The ADNP Derived Peptide,NAP Modulates the Tubulin Pool: Implication for Neurotrophic and Neuroprotective Activities

Microtubules (MTs), key cytoskeletal elements in living cells, are critical for axonal transport, synaptic transmission, and maintenance of neuronal morphology. NAP (NAPVSIPQ) is a neuroprotective peptide derived from the essential activity-dependent neuroprotective protein (ADNP). In Alzheimer’s disease models, NAP protects against tauopathy and cognitive decline. Here, we show that NAP treatment significantly affected the alpha tubulin tyrosination cycle in the neuronal differentiation model, rat pheochromocytoma (PC12) and in rat cortical astrocytes. The effect on tubulin tyrosination/detyrosination was coupled to increased MT network area (measured in PC12 cells), which is directly related to neurite outgrowth. Tubulin beta3, a marker for neurite outgrowth/neuronal differentiation significantly increased after NAP treatment. In rat cortical neurons, NAP doubled the area of dynamic MT invasion (Tyr-tubulin) into the neuronal growth cone periphery. NAP was previously shown to protect against zinc-induced MT/neurite destruction and neuronal death, here, in PC12 cells, NAP treatment reversed zinc-decreased tau-tubulin-MT interaction and protected against death. NAP effects on the MT pool, coupled with increased tau engagement on compromised MTs imply an important role in neuronal plasticity, protecting against free tau accumulation leading to tauopathy. With tauopathy representing a major pathological hallmark in Alzheimer''s disease and related disorders, the current findings provide a mechanistic basis for further development. NAP (davunetide) is in phase 2/3 clinical trial in progressive supranuclear palsy, a disease presenting MT deficiency and tau pathology.     

Novel systemically active galanin receptor 2 ligands in depression‐like behavior

Neuropeptide galanin and its three G‐protein coupled receptors, galanin receptor type 1–galanin receptor type 3 (GalR1–GalR3), are involved in the regulation of numerous physiological and disease processes, and thus represent tremendous potential in neuroscience research and novel drug lead development. One of the areas where galanin is involved is depression. Previous studies have suggested that activation of GalR2 leads to attenuation of depression‐like behavior. Unfortunately, lack of in vivo usable subtype specific ligands hinders testing the role of galanin in depression mechanisms. In this article, we utilize an approach of increasing in vivo usability of peptide‐based ligands, acting upon CNS. Thus, we have synthesized a series of novel systemically active galanin analogs, with modest preferential binding toward GalR2. We have shown that specific chemical modifications to the galanin backbone increase brain levels upon i.v. injection of the peptides. Several of the new peptides, similar to a common clinically used antidepressant medication imipramine, exerted antidepressant‐like effect in forced swim test, a mouse model of depression, at a surprisingly low dose range (< 0.5 mg/kg). We chose one of the peptides, J18, for more thorough study, and showed its efficacy also in another mouse depression model (tail suspension test), and demonstrated that its antidepressant‐like effect upon i.v. administration can be blocked by i.c.v. galanin receptor antagonist M35. The effect of the J18 was also abolished in GalR2KO animals. All this suggests that systemically administered peptide analog J18 exerts its biological effect through activation of GalR2 in the brain. The novel galanin analogs represent potential drug leads and a novel pharmaceutical intervention for depression.

     

Role of the type 2 iodothyronine deiodinase (D2) in the control of thyroid hormone signaling

Background

Thyroid hormone signaling is critical for development, growth and metabolic control in vertebrates. Although serum concentration of thyroid hormone is remarkable stable, deiodinases modulate thyroid hormone signaling on a time- and cell-specific fashion by controlling the activation and inactivation of thyroid hormone.

Scope of the review

This review covers the recent advances in D2 biology, a member of the iodothyronine deiodinase family, thioredoxin fold‐containing selenoenzymes that modify thyroid hormone signaling in a time- and cell-specific manner.

Major conclusions

D2-catalyzed T3 production increases thyroid hormone signaling whereas blocking D2 activity or disruption of the Dio2 gene leads to a state of localized hypothyroidism. D2 expression is regulated by different developmental, metabolic or environmental cues such as the hedgehog pathway, the adrenergic- and the TGR5-activated cAMP pathway, by xenobiotic molecules such as flavonols and by stress in the endoplasmic reticulum, which specifically reduces de novo synthesis of D2 via an eIF2a-mediated mechanism. Thus, D2 plays a central role in important physiological processes such as determining T3 content in developing tissues and in the adult brain, and promoting adaptive thermogenesis in brown adipose tissue. Notably, D2 is critical in the T4-mediated negative feed-back at the pituitary and hypothalamic levels, whereby T4 inhibits TSH and TRH expression, respectively. Notably, ubiquitination is a major step in the control of D2 activity, whereby T4 binding to and/or T4 catalysis triggers D2 inactivation by ubiquitination that is mediated by the E3 ubiquitin ligases WSB-1 and/or TEB4. Ubiquitinated D2 can be either targeted to proteasomal degradation or reactivated by deubiquitination, a process that is mediated by the deubiquitinases USP20/33 and is important in adaptive thermogenesis.

General significance

Here we review the recent advances in the understanding of D2 biology focusing on the mechanisms that regulate its expression and their biological significance in metabolically relevant tissues. This article is part of a Special Issue entitled Thyroid hormone signalling.     

Development and application of a DNA microarray-based yeast two-hybrid system

The yeast two-hybrid (Y2H) system is the most widely applied methodology for systematic protein–protein interaction (PPI) screening and the generation of comprehensive interaction networks. We developed a novel Y2H interaction screening procedure using DNA microarrays for high-throughput quantitative PPI detection. Applying a global pooling and selection scheme to a large collection of human open reading frames, proof-of-principle Y2H interaction screens were performed for the human neurodegenerative disease proteins huntingtin and ataxin-1. Using systematic controls for unspecific Y2H results and quantitative benchmarking, we identified and scored a large number of known and novel partner proteins for both huntingtin and ataxin-1. Moreover, we show that this parallelized screening procedure and the global inspection of Y2H interaction data are uniquely suited to define specific PPI patterns and their alteration by disease-causing mutations in huntingtin and ataxin-1. This approach takes advantage of the specificity and flexibility of DNA microarrays and of the existence of solid-related statistical methods for the analysis of DNA microarray data, and allows a quantitative approach toward interaction screens in human and in model organisms.     

A genetic basis for mechanosensory traits in humans

In all vertebrates hearing and touch represent two distinct sensory systems that both rely on the transformation of mechanical force into electrical signals. There is an extensive literature describing single gene mutations in humans that cause hearing impairment, but there are essentially none for touch. Here we first asked if touch sensitivity is a heritable trait and second whether there are common genes that influence different mechanosensory senses like hearing and touch in humans. Using a classical twin study design we demonstrate that touch sensitivity and touch acuity are highly heritable traits. Quantitative phenotypic measures of different mechanosensory systems revealed significant correlations between touch and hearing acuity in a healthy human population. Thus mutations in genes causing deafness genes could conceivably negatively influence touch sensitivity. In agreement with this hypothesis we found that a proportion of a cohort of congenitally deaf young adults display significantly impaired measures of touch sensitivity compared to controls. In contrast, blind individuals showed enhanced, not diminished touch acuity. Finally, by examining a cohort of patients with Usher syndrome, a genetically well-characterized deaf-blindness syndrome, we could show that recessive pathogenic mutations in the USH2A gene influence touch acuity. Control Usher syndrome cohorts lacking demonstrable pathogenic USH2A mutations showed no impairment in touch acuity. Our study thus provides comprehensive evidence that there are common genetic elements that contribute to touch and hearing and has identified one of these genes as USH2A.     

Dahlia spectabilis (Asteraceae, Coreopsideae), a new species from San Luis Potosí, Mexico

Dahlia spectabilis (Asteraceae, Coreopsideae), a new species from San Luis Potosí, Mexico, is described and illustrated. The plant is distinguished by its large habit, big flowering heads, and overall lack of trichomes. It occurs within the natural range for the genus and is known from only one location where it is under heavy grazing pressure.

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Resumen   Dahlia spectabilis (Asteraceae, Coreopsideae), una especie nueva del estado de San Luis Potosí, México, es descrita e ilustrada. Se distingue por su hábito más grande, su grandes inflorescencias y la falta de tricomas. Ocuriendo dento del rango natural del género, conocida solo por un poblacón, la cual está sufriendo por presión de ganado.

     

PipeCraft: Flexible open‐source toolkit for bioinformatics analysis of custom high‐throughput amplicon sequencing data

High‐throughput sequencing methods have become a routine analysis tool in environmental sciences as well as in public and private sector. These methods provide vast amount of data, which need to be analysed in several steps. Although the bioinformatics may be applied using several public tools, many analytical pipelines allow too few options for the optimal analysis for more complicated or customized designs. Here, we introduce PipeCraft, a flexible and handy bioinformatics pipeline with a user‐friendly graphical interface that links several public tools for analysing amplicon sequencing data. Users are able to customize the pipeline by selecting the most suitable tools and options to process raw sequences from Illumina, Pacific Biosciences, Ion Torrent and Roche 454 sequencing platforms. We described the design and options of PipeCraft and evaluated its performance by analysing the data sets from three different sequencing platforms. We demonstrated that PipeCraft is able to process large data sets within 24 hr. The graphical user interface and the automated links between various bioinformatics tools enable easy customization of the workflow. All analytical steps and options are recorded in log files and are easily traceable.     

Desensitizing and non-desensitizing subtypes of alpha-bungarotoxin-sensitive nicotinic acetylcholine receptors in cockroach neurons

Two alpha-bungarotoxin-sensitive nicotinic receptor subtypes in cockroach neurons are identified as desensitizing (nAChD), selectively inhibitable with 100 nM imidacloprid, and non-desensitizing (nAChN), selectively inhibitable with 100 pM methyllycaconitine. Although the desensitization rate of nAChD receptors is highly variable, pharmacology is largely independent of desensitization rate. Because desensitized states tightly bind agonists, nAChD receptors are potently inhibited by neonicotinoids and specifically measured in radiolabeled imidacloprid binding assays. However, they are not usually detected in binding assays with radiolabeled alpha-bungarotoxin, which has a Kd for the resting state of 21 nM, but binds poorly to desensitized states often present in binding assays. In contrast, nAChN receptors are specifically measured in binding assays with radiolabeled alpha-bungarotoxin, which binds them with a Kd of 1.3 nM. nAChN receptors are activated by neonicotinoids at micromolar concentrations, and allosterically by spinosyn A, with an EC50 of 27 nM. Spinosyn A weakly antagonizes nAChD receptors -23% at 10 microM. The roles of the two nAChR subtypes in insecticide poisoning are discussed.