Upregulation of Parkinson's disease-associated protein alpha-synuclein suppresses tumorigenesis via interaction with mGluR5 and gamma-synuclein in liver cancer.

Numerous epidemiological studies suggest a link between Parkinson's disease (PD) and cancer, indicating that PD-associated proteins may mediate the development of cancer. Here, we investigated a potential role of PD-associated protein α-synuclein in regulating liver cancer progression in vivo and in vitro. We found the negative correlation of α-synuclein with metabotropic glutamate receptor 5 (mGluR5) and γ-synuclein by analyzing the data from The Cancer Genome Atlas database, liver cancer patients and hepatoma cells with overexpressed α-synuclein. Moreover, upregulated α-synuclein suppressed the growth, migration, and invasion. α-synuclein was found to associate with mGluR5 and γ-synuclein, and the truncated N-terminal of α-synuclein was essential for the interaction. Furthermore, overexpressed α-synuclein exerted the inhibitory effect on hepatoma cells through the degradation of mGluR5 and γ-synuclein via α-synuclein-dependent autophagy-lysosomal pathway (ALP). Consistently, in vivo experiments with rotenone-induced rat model of PD also confirmed that, upregulated α-synuclein in liver cancer tissues through targeting on mGluR5/α-synuclein/γ-synuclein complex inhibited tumorigenesis involving in ALP-dependent degradation of mGluR5 and γ-synuclein. These findings give an insight into an important role of PD-associated protein α-synuclein accompanied by the complex of mGluR5/α-synuclein/γ-synuclein in distant communications between PD and liver cancer, and provide a new strategy in therapeutics for the treatment of liver cancer.

Response of microbial interactions in activated sludge to chlortetracycline.

Chlortetracycline (CTC) has attracted increasing attention due to its potential environmental risks. However, its effects on bacterial communities and microbial interactions in activated sludge systems remain unclear. To verify these issues, a lab-scale sequencing batch reactor (SBR) exposed to different concentrations of CTC (0, 0.05, 0.5, 1 mg/L) was carried out for 106 days. The results showed that the removal efficiencies of COD, TN, and TP were negatively affected, and the system functions could gradually recover at low CTC concentrations (≤0.05 mg/L), but high CTC concentrations (≥0.5 mg/L) caused irreversible damage. CTC significantly altered bacterial diversity and the overall bacterial community structure, and stimulated the emergence of many taxa with antibiotic resistance. Molecular ecological network analysis showed that low concentrations of CTC increased network complexity and enhanced microbial interactions, while high concentrations of CTC had the opposite effect. Sub-networks analysis of dominant phyla (Bacteriodota, Proteobacteria, and Actionobacteriota) and dominant genera (Propioniciclava, a genus from the family Pleomorphomonadaceae and WCHB1-32) also showed the same pattern. In addition, keystone species identified by Z-P analysis had low relative abundance, but they were important in maintaining the stable performance of the system. In summary, low concentrations of CTC enhanced the complexity and stability of the activated sludge system. While high CTC concentrations destabilized the stability of the overall network and then caused effluent water quality deterioration. This study provides insights into our understanding of response in the bacteria community and their network interactions under tetracycline antibiotics in activated sludge system.

Upregulated mGluR5 induces ER stress and DNA damage by regulating the NMDA receptor subunit NR2B.

Dysfunction caused by mGluR5 expression or activation is an important mechanism in the development of Parkinson's disease (PD). Early clinical studies on mGluR5 negative allosteric modulators have shown some limitations. It is therefore necessary to find a more specific approach to block mGluR5-mediated neurotoxicity. Here, we determined the role of N-methyl-D-aspartate (NMDA) receptor subunit NR2B in mGluR5-mediated ER stress and DNA damage. In vitro study, rotenone-induced ER stress and DNA damage were accompanied by an increase in mGluR5 expression and overexpressed or activated mGluR5 with agonist (RS)-2-chloro-5-hydroxyphenylglycine (CHPG) induced ER stress and DNA damage, while blocking mGluR5 with antagonist 2-methyl-6-(phenylethynyl) pyridine hydrochloride (MPEP) alleviated the effect. Furthermore, the damage caused by CHPG was blocked by NMDA receptor antagonist MK-801. Additionally, rotenone or CHPG increased the p-Src and p-NR2B, which was inhibited by MPEP. Blocking p-Src or NR2B with PP2 or CP101,606 alleviated CHPG-induced ER stress and DNA damage. Overactivation of mGluR5 accompanied with the increase of p-Src and p-NR2B in the ER stress and DNA damage was found in rotenone-induced PD rat model. These findings suggest a new mechanism wherein mGluR5 induces ER stress and DNA damage through the NMDA receptor and propose NR2B as the molecular target for therapeutic strategy for PD.

Metabotropic glutamate receptor 5 inhibits α-synuclein-induced microglia inflammation to protect from neurotoxicity in Parkinson's disease.

BACKGROUND: Microglia activation induced by α-synuclein (α-syn) is one of the most important factors in Parkinson's disease (PD) pathogenesis. However, the molecular mechanisms by which α-syn exerts neuroinflammation and neurotoxicity remain largely elusive. Targeting metabotropic glutamate receptor 5 (mGluR5) has been an attractive strategy to mediate microglia activation for neuroprotection, which might be an essential regulator to modulate α-syn-induced neuroinflammation for the treatment of PD. Here, we showed that mGluR5 inhibited α-syn-induced microglia inflammation to protect from neurotoxicity in vitro and in vivo. METHODS: Co-immunoprecipitation assays were utilized to detect the interaction between mGluR5 and α-syn in microglia. Griess, ELISA, real-time PCR, western blotting, and immunofluorescence assays were used to detect the regulation of α-syn-induced inflammatory signaling, cytokine secretion, and lysosome-dependent degradation. RESULTS: α-syn selectively interacted with mGluR5 but not mGluR3, and α-syn N terminal deletion region was essential for binding to mGluR5 in co-transfected HEK293T cells. The interaction between these two proteins was further detected in BV2 microglia, which was inhibited by the mGluR5 specific agonist CHPG without effect by its selective antagonist MTEP. Moreover, in both BV2 cells and primary microglia, activation of mGluR5 by CHPG partially inhibited α-syn-induced inflammatory signaling and cytokine secretion and also inhibited the microglia activation to protect from neurotoxicity. We further found that α-syn overexpression decreased mGluR5 expression via a lysosomal pathway, as evidenced by the lysosomal inhibitor, NH4Cl, by blocking mGluR5 degradation, which was not evident with the proteasome inhibitor, MG132. Additionally, co-localization of mGluR5 with α-syn was detected in lysosomes as merging with its marker, LAMP-1. Consistently, in vivo experiments with LPS- or AAV-α-syn-induced rat PD model also confirmed that α-syn accelerated lysosome-dependent degradation of mGluR5 involving a complex, to regulate neuroinflammation. Importantly, the binding is strengthened with LPS or α-syn overexpression but alleviated by urate, a potential clinical biomarker for PD. CONCLUSIONS: These findings provided evidence for a novel mechanism by which the association of α-syn with mGluR5 was attributed to α-syn-induced microglia activation via modulation of mGluR5 degradation and its intracellular signaling. This may be a new molecular target for an effective therapeutic strategy for PD pathology.

Current intensities altered the performance and microbial community structure of a bio-electrochemical system.

A novel integrated bio-electrochemical system with sulfur autotrophic denitrification (SAD) and electrocoagulation (BESAD-EC) system was established to remove nitrate (NO3--N) and phosphorus from contaminated groundwater. The impacts of a current intensity gradient on the system's performance and microbial community were investigated. The results showed that NO3--N and total phosphorus (TP) could be effectively removed with maximum NO3--N reduction and TP removal efficiencies of 94.2% and 75.8% at current intensities of 200 and 400 mA, respectively. Lower current intensities could improve the removal efficiencies of NO3--N (≤200 mA) and phosphorus (≤400 mA), while higher current intensity (600 mA) caused the inhibition of nutrients removal in the system. MiSeq sequencing analysis revealed that low electrical stimulation improved the diversity and richness of microbial community, while high electrical stimulation reduced their diversity and richness. The relative abundance of some genus involved in denitrification and phosphorus removal processes such as Rhizobium, Hydrogenophaga, Denitratisoma and Gemmobacter, significantly (P < 0.05) reduced under high current conditions. This could be one of the main reasons for the deterioration of denitrification and phosphorus removal performance. The results of this study could be helpful to enhance the nutrient removal performance of bio-electrochemical systems in groundwater treatment processes.

First Report of Mucor spp. Causing Root Rot of Radix pseudstellariae in Guizhou Province of China.

Radix pseudostellariae L. is one of the most common and highly-prized Chinese medicinal plants with various pharmacological effects, and mainly produced in acid soils in the Guizhou and Fujian provinces of southwestern and southeastern China, respectively (Wu et al. 2020). However, consecutive monoculture of R. pseudostellariae results in severe root rot and decline in biomass and quality of underground tubers. Root tubers of R. pseudostellariae are typically planted in December and harvested in next June. Root rot commonly starts developing in May. The disease incidence of root rot was ranging from 37 to 46% in root portions and basal stem of R. pseudostellariae under the consecutive monoculture fields in Shibing County, Guizhou Province, China (108°12'E, 27°03'N) (Li et al. 2017). Severe root rot was observed in Shibing County in May 2018. Infected plants displayed curly, withered, and yellow leaves, blight, retarded growth, root rot, and yield losses. Abundant whitish mycelia were observed on roots and surrounding soil. Two fungal isolates, designated GZ20190123 and GZ20190124, were obtained from symptomatic roots cultured on potato dextrose agar (PDA). The optimum temperature range for growth of the two isolates was 25 to 30°C. The optimum pH range for the growth of GZ20190123 was 5 to 5.5, whereas GZ20190124 grew better between pH 5 to 8.5. The mean mycelial growth rates of GZ20190123 and GZ20190124 at 30°C were 2.1 and 1.5 cm/day, respectively. Conidia of the two isolates were ovoid or obclavate and were produced in single or branched chains. The internal transcribed spacer (ITS) region was amplified with primers ITS1 and ITS4 (White et al. 1990). The sequences were deposited in GenBank as accession No. MN726736 for GZ20190123 and MN726738 for GZ20190124. Sequence comparison revealed 99% (GZ20190123) and 97% (GZ20190124) identity with previously reported isolate xsd08071 of Mucor racemosus Bull. (accession No. FJ582639.1) and isolate BM3 of Mucor fragilis Bainier (accession No. MK910058.1), respectively, which was confirmed by phylogenetic analysis. The two isolates were tested for pathogenicity on R. pseudostellariae. Six roots of R. pseudostellariae were surface-sterilized with 75% ethanol and stab inoculated with mycelia using a sterile toothpick for each isolate. Sterile distilled water was stab inoculated to twelve roots to serve as the control. Treated roots were incubated in a greenhouse with 16 h day length [light intensity 146.5 µmol/(m2·s)] and day/night temperature 26°C/18°C. The inoculated roots showed the expected symptoms on roots and sprouts 7 days after inoculation, whereas the control roots with sprouts did not show any symptom. The fungi were re-isolated from the diseased roots and confirmed as expected M. racemosus or M. fragilis based on the ITS sequences, which satisfied Koch's postulates. Thus, isolate GZ20190123 was identified as M. racemosus and GZ20190124 as M. fragilis. Previously, M. racemosus and M. fragilis have been reported as a pathogen on tomato (Kwon and Hong 2005) and grape (Ghuffar et al. 2018), respectively. To our knowledge, this is the first report of M. racemosus and M. fragilis causing root rot of R. pseudostellariae in southwestern China, where the disease could cause a significant loss to production of this important medicinal plant.