn down an elderly patient must depend exclusively on the medical clinical assessment of each case, whereas economical considerations can incorrectly influence that choice.

Auditory evoked potentials for the assessment of noise induced hearing loss

As it has been demonstrated in many animal experiments, noise can damage the cochlea and the central auditory pathways. It is very difficult in clinical studies to separate the relative contribution of both these sites. Auditory evoked potentials ABR, MLR and SVR study retrocochlear nervous conduction and collectively the results of these techniques proved an objective evaluation of the cochlear function. The Authors have studied a group of 130 sport shooters with high frequency hearing loss and found that in 38 ears a clear retrocochlear component could be recognised. Correlation with intensity, frequency and length of exposure to the traumatic noise demonstrates that explosive noise is an agent for NIHL. However athletes exposed to similar noises did not suffer from similar hearing loss, probably because of the well known individual noise susceptibility.