NPLC0393 from Gynostemma pentaphyllum ameliorates Alzheimer's disease-like pathology in mice by targeting protein phosphatase magnesium-dependent 1A phosphatase.

Alzheimer's disease (AD) is a neurodegenerative disease with clinical hallmarks of progressive cognitive impairment and memory loss. Gynostemma pentaphyllum ameliorates cognitive impairment, but the mechanisms remain obscure. Here, we determine the effect of triterpene saponin NPLC0393 from G. pentaphyllum on AD-like pathology in 3×Tg-AD mice and elucidate the underlying mechanisms. NPLC0393 was administered daily in vivo by intraperitoneal injection for 3 months and its amelioration on the cognitive impairment in 3×Tg-AD mice was assessed by new object recognition (NOR), Y-maze, Morris water maze (MWM), and elevated plus-maze (EPM) tests. The mechanisms were investigated by RT-PCR, western blot, and immunohistochemistry techniques, while verified by the 3×Tg-AD mice with protein phosphatase magnesium-dependent 1A (PPM1A) knockdown (KD) through brain-specific injection of adeno-associated virus (AAV)-ePHP-KD-PPM1A. NPLC0393 ameliorated AD-like pathology targeting PPM1A. It repressed microglial NLRP3 inflammasome activation by reducing NLRP3 transcription during priming and promoting PPM1A binding to NLRP3 to disrupt NLRP3 assembly with apoptosis-associated speck-like protein containing a CARD and pro-caspase-1. Moreover, NPLC0393 suppressed tauopathy by inhibiting tau hyperphosphorylation through PPM1A/NLRP3/tau axis and promoting microglial phagocytosis of tau oligomers through PPM1A/nuclear factor-κB/CX3CR1 pathway. PPM1A mediates microglia/neurons crosstalk in AD pathology, whose activation by NPLC0393 represents a promising therapeutic strategy for AD.

Patchouli alcohol as a selective estrogen receptor ß agonist ameliorates AD-like pathology of APP/PS1 model mice.

Clinical evidence shows that postmenpausal women are almost twice as likely to develop Alzheimer's disease (AD) as men of the same age, and estrogen is closely related to the occurrence of AD. Estrogen receptor (ER) α is mainly expressed in the mammary gland and other reproductive organs like uterus while ERß is largely distributed in the hippocampus and cardiovascular system, suggesting that ERß selective agonist is a valuable drug against neurodegenerative diseases with low tendency in inducing cancers of breast and other reproductive organs. In this study we identified a natural product patchouli alcohol (PTA) as a selective ERß agonist which improved the cognitive defects in female APP/PS1 mice, and explore the underlying mechanisms. Six-month-old female APP/PS1 mice were administered PTA (20, 40 mg · kg-1 · d-1, i.g.) for 90 days. We first demonstrated that PTA bound to ERß with a dissociation constant (KD) of 288.9 ± 35.14 nM in microscale thermophoresis. Then we showed that PTA administration dose-dependently ameliorated cognitive defects evaluated in Morris water maze and Y-maze testes. Furthermore, PTA administration reduced amyloid plaque deposition in the hippocampus by promoting microglial phagocytosis; PTA administration improved synaptic integrity through enhancing BDNF/TrkB/CREB signaling, ameliorated oxidative stress by Catalase level, and regulated Bcl-2 family proteins in the hippocampus. The therapeutic effects of PTA were also observed in vitro: PTA (5, 10, 20 µM) dose-dependently increased phagocytosis of o-FAM-Aß42 in primary microglia and BV2 cells through enhancing ERß/TLR4 signaling; PTA treatment ameliorated o-Aß25-35-induced reduction of synapse-related proteins VAMP2 and PSD95 in primary neurons through enhancing ERß/BDNF/TrkB/CREB pathways; PTA treatment alleviated o-Aß25-35-induced oxidative stress in primary neurons through targeting ERß and increasing Catalase expression. Together, this study has addressed the efficacy of selective ERß agonist in the amelioration of AD and highlighted the potential of PTA as a drug lead compound against the disease.

DW14006 as a direct AMPKα1 activator improves pathology of AD model mice by regulating microglial phagocytosis and neuroinflammation.

Alzheimer's disease (AD) is a progressively neurodegenerative disease with typical hallmarks of amyloid ß (Aß) plaque accumulation, neurofibrillary tangle (NFT) formation and neuronal death extension. In AD brain, activated microglia phagocytose Aß and neuronal debris, but also aggravate inflammation stress by releasing inflammatory factors and cytotoxins. Improving microglia on Aß catabolism and neuroinflammatory intervention is thus believed to be a promising therapeutic strategy for AD. AMP-activated protein kinase (AMPK) is highly expressed in microglia with AMPKα1 being tightly implicated in neuroinflammatory events. Since indirect AMPKα1 activators may cause side effects with undesired intracellular AMP/ATP ratio, we focused on direct AMPKα1 activator study by exploring its potential function in ameliorating AD-like pathology of AD model mice. Here, we reported that direct AMPKα1 activator DW14006 (2-(3-(7-chloro-6-(2'-hydroxy-[1,1'-biphenyl]-4-yl)-2-oxo-1,2-dihydroquinolin-3-yl)phenyl)acetic acid) effectively improved learning and memory impairments of APP/PS1 mice, and the underlying mechanisms have been intensively investigated. DW14006 reduced amyloid plaque deposition by promoting microglial o-Aß42 phagocytosis and ameliorated innate immune response by polarizing microglia to an anti-inflammatory phenotype. It selectively enhanced microglial phagocytosis of o-Aß42 by upgrading scavenger receptor CD36 through AMPKα1/PPARγ/CD36 signaling and suppressed inflammation by AMPKα1/IκB/NFκB signaling. Together, our work has detailed the crosstalk between AMPKα1 and microglia in AD model mice, and highlighted the potential of DW14006 in the treatment of AD.

Nitazoxanide, an anti-parasitic drug, efficiently ameliorates learning and memory impairments in AD model mice.

The pathogenesis of Alzheimer's disease (AD) is characterized by both accumulation of ß-amyloid (Aß) plaque and formation of neurofibrillary tangles in the brain. Recent evidence shows that autophagy activation may potently promote intracellular Aß clearance. Thus targeting autophagy becomes a promising strategy for discovery of drug leads against AD. In the present study, we established a platform to discover autophagy stimulator and screened the lab in-house FDA-approved drug library. We found that anti-parasitic drug nitazoxanide (NTZ) was an autophagy activator and could efficiently improve learning and memory impairments in APP/PS1 transgenic mice. In BV2 cells and primary cortical astrocytes, NTZ stimulated autophagy and promoted Aß clearance by inhibiting both PI3K/AKT/mTOR/ULK1 and NQO1/mTOR/ULK1 signaling pathways; NTZ treatment attenuated LPS-induced inflammation by inhibiting PI3K/AKT/IκB/NFκB signaling. In SH-SY5Y cells and primary cortical neurons, NTZ treatment restrained tau hyperphosphorylation through inhibition of PI3K/AKT/GSK3ß pathway. The beneficial effects and related signaling mechanisms from the in vitro studies were also observed in APP/PS1 transgenic mice following administration of NTZ (90 mg·kg-1·d-1, ig) for 100 days. Furthermore, NTZ administration decreased Aß level and senile plaque formation in the hippocampus and cerebral cortex of APP/PS1 transgenic mice, and improved learning and memory impairments in Morris water maze assay. In conclusion, our results highlight the potential of NTZ in the treatment of AD.

Miltefosine as a PPM1A activator improves AD-like pathology in mice by alleviating tauopathy via microglia/neurons crosstalk.

Alzheimer's disease (AD) is a progressively neurodegenerative disease without effective treatment. Here, we reported that the levels of expression and enzymatic activity of phosphatase magnesium-dependent 1A (PPM1A) were both repressed in brains of AD patient postmortems and 3 × Tg-AD mice, and treatment of adeno-associated virus (AAV)-ePHP-overexpression (OE)-PPM1A for brain-specific PPM1A overexpression or the new discovered PPM1A activator Miltefosine (MF, FDA approved oral anti-leishmanial drug) for PPM1A enzymatic activation improved the AD-like pathology in 3 × Tg-AD mice. The mechanism was intensively investigated by assay against the 3 × Tg-AD mice with brain-specific PPM1A knockdown (KD) through AAV-ePHP-KD-PPM1A injection. MF alleviated neuronal tauopathy involving microglia/neurons crosstalk by both promoting microglial phagocytosis of tau oligomers via PPM1A/Nuclear factor-κb (NF-κB)/C-X3-C Motif Chemokine Receptor 1 (CX3CR1) signaling and inhibiting neuronal tau hyperphosphorylation via PPM1A/NLR Family Pyrin Domain Containing 3 (NLRP3)/tau axis. MF suppressed microglial NLRP3 inflammasome activation by both inhibiting NLRP3 transcription via PPM1A/NF-κB/NLRP3 pathway in priming step and promoting PPM1A binding to NLRP3 to interfere NLRP3 inflammasome assembly in assembly step. Our results have highly addressed that PPM1A activation shows promise as a therapeutic strategy for AD and highlighted the potential of MF in treating this disease.

Antiallergic drug desloratadine as a selective antagonist of 5HT2A receptor ameliorates pathology of Alzheimer's disease model mice by improving microglial dysfunction.

Alzheimer's disease (AD) is a progressively neurodegenerative disease characterized by cognitive deficits and alteration of personality and behavior. As yet, there is no efficient treatment for AD. 5HT2A receptor (5HT2A R) is a subtype of 5HT2 receptor belonging to the serotonin receptor family, and its antagonists have been clinically used as antipsychotics to relieve psychopathy. Here, we discovered that clinically first-line antiallergic drug desloratadine (DLT) functioned as a selective antagonist of 5HT2A R and efficiently ameliorated pathology of APP/PS1 mice. The underlying mechanism has been intensively investigated by assay against APP/PS1 mice with selective 5HT2A R knockdown in the brain treated by adeno-associated virus (AAV)-ePHP-si-5HT2A R. DLT reduced amyloid plaque deposition by promoting microglial Aß phagocytosis and degradation, and ameliorated innate immune response by polarizing microglia to an anti-inflammatory phenotype. It stimulated autophagy process and repressed neuroinflammation through 5HT2A R/cAMP/PKA/CREB/Sirt1 pathway, and activated glucocorticoid receptor (GR) nuclear translocation to upregulate the transcriptions of phagocytic receptors TLR2 and TLR4 in response to microglial phagocytosis stimulation. Together, our work has highly supported that 5HT2A R antagonism might be a promising therapeutic strategy for AD and highlighted the potential of DLT in the treatment of this disease.

Mebhydrolin ameliorates glucose homeostasis in type 2 diabetic mice by functioning as a selective FXR antagonist.

INTRODUCTION: Type 2 diabetes mellitus (T2DM) is a chronic disease with hallmarks of hyperglycemia and hyperlipidemia. Long-term hyperglycemia damages the functions of multiple tissues and organs leading to a series of complications and disability or even death. Nuclear receptor farnesoid X receptor (FXR) antagonism has been recently discovered to exhibit beneficial effect on glucose metabolism in T2DM mice, although the underlying mechanisms remain unclear. Here, we performed the study on the discovery of new FXR antagonist and investigated the mechanism underlying the amelioration of FXR antagonism on glucose homeostasis in T2DM mice by using the determined FXR antagonist as a probe. METHODS: FXR antagonist Mebhydrolin was discovered by screening against the lab in-house FDA approved drug library through surface plasmon resonance (SPR), microscale thermophoresis (MST), AlphaScreen, mammalian one-hybrid and transactivation assays. Activity of Mebhydrolin in improving glucose homeostasis was evaluated in db/db and HFD/STZ-induced T2DM mice, and the mechanisms governing the regulation of Mebhydrolin were investigated by assays of immunostaining, Western blot, ELISA, RT-PCR against liver tissues of both T2DM mice and the T2DM mice with liver-specific FXR knockdown injected via adeno-associated-virus AAV-FXR-RNAi and mouse primary hepatocytes. Finally, molecular docking and molecular dynamics (MD) technology-based study was performed to investigate the structural basis for the antagonistic regulation of Mebhydrolin against FXR at an atomic level. FINDINGS: Mebhydrolin ameliorated blood glucose homeostasis in T2DM mice by both suppressing hepatic gluconeogenesis via FXR/miR-22-3p/PI3K/AKT/FoxO1 pathway and promoting glycogen synthesis through FXR/miR-22-3p/PI3K/AKT/GSK3ß pathway. Structurally, residues L291, M332 and Y373 of FXR were required for Mebhydrolin binding to FXR-LBD, and Mebhydrolin induced H2 and H6 shifting of FXR potently affecting the regulation of the downstream target genes. CONCLUSIONS: Our work has revealed a novel mode for the regulation of FXR against glucose metabolism in T2DM mice and highlighted the potential of Mebhydrolin in the treatment of T2DM.

DW14006 as a Direct AMPKα Activator Ameliorates Diabetic Peripheral Neuropathy in Mice.

Diabetic peripheral neuropathy (DPN) is a long-term complication of diabetes with a complicated pathogenesis. AMP-activated protein kinase (AMPK) senses oxidative stress, and mitochondrial function plays a central role in the regulation of DPN. Here, we reported that DW14006 (2-[3-(7-chloro-6-[2'-hydroxy-(1,1'-biphenyl)-4-yl]-2-oxo-1,2-dihydroquinolin-3-yl)phenyl]acetic acid) as a direct AMPKα activator efficiently ameliorated DPN in both streptozotocin (STZ)-induced type 1 and BKS db/db type 2 diabetic mice. DW14006 administration highly enhanced neurite outgrowth of dorsal root ganglion neurons and improved neurological function in diabetic mice. The underlying mechanisms have been intensively investigated. DW14006 treatment improved mitochondrial bioenergetics profiles and restrained oxidative stress and inflammation in diabetic mice by targeting AMPKα, which has been verified by assay against the STZ-induced diabetic mice injected with adeno-associated virus 8-AMPKα-RNAi. To our knowledge, our work might be the first report on the amelioration of the direct AMPKα activator on DPN by counteracting multiple risk factors including mitochondrial dysfunction, oxidative stress, and inflammation, and DW14006 has been highlighted as a potential leading compound in the treatment of DPN.

Vincamine as a GPR40 agonist improves glucose homeostasis in type 2 diabetic mice.

Vincamine, a monoterpenoid indole alkaloid extracted from the Madagascar periwinkle, is clinically used for the treatment of cardio-cerebrovascular diseases, while also treated as a dietary supplement with nootropic function. Given the neuronal protection of vincamine and the potency of ß-cell amelioration in treating type 2 diabetes mellitus (T2DM), we investigated the potential of vincamine in protecting ß-cells and ameliorating glucose homeostasis in vitro and in vivo. Interestingly, we found that vincamine could protect INS-832/13 cells function by regulating G-protein-coupled receptor 40 (GPR40)/cAMP/Ca2+/IRS2/PI3K/Akt signaling pathway, while increasing glucose-stimulated insulin secretion (GSIS) by modulating GPR40/cAMP/Ca2+/CaMKII pathway, which reveals a novel mechanism underlying GPR40-mediated cell protection and GSIS in INS-832/13 cells. Moreover, administration of vincamine effectively ameliorated glucose homeostasis in either HFD/STZ or db/db type 2 diabetic mice. To our knowledge, our current work might be the first report on vincamine targeting GPR40 and its potential in the treatment of T2DM.

Protopanaxadiol derivative DDPU improves behavior and cognitive deficit in AD mice involving regulation of both ER stress and autophagy.

Alzheimer's disease (AD) is a progressively neurodegenerative disease with typical hallmarks of amyloid ß (Aß) plaque accumulation, neurofibrillary tangle (NFT) formation and neuronal death extension. Aggressive Aß accumulation promotes senile plaque formation and perturbs endoplasmic reticulum (ER) function to trigger the unfolded protein response (UPR) leading to neuronal apoptosis. The stress-dependent activation of protein kinase RNA-like endoplasmic reticulum kinase (PERK) increases the phosphorylation of eukaryotic translation initiation factor-2α (eIF2α) to promote the preferential synthesis of ß-site APP cleavage enzyme 1 (BACE1) and Aß generation in turn. Additionally, dysfunction in autophagy has been reported to contribute to several neurodegenerative diseases including AD, and impairment in autophagy-mediated pathway may constitutively stimulate the generation of Aß in AD. Here we discovered that protopanaxadiol derivative 1-(3,4-dimethoxyphenethyl)-3-(3-dehydroxyl-20(s)-protopanaxadiol-3ß-yl)-urea (DDPU) effectively improved the activity of daily living (ADL) and cognitive deficits in APP/PS1 transgenic mice. The crosstalk between Aß and ER stress has been intensively investigated by using DDPU as a probe. DDPU reduced Aß production mainly by inhibiting the PERK/eIF2α signaling-mediated BACE1 translation and stimulated Aß clearance by promoting autophagy as a PI3K inhibitor through PI3K/AKT/mTOR signaling pathway, while exhibited neuroprotective effect involving attenuation of ER stress. DDPU might be the first reported ginsenoside derivative with dual effects on both autophagy promotion and ER stress amelioration. Our results have highlighted the potential of DDPU in the treatment of AD.