Toxicity of Amyloid-β Peptides Varies Depending on Differentiation Route of SH-SY5Y Cells

E2F1 Mediates Traumatic Brain Injury and Regulates BDNF-AS to Promote the Progression of Alzheimer's Disease

Traumatic brain injury (TBI) is one of the important risk factors for the development of Alzheimer's disease (AD). However, the molecular mechanism by which TBI promotes the progression of AD is not elucidated. In this study, we showed that the abnormal production of E2F1 is a major factor in promoting the neuropathological and cognitive deterioration of AD post-TBI. We found that repeated mild TBI can aggravate the neuropathology of AD in APP/PS1 mice. At the same time, the co-expression of E2F1 and beta-site APP cleaving enzyme 1 (BACE1) was upregulated when the mouse hippocampus was dissected. BACE1 is recognized as a rate-limiting enzyme for the production of Aβ. Here, we speculate that E2F1 may play a role in promoting BACE1 expression in AD. Therefore, we collected peripheral blood from patients with AD. Interestingly, there is a positive correlation between E2F1 and brain-derived neurotrophic factor-antisense (BDNF-AS), whereas BDNF-AS in AD can promote the expression of BACE1 and exhibit a neurotoxic effect. We established a cell model and found a regulatory relationship between E2F1 and BDNF-AS. Therefore, based on our results, we concluded that E2F1 regulates BDNF-AS, promotes the expression of BACE1, and affects the progression of AD. Furthermore, E2F1 mediates the TBI-induced neurotoxicity of AD.

Death Induced by Survival gene Elimination (DISE) correlates with neurotoxicity in Alzheimer's disease and aging

Alzheimer's disease (AD) is characterized by progressive neurodegeneration, but the specific events that cause cell death remain poorly understood. Death Induced by Survival gene Elimination (DISE) is a cell death mechanism mediated by short (s) RNAs acting through the RNA-induced silencing complex (RISC). DISE is thus a form of RNA interference, in which G-rich 6mer seed sequences in the sRNAs (position 2-7) target hundreds of C-rich 6mer seed matches in genes essential for cell survival, resulting in the activation of cell death pathways. Here, using Argonaute precipitation and RNAseq (Ago-RP-Seq), we analyze RISC-bound sRNAs to quantify 6mer seed toxicity in several model systems. In mouse AD models and aging brain, in induced pluripotent stem cell-derived neurons from AD patients, and in cells exposed to Aβ42 oligomers, RISC-bound sRNAs show a shift to more toxic 6mer seeds compared to controls. In contrast, in brains of "SuperAgers", humans over age 80 who have superior memory performance, RISC-bound sRNAs are shifted to more nontoxic 6mer seeds. Cells depleted of nontoxic sRNAs are sensitized to Aβ42-induced cell death, and reintroducing nontoxic RNAs is protective. Altogether, the correlation between DISE and Aβ42 toxicity suggests that increasing the levels of nontoxic miRNAs in the brain or blocking the activity of toxic RISC-bound sRNAs could ameliorate neurodegeneration.

Differentiating SH-SY5Y Cells into Polarized Human Neurons for Studying Endogenous and Exogenous Tau Trafficking: Four Protocols to Obtain Neurons with Noradrenergic, Dopaminergic, and Cholinergic Properties

Pathological alterations of the neuronal Tau protein are characteristic for many neurodegenerative diseases, called tauopathies. To investigate the underlying mechanisms of tauopathies, human neuronal cell models are required to study Tau physiology and pathology in vitro. Primary rodent neurons are an often used model for studying Tau, but rodent Tau differs in sequence, splicing, and aggregation propensity, and rodent neuronal physiology cannot be compared to humans. Human-induced pluripotent stem cell (hiPSC)-derived neurons are expensive and time-consuming. Therefore, the human neuroblastoma SH-SY5Y cell line is a commonly used cell model in neuroscience as it combines convenient handling and low costs with the advantages of human-derived cells. Since naïve SH-SY5Y cells show little similarity to human neurons and almost no Tau expression, differentiation is necessary to obtain human-like neurons for studying Tau protein-related aspects of health and disease. As they express in principle all six Tau isoforms seen in the human brain, differentiated SH-SY5Y-derived neurons are suitable for investigating the human microtubule-associated protein Tau and, for example, its sorting and trafficking. Here, we describe and discuss a general cultivation procedure as well as four differentiation methods to obtain SH-SY5Y-derived neurons resembling noradrenergic, dopaminergic, and cholinergic properties, based on the treatment with retinoic acid (RA), brain-derived neurotrophic factor (BDNF), and 12-O-tetrade canoylphorbol-13-acetate (TPA). TPA and RA-/TPA-based protocols achieve differentiation efficiencies of 40-50% after 9 days of treatment. The highest differentiation efficiency (~75%) is accomplished by a combination of RA and BDNF; treatment only with RA is the most time-efficient method as ~50% differentiated cells can be obtained already after 7 days.

Antioxioxidant and antiapoptotic effects of Thymosin β4 in Aβ-induced SH-SY5Y cells via the 5-HTR1A/ERK axis

Alzheimer's disease (AD) is a common amnestic cognitive impairment characterised by β-amyloid (Aβ) plaques deposit in the brain of the elderly. AD is a yet incurable disease due to its unknown exact pathogenesis and unavailability of effective remedies in clinical application. Thymosin β4 (Tβ4) is a housekeeping protein that plays important role in cell proliferation, migration and differentiation. It has the ability to protect and repair neurons however it is still unclear involvement in AD. Therefore, the aim of this study is to elucidate the role and mechanism of Tβ4 in mediating the improvement of AD. AD-like cell model was constructed in neuroblastoma cell line SH-SY5Y treated with Aβ. Overexpression of Tβ4 were done using lentivirus infection and downregulation through siRNA transfection. We performed western blot and flow cytometry to study the apoptosis and standard kits to measure the oxidative stress-associated biomarkers. There is significant increased in viability and decreased apoptosis in Tβ4 overexpression group compared to control. Furthermore, overexpression of Tβ4 suppressed the expression of pro-apoptotic markers such as Caspase-3, Caspase-8, and Bax meanwhile upregulated the expression of anti-apoptotic gene Bcl-2. Tβ4 alleviated oxidative damage by reducing MDA, LDH and ROS and increasing SOD and GSH-PX in Aβ-treated SH-SY5Y cells. We found that Tβ4 inhibit ERK/p38 MAPK pathway and intensify the expression of 5-HTR1A. Additionally, we showed that upregulation of 5-HTR1A dampened the Tβ4 to activate ERK signalling. In conclusion, our study revealed the neuroprotective role of Tβ4 in AD which may open up new therapeutic applications in AD treatment.

New, Fully Implantable Device for Selective Clearance of CSF-Target Molecules: Proof of Concept in a Murine Model of Alzheimer’s Disease

We have previously proposed a radical change in the current strategy to clear pathogenic proteins from the central nervous system (CNS) based on the cerebrospinal fluid (CSF)-sink therapeutic strategy, whereby pathogenic proteins can be removed directly from the CNS via CSF. To this aim, we designed and manufactured an implantable device for selective and continuous apheresis of CSF enabling, in combination with anti-amyloid-beta (Aβ) monoclonal antibodies (mAb), the clearance of Aβ from the CSF. Here, we provide the first proof of concept in the APP/PS1 mouse model of Alzheimer’s disease (AD). Devices were implanted in twenty-four mice (seventeen APP/PS1 and seven Wt) with low rates of complications. We confirmed that the apheresis module is permeable to the Aβ peptide and impermeable to mAb. Moreover, our results showed that continuous clearance of soluble Aβ from the CSF for a few weeks decreases cortical Aβ plaques. Thus, we conclude that this intervention is feasible and may provide important advantages in terms of safety and efficacy.

Neurotoxic amyloidogenic peptides in the proteome of SARS-COV2: potential implications for neurological symptoms in COVID-19

COVID-19 is primarily known as a respiratory disease caused by SARS-CoV-2. However, neurological symptoms such as memory loss, sensory confusion, severe headaches, and even stroke are reported in up to 30% of cases and can persist even after the infection is over (long COVID). These neurological symptoms are thought to be produced by the virus infecting the central nervous system, however we don’t understand the molecular mechanisms triggering them. The neurological effects of COVID-19 share similarities to neurodegenerative diseases in which the presence of cytotoxic aggregated amyloid protein or peptides is a common feature. Following the hypothesis that some neurological symptoms of COVID-19 may also follow an amyloid etiology we identified two peptides from the SARS-CoV-2 proteome that self-assemble into amyloid assemblies. Furthermore, these amyloids were shown to be highly toxic to neuronal cells. We suggest that cytotoxic aggregates of SARS-CoV-2 proteins may trigger neurological symptoms in COVID-19.

Here the authors report the formation of toxic clumps of protein, similar to amyloid assemblies found in Alzheimer’s disease and suggest their possible role for some of the neurological symptoms of long-COVID.

Characterization of aerosols produced during shampoo use and harmful chemicals in shampoo aerosols

To declare a shampoo toxicologically safe, one should evaluate the hazards posed by the inhalation of aerosols produced during its use. Herein, tap water was sprayed into a shampoo-filled plastic container to investigate the formation of shampoo aerosols and the possibility of their inhalation. The aerosols thus obtained had higher mass concentrations (geometric mean = 5779 μg m^-3 (PM₁₀) and 2249 μg m^-3 (PM_2.5)) than water aerosols (geometric mean = 927 μg m^-3 (PM₁₀) and 476 μg m^-3 (PM_2.5)). In particular, shampoo aerosol particles with an aerodynamic diameter of 2.5 μm, which can penetrate the alveoli when inhaled, had the highest mass concentration (geometric mean = 2000 μg m^-3). The volatile organic compounds contained in shampoo aerosols featured alcohol and ether groups attached to dodecane and tetradecane backbones; these compounds were generated by the thermal decomposition of surfactants (i.e., lauryl and laureth sulfates) during instrumental analysis. The acquired data suggest that inhalation exposure and chronic inhalation toxicity evaluations should be performed for various shampoo usage conditions to ensure inhalation safety.

LncRNA BDNF-AS as ceRNA regulates the miR-9-5p/BACE1 pathway affecting neurotoxicity in Alzheimer's disease

INTRODUCTION

The long non-coding RNA Brain-derived nutritional factor anti-sense RNA (BDNF-AS) is a type of anti-sense RNA that has been proven to play a crucial role in the occurrence and development of certain nervous system disorders. However, the role and molecular mechanism of BDNF-AS in Alzheimer's disease (AD) have not been elucidated yet.

METHODS

Peripheral blood samples were collected from outpatients with AD as well as from normal elderly individuals in the community, and the expression of BDNF-AS was analysed using quantitative reverse transcription-polymerase chain reaction. An in vitro model was constructed, and the effect of BDNF-AS expression level on the cells was measured using the CCK8 method and flow cytometry. The molecular biological mechanism of BDNF-AS in AD was examined using the luciferase reporter, MS2-RIP, and RNA pulldown assays.

RESULT

We found that the expression of BDNF-AS was elevated in the peripheral blood of patients with AD and that increased BDNF-AS expression may be associated with the cognitive status of such patients. The results confirmed that BDNF-AS could promote neurotoxicity in the in vitro model. Then, we uncovered that BDNF-AS promotes the expression of BACE1 through the competitive binding of miR-9-5p, thereby promoting amyloid deposition. Finally, through the Morris water maze, we found that the high expression of BDNF-AS promoted cognitive impairment in AD mice.

CONCLUSION

The obtained results suggest that BDNF-AS plays a crucial role in the occurrence and development of AD. As a new pathogenic gene of AD, BDNF-AS may be used as a therapeutic target or as a prognostic marker in patients with AD.

α-Lipoic Acid Has the Potential to Normalize Copper Metabolism, Which Is Dysregulated in Alzheimer's Disease

BACKGROUND

Alzheimer's disease (AD) is an age-dependent progressive neurodegenerative disorder and the most common cause of dementia. The treatment and prevention of AD present immense yet unmet needs. One of the hallmarks of AD is the formation of extracellular amyloid plaques in the brain, composed of amyloid-β (Aβ) peptides. Besides major amyloid-targeting approach there is the necessity to focus also on alternative therapeutic strategies. One factor contributing to the development of AD is dysregulated copper metabolism, reflected in the intracellular copper deficit and excess of extracellular copper.

OBJECTIVE

In the current study, we follow the widely accepted hypothesis that the normalization of copper metabolism leads to the prevention or slowing of the disease and search for new copper-regulating ligands.

METHODS

We used cell culture, ICP MS, and Drosophila melanogaster models of AD.

RESULTS

We demonstrate that the natural intracellular copper chelator, α-lipoic acid (LA) translocates copper from extracellular to intracellular space in an SH-SY5Y-based neuronal cell model and is thus suitable to alleviate the intracellular copper deficit characteristic of AD neurons. Furthermore, we show that supplementation with LA protects the Drosophila melanogaster models of AD from developing AD phenotype by improving locomotor activity of fruit fly with overexpression of human Aβ with Iowa mutation in the fly brain. In addition, LA slightly weakens copper-induced smooth eye phenotype when amyloid-β protein precursor (AβPP) and beta-site AβPP cleaving enzyme 1 (BACE1) are overexpressed in eye photoreceptor cells.

CONCLUSION

Collectively, these results provide evidence that LA has the potential to normalize copper metabolism in AD.

Tβ4 ameliorates oxidative damage and apoptosis through ERK/MAPK and 5-HT1A signaling pathway in Aβ insulted SH-SY5Y cells

AIMS

Alzheimer's disease (AD) is the most common progressive neurodegenerative disorder seriously endangering the physical and mental health of the elderly, while no effective treatments and drugs in clinical practice are available. Thymosin β4 (Tβ4) is a multifunctional polypeptide involved in many physiological and pathological processes including AD. This study aims to understand the function and molecular mechanism of Tβ4 in the development of AD.

MAIN METHODS

Neuroblastoma cell line SH-SY5Y was treated with β-amyloid (Aβ) to induce AD-like pathological changes, which serves as Alzheimer's disease model. Tβ4 was overexpressed in SH-SY5Y cells by lentivirus infection, and downregulated by siRNA transfection. Apoptosis of transfected SH-SY5Y cells after Aβ-treatment was examined by western blot and flow cytometry. Apoptotic proteins and Tβ4-related signaling pathways were also investigated by western blot.

KEY FINDINGS

We found that Tβ4 overexpression increased viability and suppressed apoptosis of Aβ-treated SH-SY5Y cells. Tβ4 ameliorated oxidative damage and suppressed reactive oxygen species production in Aβ-treated SH-SY5Y cells. Consistently, Tβ4 overexpression down-regulated the expression levels of pro-apoptotic markers such as Caspase-3, Caspase-8, and Bax, while up-regulated the expression level of anti-apoptotic gene Bcl-2 in Aβ-stimulated SH-SY5Y cells. Mechanistically, we demonstrated that Tβ4 dampened ERK/p38 MAPK signaling and enhanced 5-HTR1A expression in Aβ-treated SH-SY5Y cells. Moreover, we revealed that Tβ4 inhibited the activation of ERK pathway through up-regulating 5-HTR1A in Aβ-treated SH-SY5Y cells.

SIGNIFICANCE

Taken together, our findings provide evidences to support the neuroprotective role of Tβ4 and might open up new therapeutic applications of Tβ4 in AD treatment.

Expression and Localization of AβPP in SH-SY5Y Cells Depends on Differentiation State

Neuroblastoma cell line SH-SY5Y, due to its capacity to differentiate into neurons, easy handling, and low cost, is a common experimental model to study molecular events leading to Alzheimer's disease (AD). However, it is prevalently used in its undifferentiated state, which does not resemble neurons affected by the disease. Here, we show that the expression and localization of amyloid-β protein precursor (AβPP), one of the key molecules involved in AD pathogenesis, is dramatically altered in SH-SY5Y cells fully differentiated by combined treatment with retinoic acid and BDNF. We show that insufficient differentiation of SH-SY5Y cells results in AβPP mislocalization.

A Soft Mechanical Phenotype of SH-SY5Y Neuroblastoma and Primary Human Neurons Is Resilient to Oligomeric Aβ(1-42) Injury

Aggregated amyloid beta (Aβ) is widely reported to cause neuronal dystrophy and toxicity through multiple pathways: oxidative stress, disrupting calcium homeostasis, and cytoskeletal dysregulation. The neuro-cytoskeleton is a dynamic structure that reorganizes to maintain cell homeostasis in response to varying soluble and physical cues presented from the extracellular matrix (ECM). Due this relationship between cell health and the ECM, we hypothesize that amyloid toxicity may be directly influenced by physical changes to the ECM (stiffness and dimensionality) through mechanosensitive pathways, and while previous studies demonstrated that Aβ can distort focal adhesion signaling with pathological consequences, these studies do not address the physical contribution from a physiologically relevant matrix. To test our hypothesis that physical cues can adjust Aβ toxicity, SH-SY5Y human neuroblastoma and primary human cortical neurons were plated on soft and stiff, 2D polyacrylamide matrices or suspended in 3D collagen gels. Each cell culture was exposed to escalating concentrations of oligomeric or fibrillated Aβ(1-42) with MTS viability and lactate dehydrogenase toxicity assessed. Actin restructuring was further monitored in live cells by atomic force microscopy nanoindentation, and our results demonstrate that increasing either matrix stiffness or exposure to oligomeric Aβ promotes F-actin polymerization and cell stiffening, while mature Aβ fibrils yielded no apparent cell stiffening and minor toxicity. Moreover, the rounded, softer mechanical phenotype displayed by cells plated onto a compliant matrix also demonstrated a resilience to oligomeric Aβ as noted by a significant recovery of viability when compared to same-dosed cells plated on traditional tissue culture plastic. This recovery was reproduced pharmacologically through inhibiting actin polymerization with cytochalasin D prior to Aβ exposure. These studies indicate that the cell-ECM interface can modify amyloid toxicity in neurons and the matrix-mediated pathways that promote this protection may offer unique targets in amyloid pathologies like Alzheimer's disease.