Alzheimer's Amyloid-ß Accelerates Cell Senescence and Suppresses SIRT1 in Human Neural Stem Cells.

As a lifelong source of neurons, neural stem cells (NSCs) serve multiple crucial functions in the brain. The senescence of NSCs may be associated with the onset and progression of Alzheimer's disease (AD). Our study reveals a noteworthy finding, indicating that the AD-associated pathogenic protein amyloid-ß (Aß) substantially enhances senescence-related characteristics of human NSCs. These characteristics encompass the enhanced expression of p16 and p21, the upregulation of genes associated with the senescence-associated secretory phenotype (SASP), increased SA-ß-gal activity, and the activation of the DNA damage response. Further studies revealed that Aß treatment significantly downregulates the SIRT1 protein which plays a crucial role in regulating the aging process and decreases downstream PGC-1α and FOXO3. Subsequently, we found that SIRT1 overexpression significantly alleviates a range of Aß-induced senescent markers in human NSCs. Taken together, our results uncover that Aß accelerates cellular senescence in human NSCs, making SIRT1 a highly promising therapeutic target for senescent NSCs which may contribute to age-related neurodegenerative diseases, including AD.

Tsaokoflavanols A1-J1: Flavanol-fatty alcohol hybrids with HPL inhibitory activity from Amomum tsao-ko.

Ten previously undescribed compounds were isolated from the fruits of Amomum tsao-ko (Zingiberaceae), including nine undescribed flavanol-fatty alcohol hybrids (1-6, 10-11, 13), and a flavanol-monoterpenoid hybrid (14), along with seven known flavanol hybrids (7-9, 12, 15-17). The structures of these compounds were determined using various analyses, such as HRESIMS, 1D/2D NMR, and ECD calculations. In terms of biological activity, compounds 1, 2, 5, and 6 exhibited inhibitions of human pancreatic lipase (HPL), with IC50 values ranging from 0.017 to 0.193 mM. Some of these values were found to be stronger than that of the positive control, orlistat (IC50, 0.067 mM). Molecular docking studies were also conducted to investigate the interactions between these compounds and HPL. The docking simulations revealed the importance of the orientation of the 3,4-dihydroxyphenyl in binding with HPL. Additionally, compound 9 demonstrated cytotoxicity against HepG2, with a CC50 value of 14.96 ± 0.62 µM as determined by the MTT assay. Flow cytometry analysis indicated that compound 9 induced apoptosis in HepG2 cells. Western blot results showed an up-regulation of apoptosis-related proteins, such as p53 protein, Bax and Caspase-3 proteins, while the expression of Bcl-2 protein was down-regulated.

Galangin Rescues Alzheimer's Amyloid-ß Induced Mitophagy and Brain Organoid Growth Impairment.

Dysfunctional mitochondria and mitophagy are hallmarks of Alzheimer's disease (AD). It is widely accepted that restoration of mitophagy helps to maintain cellular homeostasis and ameliorates the pathogenesis of AD. It is imperative to create appropriate preclinical models to study the role of mitophagy in AD and to assess potential mitophagy-targeting therapies. Here, by using a novel 3D human brain organoid culturing system, we found that amyloid-ß (Aß1-42,10 µM) decreased the growth level of organoids, indicating that the neurogenesis of organoids may be impaired. Moreover, Aß treatment inhibited neural progenitor cell (NPC) growth and induced mitochondrial dysfunction. Further analysis revealed that mitophagy levels were reduced in the brain organoids and NPCs. Notably, galangin (10 µM) treatment restored mitophagy and organoid growth, which was inhibited by Aß. The effect of galangin was blocked by the mitophagy inhibitor, suggesting that galangin possibly acted as a mitophagy enhancer to ameliorate Aß-induced pathology. Together, these results supported the important role of mitophagy in AD pathogenesis and suggested that galangin may be used as a novel mitophagy enhancer to treat AD.

Rhamnose Displays an Anti-Obesity Effect Through Stimulation of Adipose Dopamine Receptors and Thermogenesis.

The imbalance between energy intake and energy expenditure leads to the prevalence of obesity worldwide. A strategy to simultaneously limit energy intake and promote energy expenditure would be an important new obesity treatment. Here, we identified rhamnose as a nonnutritive sweetener to promote adipose thermogenesis and energy expenditure. Rhamnose promotes cAMP production and PKA activation through dopamine receptor D1 in adipose tissue. As a result, rhamnose administration promotes UCP1-dependent thermogenesis and ameliorates obesity in mice. Thus, we have demonstrated a rhamnose-dopamine receptor D1-PKA axis critical for thermogenesis, and that rhamnose may have a role in therapeutic molecular diets against obesity.

Rescue of Mitochondrial SIRT3 Ameliorates Ischemia-like Injury in Human Endothelial Cells.

Structural and functional alterations of vasculature caused by age-related factors is critically involved in the pathogenesis of ischemic stroke. The longevity genes sirtuins (SIRTs) are extensively investigated in aging-associated pathologies, but their distinct roles in ischemic stroke still remain to be clarified. To address this question, we applied oxygen and glucose deprived/reperfusion (OGD/R) to induce ischemic injury in human endothelial cells (ECs), which are the main component of vasculature in the brain. The results showed that OGD/R led to various damages to ECs, including compromised cell viability, increased LDH release, overproduced ROS, enhanced apoptosis and caspase activity. Meanwhile, the expression of mitochondrial SIRT3 was robustly decreased in ECs after OGD/R treatment. Consistently, rescue of SIRT3 by ectopic expression, but not nuclear SIRT1, in ECs reversed the OGD/R-induced cell damage. Interestingly, some front-line drugs for ischemic stroke, including clopidogrel, aspirin and dl-3-n-butylphthalide (NBP), also rescued SIRT3 and reduced OGD/R-induced endothelial injury, suggesting that the recovery of SIRT3 expression was critical for the protection of these drugs. Moreover, our results demonstrated that 10-hydroxy-NBP (OHNBP), a major metabolite of NBP, showed better blood-brain barrier crossing capability than NBP, but still retained the effects on SIRT3 by NBP. Together, our results suggested that SIRT3 may serve as a potential novel target for treatment of ischemic stroke.

Alzheimer's Amyloid-ß Accelerates Cell Senescence and Suppresses the SIRT1/NRF2 Pathway in Human Microglial Cells.

Microglia play important roles in maintenance of brain homeostasis, while due to some pathological stimuli in aging-related neurodegenerative diseases including Alzheimer's disease, they are malfunctioning. Here, we demonstrated that amyloid-ß (Aß) accelerated cell senescence characterized by the upregulation of p21 and PAI-1 as well as senescence-associated beta-galactosidase (SA-ß-gal) in human microglial cells. Consistently, Aß induced the senescence-associated mitochondrial dysfunctions such as repression of ATP production, oxygen consumption rate (OCR), and mitochondrial membrane potential and enhancement of ROS production. Furthermore, Aß was found to significantly suppress mRNA expression and protein level of Sirtuin-1 (SIRT1), a key regulator of senescence, and inhibit mRNA expression and translocation of NRF2, a critical transcription factor in inflammatory responses, leading to impairment of phagocytosis. Rescue of SIRT1, as expected, could counteract the pathological effects of Aß. In summary, our findings revealed that Aß accelerates human microglial senescence mainly through its suppression of the SIRT1/NRF2 pathway and suggested that genetic and pharmaceutical rescue of SIRT1 may provide a potential alternative treatment.

Alzheimer's Amyloid-ß Accelerates Human Neuronal Cell Senescence Which Could Be Rescued by Sirtuin-1 and Aspirin.

Cellular senescence is a major biological process related to aging. Neuronal cell senescence contributes to the pathogenesis of many aging-related neurodegenerative diseases including Alzheimer's disease (AD). In this study, we showed that amyloid-ß42 oligomers (Aß), one of the core pathological players of AD, significantly upregulated the expression of senescence markers, p21, plasminogen activator inhibitor-1 (PAI-1), and SA-ß-gal (senescence-associated ß-galactosidase) in multiple human neuronal cells, including SK-N-SH cells, SH-SY5Y cells, and neural stem cell (NSC)-derived neuronal cells. Moreover, it was consistently observed among the cells that Aß promoted senescence-associated DNA damage as the levels of 8-OHdG staining, histone variant H2AX phosphorylation (γ-H2AX), and genomic DNA lesion increased. Mechanism study revealed that the exposure of Aß markedly suppressed the expression of sirtuin-1 (SIRT1), a critical regulator of aging, and the exogenous expression of SIRT1 alleviated Aß-induced cell senescence phenotypes. To our surprise, a widely used cardiovascular drug aspirin considerably rescued Aß-induced cellular senescence at least partially through its regulation of SIRT1. In conclusion, our findings clearly demonstrate that exposure of Aß alone is sufficient to accelerate the senescence of human neuronal cells through the downregulation of SIRT1.

Chimeric cerebral organoids reveal the essentials of neuronal and astrocytic APOE4 for Alzheimer's tau pathology.

The apolipoprotein E4 (APOE4) genotype is one of the strongest genetic risk factors for Alzheimer's disease (AD), and is generally believed to cause widespread pathological alterations in various types of brain cells. Here, we developed a novel engineering method of creating the chimeric human cerebral organoids (chCOs) to assess the differential roles of APOE4 in neurons and astrocytes. First, the astrogenic factors NFIB and SOX9 were introduced into induced pluripotent stem cells (iPSCs) to accelerate the induction of astrocytes. Then the above induced iPSCs were mixed and cocultured with noninfected iPSCs under the standard culturing condition of cerebral organoids. As anticipated, the functional astrocytes were detected as early as 45 days, and it helped more neurons matured in chCOs in comparation of the control human cerebral organoids (hCOs). More interestingly, this method enabled us to generate chCOs containing neurons and astrocytes with different genotypes, namely APOE3 or APOE4. Then, it was found in chCOs that astrocytic APOE4 already significantly promoted lipid droplet formation and cholesterol accumulation in neurons while both astrocytic and neuronal APOE4 contributed to the maximum effect. Most notably, we observed that the co-occurrence of astrocytic and neuronal APOE4 were required to elevate neuronal phosphorylated tau levels in chCOs while Aß levels were increased in chCOs with neuronal APOE4. Altogether, our results not only revealed the essence of both neuronal and astrocytic APOE4 for tau pathology, but also suggested chCOs as a valuable pathological model for AD research and drug discovery.

ß-Arrestin 2 and Epac2 Cooperatively Mediate DRD1-Stimulated Proliferation of Human Neural Stem Cells and Growth of Human Cerebral Organoids.

G-protein-coupled receptors (GPCRs) reportedly relay specific signals, such as dopamine and serotonin, to regulate neurogenic processes although the underlying signaling pathways are not fully elucidated. Based on our previous work, which demonstrated dopamine receptor D1 (DRD1) effectively induces the proliferation of human neural stem cells, here we continued to show the knockout of ß-arrestin 2 by CRISPR/Cas9 technology significantly weakened the DRD1-induced proliferation and neurosphere growth. Furthermore, inhibition of the downstream p38 MAPK by its specific inhibitors or small hairpin RNA mimicked the weakening effect of ß-arrestin 2 knockout. In addition, blocking of Epac2, a PKA independent signal pathway, by its specific inhibitors or small hairpin RNA also significantly reduced DRD1-induced effects. Simultaneous inhibition of ß-arrestin 2/p38 MAPK and Epac2 pathways nearly abolished the DRD1-stimulated neurogenesis, indicating the cooperative contribution of both pathways. Consistently, the expansion and folding of human cerebral organoids as stimulated by DRD1 were also mediated cooperatively by both ß-arrestin 2/p38 MAPK and Epac2 pathways. Taken together, our results reveal that GPCRs apply at least 2 different signal pathways to regulate neurogenic processes in a delicate and balanced manners.

In vivo development and single-cell transcriptome profiling of human brain organoids.

OBJECTIVES: Human brain organoids can provide not only promising models for physiological and pathological neurogenesis but also potential therapies in neurological diseases. However, technical issues such as surgical lesions due to transplantation still limit their applications. MATERIALS AND METHODS: Instead of applying mature organoids, we innovatively developed human brain organoids in vivo by injecting small premature organoids into corpus striatum of adult SCID mice. Two months after injection, single-cell transcriptome analysis was performed on 6131 GFP-labeled human cells from transplanted mouse brains. RESULTS: Eight subsets of cells (including neuronal cells expressing striatal markers) were identified in these in vivo developed organoids (IVD-organoids) by unbiased clustering. Compared with in vitro cultured human cortical organoids, we found that IVD-organoids developed more supporting cells including pericyte-like and choroid plexus cells, which are important for maintaining organoid homeostasis. Furthermore, IVD-organoids showed lower levels of cellular stress and apoptosis. CONCLUSIONS: Our study thus provides a novel method to generate human brain organoids, which is promising in various applications of disease models and therapies.

ß-arrestin 2 quenches TLR signaling to facilitate the immune evasion of EPEC.

The protein translocated intimin receptor (Tir) from enteropathogenic Escherichia coli shares sequence similarity with the host cellular immunoreceptor tyrosine-based inhibition motifs (ITIMs). The ITIMs of Tir are required for Tir-mediated immune inhibition and evasion of host immune responses. However, the underlying molecular mechanism by which Tir regulates immune inhibition remains unclear. Here we demonstrated that ß-arrestin 2, which is involved in the G-protein-coupled receptor (GPCR) signal pathway, interacted with Tir in an ITIM-dependent manner. For the molecular mechanism, we found that ß-arrestin 2 enhanced the recruitment of SHP-1 to Tir. The recruited SHP-1 inhibited K63-linked ubiquitination of TRAF6 by dephosphorylating TRAF6 at Tyr288, and inhibited K63-linked ubiquitination and phosphorylation of TAK1 by dephosphorylating TAK1 at Tyr206, which cut off the downstream signal transduction and subsequent cytokine production. Moreover, the inhibitory effect of Tir on immune responses was diminished in ß-arrestin 2-deficient mice and macrophages. These findings suggest that ß-arrestin 2 is a key regulator in Tir-mediated immune evasion, which could serve as a new therapeutic target for bacterial infectious diseases.

PL201, a Reported Rhamnoside Against Alzheimer's Disease Pathology, Alleviates Neuroinflammation and Stimulates Nrf2 Signaling.

Neuroinflammation induced by overactivated glia cells is believed to be a major hallmark of Alzheimer's disease (AD) and a hopeful target against AD. A rhamnoside PL201 was previously reported to promote neurogenesis and ameliorate AD, and in this study, we revealed that PL201 also significantly reduced accumulation of the activated microglia and proinflammatory cytokines in APP/PS1 mice. In vitro, PL201 consistently suppressed the microglia induction of proinflammatory cytokines after stimulation with lipopolysaccharides and Aß42. Further mechanistic studies demonstrated that PL201 considerably enhanced the expression level and the nuclear translocation of Nrf2, a key regulator of neuroinflammation. Moreover, PL201 effectively stimulated Nrf2 signaling cascade, including upregulation of HO-1 and downregulation of NF-κB pathway. Thus, our findings indicated the anti-neuroinflammatory effect by PL201 in vivo and suggested that PL201 or the like, with multiple functions such as neurogenesis, mitochondria maintenance, and anti-neuroinflammation, could be a promising candidate in AD treatment.

Author Correction: Suppression of glioblastoma by a drug cocktail reprogramming tumor cells into neuronal like cells.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Polysaccharides from Lycium barbarum ameliorate amyloid pathology and cognitive functions in APP/PS1 transgenic mice.

Alzheimer's disease (AD) is the most common degenerative disease of the central nervous system. It is associated with abnormal accumulation of amyloid-ß (Aß) plaques, impaired neurogenesis, and damaged cognitive functions. We have known for a long time that natural compounds and their derivatives have gained increasing attention in AD drug research due to their multiple effects and inherently enormous chemicals. In this study, we will demonstrate that polysaccharides from L. barbarum (LBP1), a traditional natural compound, can reduce Aß level and improve the cognitive functions in APP/PS1 transgenic mouse. LBP1 can enhance neurogenesis as indicated by BrdU/NeuN double labeling. Furthermore, it can restore synaptic dysfunction at hippocampus CA3-CA1 pathway. Additionally, in vitro cell assay indicates that LBP1 may affect Aß processing. In conclusion, our study indicates that LBP1 might be a potential therapeutic agent for the treatment of AD against multiple targets that include synaptic plasticity, Aß pathology and neuropathology.

An analog derived from phenylpropanoids ameliorates Alzheimer's disease-like pathology and protects mitochondrial function.

The abnormal proliferation and neurogenesis of neural progenitor cells (NPCs) is usually associated with the pathophysiology of neurodegenerative disorders such as Alzheimer's disease (AD). Mitochondrial stress is one of the most prominent features of AD and is thought to be involved in the impairment of the neurogenesis and proliferation of NPCs. Thus, restoring mitochondrial function by pharmaceutical intervention may alleviate disease-related defects in neurogenesis and is considered a potential therapeutic strategy for AD. In the present study, we found that the oral administration of PL201A, a designed analog of phenylpropanoids, which are a family of natural products with antiaging effects, promoted the neurogenesis and proliferation of NPCs and ameliorated cognitive impairment in a transgenic mouse model of AD. Furthermore, PL201A attenuated amyloid-ß-induced mitochondrial stress and promoted NPC proliferation in vitro. Further mechanistic studies showed that PL201A restored the activation of AMP-regulated protein kinase-retinoblastoma signaling, which was suppressed by amyloid-ß. Our findings suggest that PL201A may represent a promising regenerative therapeutic agent for cognitive decline in neurodegenerative diseases.

Suppression of glioblastoma by a drug cocktail reprogramming tumor cells into neuronal like cells.

Glioblastoma (GBM) is the most common and aggressive malignant tumor in adult brain. Even with the current standard therapy including surgical resection followed by postoperative radiotherapy and chemotherapy with temozolomide (Temo), GBM patients still have a poor median survival. Reprogramming of tumor cells into non-malignant cells might be a promising therapeutic strategy for malignant tumors, including GBM. Based on previous studies using small molecules to reprogram astrocytes into neuronal cells, here we further identified a FTT cocktail of three commonly used drugs (Fasudil, Tranilast, and Temo) to reprogram patient-derived GBM cells, either cultured in serum containing or serum-free medium, into neuronal like cells. FTT-treated GBM cells displayed a neuronal like morphology, expressed neuronal genes, exhibited neuronal electrophysiological properties, and showed attenuated malignancy. More importantly, FTT cocktail more significantly suppressed tumor growth and prolonged survival in GBM patient derived xenograft than Temo alone. Our study provided preclinical evidence that the neuronal reprogramming drug cocktail might be a promising strategy to improve the existing treatment for GBM.

Analysis and Improvement of a Dual-Core Photonic Crystal Fiber Sensor.

The characteristics of the dual-core photonic crystal fiber (PCF) sensor are studied using the finite element method (FEM), and the structure is improved according to the numerical simulation results. The results show that whether or not the four large air holes far away from the geometry center of the PCF are filled with analyte has no influence on the wavelength sensitivity of the sensor which means those holes can be replaced by small air holes. The wavelength sensitivity can be tuned by adjusting the sizes of the other large air holes which are as for liquid holes. The dynamic detection range of the refractive index (RI) is from 1.33 to 1.51. In particular, high linearity is obtained in the range of 1.44 to 1.51. The sensitivity is as high as 6021 nm/RIU when the liquid holes are the smallest. When liquid holes are tangential with the envelope of first layer air holes, the wavelength sensitivity is 4028 nm/RIU, and the coefficient of determination (R²) is 0.99822 when the RI of the analyte varies from 1.44 to 1.51 which shows that high sensitivity and good linearity are both obtained.

Naringin Dihydrochalcone Ameliorates Cognitive Deficits and Neuropathology in APP/PS1 Transgenic Mice.

Alzheimer's disease (AD) is a multi-factorial neurodegenerative disorder with abnormal accumulation of amyloid-ß (Aß) plaques, neuroinflammation and impaired neurogenesis. Mounting evidences suggest that single-target drugs have limited effects on clinical treatment and alternative or multiple targets are required. In recent decades, natural compounds and their derivatives have gained increasing attention in AD drug discovery due to their inherently enormous chemical and structural diversity. In this study, we demonstrated that naringin dihydrochalcone (NDC), a widely used dietary sweetener with strong antioxidant activity, improved the cognitive function of transgenic AD mice. Pathologically, NDC attenuated Aß deposition in AD mouse brain. Furthermore, NDC reduced periplaque activated microglia and astrocytes, indicating the inhibition of neuroinflammation. It also enhanced neurogenesis as investigated by BrdU/NeuN double labeling. Additionally, the inhibition of Aß level and neuroinflammation by NDC treatment was also observed in an AD cell model or a microglia cell line. Taken together, our study indicated that NDC might be a potential therapeutic agent for the treatment of AD against multiple targets that include Aß pathology, neuroinflammation and neurogenesis.

Stabilization of mouse haploid embryonic stem cells with combined kinase and signal modulation.

Mammalian haploid embryonic stem cells (haESCs) provide new possibilities for large-scale genetic screens because they bear only one copy of each chromosome. However, haESCs are prone to spontaneous diploidization through unknown mechanisms. Here, we report that a small molecule combination could restrain mouse haESCs from diploidization by impeding exit from naïve pluripotency and by shortening the S-G2/M phases. Combined with 2i and PD166285, our chemical cocktail could maintain haESCs in the haploid state for at least five weeks without fluorescence-activated cell sorting (FACS) enrichment of haploid cells. Taken together, we established an effective chemical approach for long-term maintenance of haESCs, and highlighted that proper cell cycle progression was critical for the maintenance of haploid state.