Lei-Lei Chen

Berberine ameliorates β-amyloid pathology, gliosis, and cognitive impairment in an Alzheimer's disease transgenic mouse model.

The accumulation of β-amyloid (Aβ) peptide derived from abnormal processing of amyloid precursor protein (APP) is a common pathological hallmark of Alzheimers disease (AD) brains. In this study, we evaluated the therapeutic effect of berberine (BBR) extracted from Coptis chinensis Franch, a Chinese medicinal herb, on the neuropathology and cognitive impairment in TgCRND8 mice, a well established transgenic mouse model of AD. Two-month-old TgCRND8 mice received a low (25 mg/kg per day) or a high dose of BBR (100 mg/kg per day) by oral gavage until 6 months old. BBR treatment significantly ameliorated learning deficits, long-term spatial memory retention, as well as plaque load compared with vehicle control treatment. In addition, enzyme-linked immunosorbent assay (ELISA) measurement showed that there was a profound reduction in levels of detergent-soluble and -insoluble β-amyloid in brain homogenates of BBR-treated mice. Glycogen synthase kinase (GSK)3, a major kinase involved in APP and tau phosphorylation, was significantly inhibited by BBR treatment. We also found that BBR significantly decreased the levels of C-terminal fragments of APP and the hyperphosphorylation of APP and tau via the Akt/glycogen synthase kinase 3 signaling pathway in N2a mouse neuroblastoma cells stably expressing human Swedish mutant APP695 (N2a-SwedAPP). Our results suggest that BBR provides neuroprotective effects in TgCRND8 mice through regulating APP processing and that further investigation of the BBR for therapeutic use in treating AD is warranted.

HMGB1 is involved in autophagy inhibition caused by SNCA/α-synuclein overexpression: A process modulated by the natural autophagy inducer corynoxine B

SNCA/α-synuclein and its rare mutations are considered as the culprit proteins in Parkinson disease (PD). Wild-type (WT) SNCA has been shown to impair macroautophagy in mammalian cells and in transgenic mice. In this study, we monitored the dynamic changes in autophagy process and confirmed that overexpression of both WT and SNCAA53T inhibits autophagy in PC12 cells in a time-dependent manner. Furthermore, we showed that SNCA binds to both cytosolic and nuclear high mobility group box 1 (HMGB1), impairs the cytosolic translocation of HMGB1, blocks HMGB1-BECN1 binding, and strengthens BECN1-BCL2 binding. Deregulation of these molecular events by SNCA overexpression leads to autophagy inhibition. Overexpression of BECN1 restores autophagy and promotes the clearance of SNCA. siRNA knockdown of Hmgb1 inhibits basal autophagy and abolishes the inhibitory effect of SNCA on autophagy while overexpression of HMGB1 restores autophagy. Corynoxine B, a natural autophagy inducer, restores the deficient cytosolic translocation of HMGB1 and autophagy in cells overexpressing SNCA, which may be attributed to its ability to block SNCA-HMGB1 interaction. Based on these findings, we propose that SNCA-induced impairment of autophagy occurs, in part, through HMGB1, which may provide a potential therapeutic target for PD.

HMGB1 is involved in autophagy inhibition caused by SNCA/α-synuclein overexpression

SNCA/α-synuclein and its rare mutations are considered as the culprit proteins in Parkinson disease (PD). Wild-type (WT) SNCA has been shown to impair macroautophagy in mammalian cells and in transgenic mice. In this study, we monitored the dynamic changes in autophagy process and confirmed that overexpression of both WT and SNCAA53T inhibits autophagy in PC12 cells in a time-dependent manner. Furthermore, we showed that SNCA binds to both cytosolic and nuclear high mobility group box 1 (HMGB1), impairs the cytosolic translocation of HMGB1, blocks HMGB1-BECN1 binding, and strengthens BECN1-BCL2 binding. Deregulation of these molecular events by SNCA overexpression leads to autophagy inhibition. Overexpression of BECN1 restores autophagy and promotes the clearance of SNCA. siRNA knockdown of Hmgb1 inhibits basal autophagy and abolishes the inhibitory effect of SNCA on autophagy while overexpression of HMGB1 restores autophagy. Corynoxine B, a natural autophagy inducer, restores the deficient cytosolic translocation of HMGB1 and autophagy in cells overexpressing SNCA, which may be attributed to its ability to block SNCA-HMGB1 interaction. Based on these findings, we propose that SNCA-induced impairment of autophagy occurs, in part, through HMGB1, which may provide a potential therapeutic target for PD.

LC-MS-based urinary metabolite signatures in idiopathic Parkinson's disease.

Increasing evidence has shown that abnormal metabolic phenotypes in body fluids reflect the pathogenesis and pathophysiology of Parkinsons disease (PD). These body fluids include urine; however, the relationship between, specifically, urinary metabolic phenotypes and PD is not fully understood. In this study, urinary metabolites from a total of 401 clinical urine samples collected from 106 idiopathic PD patients and 104 normal control subjects were profiled by using high-performance liquid chromatography coupled to high-resolution mass spectrometry. Our study revealed significant correlation between clinical phenotype and urinary metabolite profile. Metabolic profiles of idiopathic PD patients differed significantly and consistently from normal controls, with related metabolic pathway variations observed in steroidogenesis, fatty acid beta-oxidation, histidine metabolism, phenylalanine metabolism, tryptophan metabolism, nucleotide metabolism, and tyrosine metabolism. In the fruit fly Drosophila melanogaster, the alteration of the kynurenine pathway in tryptophan metabolism corresponded with pathogenic changes in the alpha-synuclein overexpressed Drosophila model of PD. The results suggest that LC-MS-based urinary metabolomic profiling can reveal the metabolite signatures and related variations in metabolic pathways that characterize PD. Consistent PD-related changes across species may provide the basis for understanding metabolic regulation of PD at the molecular level.

Corynoxine, a Natural Autophagy Enhancer, Promotes the Clearance of Alpha-Synuclein via Akt/mTOR Pathway

Parkinson’s disease (PD) is the second most common neurodegenerative disorder characterized by the accumulation of protein aggregates (namely Lewy bodies) in dopaminergic neurons in the substantia nigra region of the brain. Alpha-synuclein (α-syn) is the major component of Lewy bodies in PD patients, and impairment of the autophagy-lysosomal system has been linked to its accumulation. In our previous study, we identified an oxindole alkaloid Corynoxine B (Cory B), isolated from Uncaria rhynchophylla (Miq.) Jacks (Gouteng in Chinese), as a Beclin-1-dependent autophagy inducer. In this work, we show that Cory, an enantiomer of Cory B, also induces autophagy in different neuronal cell lines, including N2a and SHSY-5Y cells, which is paralleled with increased lysosomal enzyme cathepsin D. In vivo, Cory promotes the formation of autophagosomes in the fat bodies of Drosophila. By inducing autophagy, Cory promotes the clearance of wild-type and A53T α-syn in inducible PC12 cells. Interestingly, different from its enantiomer Cory B, Cory induces autophagy through the Akt/mTOR pathway as evidenced by the reduction in the levels of phospho-Akt, phospho-mTOR and phospho-p70 S6 Kinase. Collectively, our findings provide experimental evidence for developing Cory as a new autophagy enhancer from Chinese herbal medicine, which may have potential application in the prevention or treatment of PD.

A novel curcumin analog binds to and activates TFEB in vitro and in vivo independent of MTOR inhibition.

ABSTRACT Autophagy dysfunction is a common feature in neurodegenerative disorders characterized by accumulation of toxic protein aggregates. Increasing evidence has demonstrated that activation of TFEB (transcription factor EB), a master regulator of autophagy and lysosomal biogenesis, can ameliorate neurotoxicity and rescue neurodegeneration in animal models. Currently known TFEB activators are mainly inhibitors of MTOR (mechanistic target of rapamycin [serine/threonine kinase]), which, as a master regulator of cell growth and metabolism, is involved in a wide range of biological functions. Thus, the identification of TFEB modulators acting without inhibiting the MTOR pathway would be preferred and probably less deleterious to cells. In this study, a synthesized curcumin derivative termed C1 is identified as a novel MTOR-independent activator of TFEB. Compound C1 specifically binds to TFEB at the N terminus and promotes TFEB nuclear translocation without inhibiting MTOR activity. By activating TFEB, C1 enhances autophagy and lysosome biogenesis in vitro and in vivo. Collectively, compound C1 is an orally effective activator of TFEB and is a potential therapeutic agent for the treatment of neurodegenerative diseases.

Tianma Gouteng Yin, a Traditional Chinese Medicine decoction, exerts neuroprotective effects in animal and cellular models of Parkinson’s disease

Tianma Gouteng Yin (TGY) is a traditional Chinese medicine (TCM) decoction widely used to treat symptoms associated with typical Parkinson’s disease (PD). In this study, the neuroprotective effects of water extract of TGY were tested on rotenone-intoxicated and human α-synuclein transgenic Drosophila PD models. In addition, the neuroprotective effect of TGY was also evaluated in the human dopaminergic neuroblastoma SH-SY5Y cell line treated with rotenone and the rotenone intoxicated hemi-parkinsonian rats. In rotenone-induced PD models, TGY improved survival rate, alleviated impaired locomotor function of Drosophila, mitigated the loss of dopaminergic neurons in hemi-parkinsonian rats and alleviated apoptotic cell death in SH-SY5Y cells; in α-synuclein transgenic Drosophila, TGY reduced the level of α-synuclein and prevented degeneration of dopaminergic neurons. Conclusively, TGY is neuroprotective in PD models both in vivo and in vitro.

Effects of Huanglian-Jie-Du-Tang and its modified formula on the modulation of amyloid-β precursor protein processing in Alzheimer's disease models.

Huanglian-Jie-Du-Tang (HLJDT) is a famous traditional Chinese herbal formula that has been widely used clinically to treat cerebral ischemia. Recently, we found that berberine, a major alkaloid compound in HLJDT, reduced amyloid-β (Aβ) accumulation in an Alzheimer’s disease (AD) mouse model. In this study, we compared the effects of HLJDT, four single component herbs of HLJDT (Rhizoma coptidis (RC), Radix scutellariae (RS), Cortex phellodendri (CP) and Fructus gardenia (FG)) and the modified formula of HLJDT (HLJDT-M, which is free of RS) on the regulatory processing of amyloid-β precursor protein (APP) in an in vitro model of AD. Here we show that treatment with HLJDT-M and its components RC, CP, and the main compound berberine on N2a mouse neuroblastoma cells stably expressing human APP with the Swedish mutation (N2a-SwedAPP) significantly decreased the levels of full-length APP, phosphorylated APP at threonine 668, C-terminal fragments of APP, soluble APP (sAPP)-α and sAPPβ-Swedish and reduced the generation of Aβ peptide in the cell lysates of N2a-SwedAPP. HLJDT-M showed more significant APP- and Aβ- reducing effects than berberine, RC or CP treatment alone. In contrast, HLJDT, its component RS and the main active compound of RS, baicalein, strongly increased the levels of all the metabolic products of APP in the cell lysates. The extract from FG, however, did not influence APP modulation. Interestingly, regular treatment of TgCRND8 APP transgenic mice with baicalein exacerbated the amyloid plaque burden, APP metabolism and Aβ production. Taken together, these data provide convincing evidence that HLJDT and baicalein treatment can increase the amyloidogenic metabolism of APP which is at least partly responsible for the baicalein-mediated Aβ plaque increase in the brains of TgCRND8 mice. On the other hand, HLJDT-M significantly decreased all the APP metabolic products including Aβ. Further study of HLJDT-M for therapeutic use in treating AD is warranted.

NRBF2 is involved in the autophagic degradation process of APP-CTFs in Alzheimer disease models

ABSTRACT Alzheimer disease (AD) is the most common neurodegenerative disease characterized by the deposition of amyloid plaque in the brain. The autophagy-associated PIK3C3-containing phosphatidylinositol 3-kinase (PtdIns3K) complex has been shown to interfere with APP metabolism and amyloid beta peptide (Aβ) homeostasis via poorly understood mechanisms. Here we report that NRBF2 (nuclear receptor binding factor 2), a key component and regulator of the PtdIns3K, is involved in APP-CTFs homeostasis in AD cell models. We found that NRBF2 interacts with APP in vivo and its expression levels are reduced in hippocampus of 5XFAD AD mice; we further demonstrated that NRBF2 overexpression promotes degradation of APP C-terminal fragments (APP-CTFs), and reduces Aβ1–40 and Aβ1-42 levels in human mutant APP-overexpressing cells. Conversely, APP-CTFs, Aβ1–40 and Aβ1-42 levels were increased in Nrbf2 knockdown or nrbf2 knockout cells. Furthermore, NRBF2 positively regulates autophagy in neuronal cells and NRBF2-mediated reduction of APP-CTFs levels is autophagy dependent. Importantly, nrbf2 knockout attenuates the recruitment of APP and APP-CTFs into phagophores and the sorting of APP and APP-CTFs into endosomal intralumenal vesicles, which is accompanied by the accumulation of the APP and APP-CTFs into RAB5-positive early endosomes. Collectively, our results reveal the potential connection between NRBF2 and the AD-associated protein APP by showing that NRBF2 plays an important role in regulating degradation of APP-CTFs through modulating autophagy.

A Randomized Controlled Pilot Trial of Chinese Medicine (Di-TanDecoction) in the Treatment of AlzheimerâÂÂs Disease

Objective: This double-blind, randomized, placebo-controlled, add-on pilot study aimed at providing information for conducting a full-scale trial assessing “Di-tan decoction” (DTD), which is a traditional Chinese medicine (TCM) formula frequently used in TCM to treat symptoms that are now defined as Alzheimer’s disease (AD), in treating AD in the future. Methods: We randomly assigned 38 patients with AD to receive either DTD or placebo for 24 weeks. Primary outcome was changes in the total score of AD Assessment Scale-cognitive subscale (ADAS-cog) and secondary outcome was changes in the total score of Chinese version of the Disability Assessment for Dementia (C-DAD). Results: Although we observed some improvement in the total scores of ADAS-cog in the DTD group comparing to the placebo group, the changes were not statistically significant. The ADAS-cog sub-scores of the DTD group also showed non-significant trends of improvement in ideational praxis (p=0.100) and in comprehension (p=0.106) comparing to placebo group. Adverse events were mild and comparable between two groups. Conclusion: This is the first rigorous randomized control trial of DTD focusing on AD. At least five factors could explain the failure of the trends to be significant, namely length of trial, size of trial, stage of AD, palatability of the drug, and sensitivity of the scoring system. Given the limitation but with the safety and century’s use of DTD, a modified pilot study is needed to support the clinical effects of DTD. In conclusion, there is no evidence supporting the efficacy of DTD to act as a single treatment for AD.