Proline-arginine poly-dipeptide encoded by the C9orf72 repeat expansion inhibits adenosine deaminase acting on RNA.

A GGGGCC hexanucleotide repeat expansion in the C9orf72 gene is linked to the pathogenesis of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) (C9-ALS/FTD). Unconventional translation of the hexanucleotide repeat expansion generates five dipeptide repeat proteins (DPRs). The molecular mechanism underlying the DPR-linked neurotoxicity is under investigation. In this study, using cell-based models, we show that poly-proline-arginine DPR (poly-PR), the most neurotoxic DPR in vitro, binds to adenosine deaminase acting on RNA (ADAR)1p110 and ADAR2 and inhibits their RNA editing activity. We further show that poly-PR impairs cellular stress response that is mediated by ADAR1p110. These results together suggest that the poly-PR-mediated inhibition of the ADAR activity contributes to C9-ALS/FTD-linked neurotoxicity.

Mitochondrial ubiquitin ligase alleviates Alzheimer's disease pathology via blocking the toxic amyloid-ß oligomer generation.

Mitochondrial pathophysiology is implicated in the development of Alzheimer's disease (AD). An integrative database of gene dysregulation suggests that the mitochondrial ubiquitin ligase MITOL/MARCH5, a fine-tuner of mitochondrial dynamics and functions, is downregulated in patients with AD. Here, we report that the perturbation of mitochondrial dynamics by MITOL deletion triggers mitochondrial impairments and exacerbates cognitive decline in a mouse model with AD-related Aß pathology. Notably, MITOL deletion in the brain enhanced the seeding effect of Aß fibrils, but not the spontaneous formation of Aß fibrils and plaques, leading to excessive secondary generation of toxic and dispersible Aß oligomers. Consistent with this, MITOL-deficient mice with Aß etiology exhibited worsening cognitive decline depending on Aß oligomers rather than Aß plaques themselves. Our findings suggest that alteration in mitochondrial morphology might be a key factor in AD due to directing the production of Aß form, oligomers or plaques, responsible for disease development.

The proline-arginine repeat protein linked to C9-ALS/FTD causes neuronal toxicity by inhibiting the DEAD-box RNA helicase-mediated ribosome biogenesis.

A GGGGCC repeat expansion in the C9ORF72 gene has been identified as the most common genetic cause of amyotrophic lateral sclerosis and frontotemporal dementia. The repeat expansion undergoes unconventional translation to produce dipeptide repeat (DPR) proteins. Although it has been reported that DPR proteins cause neurotoxicity, the underlying mechanism has not been fully elucidated. In this study, we have first confirmed that proline-arginine repeat protein (poly-PR) reduces levels of ribosomal RNA and causes neurotoxicity and found that the poly-PR-induced neurotoxicity is repressed by the acceleration of ribosomal RNA synthesis. These results suggest that the poly-PR-induced inhibition of ribosome biogenesis contributes to the poly-PR-induced neurotoxicity. We have further identified DEAD-box RNA helicases as poly-PR-binding proteins, the functions of which are inhibited by poly-PR. The enforced reduction in the expression of DEAD-box RNA helicases causes impairment of ribosome biogenesis and neuronal cell death. These results together suggest that poly-PR causes neurotoxicity by inhibiting the DEAD-box RNA helicase-mediated ribosome biogenesis.

An Alzheimer Disease-linked Rare Mutation Potentiates Netrin Receptor Uncoordinated-5C-induced Signaling That Merges with Amyloid ß Precursor Protein Signaling.

A missense mutation (T835M) in the uncoordinated-5C (UNC5C) netrin receptor gene increases the risk of late-onset Alzheimer disease (AD) and also the vulnerability of neurons harboring the mutation to various insults. The molecular mechanisms underlying T835M-UNC5C-induced death remain to be elucidated. In this study, we show that overexpression of wild-type UNC5C causes low-grade death, which is intensified by an AD-linked mutation T835M. An AD-linked survival factor, calmodulin-like skin protein (CLSP), and a natural ligand of UNC5C, netrin1, inhibit this death. T835M-UNC5C-induced neuronal cell death is mediated by an intracellular death-signaling cascade, consisting of death-associated protein kinase 1/protein kinase D/apoptosis signal-regulating kinase 1 (ASK1)/JNK/NADPH oxidase/caspases, which merges at ASK1 with a death-signaling cascade, mediated by amyloid ß precursor protein (APP). Notably, netrin1 also binds to APP and partially inhibits the death-signaling cascade, induced by APP. These results may provide new insight into the amyloid ß-independent pathomechanism of AD.

Glycolytic flux controls D-serine synthesis through glyceraldehyde-3-phosphate dehydrogenase in astrocytes.

D-Serine is an essential coagonist with glutamate for stimulation of N-methyl-D-aspartate (NMDA) glutamate receptors. Although astrocytic metabolic processes are known to regulate synaptic glutamate levels, mechanisms that control D-serine levels are not well defined. Here we show that d-serine production in astrocytes is modulated by the interaction between the D-serine synthetic enzyme serine racemase (SRR) and a glycolytic enzyme, glyceraldehyde 3-phosphate dehydrogenase (GAPDH). In primary cultured astrocytes, glycolysis activity was negatively correlated with D-serine level. We show that SRR interacts directly with GAPDH, and that activation of glycolysis augments this interaction. Biochemical assays using mutant forms of GAPDH with either reduced activity or reduced affinity to SRR revealed that GAPDH suppresses SRR activity by direct binding to GAPDH and through NADH, a product of GAPDH. NADH allosterically inhibits the activity of SRR by promoting the disassociation of ATP from SRR. Thus, astrocytic production of D-serine is modulated by glycolytic activity via interactions between GAPDH and SRR. We found that SRR is expressed in astrocytes in the subiculum of the human hippocampus, where neurons are known to be particularly vulnerable to loss of energy. Collectively, our findings suggest that astrocytic energy metabolism controls D-serine production, thereby influencing glutamatergic neurotransmission in the hippocampus.

A mutation protective against Alzheimer's disease renders amyloid ß precursor protein incapable of mediating neurotoxicity.

Expression of a familial Alzheimer's disease (AD)-linked mutant of amyloid ß precursor protein (APP) or the binding of transforming growth factor ß2 to wild-type (wt)-APP causes neuronal death by activating an intracellular death signal (a APP-mediated intracellular death signal) in the absence of the involvement of amyloid ß (Aß) toxicity in vitro. These neuronal death models may therefore be regarded as Aß-independent neuronal death models related to AD. A recent study has shown that the A673T mutation in the APP isoform APP770 , corresponding to the A598T mutation in the most prevalent neuronal APP isoform APP695 (an AD-protective mutant of APP), is linked to a reduction in the incidence rate of AD. Consistent with this, cells expressing the AD-protective mutant of APP produce less Aß than cells expressing wt-APP. In this study, transforming growth factor ß2 caused death in cultured neuronal cells expressing wt-APP, but not in those expressing the AD-protective mutant of APP. This result suggests that the AD-protective mutation of APP reduces the incidence rate of AD by attenuating the APP-mediated intracellular death signal. In addition, a mutation that causes hereditary cerebral hemorrhage with amyloidosis-Dutch type also attenuated the APP-mediated intracellular death signal. The A598T mutation of amyloid precursor protein APP is linked to a reduction in the incidence rate of Alzheimer's disease (AD). This study shows that TGFß2 causes death in neuronal cells expressing wild-type APP, but not in those expressing the AD-protective mutant of APP, suggesting that the AD-protective mutation of APP reduces the incidence rate of AD by attenuating the APP-mediated intracellular death signal.

KCTD20, a relative of BTBD10, is a positive regulator of Akt.

BACKGROUND: BTBD10 binds to Akt and protein phosphatase 2A (PP2A) and inhibits the PP2A-mediated dephosphorylation of Akt, thereby keeping Akt activated. Previous studies have suggested that BTBD10 plays an important role in preventing motor neuronal death and accelerating the growth of pancreatic beta cells. Because levels of BTBD10 expression are much lower in many non-nervous tissues than nervous tissues, there may be a relative of BTBD10 that has BTBD10-like function in non-neuronal cells. RESULTS: A 419-amino-acid BTBD10-like protein, named KCTD20 (potassium channel tetramerization protein domain containing 20), was to found to bind to all Akt isoforms and PP2A. Overexpression of KCTD20 increased Akt phosphorylation at Thr308, as BTBD10 did, which suggests that KCTD20 as well as BTBD10 positively regulates the function of Akt. KCTD20 was ubiquitously expressed in non-nervous as well as nervous tissues. CONCLUSIONS: KCTD20 is a positive regulator of Akt and may play an important role in regulating the death and growth of some non-nervous and nervous cells.

SH3-binding protein 5 mediates the neuroprotective effect of the secreted bioactive peptide humanin by inhibiting c-Jun NH2-terminal kinase.

Humanin is a secreted bioactive peptide that suppresses cell toxicity caused by a variety of insults. The neuroprotective effect of Humanin against Alzheimer disease (AD)-related death is mediated by the binding of Humanin to its heterotrimeric Humanin receptor composed of ciliary neurotrophic receptor α, WSX-1, and gp130, as well as the activation of intracellular signaling pathways including a JAK2 and STAT3 signaling axis. Despite the elucidation of the signaling pathways by which Humanin mediates its neuroprotection, the transcriptional targets of Humanin that behaves as effectors of Humanin remains undefined. In the present study, Humanin increased the mRNA and protein expression of SH3 domain-binding protein 5 (SH3BP5), which has been known to be a JNK interactor, in neuronal cells. Similar to Humanin treatment, overexpression of SH3BP5 inhibited AD-related neuronal death, while siRNA-mediated knockdown of endogenous SH3BP5 expression attenuated the neuroprotective effect of Humanin. These results indicate that SH3BP5 is a downstream effector of Humanin. Furthermore, biochemical analysis has revealed that SH3BP5 binds to JNK and directly inhibits JNK through its two putative mitogen-activated protein kinase interaction motifs (KIMs).

The JNK/c-Jun signaling axis contributes to the TDP-43-induced cell death.

Dysregulation of transactive response DNA-binding protein-43 (TDP-43) is closely linked to the pathogenesis of amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration with ubiquitin-positive inclusions (FTLD-U). The contribution of the upregulation of TDP-43 expression to the pathogenesis has been strongly suggested by the observation that the level of TDP-43 expression is increased in both ALS and FTLD-U patients. We previously found that the low-grade (twice to five times more than the endogenous level) overexpression of TDP-43 induces neuronal cell death through the upregulation of Bim and CHOP expression and the downregulation of Bcl-xL expression. In this study, we further show that the low-grade overexpression of TDP-43 increases the level of phosphorylated c-Jun N-terminal kinase (JNK) and the co-incubation with a JNK inhibitor, the expression of a dominant-negative JNK, or the expression of a dominant-negative c-Jun inhibited the TDP-43-induced death in NSC34 motor neuronal cells. These data together suggest that the JNK/c-Jun signaling axis contributes to the TDP-43-induced cell death.

Overexpression of TDP-43 causes partially p53-dependent G2/M arrest and p53-independent cell death in HeLa cells.

It has been hypothesized that the dysregulation of transactive response DNA-binding protein-43 (TDP-43) in neurons is closely linked to the pathogenesis of amyotrophic lateral sclerosis and frontotemporal lobar degeneration with ubiquitinated inclusions. However, it remains undefined whether the dysregulation of TDP-43 in non-neuronal cells, such as glial cells, contributes to the pathogenesis of these neurodegenerative diseases. Primarily using HeLa cells, we show that a low-grade overexpression of TDP-43, 2- to 5-fold greater than endogenous expression, which is thought to mimic the gain of function of TDP-43, induced cell cycle arrest at the G2/M phase and cell death in cultured non-neuronal cells. Since the activation of p53 may induce G2/M arrest and/or cell death in many abnormal situations, we examined the mechanism underlying G2/M arrest from the standpoint of p53 regulation. It was determined that the TDP-43-induced G2/M arrest was attenuated, while TDP-43-induced death was not attenuated, in cells in which the p53 function was compromised. These data collectively indicate that TDP-43 causes G2/M arrest in a partially p53-dependent manner and it causes cell death in a p53-independent manner in cycling cells. Because it is likely that the impaired proliferation in glial cells causes a decrease in the neuron-supporting ability, these findings further suggests that the gain of function of TDP-43 may cause neurotoxicity by inducing cell cycle arrest and death in glial cells.

Amyotrophic lateral sclerosis-linked mutant VAPB enhances TDP-43-induced motor neuronal toxicity.

Transactive response DNA-binding protein-43 (TDP-43) has been thought to be generally involved in the pathogenesis of most amyotrophic lateral sclerosis (ALS) patients although it remains undefined how TDP-43 is involved in the ALS pathogenesis. In this study, we found that a P56S mutant of vesicle-associated membrane protein-associated protein B (VAPB), which has been identified to be a familial ALS-causative protein, potentiated the TDP-43-induced motor neuronal cell death, while wild-type VAPB conversely inhibited it. The P56S-VAPB-induced potentiation of the TDP-43-induced death was mediated by the up-regulation of Bim expression at the mRNA level and other undefined mechanisms that leads to the enhancement of Bim and Bax activity. These observations suggest that TDP-43 and P56S-VAPB may co-operate to involve the pathogenesis of ALS.

TDP-43-induced death is associated with altered regulation of BIM and Bcl-xL and attenuated by caspase-mediated TDP-43 cleavage.

Abnormal aggregates of transactive response DNA-binding protein-43 (TDP-43) and its hyperphosphorylated and N-terminal truncated C-terminal fragments (CTFs) are deposited as major components of ubiquitinated inclusions in most cases of amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration with ubiquitinated inclusions (FTLD-U). The mechanism underlying the contribution of TDP-43 to the pathogenesis of these neurodegenerative diseases remains unknown. In this study, we found that a 2-5-fold increase in TDP-43 expression over the endogenous level induced death of NSC34 motor neuronal cells and primary cortical neurons. TDP-43-induced death is associated with up-regulation of Bim expression and down-regulation of Bcl-xL expression. siRNA-mediated reduction of Bim expression attenuates TDP-43-induced death. Accumulated evidence indicates that caspases are activated in neurons of ALS and FTLD-U patients, and activated caspase-mediated cleavage of TDP-43 generates CTFs of TDP-43. Here, we further found that the ER (endoplasmic reticulum) stress- or staurosporine-mediated activation of caspases leads to cleavage of TDP-43 at Asp(89) and Asp(169), generating CTF35 (TDP-43-(90-414)) and CTF27 (TDP-43-(170-414)) in cultured neuronal cells. In contrast to TDP-43, CTF27 is unable to induce death while it forms aggregates. CTF35 was weaker than full-length TDP-43 in inducing death. A cleavage-resistant mutant of TDP-43 (TDP-43-D89E/D169E) showed stronger death-inducing activity than wild-type TDP-43. These results suggest that disease-related activation of caspases may attenuate TDP-43-induced toxicity by promoting TDP-43 cleavage.

Transforming growth factor beta2 level is elevated in neurons of Alzheimer's disease brains.

Our earlier studies in vitro indicated that expression of TGFbeta2 was induced by toxic amyloid betas (Abetas) in both glial and neuronal cells and increased levels of TGFbeta2 triggered a neuronal cell death pathway related to Alzheimer's disease (AD) by binding to the extracellular domain of amyloid beta precursor protein (APP). In this study we have demonstrated by immunohistochemical analysis that the levels of TGFbeta2 are elevated in cells mainly consisting of neurons of both the hippocampi and cerebral cortices of human AD brains. This result indicates that upregulation of the TGFbeta2 level is a common pathological feature of AD brains and suggests that it may be closely linked to the development of neuronal death related to AD.

ALS-linked P56S-VAPB, an aggregated loss-of-function mutant of VAPB, predisposes motor neurons to ER stress-related death by inducing aggregation of co-expressed wild-type VAPB.

A point mutation (P56S) in the vapb gene encoding an endoplasmic reticulum (ER)-integrated membrane protein [vesicle-associated membrane protein-associated protein B (VAPB)] causes autosomal-dominant amyotrophic lateral sclerosis. In our earlier study, we showed that VAPB may be involved in the IRE1/XBP1 signaling of the unfolded protein response, an ER reaction to inhibit accumulation of unfolded/ misfolded proteins, while P56S-VAPB formed insoluble aggregates and lost the ability to mediate the pathway (lossof- function), and suggested that P56S-VAPB promoted the aggregation of co-expressed wild-type (wt)-VAPB. In this study, a yeast inositol-auxotrophy assay has confirmed that P56S-VAPB is functionally a null mutant in vivo. The interaction between P56S-VAPB and wt-VAPB takes place with a high affinity through the major sperm protein domain in addition to the interaction through the C-terminal transmembrane domain. Consequently, wt-VAPB is speculated to preferentially interact with co-expressed P56S-VAPB, leading to the recruitment of wt-VAPB into cytosolic aggregates and the attenuation of its normal function. We have also found that expression of P56S-VAPB increases the vulnerability of NSC34 motoneuronal cells to ER stress-induced death. These results lead us to hypothesize that the total loss of VAPB function in unfolded protein response, induced by one P56S mutant allele, may contribute to the development of P56SVAPB- induced amyotrophic lateral sclerosis.

Anti-apoptotic action of Wnt5a in dermal fibroblasts is mediated by the PKA signaling pathways.

Wnts are secreted glycoproteins that control diverse biological processes, such as proliferation, differentiation, and apoptosis. We here found that Wnt5a inhibited apoptosis induced by serum deprivation in primary-cultured human dermal fibroblasts. Anti-apoptotic activity of Wnt5a was not inhibited by a dickkopf-1 (DKK), which blocks the canonical Wnt pathway. On the other hand, loss of function of protein kinase A (PKA), induced by treatment with PKA inhibitors, siRNA-mediated knocking down of endogenous PKA catalytic subunits, or enforced expression of dominant-negative PKA inhibited the Wnt5a anti-apoptotic activity, indicating the involvement of PKA in the Wnt5a anti-apoptotic activity. In agreement, phosphorylation levels of a cAMP response element binding protein (CREB), a representative downstream effector of PKA, the activation of which is known to lead to the pro-survival effects, was elevated by Wnt5a. In addition, Wnt5a increased the nuclear beta-catenin level and treatment with imatinib or ionomycin, either of which blocks the beta-catenin pathway, reduced the anti-apoptotic activity of Wnt5a, together suggesting the simultaneous involvement of the beta-catenin-mediated pathway in the Wnt5a anti-apoptotic activity. Based on another finding indicating that Wnt5a upregulated PKA-mediated phosphorylation of glycogen synthase kinase-3beta (GSK-3beta) at serine 9 that caused inactivation of GSK-3beta and subsequently resulted in activation of the beta-catenin pathway, we have speculated that the Wnt5a anti-apoptotic activity may be partially mediated by PKA-mediated phosphorylation of GSK-3beta and subsequent activation of the beta-catenin pathway.

A novel Akt/PKB-interacting protein promotes cell adhesion and inhibits familial amyotrophic lateral sclerosis-linked mutant SOD1-induced neuronal death via inhibition of PP2A-mediated dephosphorylation of Akt/PKB.

Akt/Protein Kinase B (PKB) family proteins (Akts), consisting of Akt1, 2, and 3, play a crucial role in multiple biological processes. We recently demonstrated that activation of Akt3 by the autosomal-recessive familial amyotrophic lateral sclerosis (ALS)-linked gene 2 (ALS2) product, alsinLF, led to the suppression of motoneuronal death induced by familial ALS-related mutant superoxide dismutase-1 (SOD1). To characterize the mechanism of neuroprotection mediated by Akt3 in detail, we performed a yeast two-hybrid system using Akt3 as a bait and identified BTBD10 as a novel Akt-interacting protein with a BTB/POZ domain. BTBD10 equally binds to any Akt. Overexpression of BTBD10 increased phosphorylation levels of Akts at both Thr(308) and Ser(473) while the reduction of the endogenous BTBD10 level resulted in a decrease in the phosphorylation levels of Akts. In vitro analysis indicated that BTBD10 bound to protein phosphatase 2A (PP2A) and inhibited dephosphorylation of Akts by PP2A. In agreement with BTBD10-mediated upregulation of the Akt phosphorylation levels, enforced expression of BTBD10 led to the suppression of mutant SOD1-induced neuronal death. Furthermore, overexpression of BTBD10 accelerated cell growth by enhancing cell adhesion. Given its ubiquitous expression, BTBD10 appears to behave as a suppressor of cell death including neuronal cell death related to ALS and an enhancer of cell growth via its positive regulation of Akt phosphorylation.

CR/periphilin is a transcriptional co-repressor involved in cell cycle progression.

CR/periphilin (CR) retards cell cycle progression mainly at the S-phase in part by transcriptionally repressing expression of Cdc7, the key regulator of DNA replication, and in part by unknown mechanisms. In this study, we show that enforced expression of CR inhibits Cdc7 promoter activity. The attachment of the DNA-binding domain of the yeast GAL4 transcription factor to CR that appears without DNA-binding sequences, enables CR to repress GAL4 promoter-mediated transcription in a histone deacetylase (HDAC) activity-dependent manner. CR forms a complex with mSin3A, a common component in transcriptional repressor complexes, as well as with HDAC1, suggesting that CR may behave as a co-repressor by functional interaction with the Sin3/HDAC co-repressor complex. We also demonstrate that an alternatively spliced variant of CR, CR-S, which is without a region encoded by exon 4 of the CR gene and is a weak interactor with HDAC1, shows a suppressing effect on CR activity.

Antidepressant-like effect of Cordyceps sinensis in the mouse tail suspension test.

Cordyceps sinensis (CS) has been known as a component of traditional medicines that elicit various biological effects such as anti-fatigue, immunomodulatory, and hypoglycemic actions. Since it has been well-established that fatigue is closely related to depression, we used the tail suspension test (TST) in mice to examine the antidepressant-like effects of hot water extract (HWCS) and supercritical fluid extract (SCCS) of CS. Immobility time in the TST was reduced by administration of SCCS (2.5-10 ml/kg, p.o.) dose-dependently though it was not reduced by treatment with HWCS (500-2000 mg/kg, p.o.). Neither HWCS nor SCCS altered locomotor activity in the open field test, excluding the possibility that the effect of SCCS is due to activation of locomotion. Pretreatment with prazosin (an adrenoreceptor antagonist) or sulpiride (a dopamine D2 receptor antagonist) reduced the effect of SCCS on the immobility time. In contrast, pretreatment with p-chlorophenylalanine (p-CPA, a serotonin synthesis inhibitor) did not alter the anti-immobility effect of SCCS. The last finding is consistent with an additional observation that SCCS had no effect on head twitch response induced by 5-hydroxy-L-tryptophan in mice. Taken altogether, these results suggest that SCCS may elicit an antidepressant-like effect by affecting the adrenergic and dopaminergic systems, but not by affecting the serotonergic system.

Wnt5a promotes adhesion of human dermal fibroblasts by triggering a phosphatidylinositol-3 kinase/Akt signal.

Frizzled-3 (Fzd3), highly expressed in both the central nervous system (CNS) and skin, plays essential roles in axonal growth and guidance during the CNS development and may be involved in maintenance of skin integrity, although its ligand remains undetermined. In this study, we demonstrate that Wnt5a specifically binds to Fzd3 in vitro and triggers phosphorylation of Akt mediated by phosphatidylinositol-3 kinase (PI3K), but not that of ERK or protein kinase C, in human primary-cultured dermal fibroblasts. We have further found that such Wnt5a/Fzd3-triggered activation of the PI3K/Akt signal promotes integrin-mediated adhesion of human dermal fibroblasts to collagen I-coated dishes. Based on another finding that Wnt5a/Fzd3-triggered activation of the PI3K/Akt signal was blocked by an excess amount of a recombinant Fzd3-cysteine-rich domain (CRD), but not by that of a recombinant Fzd6-CRD, it is concluded that Wnt5a is a natural ligand of Fzd3 that triggers the PI3K/Akt signal and promotes adhesion of human dermal fibroblasts.

Neuroprotection against neurodegenerative diseases: development of a novel hybrid neuroprotective peptide Colivelin.

Neuronal death is directly implicated in the pathogenesis of neurodegenerative diseases (NDDs). NDDs cannot be cured because the mechanisms underlying neuronal death are too complicated to be therapeutically suppressed. Neuroprotective factors, such as neurotrophins, certain growth factors, neurotrophic cytokines, and short neuroprotective peptides, support neuronal survival in both physiological and pathological conditions, suggesting that these factors may be good drug candidates for NDDs. We recently generated a novel neuroprotective peptide named Colivelin by attaching activity-dependent neurotrophic factor (ADNF) to the N-terminus of a potent Humanin derivative, AGA-(C8R)HNG17. HN was originally identified from an Alzheimer's disease (AD) brain as an endogenous neuroprotective peptide that suppresses ADrelevant toxicity. Colivelin protects neurons from death relevant to NDDs by activating two independent prosurvival signals: an ADNF-mediated Ca2+/calmodulin-dependent protein kinase IV pathway and an HN-mediated STAT3 pathway. The neuroprotective effect of Colivelin provides novel insights into therapy for NDDs.