Piceatannol-3'-O-ß-d-glucopyranoside alleviates nephropathy via regulation of High mobility group B-1 (HMGB1)/Toll-like receptor 4 (TLR4)/Nuclear factor kappa B (NF-κB) signalling pathway.

OBJECTIVES: Nephrotic syndrome (NS) remains a therapeutic challenge for nephrologists. Piceatannol-3'-O-ß-d-glucopyranoside (PG) is a major active ingredient in Quzha. The purpose of the study was to assess the renoprotection of PG. METHODS: In vitro, the podocyte protection of PG was assessed in MPC-5. SD rats were injected with adriamycin to induce nephropathy in vivo. The determination of biochemical changes and inflammatory cytokines was performed, and pathological changes were examined by histopathological examination. Immunostaining and western blot analyses were used to analyse expression levels of proteins. KEY FINDINGS: The results showed that PG improved adriamycin-induced podocyte injury, attenuated nephropathy, improved hypoalbuminemia and hyperlipidaemia, and lowered cytokine levels. The podocyte protection of PG was further verified by reduction of desmin and increasing synaptopodin expression. Furthermore, treatment with PG down-regulated the expression of HMGB1, TLR4 and NF-κB along with its upstream regulator, IKKß and yet up-regulated IκBα expression by western blot analysis. CONCLUSIONS: Overall, our data showed that PG has a favourable renoprotection in experimental nephrosis, apparently by amelioration of podocyte injury. PG might mediate these effects via modulation of the HMGB1/TLR4/NF-κB signalling pathway. The study first provides a promising leading compound for the treatment of NS.

Non-clinical safety evaluation of salvianolic acid A: acute, 4-week intravenous toxicities and genotoxicity evaluations.

BACKGROUND: Toxicological problem associated with herbal medicine is a significant public health problem. Hence, it is necessary to elaborate on the safety of herbal medicine. Salvianolic acid A (SAA) is a major active compound isolated from Danshen, a popular herbal drug and medicinal food plant in China. The aim of the present study was to explore the toxicological profile of SAA. METHODS: The acute toxicity studies were performed in mice and Beagle dogs with single administration with SAA. A 4-week subchronic toxicity was test in dogs. SAA was intravenously administered at doses of 20, 80 and 300 mg/kg. Clinical observation, laboratory testing and necropsy and histopathological examination were performed. The genotoxic potential of SAA was evaluated by 2 types of genotoxicity tests: a reverse mutation test in bacteria and bone marrow micronucleus test in mice. RESULTS: In acute toxicities, the LD50 of SAA is 1161.2 mg/kg in mice. The minimum lethal dose (MLD) and maximal non-lethal dose (MNLD) of SAA were 682 mg/kg and 455 mg/kg in dogs, respectively. The approximate lethal dose range was 455-682 mg/kg. In the study of 4-week repeated-dose toxicity in dogs, focal necrosis in liver and renal tubular epithelial cell, the decrease in relative thymus weight, as well as abnormal changes in biochemical parameters, were observed in SAA 80 or 300 mg/kg group. The no observed adverse effect level (NOAEL) of SAA was 20 mg/kg. Thymus, liver and kidneys were the toxic targets. These toxic effects were transient and reversible. These results indicated that it should note examination of liver and kidney function during the administration of SAA in clinic. Furthermore, SAA had no mutagenic effect at any tested doses. CONCLUSION: These results provide new toxicological information of SAA for its clinical application and functional food consumption.

Endogenous Bos taurus RECQL is predominantly monomeric and more active than oligomers.

There is broad consensus that RecQ family helicase is a high-order oligomer that dissociates into a dimer upon ATP binding. This conclusion is based mainly on studies of highly purified recombinant proteins, and the oligomeric states of RecQ helicases in living cells remain unknown. We show here that, in contrast to current models, monomeric RECQL helicase is more abundant than oligomer/dimer forms in living cells. Further characterization of endogenous BtRECQL and isolated monomeric BtRECQL using various approaches demonstrates that both endogenous and recombinant monomeric BtRECQL effectively function as monomers, displaying higher helicase and ATPase activities than dimers and oligomers. Furthermore, monomeric BtRECQL unfolds intramolecular G-quadruplex DNA as efficiently as human RECQL and BLM helicases. These discoveries have implications for understanding endogenous RECQL oligomeric structures and their regulation. It is worth revisiting oligomeric states of the other members of the RecQ family helicases in living cells.

Crystal structures of N-terminally truncated telomerase reverse transcriptase from fungi‡.

Telomerase plays critical roles in cellular aging, in the emergence and/or development of cancer, and in the capacity for stem-cell renewal, consists of a catalytic telomerase reverse transcriptase (TERT) and a template-encoding RNA (TER). TERs from diverse organisms contain two conserved structural elements: the template-pseudoknot (T-PK) and a helical three-way junction (TWJ). Species-specific features of the structure and function of telomerase make obtaining a more in-depth understanding of the molecular mechanism of telomerase particularly important. Here, we report the first structural studies of N-terminally truncated TERTs from Candida albicans and Candida tropicalis in apo form and complexed with their respective TWJs in several conformations. We found that Candida TERT proteins perform only one round of telomere addition in the presence or absence of PK/TWJ and display standard reverse transcriptase activity. The C-terminal domain adopts at least two extreme conformations and undergoes conformational interconversion, which regulates the catalytic activity. Most importantly, we identified a conserved tertiary structural motif, called the U-motif, which interacts with the reverse transcriptase domain and is crucial for catalytic activity. Together these results shed new light on the structure and mechanics of fungal TERTs, which show common TERT characteristics, but also display species-specific features.