Liensinine and neferine exert neuroprotective effects via the autophagy pathway in transgenic Caenorhabditis elegans.

BACKGROUND: Liensinine and neferine are the main bisbenzylisoquinoline alkaloids obtained from the seeds of Nelumbo nucifera, which commonly used as edible food and traditional medicine in Asia. It was reported that liensinine and neferine could inhibit the activities of acetylcholinesterase and cross the blood-brain barriers, suggesting their therapeutic potential for the management of Alzheimer's disease. METHODS: Here, we employed SH-SY5Y human neuroblastoma cells stably transfected with the human Swedish amyloid precursor protein (APP) mutation APP695 (APP695swe SH-SY5Y) as an in vitro model and transgenic Caenorhabditis elegans as an in vivo model to investigate the neuroprotective effects and underlying mechanism of liensinine and neferine. RESULTS: We found that liensinine and neferine could significantly improve the viability and reduce ROS levels in APP695swe SH-SY5Y cells, inhibit ß-amyloid and tau-induced toxicity, and enhance stress resistance in nematodes. Moreover, liensinine and neferine had obviously neuroprotective effects by assaying chemotaxis, 5-hydroxytryptamine sensitivity and the integrity of injured neurons in nematodes. Preliminary mechanism studies revealed that liensinine and neferine could upregulate the expression of autophagy related genes (lgg-1, unc-51, pha-4, atg-9 and ced-9) and reduce the accumulation of ß-amyloid induced autophagosomes, which suggested autophagy pathway played a key role in neuroprotective effects of these two alkaloids. CONCLUSIONS: Altogether, our findings provided a certain working foundation for the use of liensinine and neferine to treat Alzheimer's disease based on neuroprotective effects.

Autophagy Regulation Influences ß-Amyloid Toxicity in Transgenic Caenorhabditis elegans.

Alzheimer's disease (AD) is a progressive, neurodegenerative disease characterized by the accumulation of amyloid-beta (Aß) proteins in the form of plaques that cause a proteostasis imbalance in the brain. Several studies have identified autophagy deficits in both AD patients and AD animal models. Here, we used transgenic Caenorhabditis elegans to study the relationship between autophagy flux and Aß. We labeled autophagosomes with an advanced fluorescence reporter system, and used this to observe that human Aß expression caused autophagosome accumulation in C. elegans muscle. The autophagy-related drugs chloroquine and 3-MA were employed to investigate the relationship between changes in autophagic flux and the toxicity of Aß expression. We found that reducing autophagosome accumulation delayed Aß-induced paralysis in the CL4176 strain of C. elegans, and alleviated Aß-induced toxicity, thus having a neuroprotective effect. Finally, we used RNA-sequencing and proteomics to identify genes whose expression was affected by Aß aggregation in C. elegans. We identified a series of enriched autophagy-related signal pathways, suggesting that autophagosome accumulation impairs Aß protein homeostasis in nematodes. Thus, maintaining normal autophagy levels appears to be important in repairing the protein homeostasis imbalance caused by Aß expression.

Dihydro-ß-agarofuran-type sesquiterpenoids from the seeds of Celastrus virens with lifespan-extending effect on the nematode Caenorhabditis elegans.

Twelve dihydro-ß-agarofuran-type sesquiterpenoids, including five new ones (1-5), were purified from the seeds of Celastrus virens (Wang et Tang) C. Y. Chent et T. C. Kao. Their chemical structures were characterized via comprehensive spectroscopic analysis, single-crystal X-ray diffraction analysis, and computational prediction of ECD, as well as comparison of observed and reported NMR spectral data. Among the isolates, nine abundant dihydro-ß-agarofuran-type sesquiterpenoids were evaluated for their lifespan-extending activity using the nematode Caenorhabditis elegans model. As a result, compounds 1, 2, 5, 6, 8, and 9 (50 µM) significantly extended the mean survival time of C. elegans, respectively, compared with the blank control group (p < 0.05). Further Quantitative RT-PCR showed that the prolonging of lifespan mediated by compounds 1, 6, 8, and 9 were dependent on the transcription factors skn-1 and hsf-1.

Agrimophol suppresses RANKL-mediated osteoclastogenesis through Blimp1-Bcl6 axis and prevents inflammatory bone loss in mice.

Excessive activity of osteoclasts causes many bone-related diseases, such as rheumatoid arthritis and osteoporosis. Agrimophol (AGR), a phenolic compound, originated from Agrimonia pilosa Ledeb. In prior studies, AGR is reported to possess schistosomicidal and mycobactericidal activities. However, no reports covered its anti-osteoclastogenesis characteristic. In this study, we found that AGR inhibited RANKL-induced osteoclastogenesis, bone-resorption, F-actin ring formation, and the mRNA expression of osteoclast-associated genes such as CTSK, TRAP, MMP-9, and ATP6v0d2 in vitro. In addition, AGR suppressed RANKL-induced expression of c-Fos and NFATc1. However, AGR treatment did not affect NF-κB activation and MAPKs phosphorylation in RANKL-stimulated BMMs, which implicated that AGR might not influence the initial expression of NFATc1 mediated by NF-κB and MAPKs signaling. Our results further indicated that AGR did not alter phosphorylation levels of GSK3ß and the expression of calcineurin, which implicated that AGR treatment might not interfere with phosphorylation and de-phosphorylation of NFATc1 mediated by GSK3ß and calcineurin, respectively. B-lymphocyte-induced maturation protein-1 (Blimp1), which was regarded as a transcriptional repressor of negative regulators of osteoclastogenesis, was markedly attenuated in the presence of AGR, leading to the enhanced expression of B-cell lymphoma 6 (Bcl-6). Meanwhile, Blimp1 knockdown in BMMs by siRNA strongly enhanced the expression of Bcl6 and reduced NFATc1 induction by RANKL. These findings suggested that AGR inhibited RANKL-induced osteoclast differentiation through Blimp1-Bcl-6 signaling mediated modulation of NFATc1 and its target genes. Consistent with these in vitro results, AGR exhibited a protective influence in an in vivo mouse model of LPS-induced bone loss by suppressing excessive osteoclast activity and attenuating LPS-induced bone destruction. Hence, these results identified that AGR could be considered as a potential therapeutic agent against bone lysis disease.