Tau and caspase 3 as targets for neuroprotection

Distinct Impairments Characterizing Different ADNP Mutants Reveal Aberrant Cytoplasmic-Nuclear Crosstalk

(1) Background: Activity-dependent neuroprotective protein (ADNP) is essential for neuronal structure and function. Multiple de novo pathological mutations in ADNP cause the autistic ADNP syndrome, and they have been further suggested to affect Alzheimer’s disease progression in a somatic form. Here, we asked if different ADNP mutations produce specific neuronal-like phenotypes toward better understanding and personalized medicine. (2) Methods: We employed CRISPR/Cas9 genome editing in N1E-115 neuroblastoma cells to form neuron-like cell lines expressing ADNP mutant proteins conjugated to GFP. These new cell lines were characterized by quantitative morphology, immunocytochemistry and live cell imaging. (3) Results: Our novel cell lines, constitutively expressing GFP-ADNP p.Pro403 (p.Ser404* human orthologue) and GFP-ADNP p.Tyr718* (p.Tyr719* human orthologue), revealed new and distinct phenotypes. Increased neurite numbers (day 1, in culture) and increased neurite lengths upon differentiation (day 7, in culture) were linked with p.Pro403*. In contrast, p.Tyr718* decreased cell numbers (day 1). These discrete phenotypes were associated with an increased expression of both mutant proteins in the cytoplasm. Reduced nuclear/cytoplasmic boundaries were observed in the p.Tyr718* ADNP-mutant line, with this malformation being corrected by the ADNP-derived fragment drug candidate NAP. (4) Conclusions: Distinct impairments characterize different ADNP mutants and reveal aberrant cytoplasmic-nuclear crosstalk.

Neuroprotective Effect of Astragaloside IV on Cerebral Ischemia/Reperfusion Injury Rats Through Sirt1/Mapt Pathway

Background: Ischemic stroke is a common disease with poor prognosis, which has become one of the leading causes of morbidity and mortality worldwide. Astragaloside IV (AS-IV) is the main bioactive ingredient of Astragali Radix (which has been used for ischemic stroke for thousands of years) and has been found to have multiple bioactivities in the nervous system. In the present study, we aimed to explore the neuroprotective effects of AS-IV in rats with cerebral ischemia/reperfusion (CIR) injury targeting the Sirt1/Mapt pathway. Methods: Sprague-Dawley rats (male, 250-280 g) were randomly divided into the Sham group, middle cerebral artery occlusion/reperfusion (MCAO/R) group, AS-IV group, MCAO/R + EX527 (SIRT1-specific inhibitor) group, and AS-IV + EX527 group. Each group was further assigned into several subgroups according to ischemic time (6 h, 1 d, 3 d, and 7 days). The CIR injury was induced in MCAO/R group, AS-IV group, MCAO/R + EX527 group, and AS-IV + EX527 group by MCAO surgery in accordance with the modified Zea Longa criteria. Modified Neurological Severity Scores (mNSS) were used to evaluate the neurological deficits; TTC (2,3,5-triphenyltetrazolium chloride) staining was used to detect cerebral infarction area; Western Blot was used to assess the protein levels of SIRT1, acetylated MAPT (ac-MAPT), phosphorylated MAPT (p-MAPT), and total MAPT (t-MAPT); Real-time Quantitative Polymerase Chain Reaction (qRT-PCR) was used in the detection of Sirt1 and Mapt transcriptions. Results: Compared with the MCAO/R group, AS-IV can significantly improve the neurological dysfunction (p < 0.05), reduce the infarction area (p < 0.05), raise the expression of SIRT1 (p < 0.05), and alleviate the abnormal hyperacetylation and hyperphosphorylation of MAPT (p < 0.05). While compared with the AS-IV group, AS-IV + EX527 group showed higher mNSS scores (p < 0.05), more severe cerebral infarction (p < 0.05), lower SIRT1 expression (p < 0.01), and higher ac-MAPT and p-MAPT levels (p < 0.05). Conclusion: AS-IV can improve the neurological deficit after CIR injury in rats and reduce the cerebral infarction area, which exerts neuroprotective effects probably through the Sirt1/Mapt pathway.

Proteome profiling of different rat brain regions reveals the modulatory effect of prolonged maternal separation on proteins involved in cell death-related processes

Background

Early-life stress in the form of maternal separation can be associated with alterations in offspring neurodevelopment and brain functioning. Here, we aimed to investigate the potential impact of prolonged maternal separation on proteomic profiling of prefrontal cortex, hippocampus and cerebellum of juvenile and young adult rats. A special attention was devoted to proteins involved in the process of cell death and redox state maintenance.

Methods

Long-Evans pups were separated from their mothers for 3 h daily over the first 3 weeks of life (during days 2–21 of age). Brain tissue samples collected from juvenile (22-day-old) and young adult (90-day-old) rats were used for label-free quantitative (LFQ) proteomic analysis. In parallel, selected oxidative stress markers and apoptosis-related proteins were assessed biochemically and by Western blot, respectively.

Results

In total, 5526 proteins were detected in our proteomic analysis of rat brain tissue. Approximately one tenth of them (586 proteins) represented those involved in cell death processes or regulation of oxidative stress balance. Prolonged maternal separation caused changes in less than half of these proteins (271). The observed alterations in protein expression levels were age-, sex- and brain region-dependent. Interestingly, the proteins detected by mass spectrometry that are known to be involved in the maintenance of redox state were not markedly altered. Accordingly, we did not observe any significant differences between selected oxidative stress markers, such as the levels of hydrogen peroxide, reduced glutathione, protein carbonylation and lipid peroxidation in brain samples from rats that underwent maternal separation and from the corresponding controls. On the other hand, a number of changes were found in cell death-associated proteins, mainly in those involved in the apoptotic and autophagic pathways. However, there were no detectable alterations in the levels of cleaved products of caspases or Bcl-2 family members. Taken together, these data indicate that the apoptotic and autophagic cell death pathways were not activated by maternal separation either in adolescent or young adult rats.

Conclusion

Prolonged maternal separation can distinctly modulate expression profiles of proteins associated with cell death pathways in prefrontal cortex, hippocampus and cerebellum of juvenile rats and the consequences of early-life stress may last into adulthood and likely participate in variations in stress reactivity.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40659-021-00327-5.

Immune-modulatory Properties of the Octapeptide NAP in Campylobacter jejuni Infected Mice Suffering from Acute Enterocolitis

Human infections with the food-borne zoonotic pathogen Campylobacter jejuni are progressively rising and constitute serious global public health and socioeconomic burdens. Hence, application of compounds with disease-alleviating properties are required to combat campylobacteriosis and post-infectious sequelae. In our preclinical intervention study applying an acute C. jejuni induced enterocolitis model, we surveyed the anti-pathogenic and immune-modulatory effects of the octapeptide NAP which is well-known for its neuroprotective and anti-inflammatory properties. Therefore, secondary abiotic IL-10^−/− mice were perorally infected with C. jejuni and intraperitoneally treated with synthetic NAP from day 2 until day 5 post-infection. NAP-treatment did not affect gastrointestinal C. jejuni colonization but could alleviate clinical signs of infection that was accompanied by less pronounced apoptosis of colonic epithelial cells and enhancement of cell regenerative measures on day 6 post-infection. Moreover, NAP-treatment resulted in less distinct innate and adaptive pro-inflammatory immune responses that were not restricted to the intestinal tract but could also be observed in extra-intestinal and even systemic compartments. NAP-treatment further resulted in less frequent translocation of viable pathogens from the intestinal tract to extra-intestinal including systemic tissue sites. For the first time, we here provide evidence that NAP application constitutes a promising option to combat acute campylobacteriosis.

The autism/neuroprotection-linked ADNP/NAP regulate the excitatory glutamatergic synapse

Activity-dependent neuroprotective protein (ADNP), essential for brain formation, was discovered as a leading de novo mutated gene causing the autism-like ADNP syndrome. This syndrome is phenotypically characterized by global developmental delays, intellectual disabilities, speech impediments, and motor dysfunctions. The Adnp haploinsufficient mouse mimics the human ADNP syndrome in terms of synapse density and gene expression patterns, as well as in developmental, motor, and cognitive abilities. Peripheral ADNP was also discovered as a biomarker for Alzheimer's disease and schizophrenia, with nasal administration of the ADNP snippet peptide NAP (enhancing endogenous ADNP activity) leading to partial cognitive and functional protection at the cellular, animal and clinical settings. Here, a novel formulation for effective delivery of NAP is provided with superior brain penetration capabilities. Also provided are methods for treating pertinent clinical implications such as autism, cognitive impairments, olfactory deficits, and muscle strength using the formulation in the Adnp haploinsufficient mouse. Results showed a dramatically specific increase in brain/body bioavailability with the new formulation, without breaching the blood brain barrier. Additional findings included improvements using daily intranasal treatments with NAP, at the behavioral and brain structural levels, diffusion tensor imaging (DTI), translatable to clinical practice. Significant effects on hippocampal and cerebral cortical expression of the presynaptic Slc17a7 gene encoding vesicular excitatory glutamate transporter 1 (VGLUT1) were observed at the RNA and immunohistochemical levels, explaining the DTI results. These findings tie for the first time a reduction in presynaptic glutamatergic synapses with the autism/Alzheimer's/schizophrenia-linked ADNP deficiency coupled with amelioration by NAP (CP201).

Dihydrolipoamide dehydrogenase suppression induces human tau phosphorylation by increasing whole body glucose levels in a C. elegans model of Alzheimer's Disease

The microtubule associated tau protein becomes hyperphosphorylated in Alzheimer's disease (AD). While hyperphosphorylation promotes neurodegeneration, the cause and consequences of this abnormal modification are poorly understood. As impaired energy metabolism is an important hallmark of AD progression, we tested whether it could trigger phosphorylation of human tau protein in a transgenic Caenorhabditis elegans model of AD. We found that inhibition of a mitochondrial enzyme of energy metabolism, dihydrolipoamide dehydrogenase (DLD) results in elevated whole-body glucose levels as well as increased phosphorylation of tau. Hyperglycemia and tau phosphorylation were induced by either RNAi suppression of the dld-1 gene or by inhibition of the DLD enzyme by the inhibitor, 2-methoxyindole-2-carboxylic acid (MICA). Although the calcium ionophore A23187 could reduce tau phosphorylation induced by either chemical or genetic suppression of DLD, it was unable to reduce tau phosphorylation induced by hyperglycemia. While inhibition of the dld-1 gene or treatment with MICA partially reversed the inhibition of acetylcholine neurotransmission by tau, neither treatment affected tau inhibited mobility. Conclusively, any abnormalities in energy metabolism were found to significantly affect the AD disease pathology.

Intranasal Delivery of Recombinant NT4-NAP/AAV Exerts Potential Antidepressant Effect

The present study was designed to construct a recombinant adeno-associated virus (rAAV) which can express NAP in the brain and examine whether this virus can produce antidepressant effects on C57 BL/6 mice that had been subjected to open field test and forced swimming test, via nose-to-brain pathway. When the recombinant plasmid pGEM-T Easy/NT4-NAP was digested by EcoRI, 297 bp fragments can be obtained and NT4-NAP sequence was consistent with the designed sequence confirmed by DNA sequencing. When the recombinant plasmid pSSCMV/NT4-NAP was digested by EcoRI, 297 bp fragments is visible. Immunohistochemical staining of fibroblasts revealed that expression of NAP was detected in NT4-NAP/AAV group. Intranasal delivery of NT4-NAP/AAV significantly reduced immobility time when the FST was performed after 1 day from the last administration. The effects observed in the FST could not be attributed to non-specific increases in activity since intranasal delivery of NT4-NAP/AAV did not alter the behavior of the mice during the open field test. The results indicated that a recombinant AAV vector which could express NAP in cells was successfully constructed and NAP may be a potential target for therapeutic action of antidepressant treatment.

New horizons in schizophrenia treatment: autophagy protection is coupled with behavioral improvements in a mouse model of schizophrenia

Autophagy plays a key role in the pathophysiology of schizophrenia as manifested by a 40% decrease in BECN1/Beclin 1 mRNA in postmortem hippocampal tissues relative to controls. This decrease was coupled with the deregulation of the essential ADNP (activity-dependent neuroprotector homeobox), a binding partner of MAP1LC3B/LC3B (microtubule-associated protein 1 light chain 3 β) another major constituent of autophagy. The drug candidate NAP (davunetide), a peptide fragment from ADNP, enhanced the ADNP-LC3B interaction. Parallel genetic studies have linked allelic variation in the gene encoding MAP6/STOP (microtubule-associated protein 6) to schizophrenia, along with altered MAP6/STOP protein expression in the schizophrenic brain and schizophrenic-like behaviors in Map6-deficient mice. In this study, for the first time, we reveal significant decreases in hippocampal Becn1 mRNA and reversal by NAP but not by the antipsychotic clozapine (CLZ) in Map6-deficient (Map6(+/-)) mice. Normalization of Becn1 expression by NAP was coupled with behavioral protection against hyperlocomotion and cognitive deficits measured in the object recognition test. CLZ reduced hyperlocomotion below control levels and did not significantly affect object recognition. The combination of CLZ and NAP resulted in normalized outcome behaviors. Phase II clinical studies have shown NAP-dependent augmentation of functional activities of daily living coupled with brain protection. The current studies provide a new mechanistic pathway and a novel avenue for drug development.

ADNP: in search for molecular mechanisms and innovative therapeutic strategies for frontotemporal degeneration

Activity-dependent neuroprotective protein (ADNP) is deregulated in Alzheimer's disease (AD) and in schizophrenia and mutated in autism. In mice, ADNP is essential for brain formation and ADNP haploinsufficiency is associated with cognitive and social deficits and tauopathy. Tauopathy, a major pathology in AD, is also found in ~45% of frontotemporal dementias (FTDs). Tau transcript, a product of a single gene, undergoes alternative splicing. Tau splicing seems to be altered in FTD brain. In transgenic mice overexpressing a mutated tau in the cerebral cortex, significant increases in ADNP transcript expression were observed in the cerebral cortex of young transgenic mice (~disease onset) and a marked decrease with aging as compared to control littermates. ADNP is a member of the SWItch/Sucrose NonFermentable (SWI/SNF) chromatin remodeling complex also associated with alternative splicing, including tau transcript splicing. Further cellular interactions of ADNP include association with microtubules, with tau being a microtubule—associated protein. NAP (davundetide), a novel drug candidate derived from ADNP, increases ADNP-microtubule association and protects against tauopathy and cognitive deficiencies in mice. Although, NAP did not provide protection in progressive supranuclear palsy (PSP), a pure tauopathy, it increased cognitive scores in amnestic mild cognitively impaired patients and protected functional activity in schizophrenia patients. This mini-review focuses on ADNP in the context of FTD and tau/microtubules and proposes NAP as a novel drug target for future clinical evaluations.

Anti-Inflammatory Properties of NAP in Acute Toxoplasma Gondii-Induced Ileitis in Mice

The octapeptide NAP has been shown to exert neuroprotective properties. Here, we investigated potential anti-inflammatory effects of NAP in an acute ileitis model. To address this, C57BL/6j mice were perorally infected with Toxoplasma gondii (day 0). Within 1 week postinfection (p.i.), placebo (PLC)-treated mice developed acute ileitis due to Th1-type immune responses. Mice that were subjected to intraperitoneal NAP treatment from day 1 until day 6 p.i., however, developed less distinct macroscopic and microscopic disease as indicated by less body weight loss, less distinct histopathological ileal changes, and lower ileal apoptotic, but higher proliferating cell numbers, less abundance of neutrophils, macrophages, monocytes, and T lymphocytes, but higher numbers of regulatory T cells in the ileal mucosa and lamina propria, and lower concentrations of pro-inflammatory mediators in the ilea as compared to PLC controls at day 7 p.i. Remarkably, NAP-mediated anti-inflammatory effects could also be observed in extra-intestinal compartments including liver and spleen. Strikingly, lower MCP-1, TNF, and IL-12p70 serum concentrations in NAP as compared to PLC-treated mice at day 7 p.i. indicate a pronounced systemic anti-inflammatory effect of NAP in acute ileitis. These findings provide first evidence for NAP as a potential novel treatment option in intestinal inflammation.

Autophagy has a key role in the pathophysiology of schizophrenia

Autophagy is a process preserving the balance between synthesis, degradation and recycling of cellular components and is therefore essential for neuronal survival and function. Several key proteins govern the autophagy pathway including beclin1 and microtubule associated protein 1 light chain 3 (LC3). Here, we show a brain-specific reduction in beclin1 expression in postmortem hippocampus of schizophrenia patients, not detected in peripheral lymphocytes. This is in contrast with activity-dependent neuroprotective protein (ADNP) and ADNP2, which we have previously found to be deregulated in postmortem hippocampal samples from schizophrenia patients, but that now showed a significantly increased expression in lymphocytes from related patients, similar to increases in the anti-apoptotic, beclin1-interacting, Bcl2. The increase in ADNP was associated with the initial stages of the disease, possibly reflecting a compensatory effect. The increase in ADNP2 might be a consequence of neuroleptic treatment, as seen in rats subjected to clozapine treatment. ADNP haploinsufficiency in mice, which results in age-related neuronal death, cognitive and social dysfunction, exhibited reduced hippocampal beclin1 and increased Bcl2 expression (mimicking schizophrenia and normal human aging). At the protein level, ADNP co-immunoprecipitated with LC3B suggesting a direct association with the autophagy process and paving the path to novel targets for drug design.

Protein profiling reveals antioxidant and signaling activities of NAP (Davunetide) in rodent hippocampus exposed to hypobaric hypoxia

NAP (davunetide) is a clinical octapeptide and reportedly possesses neuroprotective, neurotrophic and cognitive protective properties. The information for NAP-mediated neuroproteome changes and associated signaling pathways during hypoxia will help in drug development programmes across the world. In the present study, we have evaluated the antioxidant activities of NAP in rat hippocampus exposed to hypobaric hypoxia (25,000 ft, 282 mm Hg) for 3, 6 and 12 h respectively. Using 2D-gel electrophoresis (2D-GE) with matrix-assisted laser desorption ionization time of flight (MALDI-TOF/TOF) mass spectrometry, we have identified altered expression of 80 proteins in NAP-supplemented hippocampus after hypoxia. Pathway analysis revealed that NAP supplementation significantly regulated oxidative stress response, oxidoreductase activity and cellular response to stress pathways during hypoxia. Additionally, NAP supplementation also regulated energy production pathways along with AMP-activated protein kinase (AMPK) signaling and signaling by Rho family GTPases pathways. We observed higher expression of antioxidant Sod1, Eno1, Prdx2 and Prdx5 proteins that were subsequently validated by Western blotting. A higher level of Prdx2 was also observed by immunohistochemistry in NAP-supplemented hippocampus during hypoxia. In corroboration, we are able to detect significant lower level of protein carbonyls in NAP-supplemented hypoxic hippocampus suggesting amelioration of oxidant molecules by NAP supplementation. These results emphasize the antioxidant and signaling properties of NAP in rodent hippocampus during hypobaric hypoxia.

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.

Tau oligomers as potential targets for Alzheimer's diagnosis and novel drugs

A cumulative number of approaches have been carried out to elucidate the pathogenesis of Alzheimer’s disease (AD). Tangles formation has been identified as a major event involved in the neurodegenerative process, due to the conversion of either soluble peptides or oligomers into insoluble filaments. Most of recent studies share in common the observation that formation of tau oligomers and the subsequent pathological filaments arrays is a critical step in AD etiopathogenesis. Oligomeric tau species appear to be toxic for neuronal cells, and therefore appear as an appropriate target for the design of molecules that may control morphological and functional alterations leading to cognitive impairment. Thus, current therapeutic strategies are aimed at three major types of molecules: (1) inhibitors of protein kinases and phosphatases that modify tau and that may control neuronal degeneration, (2) methylene blue, and (3) natural phytocomplexes and polyphenolics compounds able to either inhibit the formation of tau filaments or disaggregate them. Only a few polyphenolic molecules have emerged to prevent tau aggregation. In this context, fulvic acid (FA), a humic substance, has potential protective activity cognitive impairment. In fact, formation of paired helical filaments in vitro, is inhibited by FA affecting the length of fibrils and their morphology.

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.

WIN55,212-2 protects oligodendrocyte precursor cells in stroke penumbra following permanent focal cerebral ischemia in rats

AIM

To explore whether the synthetic cannabinoid receptor agonist WIN55,212-2 could protect oligodendrocyte precursor cells (OPCs) in stroke penumbra, thereby providing neuroprotection following permanent focal cerebral ischemia in rats.

METHODS

Adult male SD rats were subjected to permanent middle cerebral artery occlusion (p-MCAO). The animals were administered WIN55,212-2 at 2 h, and sacrificed at 24 h after the ischemic insult. The infarct volumes and brain swelling were assessed. The expression of cannabinoid receptor type 1 (CB1) in the stroke penumbra was examined using Western blot assay. The pathological changes and proliferation of neural glial antigen 2-positive OPCs (NG2(+) cells) in the stroke penumbra were studied using immunohistochemistry staining.

RESULTS

p-MCAO significantly increased the expression of CB1 within the stroke penumbra with the highest level appearing at 2 h following the ischemic insult. Administration of WIN55,212-2 (9 mg/kg, iv) significantly attenuated the brain swelling, and reduced the infarct volume as well as the number of tau-immunoreactive NG2(+) cells (tau-1(+)/NG2(+) cells) in the stroke penumbra. Moreover, WIN55,212-2 significantly promoted the proliferation of NG2(+) cells in the stroke penumbra and in the ipsilateral subventricular zone at 24 h following the ischemic insult. Administration of the selective CB1 antagonist rimonabant (1 mg/kg, iv) partially blocked the effects caused by WIN55,212-2.

CONCLUSION

Tau-1 is expressed in NG2(+) cells following permanent focal cerebral ischemic injury. Treatment with WIN55,212-2 reduces the number of tau-1(+)/NG2(+) cells and promotes NG2(+) cell proliferation in the stroke penumbra, which are mediated partially via CB1 and may contribute to its neuroprotective effects.

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.

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.