A femtomolar-acting neuroprotective peptide induces increased levels of heat shock protein 60 in rat cortical neurons: a potential neuroprotective mechanism

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.

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.

Neuroprotective effects of the gliopeptide ODN in an in vivo model of Parkinson's disease

Parkinson's disease (PD) is a neurodegenerative disorder characterized by a progressive loss of dopamine (DA) neurons through apoptotic, inflammatory and oxidative stress mechanisms. The octadecaneuropeptide (ODN) is a diazepam-binding inhibitor (DBI)-derived peptide, expressed by astrocytes, which protects neurons against oxidative cell damages and apoptosis in an in vitro model of PD. The present study reveals that a single intracerebroventricular injection of 10 ng ODN 1 h after the last administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) prevented the degeneration of DA neurons induced by the toxin in the substantia nigra pars compacta of mice, 7 days after treatment. ODN-mediated neuroprotection was associated with a reduction of the number of glial fibrillary acidic protein-positive reactive astrocytes and a strong inhibition of the expression of pro-inflammatory genes such as interleukins 1β and 6, and tumor necrosis factor-α. Moreover, ODN blocked the inhibition of the anti-apoptotic gene Bcl-2, and the stimulation of the pro-apoptotic genes Bax and caspase-3, induced by MPTP in the substantia nigra pars compacta. ODN also decreased or even in some cases abolished MPTP-induced oxidative damages, overproduction of reactive oxygen species and accumulation of lipid oxidation products in DA neurons. Furthermore, DBI knockout mice appeared to be more vulnerable than wild-type animals to MPTP neurotoxicity. Taken together, these results show that the gliopeptide ODN exerts a potent neuroprotective effect against MPTP-induced degeneration of nigrostriatal DA neurons in mice, through mechanisms involving downregulation of neuroinflammatory, oxidative and apoptotic processes. ODN may, thus, reduce neuronal damages in PD and other cerebral injuries involving oxidative neurodegeneration.

Alcohol Teratogenesis: Mechanisms of Damage and Strategies for Intervention

There are multiple mechanisms by which alcohol can damage the developing brain, but the type of damage induced will depend on the amount and developmental timing of exposure, along with other maternal and genetic factors. This article reviews current perspectives on how ethanol can produce neuroteratogenic effects by its interactions with molecular regulators of brain development. The current evidence suggests that alcohol produces many of its damaging effects by exerting specific actions on molecules that regulate key developmental processes (e.g., L1 cell adhesion molecule, alcohol dehydrogenase, catalase), interfering with the early development of midline serotonergic neurons and disrupting their regulatory-signaling function for other target brain structures, interfering with trophic factors that regulate neurogenesis and cell survival, or inducing excessive cell death via oxidative stress or activation of caspase-3 proteases. The current understanding of pathogenesis mechanisms suggests several strategic approaches to develop rational molecular prevention. However, the development of behavioral and biologic treatments for alcohol-affected children is crucial because it is unlikely that effective delivery of preventative interventions can realistically be achieved in ways to prevent prenatal damage in at-risk pregnancies. Toward that end, behavioral training that promotes experience-dependent neuroplasticity has been effective in a rat model of cerebellar damage induced by alcohol exposure during the period of brain development that is comparable to that of the human third trimester.

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.

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.

Curcumin protects against staurosporine toxicity in rat neurons

OBJECTIVE

Curcumin is extracted from the turmeric plant (Curcuma longa Linn.) and is widely used as a food additive and traditional medicine. The present study investigated the activity of curcumin against staurosporine (STS) toxicity in cell culture.

METHODS

Rat hippocampal neurons in primary culture were exposed to STS (20 μmol/L) and treated with curcumin (20 μmol/L). Cell viability was tested by MTT assay and reactive oxygen species (ROS) were measured using the MitoSOX™ red mitochondrial superoxide indicator. Western blot was used to assess changes in the levels of caspase-3 (Csp3), heat shock protein 70 (Hsp70) and Akt.

RESULTS

The results showed that curcumin protects against STS-induced cytotoxicity in rat hippocampal neurons. Csp3, Hsp70, Akt and ROS activation may be involved in this protection.

CONCLUSION

Curcumin could be a potential drug for combination with STS in cancer treatment to reduce the unwanted cytotoxicity of STS.

Neuroprotection from diazinon-induced toxicity in differentiating murine N2a neuroblastoma cells

In previous work, the outgrowth of axon-like processes by differentiating mouse N2a neuroblastoma cells was shown to be inhibited by exposure to 10 microM diazinon. In the present work, N2a cells were induced to differentiate for 24 h in the presence and absence of 10 microM diazinon and 20% (v/v) conditioned medium derived from differentiating rat C6 glioma cells. Cells were then stained or lysed for morphological and biochemical analyses, respectively. The data showed that co-treatment with conditioned medium prevented the neurite inhibitory effect of diazinon. Furthermore, a significant recovery was also observed in the reduced levels of neurofilament heavy chain (NFH), heat shock protein-70 (HSP-70) and growth-associated protein-43 (GAP-43) observed as a result of diazinon treatment in the absence of conditioned medium, as seen by densitometric analysis of Western blots of cell lysates probed with monoclonal antibodies N52, BRM-22 and GAP-7B10. By contrast, no significant change was noted in the reactivity of cell lysates with antibodies against alpha- and beta-tubulin under any condition tested. After pre-incubation with a polyclonal anti-glial cell line-derived neurotrophic factor (GDNF) antibody, conditioned medium derived from rat C6 glioma cells lost its ability to protect N2a cells against the neurite inhibitory effects of diazinon. In conclusion, these data demonstrate that C6 conditioned medium protects N2a cells from the neurite inhibitory effects of diazinon by blocking molecular events leading to axon damage and that GDNF is implicated in these effects.

VIP, from gene to behavior and back: summarizing my 25 years of research

Vasoactive intestinal peptide (VIP) is an interesting example of a 28-amino acid neuropeptide that is abundantly expressed in discrete brain regions/neurons and hence may contribute to brain function. This short review summarizes my own point of view and encompasses 25 years of work and over 100 publications targeting the understanding of VIP production and biological activity. The review starts with our original cloning of the VIP gene, it then continues to discoveries of regulation of VIP synthesis and the establishment of the first VIP transgenic mice. The review ends with the identification of novel VIP analogs that helped decipher VIP's important role during development, in regulation of the biological clock(s) and diurnal rhythms, sexual activity, learning and memory as well as social behavior, and cancer. This review cites only articles that I have coauthored and gives my own perspective of this exciting ever-growing field.

Peptidergic agonists of activity-dependent neurotrophic factor protect against prenatal alcohol-induced neural tube defects and serotonin neuron loss

INTRODUCTION

Prenatal alcohol exposure via maternal liquid diet consumption by C57BL/6 (B6) mice causes conspicuous midline neural tube deficit (dysraphia) and disruption of genesis and development of serotonin (5-HT) neurons in the raphe nuclei, together with brain growth retardation. The current study tested the hypothesis that concurrent treatment with either an activity-dependent neurotrophic factor (ADNF) agonist peptide [SALLRSIPA, (SAL)] or an activity-dependent neurotrophic protein (ADNP) agonist peptide [NAPVSIPQ, (NAP)] would protect against these alcohol-induced deficits in brain development.

METHODS

Timed-pregnant B6 dams consumed alcohol from embryonic day 7 (E7, before the onset of neurulation) until E15. Fetuses were obtained on E15 and brain sections processed for 5-HT immunocytochemistry, for evaluation of morphologic development of the brainstem raphe and its 5-HT neurons. Additional groups were treated either with SAL or NAP daily from E7 to E15 to assess the potential protective effects of these peptides. Measures of incomplete occlusion of the ventral canal and the frequency and extent of the openings in the rhombencephalon were obtained to assess fetal dysraphia. Counts of 5-HT-immunostained neurons were also obtained in the rostral and caudal raphe.

RESULTS

Prenatal alcohol exposure resulted in abnormal openings along the midline and delayed closure of ventral canal in the brainstem. This dysraphia was associated with reductions in the number of 5-HT neurons both in the rostral raphe nuclei (that gives rise to ascending 5-HT projections) and in the caudal raphe (that gives rise to the descending 5-HT projections). Concurrent treatment of the alcohol-consuming dams with SAL prevented dysraphia and protected against the alcohol-induced reductions in 5-HT neurons in both the rostral and caudal raphe. NAP was less effective in protecting against dysraphia and did not protect against 5-HT loss in the rostral raphe, but did protect against loss in the caudal raphe.

CONCLUSIONS

These findings further support the potential usefulness of these peptides for therapeutic interventions in pregnancies at risk for alcohol-induced developmental deficits. Notably, the ascending 5-HT projections of the rostral raphe have profound effects in regulating forebrain development and function, and the descending 5-HT projections of the caudal raphe are critical for regulating respiration. Protection of the rostral 5-HT-system may help prevent structural and functional deficits linked to abnormal forebrain development, and protection of the caudal systems may also reduce the increased risk for sudden infant death syndrome associated with prenatal alcohol exposure.

Chaperones and proteases: cellular fold-controlling factors of proteins in neurodegenerative diseases and aging

The formation of toxic protein aggregates is a common denominator to many neurodegenerative diseases and aging. Accumulation of toxic, possibly infectious protein aggregates induces a cascade of events, such as excessive inflammation, the production of reactive oxygen species, apoptosis and neuronal loss. A network of highly conserved molecular chaperones and of chaperone-related proteases controls the fold-quality of proteins in the cell. Most molecular chaperones can passively prevent protein aggregation by binding misfolding intermediates. Some molecular chaperones and chaperone-related proteases, such as the proteasome, can also hydrolyse ATP to forcefully convert stable harmful protein aggregates into harmless natively refoldable, or protease-degradable, polypeptides. Molecular chaperones and chaperone-related proteases thus control the delicate balance between natively folded functional proteins and aggregation-prone misfolded proteins, which may form during the lifetime and lead to cell death. Abundant data now point at the molecular chaperones and the proteases as major clearance mechanisms to remove toxic protein aggregates from cells, delaying the onset and the outcome of protein-misfolding diseases. Therapeutic approaches include treatments and drugs that can specifically induce and sustain a strong chaperone and protease activity in cells and tissues prone to toxic protein aggregations.

Neuroprotective effect of the peptides ADNF-9 and NAP on hypoxic-ischemic brain injury in neonatal rats

Perinatal asphyxia is an important cause of neonatal mortality and subsequent serious sequelae such as motor and cognitive deficits and seizures. Recent studies have demonstrated that short peptides derived from activity-dependent neurotrophic factor (ADNF) and activity-dependent neuroprotective protein (ADNP) are neuroprotective at femtomolar concentrations. However, the effect of these peptides on the hypoxic-ischemic brain injury model is unknown. The aim of this study is to investigate the effects of the peptides ADNF-9 and NAP on neurodegeneration and cerebral nitric oxide (NO) production in a neonatal rat model of hypoxic-ischemic brain injury. Seven-day-old Wistar Albino rat pups have been used in the study (n=42). Experimental groups in the study were: sham-operated group, ADNF-9-treated hypoxia-ischemia group, NAP-treated hypoxia-ischemia group, ADNF-9+NAP-treated hypoxia-ischemia group, and vehicle-treated group. In hypoxia-ischemia groups, left common carotid artery was ligated permanently on the seventh postnatal day. Two hours after the procedure, hypoxia (92% nitrogen and 8% oxygen) was applied for 2.5 h. ADNF-9, NAP, and ADNF-9+NAP were injected (intraperitoneally; i.p.) as a single dose immediately after the hypoxia period. Brain nitrite levels, neuronal cell death, and apoptosis were evaluated in both hemispheres (carotid ligated or nonligated) 72 h after the hypoxic-ischemic insult. Histopathological evaluation demonstrated that ADNF-9 and NAP significantly diminished number of "apoptotic cells" in the hippocampal CA1, CA2, CA3, and gyrus dentatus regions in both hemispheres (ligated and nonligated). When compared with vehicle-treated group, combination treatment with ADNF-9+NAP did not significantly reduce "apoptotic cell death" in any of the hemispheres. ADNF-9 and NAP, when administered separately, significantly preserved the number of neurons CA1, CA2, CA3, and dentate gyrus regions of the hippocampus, when compared with vehicle-treated group. The density of the CA1, CA2, and dentate gyrus neurons was significantly higher when combination therapy with ADNF-9+NAP was used in the carotid ligated hemispheres. In the nonligated hemispheres, combination therapy preserved the number of neurons only in the CA1 and dentate gyrus regions. Brain nitrite levels were evaluated by Griess reagent and showed that hypoxic-ischemic injury caused a significant increase in NO production. Brain nitrite levels in ADNF-9+NAP-treated animals were not different in carotid ligated or nonligated hemispheres. The peptides ADNF-9 and NAP significantly decreased NO overproduction in the hypoxic-ischemic hemisphere, whereas no significant change appeared in hypoxia alone and also in the sham-operated group. These results suggest the beneficial neuroprotective effect of ADNF-9 and NAP in this model of neonatal hypoxic-ischemic brain injury. To our knowledge, this is the first study that demonstrates a protective effect of these peptides against hypoxia-ischemia in the developing brain.

Differential effects of mitochondrial heat shock protein 60 and related molecular chaperones to prevent intracellular beta-amyloid-induced inhibition of complex IV and limit apoptosis

Defects in mitochondrial oxidative metabolism, in particular decreased activity of cytochrome c oxidase, have been reported in Alzheimer disease tissue and in cultured cells that overexpress amyloid precursor protein. Mitochondrial dysfunction contributes to neurodegeneration in Alzheimer disease partly through formation of reactive oxygen species and the release of sequestered molecules that initiate programmed cell death pathways. The heat shock proteins (HSP) are cytoprotective against a number of stressors, including accumulations of misfolded proteins and reactive oxygen species. We reported on the property of Hsp70 to protect cultured neurons from cell death caused by intraneuronal beta-amyloid. Here we demonstrate that Hsp60, Hsp70, and Hsp90 both alone and in combination provide differential protection against intracellular beta-amyloid stress through the maintenance of mitochondrial oxidative phosphorylation and functionality of tricarboxylic acid cycle enzymes. Notably, beta-amyloid was found to selectively inhibit complex IV activity, an effect selectively neutralized by Hsp60. The combined effect of HSPs was to reduce the free radical burden, preserve ATP generation, decrease cytochrome c release, and prevent caspase-9 activation, all important mediators of beta-amyloid-induced neuronal dysfunction and death.

Class II G protein-coupled receptors and their ligands in neuronal function and protection

G protein-coupled receptors (GPCRs) play pivotal roles in regulating the function and plasticity of neuronal circuits in the nervous system. Among the myriad of GPCRs expressed in neural cells, class II GPCRs which couples predominantly to the Gs-adenylate cyclase-cAMP signaling pathway, have recently received considerable attention for their involvement in regulating neuronal survival. Neuropeptides that activate class II GPCRs include secretin, glucagon-like peptides (GLP-1 and GLP-2), growth hormone-releasing hormone (GHRH), pituitary adenylate cyclase activating peptide (PACAP), corticotropin-releasing hormone (CRH), vasoactive intestinal peptide (VIP), parathyroid hormone (PTH), and calcitonin-related peptides. Studies of patients and animal and cell culture models, have revealed possible roles for class II GPCRs signaling in the pathogenesis of several prominent neurodegenerative conditions including stroke, Alzheimer's, Parkinson's, and Huntington's diseases. Many of the peptides that activate class II GPCRs promote neuron survival by increasing the resistance of the cells to oxidative, metabolic, and excitotoxic injury. A better understanding of the cellular and molecular mechanisms by which class II GPCRs signaling modulates neuronal survival and plasticity will likely lead to novel therapeutic interventions for neurodegenerative disorders.

Peptide-mediated protection from ethanol-induced neural tube defects

Ethanol inhibition of L1-mediated cell adhesion may contribute to the spectrum of neurological, behavioral and morphological abnormalities associated with prenatal ethanol exposure. We showed previously that the neuroprotective peptides NAPVSIPQ (NAP) and SALLRSIPA (SAL) antagonize ethanol inhibition of L1 adhesion and prevent ethanol-induced growth retardation in mouse whole embryo culture. Here we ask whether NAP and SAL also prevent ethanol-induced major malformations of the nervous system. Gestational day 8.0 (3-5 somites) C57BL/6J mouse embryos were grown for 6 h in control medium, 100 mM ethanol and 10(-10) M peptides and then maintained for an additional 20 h in control medium. At the end of the culture period, only embryos having 18-19 somite pairs were examined and compared for the degree of neural tube closure. Ethanol exposure resulted in neural tube defects (NTDs) consistent with total dysraphia and anencephaly. Co-incubation with ethanol and L-NAP (all L-amino acids), D-NAP (all D-amino acids) or SAL significantly increased the percentage of embryos that had begun to close their neural folds at the level of the forebrain/midbrain junction or that had progressed beyond this stage of closure. P7A-NAP (NAPVSIAQ), which lacks neuroprotective activity, but retains activity as an antagonist of ethanol inhibition of L1 adhesion, was effective in preventing ethanol-induced NTDs. In contrast, I6A-NAP (NAPVSAPQ), which shows reduced efficacy as an ethanol antagonist but retains its neuroprotective efficacy, did not significantly diminish the induction of NTDs by ethanol. These findings demonstrate the ability of NAP and SAL to prevent ethanol-induced NTDs and support the hypothesis that ethanol teratogenesis is caused in part by ethanol inhibition of L1-mediated cell adhesion.

Activity-dependent neurotrophic factor-9 and NAP promote neurite outgrowth in rat hippocampal and cortical cultures

Activity-dependent neurotrophic factor (ADNF) is a novel, femtomolar-acting, glial-derived polypeptide (14 kDa) known to protect neurons from a variety of toxic insults. The active site for ADNF function is localized to a 9-amino-acid stretch (SALLRSIPA; ADNF-9). A few years later, a novel ADNF-9-like active peptide (NAPVSIPQ or NAP) was identified and shown to be expressed in the CNS and exhibit an activity profile similar to ADNF-9. Such studies suggest that ADNF-9 and NAP might function like other known neurotrophins and play a role in neural development and maintenance. The purpose of the present studies was to determine if ADNF-9 or NAP affects neurite outgrowth and synaptogenesis in rat hippocampal and cortical cultures. Using MAP2-FITC immunofluorescent labeling, we found that ADNF-9 and NAP promoted neurite outgrowth in a concentration-dependent manner, with maximal activity observed at femtomolar concentrations. Both peptides stimulated robust outgrowth in hippocampal cells (approximately 150% of control; p < 0.01) with a modest effect on cortical cells (approximately 20% of control; p < 0.05) similar to other known growth factors. However, the outgrowth-promoting effect was abolished in the absence of serum, suggesting that soluble factors might be necessary for the neurotrophic activity. Finally, we found that ADNF-9 and NAP increased synaptophysin expression in both rat hippocampal and cortical cultures. These results suggest that ADNF-9 and NAP might contribute to neuronal plasticity associated with development and repair after injury.

Neuroprotective effect of activity-dependent neurotrophic factor against toxicity from familial amyotrophic lateral sclerosis-linked mutant SOD1 in vitro and in vivo

Amyotrophic lateral sclerosis (ALS) is the most common fatal motor neuron disease, affecting mostly middle-aged people. There are no curative therapies for ALS. Several lines of evidence have supported the notion that the proapoptotic property of familial ALS (FALS)-linked mutant Cu/Zn-superoxide dismutase-1 (SOD1) genes may play an important role in the pathogenesis of some FALS cases. Here we found that activity-dependent neurotrophic factor (ADNF), a neurotrophic factor originally identified to have the anti-Alzheimer's disease (AD) activity, protected against neuronal cell death caused by FALS-linked A4T-, G85R- and G93R-SOD1 in a dose-responsive fashion. Notably, ADNF-mediated complete suppression of SOD1 mutant-induced neuronal cell death occurs at concentrations as low as 100 fM. ADNF maintains the neuroprotective activity even at concentrations of more than 1 nM. This is in clear contrast to the previous finding that ADNF loses its protective activity against neurotoxicity induced by AD-relevant insults, including some familial AD genes and amyloid beta peptide at concentrations of more than 1 nM. Characterization of the neuroprotective activity of ADNF against cell death caused by SOD1 mutants revealed that CaMKIV and certain tyrosine kinases are involved in ADNF-mediated neuroprotection. Moreover, in vivo studies showed that intracerebroventricularly administered ADNF significantly improved motor performance of G93A-SOD1 transgenic mice, a widely used model of FALS, although survival was extended only marginally. Thus, the neuroprotective activity of ADNF provides a novel insight into the development of curative drugs for ALS.

Immunological aspects of heat-shock proteins-the optimum stress of life

This review summarizes the complex role of heat-shock proteins (Hsp) in immune reactions, especially the cellular effects of heat-shock proteins during the recognition processes by innate immunity. The role of heat-shock proteins in the pathogenesis of two multifactorial diseases, i.e. inflammatory bowel disease (IBD) and atherosclerosis is highlighted. A new hypothesis on "immunodeficiency burden" is presented. According to this hypothesis, susceptibility to any multifactorial disease in any given subject and in the presence of specific environmental factors is the aggregate effect of polymorphisms resulting in the failure of protective immunity with consequent disease.

Differential effects of ethanol antagonism and neuroprotection in peptide fragment NAPVSIPQ prevention of ethanol-induced developmental toxicity

NAPVSIPQ (NAP), an active fragment of the glial-derived activity-dependent neuroprotective protein, is protective at femtomolar concentrations against a wide array of neural insults and prevents ethanol-induced fetal wastage and growth retardation in mice. NAP also antagonizes ethanol inhibition of L1-mediated cell adhesion (ethanol antagonism). We performed an Ala scanning substitution of NAP to determine the role of ethanol antagonism and neuroprotection in NAP prevention of ethanol embryotoxicity. The Ser-Ile-Pro region of NAP was crucial for both ethanol antagonism and protection of cortical neurons from tetrodotoxin toxicity (neuroprotection). Ala replacement of either Ser-5 or Pro-7 (P7A-NAP) abolished NAP neuroprotection but minimally changed the efficacy of NAP ethanol antagonism. In contrast, Ala replacement of Ile-6 (I6A-NAP) caused a decrease in potency (>2 logarithmic orders) with only a small reduction (<10%) in the efficacy of NAP neuroprotection but markedly reduced the efficacy (50%) and the potency (5 logarithmic orders) of NAP ethanol antagonism. Ethanol significantly reduced the number of paired somites in mouse whole-embryo culture; this effect was prevented significantly by 100 pM NAP or by 100 pM P7A-NAP, but not by 100 pM I6A-NAP. The structure-activity relation for NAP prevention of ethanol embryotoxicity was similar to that for NAP ethanol antagonism and different from that for NAP neuroprotection. These findings support the hypothesis that NAP antagonism of ethanol inhibition of L1 adhesion plays a central role in NAP prevention of ethanol embryotoxicity and highlight the potential importance of ethanol effects on L1 in the pathophysiology of fetal alcohol syndrome.

Peptide antagonists of ethanol inhibition of l1-mediated cell-cell adhesion

Ethanol inhibits cell-cell adhesion mediated by the L1 cell adhesion molecule. 1-Octanol potently antagonizes this cellular action of ethanol and also prevents ethanol-induced dysmorphology and cell death in mouse whole embryo culture. NAPVSIPQ (NAP) and SALLRSIPA (SAL) are active peptide fragments of two neuroprotective proteins: activity-dependent neuroprotective protein and activity-dependent neurotrophic factor. NAP and SAL are neuroprotective at femtomolar concentrations against a variety of neurotoxins and also prevent ethanol teratogenesis in mice. To explore the cellular basis for this action, we asked whether NAP and SAL antagonize ethanol inhibition of L1 adhesion. Aggregation assays were carried out in ethanol-sensitive, human L1-transfected NIH/3T3 cells in the absence and presence of NAP and SAL. Neither NAP nor SAL altered L1 adhesion or L1 expression; however, both peptides potently and completely antagonized the inhibition of L1 adhesion by 100 mM ethanol (EC(50): NAP, 6 x 10(-14) M; SAL, 4 x 10(-11) M). NAP also antagonized ethanol inhibition of cell-cell adhesion in bone morphogenetic protein-7-treated NG108-15 cells. In L1-expressing NIH/3T3 cells, SAL antagonism was reversible and could be overcome by increasing concentrations of ethanol. In contrast, NAP antagonism was irreversible and could not be overcome by increasing agonist concentration. Two scrambled NAP peptides (ASPNQPIV and PNIQVASP) were not antagonists at concentrations as high as 10(-7) M. Thus, two structurally unrelated classes of compounds, alcohols and small polypeptides, share two common actions: antagonism of ethanol inhibition of L1-mediated cell adhesion and prevention of ethanol teratogenesis. These findings support the hypothesis that ethanol inhibition of L1 adhesion contributes to ethanol teratogenesis.

A novel VIP responsive gene. Activity dependent neuroprotective protein

Activity dependent neuroprotective protein (ADNP, 828 amino acids, pI 5.99) is a glial-derived protein that contains a femtomolar active neuroprotective peptide, NAPVSIPQ (NAP). VIP induces a two- to threefold increase in ADNP mRNA in astrocytes, suggesting that ADNP is a VIP-responsive gene. ADNP is widely distributed in the mouse hippocampus, cerebellum, and cerebral cortex. VIP has been shown to possess neuroprotective activity that may be exerted through the activation of glial proteins. We suggest that ADNP may be part of the VIP protection pathway through the femtomolar-acting NAP and through putative interaction with other macromolecules.

Melatonin protects against 6-OHDA-induced neurotoxicity in rats: a role for mitochondrial complex I activity

Unilateral injection into the right substantia nigra of the catecholaminergic neurotoxin 6-hydroxydopamine (6-OHDA) produces extensive loss of dopaminergic cells ('hemi-parkinsonian rat'). The pineal hormone melatonin, which is a potent antioxidant against different reactive oxygen species and has been reported to be neuroprotective in vivo and in vitro, was evaluated for potential anti-Parkinson effects in this model. Imbalance in dopaminergic innervation between the striata produced by intranigral administration of 6-OHDA results in a postural asymmetry causing rotation away from the nonlesioned side. Melatonin given systemically prevented apomorphine-induced circling behavior in 6-OHDA-lesioned rats. Reduced activity of mitochondrial oxidative phosphorylation enzymes has been suggested in some neurodegenerative diseases; in particular, selective decrease in complex I activity is observed in the substantia nigra of Parkinson's disease patients. Analysis of mitochondrial oxidative phosphorylation enzyme activities in nigral tissue from 6-OHDA-lesioned rats by a novel BN-PAGE histochemical procedure revealed a clear loss of complex I activity, which was protected against in melatonin-treated animals. A good correlation between behavioral parameters and enzymatic (complex I) analysis was observed independent of melatonin administration. A deficit in mitochondrial complex I could conceivably contribute to cell death in parkinsonism via free radical mechanisms, both directly via reactive oxygen species production and by decreased ATP synthesis and energy failure. Melatonin may have potential utility in the treatment of neurodegenerative disorders where oxidative stress is a participant.

A novel peptide prevents death in enriched neuronal cultures

We have recently cloned a novel protein (activity-dependent neuroprotective protein, ADNP) containing an 8-amino-acid, femtomolar-acting peptide, NAPVSIPQ (NAP). Here we show, for the first time, that NAP exerted a protective effect on glia-depleted neurons in culture. The number of surviving neurons was assessed in cerebral cortical cultures derived from newborn rats. In these cultures, a 24-h treatment with the beta-amyloid peptide (the Alzheimer's disease associated toxin) induced a 30-40% reduction in neuronal survival that was prevented by NAP (10(-13)-10(-11) M). Maximal survival was achieved at NAP concentrations of 10(-12) M. In a second set of experiments, a 5-day incubation period, with NAP added once (at the beginning of the incubation period) exhibited maximal protection at 10(-10) M NAP. In a third set of experiments, a 10-min period of glucose deprivation resulted in a 30-40% neuronal death that was prevented by a 24-h incubation with NAP. Glucose deprivation coupled with beta-amyloid treatment did not increase neuronal death, suggesting a common pathway. We thus conclude, that NAP can prevent neurotoxicity associated with direct action of the beta-amyloid peptide on neurons, perhaps through protection against impaired glucose metabolism.

Nuclear factor-kappaB mediates the cell survival-promoting action of activity-dependent neurotrophic factor peptide-9

Activity-dependent neurotrophic factor (ADNF) is produced by astrocytes in response to neuronal depolarization and, in turn, promotes neuronal survival. A nineamino acid ADNF peptide (ADNF9) exhibits full neurotrophic activity and potently protects cultured embryonic rat hippocampal neurons from oxidative injury and apoptosis. Picomolar concentrations of ADNF9 induced an increase in nuclear factor-kappaB (NF-kappaB) DNA-binding activity within 1 h of exposure, with a maximum increase of approximately 10-fold by 6 h. Activation of NF-kappaB was correlated with increased resistance of neurons to apoptosis induced by exposure to Fe(2+). The antiapoptotic action of ADNF9 was abolished when NF-kappaB activation was specifically blocked with kappaB decoy DNA. Oxidative stress was attenuated in neurons pretreated with ADNF9, and this effect of ADNF9 was blocked by kappaB decoy DNA, suggesting that ADNF9 suppresses apoptosis by reducing oxidative stress. ADNF9 also prevented neuronal apoptosis following trophic factor withdrawal via an NF-kappaB-mediated mechanism. Thus, NF-kappaB mediates the neuron survival-promoting effects of ADNF9 in experimental models relevant to developmental neuronal death and neurodegenerative disorders.

Vasoactive intestinal peptide (VIP) prevents neurotoxicity in neuronal cultures: relevance to neuroprotection in Parkinson's disease

Vasoactive intestinal peptide (VIP) provides neuroprotection against beta-amyloid toxicity in models of Alzheimer's disease. A superactive analogue, stearyl-Nle17-VIP (SNV) is a 100-fold more potent than VIP. In primary neuronal cultures, VIP protective activity may be mediated by femtomolar-acting glial proteins such as activity-dependent neurotrophic factor (ADNF), activity-dependent neuroprotective protein (ADNP), peptide derivatives ADNF-9 (9aa) and NAP (8aa), respectively. It has been hypothesized that beta-amyloid induces oxidative stress leading to neuronal cell death. Similarly, dopamine and its oxidation products were suggested to trigger dopaminergic nigral cell death in Parkinson's disease. We now examined the possible protective effects of VIP against toxicity of dopamine, 6-hydroxydopamine (6-OHDA) and 1-methyl-4-phenylpyridinium ion (MPP+) in neuronal cultures [rat pheochromocytoma (PC12), human neuroblastoma (SH-SY5Y) and rat cerebellar granular cells]. Remarkably low concentrations of VIP (10(-16)-10(-8) M), ADNF-9 and NAP (10(-18)-10(-10) M) protected against dopamine and 6-OHDA toxicity in PC12 and neuroblastoma cells. VIP (10(-11)-10(-9) M) and SNV (10(-13)-10(-11) M), protected cerebellar granule neurons against 6-OHDA. In contrast, VIP did not rescue neurons from death associated with MPP+. Since dopamine toxicity is linked to the red/ ox state of the cellular glutathione, we investigated neuroprotection in cells depleted of reduced glutathione (GSH). Buthionine sulfoximine (BSO), a selective inhibitor of glutathione synthesis, caused a marked reduction in GSH in neuroblastoma cells and their viability decreased by 70-90%. VIP, SNV or NAP (over a wide concentration range) provided significant neuroprotection against BSO toxicity. These results show that the mechanism of neuroprotection by VIP/SNV/NAP may be mediated through raising cellular resistance against oxidative stress. Our data suggest these compounds as potential lead compounds for protective therapies against Parkinson's disease.