A femtomolar-acting neuroprotective peptide

Retinal VIP-amacrine cells: their development, structure, and function

Amacrine cells (ACs) are the most structurally and functionally diverse neuron type in the retina. Different ACs have distinct functions, such as neuropeptide secretion and inhibitory connection. Vasoactive intestinal peptide (VIP) -ergic -ACs are retina gamma-aminobutyric acid (GABA) -ergic -ACs that were discovered long ago. They secrete VIP and form connections with bipolar cells (BCs), other ACs, and retinal ganglion cells (RGCs). They have a specific structure, density, distribution, and function. They play an important role in myopia, light stimulated responses, retinal vascular disease and other ocular diseases. Their significance in the study of refractive development and disease is increasing daily. However, a systematic review of the structure and function of retinal VIP-ACs is lacking. We discussed the detailed characteristics of VIP-ACs from every aspect across species and providing systematic knowledge base for future studies. Our review led to the main conclusion that retinal VIP-ACs develop early, and although their morphology and distribution across species are not the same, they have similar functions in a wide range of ocular diseases based on their function of secreting neuropeptides and forming inhibitory connections with other cells.

Tau, ADNP, and sex

With 50 years to the original discovery of Tau, I gave here my perspective, looking through the prism of activity-dependent neuroprotective protein (ADNP), and the influence of sex. My starting point was vasoactive intestinal peptide (VIP), a regulator of ADNP. I then moved to the original discovery of ADNP and its active neuroprotective site, NAP, drug candidate, davunetide. Tau-ADNP-NAP interactions were then explained with emphasis on sex and future translational medicine.

Chromatin remodeler Activity-Dependent Neuroprotective Protein (ADNP) contributes to syndromic autism

BACKGROUND

Individuals affected with autism often suffer additional co-morbidities such as intellectual disability. The genes contributing to autism cluster on a relatively limited number of cellular pathways, including chromatin remodeling. However, limited information is available on how mutations in single genes can result in such pleiotropic clinical features in affected individuals. In this review, we summarize available information on one of the most frequently mutated genes in syndromic autism the Activity-Dependent Neuroprotective Protein (ADNP).

RESULTS

Heterozygous and predicted loss-of-function ADNP mutations in individuals inevitably result in the clinical presentation with the Helsmoortel-Van der Aa syndrome, a frequent form of syndromic autism. ADNP, a zinc finger DNA-binding protein has a role in chromatin remodeling: The protein is associated with the pericentromeric protein HP1, the SWI/SNF core complex protein BRG1, and other members of this chromatin remodeling complex and, in murine stem cells, with the chromodomain helicase CHD4 in a ChAHP complex. ADNP has recently been shown to possess R-loop processing activity. In addition, many additional functions, for instance, in association with cytoskeletal proteins have been linked to ADNP.

CONCLUSIONS

We here present an integrated evaluation of all current aspects of gene function and evaluate how abnormalities in chromatin remodeling might relate to the pleiotropic clinical presentation in individual"s" with Helsmoortel-Van der Aa syndrome.

Activity-dependent neuroprotective protein (ADNP)-end-binding protein (EB) interactions regulate microtubule dynamics toward protection against tauopathy

The 1102-amino-acid activity-dependent neuroprotective protein (ADNP) was originally discovered by expression cloning through the immunological identification of its 8-amino-acid sequence NAPVSIPQ (NAP), constituting the smallest active neuroprotective fragment of the protein. ADNP expression is essential for brain formation and cognitive function and is dysregulated in a variety of neurodegenerative diseases (Alzheimer's disease, Parkinson's disease, and schizophrenia). ADNP has been found to be mutated in autism, with an estimated prevalence of 0.17% (together, these autism cases now constitute ADNP syndrome cases) and our recent results showed somatic mutations in ADNP in Alzheimer's disease brains correlating with tauopathy. Furthermore, Adnp haploinsufficiency in mice causes an age-dependent reduction in cognitive functions coupled with tauopathy-like features such as an increased formation of tangle-like structures, defective axonal transport, and Tau hyperphosphorylation. ADNP and its derived peptides, NAP and SKIP, directly interact with end-binding proteins (EBs), which decorate plus-tips of the growing axonal cytoskeleton-microtubules (MTs). Functionally, NAP and SKIP are neuroprotective and stimulate axonal transport. Clinical trials have suggested the potential efficacy of NAP (davunetide, CP201) for improving cognitive performance/functional activities of daily living in amnestic mild cognitive impairment (aMCI) and schizophrenia patients, respectively. However, NAP was not found to be an effective treatment (though well-tolerated) for progressive supranuclear palsy (PSP) patients. Here we review the molecular mechanism of NAP activity on MTs and how NAP modulates the MT-Tau-EBs crosstalk. We offer a molecular explanation for the different protective potency of NAP in selected tauopathies (aMCI vs. PSP) expressing different ratios/pathologies of the alternatively spliced Tau mRNA and its resulting protein (aMCI expressing similar quantities of the dynamic Tau 3-MT binding isoform (Tau3R) and the Tau 4-MT binding isoform (Tau4R) and PSP enriched in Tau4R pathology). We reveal the direct effect of truncated ADNPs (resulting from de novo autism and newly discovered Alzheimer's disease-related somatic mutations) on MT dynamics. We show that the peptide SKIP affects MT dynamics and MT-Tau association. Since MT impairment is linked with neurodegenerative and neurodevelopmental conditions, the current study implicates a paucity/dysregulation of MT-interacting endogenous proteins, like ADNP, as a contributing mechanism and provides hope for NAP and SKIP as MT-modulating drug candidates.

Protective Effects of Pituitary Adenylate Cyclase-Activating Polypeptide and Vasoactive Intestinal Peptide Against Cognitive Decline in Neurodegenerative Diseases

Cognitive impairment is one of the major symptoms in most neurodegenerative disorders such as Alzheimer’s (AD), Parkinson (PD), and Huntington diseases (HD), affecting millions of people worldwide. Unfortunately, there is no treatment to cure or prevent the progression of those diseases. Cognitive impairment has been related to neuronal cell death and/or synaptic plasticity alteration in important brain regions, such as the cerebral cortex, substantia nigra, striatum, and hippocampus. Therefore, compounds that can act to protect the neuronal loss and/or to reestablish the synaptic activity are needed to prevent cognitive decline in neurodegenerative diseases. Pituitary adenylate cyclase-activating polypeptide (PACAP) and vasoactive intestinal peptide (VIP) are two highly related multifunctional neuropeptides widely distributed in the central nervous system (CNS). PACAP and VIP exert their action through two common receptors, VPAC1 and VPAC2, while PACAP has an additional specific receptor, PAC1. In this review article, we first presented evidence showing the therapeutic potential of PACAP and VIP to fight the cognitive decline observed in models of AD, PD, and HD. We also reviewed the main transduction pathways activated by PACAP and VIP receptors to reduce cognitive dysfunction. Furthermore, we identified the therapeutic targets of PACAP and VIP, and finally, we evaluated different novel synthetic PACAP and VIP analogs as promising pharmacological tools.

VIP/PACAP-Based Drug Development: The ADNP/NAP-Derived Mirror Peptides SKIP and D-SKIP Exhibit Distinctive in vivo and in silico Effects

Activity-dependent neuroprotective protein (ADNP) was discovered and first characterized in the laboratory of Prof. Illana Gozes to be regulated by vasoactive intestinal peptide (VIP), and pituitary adenylate cyclase-activating peptide (PACAP) toward neuroprotection. Importantly, ADNP is a master regulator of >400 genes, essential for brain formation, while its haploinsufficiency causes cognitive impairments. Recently, de novo mutations in ADNP were identified as leading to the autism-like ADNP syndrome, mimicked by the Adnp-deficient mouse model. Furthermore, novel peptide derivatives of the neuroprotective ADNP-snippet NAP (NAPVSIPQ), developed in our laboratory, include SKIP and the mirroring all D-amino acid SKIP (D-SKIP). We now extended previous evidence suggesting potential antagonistic features for D-SKIP, compared with the neuroprotective peptide SKIP, as was observed by NMR analysis and social/olfactory functional testing. Here, an impact of the Adnp genotype was observed in the Morris Water Maze (MWM) test measuring cognition, coupled with improvement by SKIP, opposing the inert/exacerbating effect of D-SKIP. In the elevated plus-maze and open field tests measuring anxiety-related behaviors, contrasting effects of SKIP and D-SKIP were found, with SKIP improving/preserving the normal phenotype of the mouse, and D-SKIP causing alterations. Lastly, an in silico analysis suggested that SKIP and D-SKIP bind the microtubule end binding (EB) proteins EB1 and EB3 in different conformations, thereby indicating distinctive natures for the two peptides, potentially mediating differential in vivo effects. Altogether, our findings corroborate the notion of D-SKIP acting as an antagonist, thus distinguishing it from the neuroprotective SKIP.

Targeting Ligands Deliver Model Drug Cargo into the Central Nervous System along Autonomic Neurons

While biologic drugs such as proteins, peptides, or nucleic acids have shown promise in the treatment of neurodegenerative diseases, the blood-brain barrier (BBB) severely limits drug delivery to the central nervous system (CNS) after systemic administration. Consequently, drug delivery challenges preclude biological drug candidates from the clinical armamentarium. In order to target drug delivery and uptake into to the CNS, we used an in vivo phage display screen to identify peptides able to target drug-uptake by the vast array of neurons of the autonomic nervous system (ANS). Using next-generation sequencing, we identified 21 candidate targeted ANS-to-CNS uptake ligands (TACL) that enriched bacteriophage accumulation and delivered protein-cargo into the CNS after intraperitoneal (IP) administration. The series of TACL peptides were synthesized and tested for their ability to deliver a model enzyme (NeutrAvidin-horseradish peroxidase fusion) to the brain and spinal cord. Three TACL-peptides facilitated significant active enzyme delivery into the CNS, with limited accumulation in off-target organs. Peptide structure and serum stability is increased when internal cysteine residues are cyclized by perfluoroarylation with decafluorobiphenyl, which increased delivery to the CNS further. TACL-peptide was demonstrated to localize in parasympathetic ganglia neurons in addition to neuronal structures in the hindbrain and spinal cord. By targeting uptake into ANS neurons, we demonstrate the potential for TACL-peptides to bypass the blood-brain barrier and deliver a model drug into the brain and spinal cord.

A Novel Microtubule-Tau Association Enhancer and Neuroprotective Drug Candidate: Ac-SKIP

Activity-dependent neuroprotective protein (ADNP) has been initially discovered through its eight amino acid sequence NAPVSIPQ, which shares SIP motif with SALLRSIPA - a peptide derived from activity-dependent neurotrophic factor (ADNF). Mechanistically, both NAPVSIPQ and SALLRSIPA contain a SIP motif that is identified as a variation of SxIP domain, providing direct interaction with microtubule end-binding proteins (EBs). The peptide SKIP was shown before to provide neuroprotection in vitro and protect against Adnp-related axonal transport deficits in vivo. Here we show, for the first time that SKIP enhanced microtubule dynamics, and prevented Tau-microtubule dissociation and microtubule disassembly induced by the Alzheimer's related zinc intoxication. Furthermore, we introduced, CH₃CO-SKIP-NH₂ (Ac-SKIP), providing efficacious neuroprotection. Since microtubule - Tau organization and dynamics is central in axonal microtubule cytoskeleton and transport, tightly related to aging processes and Alzheimer's disease, our current study provides a compelling molecular explanation to the in vivo activity of SKIP, placing SKIP motif as a central focus for MT-based neuroprotection in tauopathies with axonal transport implications.

Protective effect of a 3 kDa peptide obtained from beef myofibrillar protein using alkaline-AK on neuronal cells

The protective effect of two 3 kDa peptide fractions (AK3KF1 and AK3KF2), obtained from beef myofibrillar protein using an inexpensive enzyme (alkaline-AK) on human neuronal cells (SH-SY5Y) against H₂O₂-induced apoptosis was investigated. These peptides were isolated and further separated by fast protein liquid chromatography (FPLC), and their protective effect against H₂O₂-mediated cell death was measured by determining cell viability, nitric oxide (NO) production, mitochondrial membrane potential (MMP), apoptosis, morphological changes in cell nuclei, and in vitro antioxidant assays. The results indicated that treatment with peptide fractions increased cell viability and MMP, and decreased NO production, fragmentation of cell nuclei, and apoptosis in H₂O₂-treated SH-SY5Y cells. This is the first study to report neuroprotective effects of a peptide obtained from beef myofibrillar protein. The peptide sequence was identified as Thr-Gln-Lys-Lys-Val-Ile-Phe-Cys (TQKKVIFC). Thus, these findings suggest that TQKKVIFC can prevent neuronal cell death and could be useful in preventing neurodegenerative diseases.

NAP modulates hyperglycemic-inflammatory event of diabetic retina by counteracting outer blood retinal barrier damage

Diabetic retinopathy (DR) is a common microvascular complication of diabetes. Prolonged hyperglycemia stimulates inflammatory pathway characterized by the release of some cytokines leading to the impairment of blood retinal barrier (BRB). NAP exerts a protective effect in various eye diseases, including DR. So far, the role of NAP in the modulation of inflammatory event during early phase of this pathology has not been investigated yet. In the current study, we have studied the retinal protective effect of NAP, injected into the eye, in diabetic rats. NAP treatment exerts a dual effect downregulating interleukin (IL)-1β and its related receptors and upregulating IL-1Ra expression. We have also tested the role of this peptide in human retinal epithelial cells (ARPE19) cultured on a semipermeable support and exposed to hyperglycemic-inflammatory insult, representing a in vitro model of diabetic macular edema, a clinical manifestation of DR. The results have shown that NAP prevents outer BRB impairment by upregulating the tight junctions. In conclusion, deepened characterization of NAP action mechanism on hyperglycemic-inflammatory damage may be useful to develop a new strategy to prevent retinal damage during DR.

Vasoactive Intestinal Peptide Decreases β-Amyloid Accumulation and Prevents Brain Atrophy in the 5xFAD Mouse Model of Alzheimer's Disease

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by extracellular deposits of fibrillary β-amyloid (Aβ) plaques in the brain that initiate an inflammatory process resulting in neurodegeneration. The neuronal loss associated with AD results in gross atrophy of affected regions causing a progressive loss of cognitive ability and memory function, ultimately leading to dementia. Growing evidence suggests that vasoactive intestinal peptide (VIP) could be beneficial for various neurodegenerative diseases, including AD. The study investigated the effects of VIP on 5xFAD, a transgenic mouse model of AD. Toward this aim, we used 20 5xFAD mice in two groups (n = 10 each), VIP-treated (25 ng/kg i.p. injection, three times per week) and saline-treated (the drug's vehicle) following the same administration regimen. Treatment started at 1 month of age and ended 2 months later. After 2 months of treatment, the mice were euthanized, their brains dissected out, and immunohistochemically stained for Aβ₄₀ and Aβ₄₂ on serial sections. Then, plaque analysis and stereological morphometric analysis were performed in different brain regions. Chronic VIP administration in 5xFAD mice significantly decreased the levels of Aβ₄₀ and Aβ₄₂ plaques in the subiculum compared to the saline treated 5xFAD mice. VIP treatment also significantly decreased Aβ₄₀ and Aβ₄₂ plaques in cortical areas and significantly increased the hippocampus/cerebrum and corpus callosum/cerebrum ratio but not the cerebral cortex/cerebrum ratio. In summary, we found that chronic administration of VIP significantly decreased Aβ plaques and preserved against atrophy for related brain regions in 5xFAD AD mice.

A review of interventions against fetal alcohol spectrum disorder targeting oxidative stress

INTRODUCTION

Fetal alcohol spectrum disorder is caused by maternal ethanol exposure; it causes physical, behavioral, cognitive, and neural impairments (Murawski et al., 2015). Mechanisms of FASD causing damage are not yet fully elucidated. Oxidative stress might be one of its mechanisms (Henderson et al., 1995). Yet no effective treatment against FASD has been found other than ethanol abstention (Long et al., 2010).

METHODS

This review summarizes relevant literatures regarding interventions targeting oxidative stress that may relieve fetal alcohol spectrum disorder.

RESULTS

Astaxanthin was found to mitigate embryonic growth retardation induced by prenatal ethanol treatment through ameliorating the down regulation of hydrogen peroxide (H2O2) and malondialdehyde (MDA) caused by alcohol in a mice model (Zheng et al., 2014; Vabulas et al., 2002). Vitamin E protected against fatal alchol spectrum disorders by ameliorating oxidative stress in rat models (Mitchell et al., 1999a), and yielded a better outcome when it was combined with Vitamin C (Packer et al., 1979; Peng et al., 2005). Vitamin C mitigated embryonic retardation caused by alcohol and reversed ethanol induced NF-κB activation and ROS (reactive oxygen species) formation in a Xenopus laevis model (Peng et al., 2005). Beta carotene supplement was proved to protect against neurotoxicity in hippocampal cultures of embryos induced by alcohol in a rats model (Mitchell et al., 1999a). Prenatal folic acid supplement reversed the decrease of body weight caused by maternal ethanol treatment and ameliorated the increment of glutathione reductase specific activities as well as the increase of thiobarbituric acid reactive substances (TBARS) induced by alcohol in a rats model (Cano et al., 2001). Omega-3 fatty acids reversed the decrease of reduced glutathione (GSH) levels in brain caused by prenatal ethanol treatment in a rats model (Patten et al., 2013). EUK-134 treatment reduced the incidence of forelimb defects caused by ethanol treatment in a mice model (Chen et al., 2004). Pretreatment of activity-dependent neurotrophic factor-9 (ADNF-9) and NAPVSIPQ (NAP) protected against prenatal ethanol induced fetal death as well as fetal growth abnormalities in a mice model, and such treatment reversed the decrease of the rate of reduced glutathione (GSH)/ oxidative glutathione (GSSG) caused by alcohol (Spong et al., 2001).

CONCLUSION

By now interventions against fetal alcohol spectrum disorder targeting oxidative stress includes astaxanthin, Ascorbic acid (Vitamin C), Vitamin E, beta-carotene, (-)-Epigallocatechin-3-gallate (EGCG), Omega-3 fatty acids, etc (see Fig. 1). However, most interventions are only assayed in animal models, more clinical trials are needed to show whether antioxidants make an effort against FASD damage.

Sexual divergence in activity-dependent neuroprotective protein impacting autism, schizophrenia, and Alzheimer's disease

Discovered in our laboratory, activity-dependent neuroprotective protein (ADNP) interacts with key regulatory proteins, including the chromatin remodeling complex SWI/SNF, proteins associated with RNA splicing, RNA translation, microtubule dynamics, and autophagy. ADNP regulates > 400 genes during mouse embryonic development and is essential for neural tube closure. ADNP key functions extend from mice to men, with mutations causing ADNP-related ID/autism syndrome, also known as the Helsmoortel-Van der Aa syndrome. ADNP mRNA increases in lymphocytes derived from schizophrenia patients and in patients suffering from mild cognitive impairment (MCI) and further increases in Alzheimer's disease patients compared with controls. Serum ADNP levels correlate with IQ. NAP (davunetide), an ADNP snippet drug candidate, protects cognition in patients suffering from amnestic MCI preceding Alzheimer's disease and significantly enhances functional daily activities in schizophrenia patients toward future development. It is important to note that ADNP is sexually regulated in the brains of birds, mice, and men and in lymphocytes of patients suffering from schizophrenia. ADNP haploinsufficiency in mice results in significantly decreased axonal transport (with male-female differences) changes in gene expression in a sex-dependent manner, including key regulatory mechanisms during brain and heart development and function and behavioral outcomes. These findings pave the path for better understanding of brain function through the prism of sex differences. © 2016 Wiley Periodicals, Inc.

Microtubule stabilising peptides rescue tau phenotypes in-vivo

The microtubule cytoskeleton is a highly dynamic, filamentous network underpinning cellular structure and function. In Alzheimer's disease, the microtubule cytoskeleton is compromised, leading to neuronal dysfunction and eventually cell death. There are currently no disease-modifying therapies to slow down or halt disease progression. However, microtubule stabilisation is a promising therapeutic strategy that is being explored. We previously investigated the disease-modifying potential of a microtubule-stabilising peptide NAP (NAPVSIPQ) in a well-established Drosophila model of tauopathy characterised by microtubule breakdown and axonal transport deficits. NAP prevented as well as reversed these phenotypes even after they had become established. In this study, we investigate the neuroprotective capabilities of an analogous peptide SAL (SALLRSIPA). We found that SAL mimicked NAP's protective effects, by preventing axonal transport disruption and improving behavioural deficits, suggesting both NAP and SAL may act via a common mechanism. Both peptides contain a putative 'SIP' (Ser-Ile-Pro) domain that is important for interactions with microtubule end-binding proteins. Our data suggests this domain may be central to the microtubule stabilising function of both peptides and the mechanism by which they rescue phenotypes in this model of tauopathy. Our observations support microtubule stabilisation as a promising disease-modifying therapeutic strategy for tauopathies like Alzheimer's disease.

Nap Interferes with Hypoxia-Inducible Factors and VEGF Expression in Retina of Diabetic Rats

The retinal microvascular damage is a complication of diabetic retinopathy (DR). Hyperglycemia and hypoxia are responsible of aberrant vessel's proliferation. The cellular response to hypoxia is mediated through activation of hypoxia-inducible factors (HIFs). Among these, HIF-1α modulates expression of its target gene, VEGF, whose upregulation controls the angiogenic event during DR development. In a previous study, we have demonstrated that a small peptide, NAP, is able to protect retina from hyperglycemic insult. Here, we have demonstrated that its intraocular administration in a rat model of diabetic retinopathy has reduced expression of HIF-1α, HIF-2α, and VEGF by increasing HIF-3α levels. These data have been also confirmed by immunolocalization study by confocal microscopy. Although these evidences need to be further deepened to understand the molecular mechanism involved in the protective NAP action, the present data suggest that this small peptide may be effective to prevent the development of this ocular pathology.

Peptide Pharmacological Approaches to Treating Traumatic Brain Injury: a Case for Arginine-Rich Peptides

Traumatic brain injury (TBI) has a devastating effect on victims and their families, and has profound negative societal and economic impacts, a situation that is further compounded by the lack of effective treatments to minimise injury after TBI. The current strategy for managing TBI is partly through preventative measures and partly through surgical and rehabilitative interventions. Secondary brain damage remains the principal focus for the development of a neuroprotective therapeutic. However, the complexity of TBI pathophysiology has meant that single-action pharmacological agents have been largely unsuccessful in combatting the associated brain injury cascades, while combination therapies to date have proved equally ineffective. Peptides have recently emerged as promising lead agents for the treatment of TBI, especially those rich in the cationic amino acid, arginine. Having been shown to lessen the impact of ischaemic stroke in animal models, there are reasonable grounds to believe that arginine-rich peptides may have neuroprotective therapeutic potential in TBI. Here, we review a range of peptides previously examined as therapeutic agents for TBI. In particular, we focus on cationic arginine-rich peptides -- a new class of agents that growing evidence suggests acts through multiple neuroprotective mechanisms.

The effects of vasoactive intestinal peptide in neurodegenerative disorders

Neurodegenerative disorders (NDDs) are characterized by neuronal death in the brain. The mechanism of the neuronal death is too complicated to be fully understood, although in many NDDs, aging and neurotoxins are known risk factors. In the central and peripheral nervous system, vasoactive intestinal peptide (VIP), a 28-amino acid neuropeptide, is released to support neuronal survival in both physiological and pathological condition. VIP can inhibit the neurodegeneration induced by the loss of neurons. The indirect protection effect is mainly mediated by glial cells through the production of neurotrophic factor(s) and inhibition of proinflammatory mediators. By remolding the structure and improving the transfer efficiency of VIP, its nerve protective function could be further improved. Its neuroprotective action and efficacy in inhibiting a broad range of inflammatory responses make VIP or related peptides becoming a novel therapeutic method to NDDs. In this review, we aim to summarize the relationship between VIP and NDDs.

Neuropeptides shaping the central nervous system development: Spatiotemporal actions of VIP and PACAP through complementary signaling pathways

Pituitary adenylate cyclase-activating polypeptide (PACAP) and vasoactive intestinal peptide (VIP) are neuropeptides with wide, complementary, and overlapping distributions in the central and peripheral nervous systems, where they exert important regulatory roles in many physiological processes. VIP and PACAP display a large range of biological cellular targets and functions in the adult nervous system including regulation of neurotransmission and neuroendocrine secretion and neuroprotective and neuroimmune responses. As the main focus of the present review, VIP and PACAP also have been long implicated in nervous system development and maturation through their interaction with the seven transmembrane domain G protein-coupled receptors, PAC1, VPAC1, and VPAC2, initiating multiple signaling pathways. Compared with PAC1, which solely binds PACAP with very high affinity, VPACs exhibit high affinities for both VIP and PACAP but differ from each other because of their pharmacological profile for both natural accessory peptides and synthetic or chimeric molecules, with agonistic and antagonistic properties. Complementary to initial pharmacological studies, transgenic animals lacking these neuropeptides or their receptors have been used to further characterize the neuroanatomical, electrophysiological, and behavioral roles of PACAP and VIP in the developing central nervous system. In this review, we recapitulate the critical steps and processes guiding/driving neurodevelopment in vertebrates and superimposing the potential contribution of PACAP and VIP receptors on the given timeline. We also describe how alterations in VIP/PACAP signaling may contribute to both (neuro)developmental and adult pathologies and suggest that tuning of VIP/PACAP signaling in a spatiotemporal manner may represent a novel avenue for preventive therapies of neurological and psychiatric disorders. © 2016 Wiley Periodicals, Inc.

The cytoskeleton as a drug target for neuroprotection: the case of the autism- mutated ADNP

Fifteen years ago we discovered activity-dependent neuroprotective protein (ADNP), and showed that it is essential for brain formation/function. Our protein interaction studies identified ADNP as a member of the chromatin remodeling complex, SWI/SNF also associated with alternative splicing of tau and prediction of tauopathy. Recently, we have identified cytoplasmic ADNP interactions with the autophagy regulating microtubule-associated protein 1 light chain 3 (LC3) and with microtubule end-binding (EB) proteins. The ADNP-EB-binding SIP domain is shared with the ADNP snippet drug candidate, NAPVSIPQ termed NAP (davunetide). Thus, we identified a precise target for ADNP/NAP (davunetide) neuroprotection toward improved drug development.

In vivo and in vitro ketamine exposure exhibits a dose-dependent induction of activity-dependent neuroprotective protein in rat neurons

Anesthetic doses of ketamine induce apoptosis, as well as gene expression of activity-dependent neuroprotective protein (ADNP), a putative homeodomain transcription factor in rat pups (P7). This study investigated if ketamine induced ADNP protein in a dose-dependent manner in vitro and in vivo using primary cultures of cortical neurons and neonatal pups (P7). In vivo immunohistochemistry demonstrated a sub-anesthetic dose of ketamine increased ADNP in the somatosensory cortex (SCC) which was previously identified to be damaged by repeated exposure to anesthetic doses of ketamine. Administration of low-dose ketamine prior to full sedation prevented caspase-3 activation in the hippocampus and SCC. Primary cultures of cortical neurons treated with ketamine (10 μM-10mM) at 3 days-in vitro (3 DIV) displayed a concentration-dependent decrease in expanded growth cones. Furthermore, neuronal production and localization of ADNP varied as a function of both ketamine concentration and length of exposure. Taken together, these data support the model that ADNP induction may be partially responsible for the efficacy of a low-dose ketamine pre-treatment in preventing ketamine-induced neuronal cell death.

Prevention of learning deficit in a Down syndrome model

OBJECTIVE

To evaluate whether peptides given to adult mice with Down syndrome prevent learning deficits, and to delineate the mechanisms behind the protective effect.

METHODS

Ts65Dn mice were treated for 9 days with peptides D-NAPVSIPQ (NAP)+D-SALLRSIPA (SAL) or placebo, and wild-type animals were treated with placebo. Beginning on treatment day 4, the mice were tested for learning using the Morris watermaze. Probe tests for long-term memory were performed on treatment day 9 and 10 days after treatment stopped. Open-field testing was performed before and after the treatment. Calibrator-normalized relative real-time polymerase chain reaction (PCR) with glyceraldehyde-3-phosphate dehydrogenase (GAPD) standardization was performed on the whole brain and hippocampus for activity-dependent neuroprotective protein, vasoactive intestinal peptide (VIP), glial fibrillary acidic protein (GFAP), NR2B, NR2A, and γ-aminobutyric acid type A (GABAA)-α5. Statistics included analysis of variance and the Fisher protected least significant difference, with P<.05 significant.

RESULTS

The Ts65Dn plus placebo animals did not learn over the 5-day period compared with the controls (P<.001). The Ts65Dn +(D-NAP+D-SAL) learned significantly better than the Ts65Dn plus placebo (P<.05), and they retained learning similar to controls on treatment day 9, but not after 10 days of no treatment. Treatment with D-NAP+D-SAL prevented the Ts65Dn hyperactivity. Adult administration of D-NAP+D-SAL prevented changes in activity-dependent neuroprotective protein, intestinal peptide, and NR2B with levels similar to controls (all P<.05).

CONCLUSION

Adult treatment with D-NAP+D-SAL prevented learning deficit in Ts65Dn, a model of Down syndrome. Possible mechanisms of action include reversal of vasoactive intestinal peptide and activity-dependent neuroprotective protein dysregulation, as well as increasing expression of NR2B, thus facilitating learning.

NAP reduces murine microvascular endothelial cells proliferation induced by hyperglycemia

Hyperglycemia has been identified as a risk factor responsible for micro- and macrovascular complications in diabetes. NAP (Davunetide) is a peptide whose neuroprotective actions are widely demonstrated, although its biological role on endothelial dysfunctions induced by hyperglycemia remains uninvestigated. In the present study we hypothesized that NAP could play a protective role on hyperglycemia-induced endothelial cell proliferation. To this end we investigated the effects of NAP on an in vitro model of murine microvascular endothelial cells grown in high glucose for 7 days. The MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) assay and cyclin D1 protein expression analysis revealed that NAP treatment significantly reduces viability and proliferation of the cells. Hyperglycemia induced the activation of mitogen-activated protein kinase/extracellular signal-regulated protein kinase and/or phosphatidylinositol-3 kinase/Akt pathways in a time-dependent manner. NAP treatment reduced the phosphorylation levels of ERK and AKT in cells grown in high glucose. These evidences suggest that NAP might be effective in the regulation of endothelial dysfunction induced by hyperglycemia.

Davunetide (NAP) protects the retina against early diabetic injury by reducing apoptotic death

Davunetide (NAP) is an eight amino acid peptide that has been shown to provide potent neuroprotection. In the present study, we investigated the neuroprotective effect of NAP in diabetic retinopathy using an in vivo streptozotocin (STZ)-induced diabetic model. A single intraocular injection of NAP (100 μg/mL) or vehicle was administered 1 week after STZ injection. Three weeks after diabetes induction, we assessed the retinal expression and distribution of apoptosis markers, cleaved caspase-3, and Bcl2, by Western blot and immunofluorescent analysis. Furthermore, we evaluated the activation of mitogen-activated protein kinase/extracellular signal-regulated protein kinase (MAPK/ERK) and/or phosphatidylinositol-3 kinase/Akt pathways by measuring the protein levels of p-ERK and p-AKT with or without NAP treatment. Results demonstrated that NAP treatment reduced apoptotic event in diabetic retina, and it restored cleaved caspase-3 expression levels in the retina of STZ-injected rats as well as the decreased Bcl2. NAP treatment improved cellular survival through the activation of the MAPK/ERK pathway. Taken together, these findings suggested that NAP might be useful to treat retinal degenerative diseases.

Neuropeptides in learning and memory

Dementia conditions and memory deficits of different origins (vascular, metabolic and primary neurodegenerative such as Alzheimer's and Parkinson's diseases) are getting more common and greater clinical problems recently in the aging population. Since the presently available cognitive enhancers have very limited therapeutical applications, there is an emerging need to elucidate the complex pathophysiological mechanisms, identify key mediators and novel targets for future drug development. Neuropeptides are widely distributed in brain regions responsible for learning and memory processes with special emphasis on the hippocampus, amygdala and the basal forebrain. They form networks with each other, and also have complex interactions with the cholinergic, glutamatergic, dopaminergic and GABA-ergic pathways. This review summarizes the extensive experimental data in the well-established rat and mouse models, as well as the few clinical results regarding the expression and the roles of the tachykinin system, somatostatin and the closely related cortistatin, vasoactive intestinal polypeptide (VIP) and pituitary adenylate-cyclase activating polypeptide (PACAP), calcitonin gene-related peptide (CGRP), neuropeptide Y (NPY), opioid peptides and galanin. Furthermore, the main receptorial targets, mechanisms and interactions are described in order to highlight the possible therapeutical potentials. Agents not only symptomatically improving the functional impairments, but also inhibiting the progression of the neurodegenerative processes would be breakthroughs in this area. The most promising mechanisms determined at the level of exploratory investigations in animal models of cognitive disfunctions are somatostatin sst4, NPY Y2, PACAP-VIP VPAC1, tachykinin NK3 and galanin GALR2 receptor agonisms, as well as delta opioid receptor antagonism. Potent and selective non-peptide ligands with good CNS penetration are needed for further characterization of these molecular pathways to complete the preclinical studies and decide if any of the above described targets could be appropriate for clinical investigations.

Experimental methods for testing the effects of neurotrophic peptide, ADNF-9, against alcohol-induced apoptosis during pregnancy in c57bl/6 mice

Experimental designs for investigating the effects of prenatal alcohol exposure during early embryonic stages in fetal brain growth are challenging. This is mostly due to the difficulty of microdissection of fetal brains and their sectioning for determination of apoptotic cells caused by prenatal exposure to alcohol. The experiments described here provide visualized techniques from mice breeding to the identification of cell death in fetal brain tissue. This study used C57BL/6 mice as the animal model for studying fetal alcohol exposure and the role of trophic peptide against alcohol-induced apoptosis. The breeding consists of a 2-hr matting window to determine the exact stage of embryonic age. An established fetal alcohol exposure model has been used in this study to determine the effects of prenatal alcohol exposure in fetal brains. This involves free access to alcohol or pair-fed liquid diets as the sole source of nutrients for the pregnant mice. The techniques involving dissection of fetuses and microdissection of fetal brains are described carefully, since the latter can be challenging. Microdissection requires a stereomicroscope and ultra-fine forceps. Step-by-step procedures for dissecting the fetal brains are provided visually. The fetal brains are dissected from the base of the primordium olfactory bulb to the base of the metencephalon. For investigating apoptosis, fetal brains are first embedded in gelatin using a peel-away mold to facilitate their sectioning with a vibratome apparatus. Fetal brains embedded and fixed in paraformaldehyde are easily sectioned, and the free floating sections can be mounted in superfrost plus slides for determination of apoptosis or cell death. TUNEL (TdT-mediated dUTP Nick End Labeling; TdT: terminal deoxynucleotidyl transferase) assay has been used to identify cell death or apoptotic cells. It is noteworthy that apoptosis and cell-mediated cytotoxicity are characterized by DNA fragmentation. Thus, the visualized TUNEL-positive cells are indicative of cell death or apoptotic cells. The experimental designs here provide information about the use of an established liquid diet for studying the effects of alcohol and the role of neurotrophic peptides during pregnancy in fetal brains. This involves breeding and feeding pregnant mice, microdissecting fetal brains, and determining apoptosis. Together, these visual and textual techniques might be a source for investigating prenatal exposure of harmful agents in fetal brains.

D-NAP prophylactic treatment in the SOD mutant mouse model of amyotrophic lateral sclerosis: review of discovery and treatment of tauopathy

Davunetide (NAP) is a leading drug candidate being tested against tauopathy. Davunetide is an eight-amino-acid peptide fragment derived by structure-activity studies from activity-dependent neuroprotective protein, activity-dependent neuroprotective protein (ADNP). ADNP is essential for brain formation. ADNP haploinsufficiency in mice results in tauopathy and cognitive deficits ameliorated by davunetide treatment. This article summarizes in brief recent reviews about NAP protection against tauopathy including the all D-amino acid analogue-D-NAP (AL-408). D-NAP was discovered to have similar neuroprotective functions to NAP in vitro. Here, D-NAP was tested as prophylactic as well as therapeutic treatment for amytrophic lateral sclerosis (ALS) in the widely used TgN(SOD1-G93A)1Gur transgenic mouse model. Results showed D-NAP-associated prophylactic protection, thus daily treatment starting from day 2 of age resulted in a prolonged life course in the D-NAP-treated mice, which was coupled to a significant decrease in tau hyperphosphorylation. These studies correlate protection against tau hyperphosphorylation and longevity in a severe model of ALS-like motor impairment and early mortality. NAP is a first-in-class drug candidate/investigation compound providing neuroprotection coupled to inhibition of tau pathology. D-NAP (AL-408) is a pipeline product.

Neurotrophic Peptides: Potential Drugs for Treatment of Amyotrophic Lateral Sclerosis and Alzheimer's disease

Neurodegenerative diseases are characterized by the progressive loss of neurons and glial cells in the central nervous system correlated to their symptoms. Among these neurodegenerative diseases are Alzheimer's disease (AD) and amyotrophic lateral sclerosis (ALS). Neurodegeneration is mostly restricted to specific neuronal populations: cholinergic neurons in AD and motoneurons in ALS. The demonstration that the onset and progression of neurodegenerative diseases in models of transgenic mice, in particular, is delayed or improved by the application of neurotrophic factors and derived peptides from neurotrophic factors has emphasized their importance in neurorestoration. A range of neurotrophic factors and growth peptide factors derived from activity-dependent neurotrophic factor/activity-dependent neuroprotective protein has been suggested to restore neuronal function, improve behavioral deficits and prolong the survival in animal models. In this review article, we focus on the role of trophic peptides in the improvement of AD and ALS. An understanding of the molecular pathways involved with trophic peptides in these neurodegenerative diseases may shed light on potential therapies.

Regulation of microglia activity by glaucocalyxin-A: attenuation of lipopolysaccharide-stimulated neuroinflammation through NF-κB and p38 MAPK signaling pathways

Microglial cells are the resident macrophages and intrinsic arm of the central nervous system innate immune defense. Microglial cells become activated in response to injury, infection, environmental toxins, and other stimuli that threaten neuronal survival. Therefore, regulating microglial activation may have therapeutic benefits that lead to alleviating the progression of inflammatory-mediated neurodegeneration. In the present study, we investigated the effect of glaucocalyxin A (GLA) isolated from Rabdosia japonica on the production of pro-inflammatory mediators in lipopolysaccharide (LPS)-stimulated primary microglia and BV-2 cells. GLA significantly inhibited LPS-induced production of nitric oxide and reversed the morphological changes in primary microglia. Further, GLA suppressed expression of inducible nitric oxide synthase and cyclooxygenase-2 dose-dependently at the mRNA and protein levels. The production of proinflammatory cytokines such as tumor necrosis factor-α, interleukin-1β (IL)-1β, and IL-6 were inhibited by suppressing their transcriptional activity. Furthermore, GLA suppressed nuclear factor-κB activation by blocking degradation of IκB-α and inhibited the induction of lipocalin-2 expression in LPS-stimulated BV-2 cells. Mechanistic study revealed that the inhibitory effects of GLA were accompanied by blocking the p38 mitogen activated protein kinase signaling pathway in activated microglia. In conclusion, given that microglial activation contributes to the pathogenesis of neurodegenerative diseases, GLA could be developed as a potential therapeutic agent for treating microglia-mediated neuroinflammatory diseases.

Neurotrophic peptides, ADNF-9 and NAP, prevent alcohol-induced apoptosis at midgestation in fetal brains of C57BL/6 mouse

Prenatal alcohol exposure is known to induce fetal brain growth deficits at different embryonic stages. We focused this study on investigating the neuroprotective effects against alcohol-induced apoptosis at midgestation using activity-dependent neurotrophic factor (ADNF)-9, a peptide (SALLRSIPA) derived from activity-dependent neurotrophic factor, and NAP, a peptide (NAPVSIPQ) derived from activity-dependent neuroprotective protein. We used an established fetal alcohol exposure mouse model. On embryonic day 7 (E7), weight-matched pregnant females were assigned to the following groups: (1) ethanol liquid diet (ALC) group with 25 % (4.49 %, v/v) ethanol-derived calories, (2) pair-fed (PF) control group, (3) ALC combined with i.p. injections (1.5 mg/kg) of ADNF-9 (ALC/ADNF-9) group, (4) ALC combined with i.p. injections (1.5 mg/kg) of NAP (ALC/NAP) group, (5) PF liquid diet combined with i.p. injections of ADNF-9 (PF/ADNF-9) group, and (6) PF liquid diet combined with i.p. injections of NAP (PF/NAP) group. On day 15 (E15), fetal brains were collected, weighed, and assayed for TdT-mediated dUTP nick end labeling (TUNEL) staining. ADNF-9 or NAP was administered daily from E7 to E15 alongside PF or ALC liquid diet exposure. Our results show that NAP and ADNF-9 significantly prevented alcohol-induced weight reduction of fetal brains. Apoptosis was determined by TUNEL staining; NAP or ADNF-9 administration alongside alcohol exposure significantly prevented alcohol-induced increase in TUNEL-positive cells in primordium of the cingulate cortex and ganglionic eminence. These findings may pave the path toward potential therapeutics against alcohol intoxication during pregnancy stages.

Subcellular localization and secretion of activity-dependent neuroprotective protein in astrocytes

Activity-dependent neuroprotective protein (ADNP, approximately 123562.8 Da), is synthesized in astrocytes and expression of ADNP mRNA is regulated by the neuroprotective peptide vasoactive intestinal peptide (VIP). The gene that encodes ADNP is conserved in human, rat and mouse, and contains a homeobox domain profile that includes a nuclear-export signal and a nuclear-localization signal. ADNP is essential for embryonic brain development, and NAP, an eight-amino acid peptide that is derived from ADNP, confers potent neuroprotection. Here, we investigate the subcellular localization of ADNP through cell fractionation, gel electrophoresis, immunoblotting and immunocytochemistry using alpha-CNAP, an antibody directed to the neuroprotective NAP fragment that constitutes part of an N-terminal epitope of ADNP. Recombinant ADNP was used as a competitive ligand to measure antibody specificity. ADNP-like immunoreactivity was found in the nuclear cell fraction of astrocytes and in the cytoplasm. In the cytoplasm, ADNP-like immunoreactivity colocalized with tubulin-like immunoreactivity and with microtubular structures, but not with actin microfilaments. Because microtubules are key components of developing neurons and brain, possible interaction between tubulin and ADNP might indicate a functional correlate to the role of ADNP in the brain. In addition, ADNP-like immunoreactivity in the extracellular milieu of astrocytes increased by approximately 1.4 fold after incubation of the astrocytes with VIP. VIP is known to cause astrocytes to secrete neuroprotective/neurotrophic factors, and we suggest that ADNP constitutes part of this VIP-stimulated protective milieu.

Lateralized hippocampal effects of vasoactive intestinal peptide on learning and memory in rats in a model of depression

RATIONALE

Findings of pharmacological studies revealed that vasoactive intestinal peptide (VIP) plays a modulatory role in learning and memory. A role of the peptide in the neurobiological mechanisms of affective disorders was also suggested.

OBJECTIVE

The objectives are to study the involvement of VIP in learning and memory processes after unilateral and bilateral local application into hippocampal CA1 area in rats with a model of depression (bilateral olfactory bulbectomy--OBX) and to test whether VIP receptors could affect cognition.

RESULTS

VIP (50 ng) and combination (VIP(6-28) 10 ng + VIP 50 ng) microinjected bilaterally or into the right CA1 area improved the learning and memory of OBX rats in shuttle-box and step-through behavioral tests as compared to the saline-treated OBX controls. Left-side VIP microinjections did not affect the number of avoidances (shuttle box) and learning criteria (step through) as compared to the left-side saline-treated OBX controls. The administration of the combination into left CA1 influenced positively the performance in the step-through task. VIP antagonist (VIP(6-28), 10 ng) did not affect learning and memory of OBX rats. These findings suggest asymmetric effect of VIP on cognitive processes in hippocampus of rats with OBX model of depression.

CONCLUSION

Our results point to a lateralized modulatory effect of VIP injected in the hippocampal CA1 area on the avoidance deficits in OBX rats. The right CA1 area was predominantly involved in the positive effect of VIP on learning and memory. A possible role of the PAC1 receptors is suggested.

VPAC receptors: structure, molecular pharmacology and interaction with accessory proteins

The vasoactive intestinal peptide (VIP) is a neuropeptide with wide distribution in both central and peripheral nervous systems, where it plays important regulatory role in many physiological processes. VIP displays a large biological functions including regulation of exocrine secretions, hormone release, fetal development, immune responses, etc. VIP appears to exert beneficial effect in neuro-degenerative and inflammatory diseases. The mechanism of action of VIP implicates two subtypes of receptors (VPAC1 and VPAC2), which are members of class B receptors belonging to the super-family of GPCR. This article reviews the current knowledge regarding the structure and molecular pharmacology of VPAC receptors. The structure-function relationship of VPAC1 receptor has been extensively studied, allowing to understand the molecular basis for receptor affinity, specificity, desensitization and coupling to adenylyl cyclase. Those studies have clearly demonstrated the crucial role of the N-terminal ectodomain (N-ted) of VPAC1 receptor in VIP recognition. By using different approaches including directed mutagenesis, photoaffinity labelling, NMR, molecular modelling and molecular dynamic simulation, it has been shown that the VIP molecule interacts with the N-ted of VPAC1 receptor, which is itself structured as a 'Sushi' domain. VPAC1 receptor also interacts with a few accessory proteins that play a role in cell signalling of receptors. Recent advances in the structural characterization of VPAC receptor and more generally of class B GPCRs will lead to the design of new molecules, which could have considerable interest for the treatment of inflammatory and neuro-degenerative diseases.

Vasoactive intestinal peptide enhances striatal plasticity and prevents dopaminergic cell loss in Parkinsonian rats

Destruction of the nigrostriatal dopaminergic pathway by the administration of 6-OHDA generates an animal model of Parkinson's disease. The main characteristic of this progressive neurological disorder is the loss of the dopaminergic neurons located in the substantia nigra pars compacta (SNc). Dopaminergic inputs from the SNc innervate the medium spiny neurons of the striatum and modulate the spontaneous activity of the primary output nuclei of the basal ganglia, globus pallidus interna, and substantia nigra pars reticulata. In our previous studies, we showed that systematically administered vasoactive intestinal peptide (VIP) is effective at reversing motor deficits, decreasing neuronal cell death, and repairing the myelin sheet in parkinsonian rats. In the current study, the effects of VIP on the dendritic morphology of the striatal neurons and the number of dopaminergic neurons in the SNc were examined in 6-OHDA-lesioned rats using Golgi-Cox staining and design-based stereological methods, respectively. Adult Sprague-Dawley rats were separated into sham-operated, bilaterally 6-OHDA lesioned and lesioned + i.p. VIP-injected (25 ng/kg) groups. VIP was first injected 1 h after the intrastriatal 6-OHDA microinjection (every 2 days for 15 days). The 6-OHDA significantly decreased the total number of dopaminergic neurons, branching, and spine density of the medium spiny neurons in the striatum. VIP significantly increased the number of neurons immunostained with tyrosine hydroxylase and the density of spines without altering the branching and the total length of dendrites. In conclusion, VIP might display synaptogenetic activity by enhancing the spine density in the striatum of the parkinsonian rats.

Cholesteryl-functionalized ADNF-9 peptide: enhanced membrane transport through mouse neuroblastoma Neuro-2a cells

A cholesteryl-functionalized derivative of activity dependent neurotrophic factor-9 peptide (a nine amino acid core peptide of activity-dependent neurotrophic factor, acting against Alzheimer's disease) was synthesized aiming at the improvement of its bioavailability. Therefore, its uptake was comparatively investigated with that of its parent peptide by employing mouse neuroblastoma Neuro-2a cells. Owing to the hydrophobic character of this cholesteryl-functionalized peptide, it exhibited enhanced permeability and intracellular uptake while it also retained its low cytotoxicity at concentrations up to 1 μM. FACS analysis also revealed that when Neuro-2a cells were treated with this activity dependent neurotrophic factor-9 derivative, at a concentration of 50 nM, an almost 100% uptake was obtained. In addition, in vitro biological activity experiments showed that the functionalized peptide retained its neurotrophic activity at femtomolar concentration range.

Activity-dependent neurotrophic factor-derived peptide prevents alcohol-induced apoptosis, in part, through Bcl2 and c-Jun N-terminal kinase signaling pathways in fetal brain of C57BL/6 mouse

Fetal alcohol exposure is known to induce alteration in fetal brain development. In this study, we focused on neuroprotection against the effects of alcohol exposure using ADNF-9, a peptide derived from activity-dependent neurotrophic factor. We used a mouse model of fetal alcohol exposure to identify the intracellular mechanisms underlying the neuroprotective effects of ADNF-9. On embryonic day 7 (E7), weight-matched pregnant females were assigned to the following groups: (1) ethanol liquid diet (ALC) of 25% (4.49%, v/v) ethanol-derived calories; (2) pair-fed control (PF); (3) ALC combined with administration (i.p.) of ADNF-9 (ALC/ADNF-9); and (4) pair-fed combined with administration (i.p.) of ADNF-9 (PF/ADNF-9). On E13, fetal brains were collected, weighed, and apoptosis was determined using TdT-mediated dUTP nick-end labeling (TUNEL) assay. Bcl2 protein and phospho-c-Jun N-terminal kinase (JNK) levels were determined using Western blot and enzyme immunometric assay, respectively. ADNF-9 administration significantly prevented alcohol-induced reductions in fetal brain weight. In addition, ADNF-9 prevented an alcohol-induced increase in cell death in the primordium of the cerebral cortex and ganglionic eminence. Western blot analysis of the mitochondrial protein fractions revealed that ADNF-9 administration prevented an alcohol-induced reduction in the Bcl2 level. Moreover, an analysis of the proteins in the upstream signaling pathway revealed that ADNF-9 downregulated the phosphorylation of JNK. These data indicate that the mitochondrial Bcl2 pathway and JNK upstream signaling pathway are the intracellular targets of ADNF-9. The neuroprotective mechanism of action of ADNF-9 provides a direction for potential therapeutics against alcohol-induced neural damage involving mitochondrial dysfunction.

Neuroprotective peptide ADNF-9 in fetal brain of C57BL/6 mice exposed prenatally to alcohol

Background

A derived peptide from activity-dependent neurotrophic factor (ADNF-9) has been shown to be neuroprotective in the fetal alcohol exposure model. We investigated the neuroprotective effects of ADNF-9 against alcohol-induced apoptosis using TUNEL staining. We further characterize in this study the proteomic architecture underlying the role of ADNF-9 against ethanol teratogenesis during early fetal brain development using liquid chromatography in conjunction with tandem mass spectrometry (LC-MS/MS).

Methods

Pregnant C57BL/6 mice were exposed from embryonic days 7-13 (E7-E13) to a 25% ethanol-derived calorie [25% EDC, Alcohol (ALC)] diet, a 25% EDC diet simultaneously administered i.p. ADNF-9 (ALC/ADNF-9), or a pair-fed (PF) liquid diet. At E13, fetal brains were collected from 5 dams from each group, weighed, and frozen for LC-MS/MS procedure. Other fetal brains were fixed for TUNEL staining.

Results

Administration of ADNF-9 prevented alcohol-induced reduction in fetal brain weight and alcohol-induced increases in cell death. Moreover, individual fetal brains were analyzed by LC-MS/MS. Statistical differences in the amounts of proteins between the ALC and ALC/ADNF-9 groups resulted in a distinct data-clustering. Significant upregulation of several important proteins involved in brain development were found in the ALC/ADNF-9 group as compared to the ALC group.

Conclusion

These findings provide information on potential mechanisms underlying the neuroprotective effects of ADNF-9 in the fetal alcohol exposure model.

Targeting VIP and PACAP receptor signalling: new therapeutic strategies in multiple sclerosis

MS (multiple sclerosis) is a chronic autoimmune and neurodegenerative pathology of the CNS (central nervous system) affecting approx. 2.5 million people worldwide. Current and emerging DMDs (disease-modifying drugs) predominantly target the immune system. These therapeutic agents slow progression and reduce severity at early stages of MS, but show little activity on the neurodegenerative component of the disease. As the latter determines permanent disability, there is a critical need to pursue alternative modalities. VIP (vasoactive intestinal peptide) and PACAP (pituitary adenylate cyclase-activating peptide) have potent anti-inflammatory and neuroprotective actions, and have shown significant activity in animal inflammatory disease models including the EAE (experimental autoimmune encephalomyelitis) MS model. Thus, their receptors have become candidate targets for inflammatory diseases. Here, we will discuss the immunomodulatory and neuroprotective actions of VIP and PACAP and their signalling pathways, and then extensively review the structure–activity relationship data and biophysical interaction studies of these peptides with their cognate receptors.

Adeno-associated viral vector-mediated expression of NT4-ADNF-9 fusion gene protects against aminoglycoside-induced auditory hair cell loss in vitro

CONCLUSION

The present study suggests that adeno-associated viral vector AAV2-mediated expression of activity-dependent neurotrophic factor-9 (ADNF-9) in the cochlea could be a promising approach to protect the cochlea from aminoglycoside-induced impairment, although a further in vivo study is needed.

OBJECTIVES

To construct vectors over-expressing ADNF-9 to overcome its short half-life and investigate the effect of ADNF-9 on aminoglycoside-induced hair cell impairment.

METHODS

We ligated ADNF-9 cDNA to the signal and leader peptides of neurotrophin 4 (NT4) and the fusion gene was named NT4-ADNF-9. NT4-ADNF-9 was subcloned into the prokaryotic expression vector pBV220 to obtain pBV220/NT4-ADNF-9. The induced recombinant ADNF-9 proteins were added into the dorsal root ganglia (DRG) cultures of embryonic day 8 chickens. In addition, we constructed the recombinant vector rAAV-NT4-ADNF-9 and transfected rat neonatal organ of Corti explants in the presence of aminoglycoside G418.

RESULTS

Our data showed that the induced expression of ADNF-9 protein could promote cultured DRG neuronal survival and neurite outgrowth. In addition, transfection of rAAV-NT4-ADNF-9 could prevent hair cell loss induced by G418 treatment in the rat organ of Corti.

The cellular prion protein in multiple sclerosis: A potential target for neurotherapeutics?

Multiple sclerosis (MS) is a debilitating disease that affects millions. There is no known cure for the disease and neither is the cause of the disease known. Recent studies have indicated that it is a multi-factorial disease with several genes involved. Importantly, sunlight and vitamin D have been implicated in the progression of the disease. The pathogenesis of MS chiefly involves loss of oligodendrocytes, which in addition to being killed by inflammatory mediators in the CNS, also succumbs to loss of trophic support from astrocytes. Neurotrophins play an important role in myelination and the cellular prion protein (PrPC) is a key player in this process. Although the physiological roles of PrPC remain to be fully understood, increasing evidence suggests multiple roles for PrPC in regulation of cellular immunity and for its interaction with several neurotrophins that are necessary for homeostasis of the nervous system. This mini-review focuses on the findings establishing a crucial role for PrPC in the neuropathogenesis of MS, emphasizing its neuroprotective role. Since MS is a multi-factorial disease with unknown etiology and no cure, this review aims to highlight endogenous repair mechanisms mediated by PrPC that might contribute to functional recovery in MS patients.

The vasoactive intestinal peptide-receptor system is involved in human glioblastoma cell migration

Glioblastoma multiforme (GBM) is the most aggressive form of brain tumor in adults. This cancer has an infiltrative nature and the median survival of patients is about one year. Vasoactive intestinal peptide (VIP) belongs to a structurally related family of polypeptides and is a major regulatory factor in the central and peripheral nervous systems. VIP regulates proliferation of astrocytes and of numerous cancer cell lines and modulates migration in prostatic and colonic cancer cell lines. Little is known about the involvement of VIP and its receptors (VIP-receptor system) in proliferation or migration of GBM cells. The effects of VIP, PACAP and of synthetic VIP antagonists were tested in two human GBM cell lines, M059K and M059J, established from two different parts of a single tumor. In these cells, the data revealed that the VIP-receptor system did not affect proliferation but controlled cell migration. Indeed, in M059K cells which express components of the VIP receptor system, the VIP receptor antagonists and a PACAP antibody enhanced migration. The VIP receptor antagonists increased generation of typical migration-associated processes: filopodia and lamellipodia, and activation of Rac1 and Cdc42 GTPases. Reciprocally, in M059J cells which poorly express the VIP-receptor system, treatments with the agonists VIP and PACAP resulted in decreased cell migration. Furthermore, the peptides appeared to act through a subclass of binding sites displaying an uncommon very high affinity for these ligands. Taken together, these observations suggest that components of the VIP-receptor system negatively regulate cell migration, thus showing potential anti-oncogenic properties.