Dual modulators of aggregation and dissociation of amyloid beta and tau: In vitro, in vivo, and in silico studies of Uncaria rhynchophylla and its bioactive components.

A prominent characteristic of Alzheimer's disease (AD) is the deposition of both amyloid-ß (Aß) peptide and tau protein in the brain. Aß and tau not only induce toxicity through self-aggregation but also induce more potent toxicity through the synergistic action of Aß and tau. In particular, neurotoxic aggregates of Aß and tau directly affect several AD pathologies including neuroinflammation and cognitive decline. Therefore, there is increasing interest in strategies to modulate the aggregation and dissociation of Aß and tau for treatment of AD. Our recent study found that Uncaria rhynchophylla (UR) has a therapeutic effect on AD via the inhibition of Aß aggregation and attenuating Aß-mediated pathogenesis of AD. However, no studies have investigated whether UR has anti- and disaggregation effects on both Aß and tau. In this study, we showed the significant effects of UR on aggregation and dissociation of Aß42 and tau K18 using a thioflavin T (ThT) assay. In addition, histological study revealed an inhibitory effect of UR on the accumulation of Aß and tau and AD-related pathologies in 3xTg mice with both Aß and tau pathology. Furthermore, we found that rhynchophylline and corynoxeine, bioactive components of UR, could modulate the aggregation and dissociation of both Aß and tau using molecular docking simulation, isothermal titration calorimetry, and ThT assays. In conclusion, our results demonstrate that UR can inhibit the aggregation of Aß and tau and promote the degradation of their aggregates in AD.

Relationship between adult subventricular neurogenesis and Alzheimer's disease: Pathologic roles and therapeutic implications.

Alzheimer's disease (AD) is a neurodegenerative disease that is characterized by irreversible cognitive declines. Senile plaques formed by amyloid-ß (Aß) peptides and neurofibrillary tangles, consisting of hyperphosphorylated tau protein accumulation, are prominent neuropathological features of AD. Impairment of adult neurogenesis is also a well-known pathology in AD. Adult neurogenesis is the process by which neurons are generated from adult neural stem cells. It is closely related to various functions, including cognition, as it occurs throughout life for continuous repair and development of specific neural pathways. Notably, subventricular zone (SVZ) neurogenesis, which occurs in the lateral ventricles, transports neurons to several brain regions such as the olfactory bulb, cerebral cortex, striatum, and hippocampus. These migrating neurons can affect cognitive function and behavior in different neurodegenerative diseases. Despite several studies indicating the importance of adult SVZ neurogenesis in neurodegenerative disorders, the pathological alterations and therapeutic implications of impaired adult neurogenesis in the SVZ in AD have not yet been fully explained. In this review, we summarize recent progress in understanding the alterations in adult SVZ neurogenesis in AD animal models and patients. Moreover, we discuss the potential therapeutic approaches for restoring impaired adult SVZ neurogenesis. Our goal is to impart to readers the importance of adult SVZ neurogenesis in AD and to provide new insights through the discussion of possible therapeutic approaches.

Platycodon grandiflorum Root Protects against Aß-Induced Cognitive Dysfunction and Pathology in Female Models of Alzheimer's Disease.

Alzheimer's disease (AD) is a devastating neurodegenerative disease characterized by irreversible cognitive dysfunction. Amyloid beta (Aß) peptide is an important pathological factor that triggers the progression of AD through accumulation and aggregation, which leads to AD-related pathologies that consequently affect cognitive functions. Interestingly, several studies have reported that Platycodon grandiflorum root extract (PGE), besides exhibiting other bioactive effects, displays neuroprotective, anti-neuroinflammatory, and cognitive-enhancing effects. However, to date, it is not clear whether PGE can affect AD-related cognitive dysfunction and pathogenesis. Therefore, to investigate whether PGE influences cognitive impairment in an animal model of AD, we conducted a Y-maze test using a 5XFAD mouse model. Oral administration of PGE for 3 weeks at a daily dose of 100 mg/kg significantly ameliorated cognitive impairment in 5XFAD mice. Moreover, to elucidate the neurohistological mechanisms underlying the PGE-mediated alleviative effect on cognitive dysfunction, we performed histological analysis of hippocampal formation in these mice. Histopathological analysis showed that PGE significantly alleviated AD-related pathologies such as Aß accumulation, neurodegeneration, oxidative stress, and neuroinflammation. In addition, we observed a neuroprotective and antioxidant effect of PGE in mouse hippocampal neurons. Our findings suggest that administration of PGE might act as one of the therapeutic agents for AD by decreasing Aß related pathology and ameliorating Aß induced cognitive impairment.

mTOR-Dependent Role of Sestrin2 in Regulating Tumor Progression of Human Endometrial Cancer.

Oncogenic activation of the mammalian target of rapamycin complex 1 (mTORC1) leads to endometrial cancer cell growth and proliferation. Sestrin2 (SESN2), a highly conserved stress-inducible protein, is involved in homeostatic regulation via inhibition of reactive oxygen species (ROS) and mTORC1. However, the role of SESN2 in human endometrial cancer remains to be investigated. Here, we investigated expression, clinical significance, and underlying mechanisms of SESN2 in endometrial cancer. SESN2 was upregulated more in endometrial cancer tissues than in normal endometrial tissues. Furthermore, upregulation of SESN2 statistically correlated with shorter overall survival and disease-free survival in patients with endometrial cancer. SESN2 expression strongly correlated with mTORC1 activity, suggesting its impact on prognosis in endometrial cancer. Additionally, knockdown of SESN2 promoted cell proliferation, migration, and ROS production in endometrial cancer cell lines HEC-1A and Ishikawa. Treatment of these cells with mTOR inhibitors reversed endometrial cancer cell proliferation, migration, and epithelial-mesenchymal transition (EMT) marker expression. Moreover, in a xenograft nude mice model, endometrial cancer growth increased by SESN2 knockdown. Thus, our study provides evidence for the prognostic significance of SESN2, and a relationship between SESN2, the mTORC1 pathway, and endometrial cancer growth, suggesting SESN2 as a potential therapeutic target in endometrial cancer.

Sestrin2 alleviates palmitate-induced endoplasmic reticulum stress, apoptosis, and defective invasion of human trophoblast cells.

PROBLEM: Maternal obesity induces elevated saturated fatty acid palmitate levels in the blood and causes pregnancy complications such as gestational diabetes, preeclampsia, fetal growth abnormalities, and stillbirth. Sestrin2, a highly conserved stress-inducible protein, is involved in the cellular responses of various stress conditions and homeostatic regulation. However, the effects of Sestrin2 on trophoblast cells have not yet been investigated. Here, we investigated the role of Sestrin2 in palmitate-induced lipotoxicity and its underlying mechanisms in human first-trimester trophoblast cells (Sw.71). METHOD OF STUDY: Mouse placental tissues were obtained from low-fat diet-fed mice (n = 14) and high-fat diet-fed mice (n = 14) at gestation day 17.5. Sw.71 cells were treated with palmitate or bovine serum albumin as vehicle controls. The role of Sestrin2 in palmitate-induced lipotoxicity was examined by immunocytochemistry, immunoblot analysis, quantitative real-time PCR, and invasion assay. RESULTS: Expression of placental Sestrin2 was elevated in high-fat diet-fed dams compared to that of low-fat diet-fed dams. Prolonged treatment of Sw.71 cells with palmitate-induced endoplasmic reticulum (ER) stress-dependent expressions of Sestrin2 protein and mRNA, and the treatment also triggered apoptosis. Knockdown of Sestrin2 increased palmitate-mediated ER stress, inflammatory signaling, and apoptosis. Furthermore, Sestrin2 suppressed impaired trophoblast invasion caused by palmitate and attenuated palmitate-induced ER stress and inflammation via AMPK/mTORC1 pathways. CONCLUSION: Our study provides the relationship between Sestrin2, AMPK/mTORC1 pathway, and trophoblast function, suggesting that Sestrin2 may be a novel potential therapeutic target for the prevention of pregnancy complications.