davunetide and Tauopathies

This review focuses on the therapeutic effects and mechanisms of action of NAP (davunetide), an eight amino acid snippet derived from activity-dependent neuroprotective protein (ADNP) which was discovered in our laboratory. We have recently described the effects of NAP in neurodegenerative disorders, and we now review the beneficial effects of NAP and other microtubule-stabilizing agents on impairments in axonal transport. Experiments in animal models of microtubule-deficiency including tauopathy (spanning from drosophila to mammals) showed protection of axonal transport by microtubule-stabilizers and NAP, which was coupled to motor and cognitive protection. Clinical trials with NAP (davunetide) are reviewed paving the path to future developments.

Topics: Animals; Antineoplastic Agents; Axonal Transport; Brain; Clinical Trials as Topic; Humans; Mice; Microtubules; Molecular Targeted Therapy; Neurodegenerative Diseases; Neuroprotective Agents; Oligopeptides; Rats; tau Proteins; Tauopathies; Tubulin Modulators

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.

Topics: Amyotrophic Lateral Sclerosis; Animals; Disease Models, Animal; Drug Evaluation, Preclinical; Female; Humans; Male; Mice; Mice, Inbred C57BL; Mice, Transgenic; Neuroprotective Agents; Oligopeptides; Phosphorylation; Point Mutation; Protein Processing, Post-Translational; Recombinant Fusion Proteins; Superoxide Dismutase; Superoxide Dismutase-1; tau Proteins; Tauopathies

Activity-dependent neuroprotective protein (ADNP) is essential for brain formation and partial deficiency in ADNP results in cognitive deficits coupled with tauopathy and neuronal cell death. Our previous results indicated that a peptide snippet from ADNP, NAPVSIPQ (NAP, generic name, davunetide) can restore in part ADNP deficiencies. NAP interacts with tubulin and this interaction is displaced by the NAP related peptide that is derived from activity-dependent neurotrophic factor (ADNF), SALLRSIPA (SAL) and its all D-amino acid peptide derivative (D-SAL, also known as AL-309). Both NAP and D-SAL were shown to protect neurons against amyloid beta toxicity however the mechanism of protection is still under investigation. In addition, NAP protects against tau hyperphosphorylation associated with ADNP deficiency, in vivo. To investigate whether the mechanism of in vitro neuroprotection relates to the in vivo protection against tauopathy and to draw potential additional parallelism between NAP and D-SAL, we asked if: 1]NAP and D-SAL protect against amyloid beta related tau hyperphosphorylation in vitro; and 2] D-SAL protects against haploinsufficiency in ADNP, inhibiting tauopathy in vivo. Assessment of NAP and D-SAL neuroprotection in primary cortical neuro-glial cultures treated with amyloid beta showed that both peptides reduced toxin-related neuronal damage and protected against tau hyperphosphorylation. In vivo, chronic D-SAL administration protected against tau hyperphosphorylation associated with ADNP deficiency (ADNP+/- mice), showing for the first time protection against deficits in odor discrimination and in social recognition. These studies associate neuroprotection in vivo and in vitro and provide a broad base for future drug development based on NAP and D-SAL against multiple neurodegenerative conditions.

Topics: Amyloid beta-Peptides; Animals; Homeodomain Proteins; Humans; Mice; Nerve Tissue Proteins; Neurons; Neuroprotective Agents; Oligopeptides; Peptide Fragments; Phosphorylation; tau Proteins; Tauopathies

Topics: Amino Acid Motifs; Amyotrophic Lateral Sclerosis; Animals; Axonal Transport; Cell Line, Tumor; Disease Models, Animal; Dynamins; Endocytosis; Homeodomain Proteins; Hydrazones; Mice; Mice, Knockout; Microtubule-Associated Proteins; Microtubules; Nerve Tissue Proteins; Neurons; Neuroprotective Agents; Oligopeptides; Parkinsonian Disorders; Tauopathies

The microtubule (MT) associated protein Tau is instrumental for the regulation of MT assembly and dynamic instability, orchestrating MT-dependent cellular processes. Aberration in Tau post-translational modifications ratio deviation of spliced Tau isoforms 3 or 4 MT binding repeats (3R/4R) have been implicated in neurodegenerative tauopathies. Activity-dependent neuroprotective protein (ADNP) is vital for brain formation and cognitive function. ADNP deficiency in mice causes pathological Tau hyperphosphorylation and aggregation, correlated with impaired cognitive functions. It has been previously shown that the ADNP-derived peptide NAP protects against ADNP deficiency, exhibiting neuroprotection, MT interaction and memory protection. NAP prevents MT degradation by recruitment of Tau and end-binding proteins to MTs and expression of these proteins is required for NAP activity. Clinically, NAP (davunetide, CP201) exhibited efficacy in prodromal Alzheimer's disease patients (Tau3R/4R tauopathy) but not in progressive supranuclear palsy (increased Tau4R tauopathy). Here, we examined the potential preferential interaction of NAP with 3R vs. 4R Tau, toward personalized treatment of tauopathies. Affinity-chromatography showed that NAP preferentially interacted with Tau3R protein from rat brain extracts and fluorescence recovery after photobleaching assay indicated that NAP induced increased recruitment of human Tau3R to MTs under zinc intoxication, in comparison to Tau4R. Furthermore, we showed that NAP interaction with tubulin (MTs) was inhibited by obstruction of Tau-binding sites on MTs, confirming the requirement of Tau-MT interaction for NAP activity. The preferential interaction of NAP with Tau3R may explain clinical efficacy in mixed vs. Tau4R pathologies, and suggest effectiveness in Tau3R neurodevelopmental disorders.

Topics: Alzheimer Disease; Animals; Brain; Cell Line, Tumor; Cell Survival; Cognition; Fluorescence Recovery After Photobleaching; Homeodomain Proteins; Humans; Mice; Microtubules; Oligopeptides; Paclitaxel; Phosphorylation; Protein Binding; Protein Domains; Protein Processing, Post-Translational; Rats; Rats, Sprague-Dawley; tau Proteins; Tauopathies; Tubulin; Zinc

Alzheimer's disease (AD) is a devastating neurodegenerative disease causing irreversible cognitive decline in the elderly. There is no disease-modifying therapy for this condition and the mechanisms underpinning neuronal dysfunction and neurodegeneration are unclear. Compromised cytoskeletal integrity within neurons is reported in AD. This is believed to result from loss-of-function of the microtubule-associated protein tau, which becomes hyper-phosphorylated and deposits into neurofibrillary tangles in AD. We have developed a Drosophila model of tauopathy in which abnormal human tau mediates neuronal dysfunction characterised by microtubule destabilisation, axonal transport disruption, synaptic defects and behavioural impairments. Here we show that a microtubule-stabilising drug, NAPVSIPQ (NAP), prevents as well as reverses these phenotypes even after they have become established. Moreover, it does not alter abnormal tau levels indicating that it by-passes toxic tau altogether. Thus, microtubule stabilisation is a disease-modifying therapeutic strategy protecting against tau-mediated neuronal dysfunction, which holds great promise for tauopathies like AD.

Topics: Animals; Axonal Transport; Disease Models, Animal; Drosophila; Microtubules; Motor Activity; Neurons; Oligopeptides; Phosphorylation; Synapses; tau Proteins; Tauopathies

It is commonly stated that microtubules gradually disintegrate as tau becomes dissociated from them in tauopathies such as Alzheimer's disease. However, there has been no compelling evidence to date that such disintegration is due to depolymerization of microtubules from their ends. In recent studies, we have shown that neurons contain sufficient levels of the microtubule-severing protein termed katanin to completely break down the axonal microtubule array if not somehow attenuated. The presence of tau on axonal microtubules renders them notably less sensitive to katanin, prompting us to posit that microtubule disintegration in tauopathies may result from elevated severing of the microtubules as they lose tau. In support of this hypothesis, we demonstrate here that pathogenic tau mutants that bind less strongly to microtubules than wild-type tau provide correspondingly less protection against katanin-based severing. Using cultured rat hippocampal neurons, we pursued two potential therapies for fortifying axonal microtubules against excess severing by katanin, under conditions of tau depletion. We found that either deacetylating the microtubules via overexpression of HDAC6 or treating the neurons with NAP, a microtubule-interacting neuroprotective peptide, resulted in notable protection of the microtubules against katanin-based loss. In both cases, we found that these treatments also diminished the characteristic increase in axonal branching that normally accompanies tau depletion, an effect that is also known to be directly related to the severing of microtubules. These observations may be useful in developing therapeutic regimes for preserving microtubules against loss in the axons of patients suffering from tauopathies.

Topics: Adenosine Triphosphatases; Animals; Cell Line; Gene Expression Regulation; Hippocampus; Histone Deacetylase 6; Histone Deacetylases; Humans; Katanin; Microtubules; Mutant Proteins; Neurons; Oligopeptides; Rats; RNA Interference; tau Proteins; Tauopathies; Tubulin

NAP (NAPVSIPQ) provides broad neuroprotection through microtubule interaction. Here, NAP was investigated for neuroprotection in an in vivo tauopathy model. Transgenic mice (2-month-old) that express the human double mutant tau protein [P301S;K257T] fused to the tau promoter, were subjected to daily intranasal drug treatment for approximately 5 months. Results showed increased performance in the NAP-treated mice compared to controls, as demonstrated in the Morris water maze, (p<0.05). Treatment continued for 5 additional months and mouse cortices were biochemically analyzed. Protein extraction identified increased tau protein content in the heat-stable soluble fraction, which contains microtubule-associated tau, in the 1-year-old NAP-treated mice as compared to vehicle-controls. Tau phosphorylation (Ser 202) increased in the tau-transgenic mice compared to control mice, and was significantly reduced in NAP-treated mice. The current studies show for the first time activity for NAP in a "pure" tauopathy model, positioning it as a promising drug candidate in multiple neurodegenerative tauopathies.

Topics: Animals; Brain; Cytoprotection; Disease Models, Animal; Humans; In Vitro Techniques; Memory Disorders; Mice; Mice, Transgenic; Neurofibrillary Tangles; Neuroprotective Agents; Oligopeptides; Phosphorylation; Solubility; tau Proteins; Tauopathies; Treatment Outcome

Neurofibrillary tangles composed of aggregated, hyperphosphorylated tau in an abnormal conformation represent one of the major pathological hallmarks of Alzheimer's disease (AD) and other tauopathies. However, recent data suggest that the pathogenic processes leading to cognitive impairment occur before the formation of classic tangles. In the earliest stages of tauopathy, tau detaches from microtubules and accumulates in the cytosol of the somatodendritic compartment of cells. Either as a cause or an effect, tau becomes hyperphosphorylated and aggregates into paired helical filaments that comprise the tangles. To assess whether an agent that modulates microtubule function can inhibit the pathogenic process and prevent cognitive deficits in a transgenic mouse model with AD-relevant tau pathology, we administered the neuronal tubulin-preferring agent, NAPVSIPQ (NAP). Three months of treatment with NAP at an early-to-moderate stage of tauopathy reduced the levels of hyperphosphorylated soluble and insoluble tau. A 6-month course of treatment improved cognitive function. Although nonspecific tubulin-interacting agents commonly used for cancer therapy are associated with adverse effects due to their anti-mitotic activity, no adverse effects were found after 6 months of exposure to NAP. Our results suggest that neuronal microtubule interacting agents such as NAP may be useful therapeutic agents for the treatment or prevention of tauopathies.

Topics: Alzheimer Disease; Animals; Cognition; Disease Models, Animal; Mice; Mice, Transgenic; Microtubules; Neurons; Oligopeptides; tau Proteins; Tauopathies; Treatment Outcome