Death-associated protein kinase 1 mediates Aβ42 aggregation-induced neuronal apoptosis and tau dysregulation in Alzheimer's disease

YAP in development and disease: Navigating the regulatory landscape from retina to brain

The distinctive role of Yes-associated protein (YAP) in the nervous system has attracted widespread attention. This comprehensive review strategically uses the retina as a vantage point, embarking on an extensive exploration of YAP's multifaceted impact from the retina to the brain in development and pathology. Initially, we explore the crucial roles of YAP in embryonic and cerebral development. Our focus then shifts to retinal development, examining in detail YAP's regulatory influence on the development of retinal pigment epithelium (RPE) and retinal progenitor cells (RPCs), and its significant effects on the hierarchical structure and functionality of the retina. We also investigate the essential contributions of YAP in maintaining retinal homeostasis, highlighting its precise regulation of retinal cell proliferation and survival. In terms of retinal-related diseases, we explore the epigenetic connections and pathophysiological regulation of YAP in diabetic retinopathy (DR), glaucoma, and proliferative vitreoretinopathy (PVR). Lastly, we broaden our exploration from the retina to the brain, emphasizing the research paradigm of "retina: a window to the brain." Special focus is given to the emerging studies on YAP in brain disorders such as Alzheimer's disease (AD) and Parkinson's disease (PD), underlining its potential therapeutic value in neurodegenerative disorders and neuroinflammation.

Is autism a PIN1 deficiency syndrome? A proposed etiological role for glyphosate

Autism is a neurodevelopmental disorder, the prevalence of which has increased dramatically in the United States over the past two decades. It is characterized by stereotyped behaviors and impairments in social interaction and communication. In this paper, we present evidence that autism can be viewed as a PIN1 deficiency syndrome. Peptidyl-prolyl cis/trans isomerase, NIMA-Interacting 1 (PIN1) is a peptidyl-prolyl cis/trans isomerase, and it has widespread influences in biological organisms. Broadly speaking, PIN1 deficiency is linked to many neurodegenerative diseases, whereas PIN1 over-expression is linked to cancer. Death-associated protein kinase 1 (DAPK1) strongly inhibits PIN1, and the hormone melatonin inhibits DAPK1. Melatonin deficiency is strongly linked to autism. It has recently been shown that glyphosate exposure to rats inhibits melatonin synthesis as a result of increased glutamate release from glial cells and increased expression of metabotropic glutamate receptors. Glyphosate's inhibition of melatonin leads to a reduction in PIN1 availability in neurons. In this paper, we show that PIN1 deficiency can explain many of the unique morphological features of autism, including increased dendritic spine density, missing or thin corpus callosum, and reduced bone density. We show how PIN1 deficiency disrupts the functioning of powerful high-level signaling molecules, such as nuclear factor erythroid 2-related factor 2 (NRF2) and p53. Dysregulation of both of these proteins has been linked to autism. Severe depletion of glutathione in the brain resulting from chronic exposure to oxidative stressors and extracellular glutamate leads to oxidation of the cysteine residue in PIN1, inactivating the protein and further contributing to PIN1 deficiency. Impaired autophagy leads to increased sensitivity of neurons to ferroptosis. It is imperative that further research be conducted to experimentally validate whether the mechanisms described here take place in response to chronic glyphosate exposure and whether this ultimately leads to autism.

Role of MARK2 in the nervous system and cancer

Microtubule-Affinity Regulating Kinase 2 (MARK2), a member of the serine/threonine protein kinase family, phosphorylates microtubule-associated proteins, playing a crucial role in cancer and neurodegenerative diseases. This kinase regulates multiple signaling pathways, including the WNT, PI3K/AKT/mTOR (PAM), and NF-κB pathways, potentially linking it to cancer and the nervous system. As a crucial regulator of the PI3K/AKT/mTOR pathway, the loss of MARK2 inhibits the growth and metastasis of cancer cells. MARK2 is involved in the excessive phosphorylation of tau, thus influencing neurodegeneration. Therefore, MARK2 emerges as a promising drug target for the treatment of cancer and neurodegenerative diseases. Despite its significance, the development of inhibitors for MARK2 remains limited. In this review, we aim to present detailed information on the structural features of MARK2 and its role in various signaling pathways associated with cancer and neurodegenerative diseases. Additionally, we further characterize the therapeutic potential of MARK2 in neurodegenerative diseases and cancer, and hope to facilitate basic research on MARK2 and the development of inhibitors targeting MARK2.

Activation of transient receptor potential vanilloid 1 ameliorates tau accumulation-induced synaptic damage and cognitive dysfunction via autophagy enhancement

AIMS

The autophagy-lysosomal pathway is important for maintaining cellular proteostasis, while dysfunction of this pathway has been suggested to drive the aberrant intraneuronal accumulation of tau protein, leading to synaptic damage and cognitive impairment. Previous studies have demonstrated that the activation of transient receptor potential vanilloid 1 (TRPV1) by capsaicin has a positive impact on cognition and AD-related biomarkers. However, the effect and mechanism of TPRV1 activation on neuronal tau homeostasis remain elusive.

METHODS

A mouse model of tauopathy was established by overexpressing full-length human tau in the CA3 area. Mice were fed capsaicin diet (0.0125%) or normal diet for 9 weeks. The cognitive ability, synaptic function, tau phosphorylation levels, and autophagy markers were detected. In vitro, capsaicin-induced alterations in cellular autophagy and tau degradation were characterized using two cell models. Besides, various inhibitors were applied to validate the role of TRPV1-mediated autophagy enhancement in tau clearance.

RESULTS

We observed that TRPV1 activation by capsaicin effectively mitigates hippocampal tau accumulation-induced synaptic damages, gliosis, and cognitive impairment in vivo. Capsaicin promotes the degradation of abnormally accumulated tau through enhancing autophagic function in neurons, which is dependent on TRPV1-mediated activation of AMP-activated protein kinase (AMPK) and subsequent inhibition of the mammalian target of rapamycin (mTOR). Blocking AMPK activation abolishes capsaicin-induced autophagy enhancement and tau degradation in neurons.

CONCLUSION

Our findings reveal that capsaicin-induced TRPV1 activation confers neuroprotection by restoring neuronal tau homeostasis via modulating cellular autophagy and provides additional evidence to support the potential of TRPV1 as a therapeutic target for tauopathies.

Death-associated protein kinase 1 as a therapeutic target for Alzheimer's disease

Alzheimer's disease (AD) is the most prevalent form of dementia in the elderly and represents a major clinical challenge in the ageing society. Neuropathological hallmarks of AD include neurofibrillary tangles composed of hyperphosphorylated tau, senile plaques derived from the deposition of amyloid-β (Aβ) peptides, brain atrophy induced by neuronal loss, and synaptic dysfunctions. Death-associated protein kinase 1 (DAPK1) is ubiquitously expressed in the central nervous system. Dysregulation of DAPK1 has been shown to contribute to various neurological diseases including AD, ischemic stroke and Parkinson's disease (PD). We have established an upstream effect of DAPK1 on Aβ and tau pathologies and neuronal apoptosis through kinase-mediated protein phosphorylation, supporting a causal role of DAPK1 in the pathophysiology of AD. In this review, we summarize current knowledge about how DAPK1 is involved in various AD pathological changes including tau hyperphosphorylation, Aβ deposition, neuronal cell death and synaptic degeneration. The underlying molecular mechanisms of DAPK1 dysregulation in AD are discussed. We also review the recent progress regarding the development of novel DAPK1 modulators and their potential applications in AD intervention. These findings substantiate DAPK1 as a novel therapeutic target for the development of multifunctional disease-modifying treatments for AD and other neurological disorders.

Effect and Mechanism of Rapamycin on Cognitive Deficits in Animal Models of Alzheimer's Disease: A Systematic Review and Meta-analysis of Preclinical Studies

Background

Alzheimer's disease (AD), the most common form of dementia, remains long-term and challenging to diagnose. Furthermore, there is currently no medication to completely cure AD patients. Rapamycin has been clinically demonstrated to postpone the aging process in mice and improve learning and memory abilities in animal models of AD. Therefore, rapamycin has the potential to be significant in the discovery and development of drugs for AD patients.

Objective

The main objective of this systematic review and meta-analysis was to investigate the effects and mechanisms of rapamycin on animal models of AD by examining behavioral indicators and pathological features.

Methods

Six databases were searched and 4,277 articles were retrieved. In conclusion, 13 studies were included according to predefined criteria. Three authors independently judged the selected literature and methodological quality. Use of subgroup analyses to explore potential mechanistic effects of rapamycin interventions: animal models of AD, specific types of transgenic animal models, dosage, and periodicity of administration.

Results

The results of Morris Water Maze (MWM) behavioral test showed that escape latency was shortened by 15.60 seconds with rapamycin therapy, indicating that learning ability was enhanced in AD mice; and the number of traversed platforms was increased by 1.53 times, indicating that the improved memory ability significantly corrected the memory deficits.

CONCLUSIONS

Rapamycin therapy reduced age-related plaque deposition by decreasing AβPP production and down-regulating β-secretase and γ-secretase activities, furthermore increased amyloid-β clearance by promoting autophagy, as well as reduced tau hyperphosphorylation by up-regulating insulin-degrading enzyme levels.

Tu-Xian Decoction ameliorates diabetic cognitive impairment by inhibiting DAPK-1

Tu-Xian decoction (TXD), a traditional Chinese medicine (TCM) formula, has been frequently administered to manage diabetic cognitive impairment (DCI). Despite its widespread use, the mechanisms underlying TXD's protective effects on DCI have yet to be fully elucidated. As a significant regulator in neurodegenerative conditions, death-associated protein kinase-1 (DAPK-1) serves as a focus for understanding the action of TXD. This study was designed to whether TXD mediates its beneficial outcomes by inhibiting DAPK-1. To this end, a diabetic model was established using Sprague-Dawley (SD) rats through a high-fat, high-sugar (HFHS) diet regimen, followed by streptozotocin (STZ) injection. The experimental cohort was stratified into six groups: Control, Diabetic, TC-DAPK6, high-dose TXD, medium-dose TXD, and low-dose TXD groups. Following a 12-week treatment period, various assessments-including blood glucose levels, body weight measurements, Morris water maze (MWM) testing for cognitive function, brain magnetic resonance imaging (MRI), and histological analyses using hematoxylin-eosin (H&E), and Nissl staining-were conducted. Protein expression in the hippocampus was quantified through Western blotting analysis. The results revealed that TXD significantly improved spatial learning and memory abilities, and preserved hippocampal structure in diabetic rats. Importantly, TXD administration led to a down-regulation of proteins indicative of neurological damage and suppressed DAPK-1 activity within the hippocampal region. These results underscore TXD's potential in mitigating DCIvia DAPK-1 inhibition, positioning it as a viable therapeutic candidate for addressing this condition. Further investigation into TXD's molecular mechanisms may elucidate new pathways for the treatment of DCI.

Identification of potential death-associated protein kinase-1 (DAPK1) inhibitors by an integrated ligand-based and structure-based computational drug design approach

Death-associated protein kinase 1 (DAPK1) is a calcium/calmodulin (Ca2+/CaM)-dependent serine/threonine kinase that is abundantly expressed in the memory- and cognition-related brain areas. DAPK1 is associated with several pathological hallmarks of Alzheimer's disease (AD); it is an attractive target for designing a novel DAPK1 inhibitor as an effective therapeutic treatment for AD. In the present study, we have used an integrated ligand-based and structure-based drug design method to identify DAPK1 inhibitors. The pharmacophoric features of compound 38 G (PDB ID 4TXC) were mapped, and the models were evaluated using enrichment factor (EF) and goodness of hit (GH) score. The selected models were used to screen Zinc 15 compounds library. The identified hits were passed through drug-likeliness and PAINS filtering. The docking study was performed in three steps to yield molecules with good binding energy and ligand-target interactions. Finally, three hits were obtained, that is, ZINC000020648330, ZINC000006755051 and ZINC000020650468, which were subjected to rigorous molecular dynamics simulation. All three hits exhibited optimal stability under simulated conditions and low predicted toxicity.Communicated by Ramaswamy H. Sarma.

Death-associated protein kinase 1 phosphorylates MDM2 and inhibits its protein stability and function

Breast cancer is one of the major malignancies in women, and most related deaths are due to recurrence, drug resistance, and metastasis. The expression of the mouse double minute 2 (MDM2) oncogene is upregulated in breast cancer; however, its regulatory mechanism has yet to be fully elucidated. Herein, we identified the tumor suppressor death-associated protein kinase 1 (DAPK1) as a novel MDM2 regulator by unbiased peptide library screening. DAPK1 is directly bound to MDM2 and phosphorylates it at Thr419. DAPK1-mediated MDM2 phosphorylation promoted its protein degradation via the ubiquitin-proteasome pathway, resulting in upregulated p53 expression. DAPK1 overexpression, but not its kinase activity-deficient form, decreased colony formation and increased doxorubicin-induced cell death; however, DAPK1 knockdown produced the opposite effects in human breast cancer cells. In a xenograft tumorigenesis assay, DAPK1 overexpression significantly reduced tumor formation, whereas inhibition of DAPK1 kinase activity reduced its antitumorigenic effect. Finally, DAPK1 expression was negatively correlated with MDM2 levels in human breast cancer tissues. Thus, these results suggest that DAPK1-mediated MDM2 phosphorylation and its protein degradation may contribute to its antitumorigenic function in breast cancer.

Roles of microRNA-124 in traumatic brain injury: a comprehensive review

Traumatic brain injury (TBI) is a prominent global cause of mortality due to the limited availability of effective prevention and treatment strategies for this disorder. An effective molecular biomarker may contribute to determining the prognosis and promoting the therapeutic efficiency of TBI. MicroRNA-124 (miR-124) is most abundantly expressed in the brain and exerts different biological effects in a variety of diseases by regulating pathological processes of apoptosis and proliferation. Recently, increasing evidence has demonstrated the association between miR-124 and TBI, but there is still a lack of relevant literature to summarize the current evidence on this topic. Based on this review, we found that miR-124 was involved as a regulatory factor in cell apoptosis and proliferation, and was also strongly related with the pathophysiological development of TBI. MiR-124 played an essential role in TBI by interacting with multiple biomolecules and signaling pathways, such as JNK, VAMP-3, Rela/ApoE, PDE4B/mTOR, MDK/TLR4/NF-κB, DAPK1/NR2B, JAK/STAT3, PI3K/AKT, Ras/MEK/Erk. The potential benefits of upregulating miR-124 in facilitating TBI recovery have been identified. The advancement of miRNA nanocarrier system technology presents an opportunity for miR-124 to emerge as a novel therapeutic target for TBI. However, the specific mechanisms underlying the role of miR-124 in TBI necessitate further investigation. Additionally, comprehensive large-scale studies are required to evaluate the clinical significance of miR-124 as a therapeutic target for TBI.

Long-term normalization of calcineurin activity in model mice rescues Pin1 and attenuates Alzheimer's phenotypes without blocking peripheral T cell IL-2 response

BACKGROUND

Current treatments for Alzheimer's disease (AD) have largely failed to yield significant therapeutic benefits. Novel approaches are desperately needed to help address this immense public health issue. Data suggests that early intervention at the first stages of mild cognitive impairment may have a greater chance for success. The calcineurin (CN)-Pin1 signaling cascade can be selectively targeted with tacrolimus (FK506), a highly specific, FDA-approved CN inhibitor used safely for > 20 years in solid organ transplant recipients. AD prevalence was significantly reduced in solid organ recipients treated with FK506.

METHODS

Time release pellets were used to deliver constant FK506 dosage to APP/PS1 mice without deleterious manipulation or handling. Immunofluorescence, histology, molecular biology, and behavior were used to evaluate changes in AD pathology.

RESULTS

FK506 can be safely and consistently delivered into juvenile APP/PS1 mice via time-release pellets to levels roughly seen in transplant patients, leading to the normalization of CN activity and reduction or elimination of AD pathologies including synapse loss, neuroinflammation, and cognitive impairment. Pin1 activity and function were rescued despite the continuing presence of high levels of transgenic Aβ42. Indicators of neuroinflammation including Iba1 positivity and IL-6 production were also reduced to normal levels. Peripheral blood mononuclear cells (PBMC) obtained during treatment or splenocytes isolated at euthanasia activated normally after mitogens.

CONCLUSIONS

Low-dose, constant FK506 can normalize CNS CN and Pin1 activity, suppress neuroinflammation, and attenuate AD-associated pathology without blocking peripheral IL-2 responses making repurposed FK506 a viable option for early, therapeutic intervention in AD.

Function and regulation of cis P-tau in the pathogenesis and treatment of conventional and nonconventional tauopathies

Conventional tauopathies are a group of disease characterized by tau inclusions in the brains, including Alzheimer's disease (AD), Pick's disease (PiD), progressive supranuclear palsy (PSP), corticobasal degeneration (CBD), and certain types of frontotemporal dementia (FTD), among which AD is the most prevalent. Extensive post-translational modifications, especially hyperphosphorylation, and abnormal aggregation of tau protein underlie tauopathy. Cis-trans isomerization of protein plays an important role in protein folding, function, and degradation, which is regulated by peptidyl-proline isomerases (PPIases). Peptidyl-prolyl cis-trans isomerase NIMA-interacting 1 (Pin1), the only PPIase found to isomerize Pro following phosphorylated Ser or Thr residues, alters phosphorylated tau protein conformation at pT231-P motif. The cis P-tau but not trans P-tau serves as an early driver of multiple neurodegenerative disease, encompassing AD, traumatic brain injury (TBI), chronic traumatic encephalopathy (CTE), and vascular contributions to cognitive impairment and dementia (VCID). Cis but not trans P-tau is resistant to protein dephosphorylation and degradation, and also prone to protein aggregation. Cis P-tau loses its ability to stabilize microtubule, causing and spreading tauopathy mainly in axons, a pathological process called cistauosis. The conformation-specific monoclonal antibody that targets only the cis P-tau serves as a very early diagnosis method and a potential treatment of not only conventional tauopathies but also nonconventional tauopathies such as VCID, with clinical trials ongoing. Notably, cis P-tau antibody is the only clinical-stage Alzheimer's therapeutic that has shown the efficacy in animal models of not only AD but also TBI and stroke, which are very early stages of dementia. Here we review the identification and pathological consequences of cis pt231-tau, the role of its regulator Pin1, as well as the clinical implication of cis pt231-tau conformation-specific antibody in conventional and nonconventional tauopathies.

Realization of Amyloid-like Aggregation as a Common Cause for Pathogenesis in Diseases

Amyloids were conventionally referred to as extracellular and intracellular accumulation of Aβ42 peptide, which causes the formation of plaques and neurofibrillary tangles inside the brain leading to the pathogenesis in Alzheimer's disease. Subsequently, amyloid-like deposition was found in the etiology of prion diseases, Parkinson's disease, type II diabetes, and cancer, which was attributed to the aggregation of prion protein, α-Synuclein, islet amyloid polypeptide protein, and p53 protein, respectively. Hence, traditionally amyloids were considered aggregates formed exclusively by proteins or peptides. However, since the last decade, it has been discovered that other metabolites, like single amino acids, nucleobases, lipids, glucose derivatives, etc., have a propensity to form amyloid-like toxic assemblies. Several studies suggest direct implications of these metabolite assemblies in the patho-physiology of various inborn errors of metabolisms like phenylketonuria, tyrosinemia, cystinuria, and Gaucher's disease, to name a few. In this review, we present a comprehensive literature overview that suggests amyloid-like structure formation as a common phenomenon for disease progression and pathogenesis in multiple syndromes. The review is devoted to providing readers with a broad knowledge of the structure, mode of formation, propagation, and transmission of different extracellular amyloids and their implications in the pathogenesis of diseases. We strongly believe a review on this topic is urgently required to create awareness about the understanding of the fundamental molecular mechanism behind the origin of diseases from an amyloid perspective and possibly look for a common therapeutic strategy for the treatment of these maladies by designing generic amyloid inhibitors.

Electrostatic assembly of gold nanoparticle and metal-organic framework nanoparticles attenuates amyloid β aggregate-mediated neurotoxicity

The deposition of amyloid β (Aβ) is a conventional pathological hallmark of Alzheimer's disease (AD). Consequently, the inhibition of Aβ aggregation combined with the disaggregation of Aβ fibrils is an important therapeutic method for AD treatment. In this study, a gold nanoparticle-decorated porous metal organic framework MIL-101(Fe) (AuNPs@PEG@MIL-101) was created as an Aβ inhibitor. The high positively charged MIL-101 induced a high number of Aβ₄₀ to be absorbed or aggregated on the surface of nanoparticles. In addition, AuNPs improved the surface property of MIL-101, causing it to uniformly bind Aβ monomers and Aβ fibrils. Thus, this framework can efficiently suppress extracellular Aβ monomer fibrillation and disrupt the preformed Aβ fibers. AuNPs@PEG@MIL-101 also decreases intracellular Aβ₄₀ aggregation and the amount of Aβ₄₀ immobilized on the cell membrane, thus protecting PC12 cells from Aβ₄₀-induced microtubular defects and cell membrane damage. In summary, AuNPs@PEG@MIL-101 shows great potential for application in AD therapy.

Ablation of Death-Associated Protein Kinase 1 Changes the Transcriptomic Profile and Alters Neural-Related Pathways in the Brain

Death-associated protein kinase 1 (DAPK1), a Ca2+/calmodulin-dependent serine/threonine kinase, mediates various neuronal functions, including cell death. Abnormal upregulation of DAPK1 is observed in human patients with neurological diseases, such as Alzheimer’s disease (AD) and epilepsy. Ablation of DAPK1 expression and suppression of DAPK1 activity attenuates neuropathology and behavior impairments. However, whether DAPK1 regulates gene expression in the brain, and whether its gene profile is implicated in neuronal disorders, remains elusive. To reveal the function and pathogenic role of DAPK1 in neurological diseases in the brain, differential transcriptional profiling was performed in the brains of DAPK1 knockout (DAPK1-KO) mice compared with those of wild-type (WT) mice by RNA sequencing. We showed significantly altered genes in the cerebral cortex, hippocampus, brain stem, and cerebellum of both male and female DAPK1-KO mice compared to those in WT mice, respectively. The genes are implicated in multiple neural-related pathways, including: AD, Parkinson’s disease (PD), Huntington’s disease (HD), neurodegeneration, glutamatergic synapse, and GABAergic synapse pathways. Moreover, our findings imply that the potassium voltage-gated channel subfamily A member 1 (Kcna1) may be involved in the modulation of DAPK1 in epilepsy. Our study provides insight into the pathological role of DAPK1 in the regulatory networks in the brain and new therapeutic strategies for the treatment of neurological diseases.

NMDA Receptor GluN2B Subunit Is Involved in Excitotoxicity Mediated by Death-Associated Protein Kinase 1 in Alzheimer's Disease

BACKGROUND

Alzheimer's disease (AD) is the most common form of neurodegenerative dementia among the elderly. Excitotoxicity has been implicated as playing a dominant role in AD, especially related to the hyperactivation of excitatory neurons. Death-associated protein kinase 1 (DAPK1) is a calcium/calmodulin-dependent kinase and involved in the pathogenesis of AD, but the roles and mechanisms of DAPK1 in excitotoxicity in AD are still uncertain.

OBJECTIVE

We mainly explored the underlying mechanisms of DAPK1 involved in the excitotoxicity of AD and its clinical relevance.

METHODS

Differentiated SH-SY5Y human neuroblastoma cells, PS1 V97 L transgenic mice, and human plasma samples were used. Protein expression was assayed by immunoblotting, and intracellular calcium and neuronal damage were analyzed by flow cytometry. Plasma DAPK1 was measured by ELISA.

RESULTS

We found that DAPK1 was activated after amyloid-β oligomers (AβOs) exposure in differentiated SH-SY5Y cells. Besides, we found the phosphorylation of GluN2B subunit at Ser1303 was increased, which contributing to excitotoxicity and Ca2+ overload in SH-SY5Y cells. Inhibiting DAPK1 activity, knockdown of DAPK1 expression, and antagonizing GluN2B subunits could effectively prevent AβOs-induced activation of GluN2B subunit, Ca2+ overload, and neuronal apoptosis. Additionally, we found that DAPK1 was elevated in the brain of AD transgenic mouse and in the plasma of AD patients.

CONCLUSION

Our finding will help to understand the mechanism of DAPK1 in the excitotoxicity in AD and provide a reference for the diagnosis and therapy of AD.

Detection and modulation of neurodegenerative processes using graphene-based nanomaterials: Nanoarchitectonics and applications

Neurodegenerative disorders (NDDs) are caused by progressive loss of functional neurons following the aggregation and fibrillation of proteins in the central nervous system. The incidence rate continues to rise alarmingly worldwide, particularly in aged population, and the success of treatment remains limited to symptomatic relief. Graphene nanomaterials (GNs) have attracted immense interest on the account of their unique physicochemical and optoelectronic properties. The research over the past two decades has recognized their ability to interact with aggregation-prone neuronal proteins, regulate autophagy and modulate the electrophysiology of neuronal cells. Graphene can prevent the formation of higher order protein aggregates and facilitate the clearance of such deposits. In this review, after highlighting the role of protein fibrillation in neurodegeneration, we have discussed how GN-protein interactions can be exploited for preventing neurodegeneration. A comprehensive understanding of such interactions would contribute to the exploration of novel modalities for controlling neurodegenerative processes.

MiR-191-5p Attenuates Tau Phosphorylation, Aβ Generation, and Neuronal Cell Death by Regulating Death-Associated Protein Kinase 1

Dysregulation of microRNAs has been implicated in diverse diseases, including Alzheimer's disease (AD). MiR-191-5p in plasma/serum has been identified as a novel and promising noninvasive diagnostic biomarker for AD. However, whether miR-191-5p is involved in AD pathogenesis is largely unknown, and its levels in human AD brains are undetermined. Herein, we demonstrated that miR-191-5p downregulated tau phosphorylation at multiple AD-related sites and promoted neurite outgrowth using immunoblotting, immunofluorescence, and neurite outgrowth assays. Moreover, immunoblotting and enzyme-linked immunosorbent assays indicated that miR-191-5p decreased amyloid precursor protein phosphorylation levels and beta-amyloid (Aβ) generation. Furthermore, miR-191-5p reduced ceramide-induced neuronal cell death analyzed by trypan blue staining, the in situ cell death detection kit, and Annexin V-FITC/PI flow cytometry. Next, we verified that death-associated protein kinase 1 (DAPK1) was a direct target of miR-191-5p through the dual luciferase reporter assay and confirmed that the effects of miR-191-5p were antagonized by restoration of DAPK1 expression. Finally, the hippocampal miR-191-5p level was found to be decreased in humans with AD compared with controls and was inversely correlated with the DAPK1 expression level. Collectively, these findings suggest that miR-191-5p might exert inhibitory effects on tau phosphorylation, Aβ secretion, and neuronal cell death by directly targeting DAPK1, providing an attractive therapeutic option for AD.

New insights into the characteristics of DRAK2 and its role in apoptosis: From molecular mechanisms to clinically applied potential

As a member of the death-associated protein kinase (DAPK) family, DAP kinase-associated apoptosis-inducing kinase 2 (DRAK2) performs apoptosis-related functions. Compelling evidence suggests that DRAK2 is involved in regulating the activation of T lymphocytes as well as pancreatic β-cell apoptosis in type I diabetes. In addition, DRAK2 has been shown to be involved in the development of related tumor and non-tumor diseases through a variety of mechanisms, including exacerbation of alcoholic fatty liver disease (NAFLD) through SRSF6-associated RNA selective splicing mechanism, regulation of chronic lymphocytic leukemia and acute myeloid leukemia, and progression of colorectal cancer. This review focuses on the structure, function, and upstream pathways of DRAK2 and discusses the potential and challenges associated with the clinical application of DRAK2-based small-molecule inhibitors, with the aim of advancing DRAK2 research.

miR-143-3p Inhibits Aberrant Tau Phosphorylation and Amyloidogenic Processing of APP by Directly Targeting DAPK1 in Alzheimer’s Disease

The neuropathology of Alzheimer’s disease (AD) is characterized by intracellular aggregation of hyperphosphorylated tau and extracellular accumulation of beta-amyloid (Aβ). Death-associated protein kinase 1 (DAPK1), as a novel therapeutic target, shows promise for the treatment of human AD, but the regulatory mechanisms of DAPK1 expression in AD remain unclear. In this study, we identified miR-143-3p as a promising candidate for targeting DAPK1. miR-143-3p directly bound to the 3′ untranslated region of human DAPK1 mRNA and inhibited its translation. miR-143-3p decreased tau phosphorylation and promoted neurite outgrowth and microtubule assembly. Moreover, miR-143-3p attenuated amyloid precursor protein (APP) phosphorylation and reduced the generation of Aβ40 and Aβ42. Furthermore, restoring DAPK1 expression with miR-143-3p antagonized the effects of miR-143-3p in attenuating tau hyperphosphorylation and Aβ production. In addition, the miR-143-3p levels were downregulated and correlated inversely with the expression of DAPK1 in the hippocampus of AD patients. Our results suggest that miR-143-3p might play critical roles in regulating both aberrant tau phosphorylation and amyloidogenic processing of APP by targeting DAPK1 and thus offer a potential novel therapeutic strategy for AD.

Blocking ERK-DAPK1 Axis Attenuates Glutamate Excitotoxicity in Epilepsy

Glutamate excitotoxicity induces neuronal cell death during epileptic seizures. Death-associated protein kinase 1 (DAPK1) expression is highly increased in the brains of epilepsy patients; however, the underlying mechanisms by which DAPK1 influences neuronal injury and its therapeutic effect on glutamate excitotoxicity have not been determined. We assessed multiple electroencephalograms and seizure grades and performed biochemical and cell death analyses with cellular and animal models. We applied small molecules and peptides and knocked out and mutated genes to evaluate the therapeutic efficacy of kainic acid (KA), an analog of glutamate-induced neuronal damage. KA administration increased DAPK1 activity by promoting its phosphorylation by activated extracellular signal-regulated kinase (ERK). DAPK1 activation increased seizure severity and neuronal cell death in mice. Selective ERK antagonist treatment, DAPK1 gene ablation, and uncoupling of DAPK1 and ERK peptides led to potent anti-seizure and anti-apoptotic effects in vitro and in vivo. Moreover, a DAPK1 phosphorylation-deficient mutant alleviated glutamate-induced neuronal apoptosis. These results provide novel insight into the pathogenesis of epilepsy and indicate that targeting DAPK1 may be a potential therapeutic strategy for treating epilepsy.