• Ca

      Wong, Vincent K-W.; Qiu, Congling; Xu, Su-Wei; Law, Betty Yuen Kwan; Zeng, Wu; Wang, Hui; Michelangeli, Francesco; Dias, Ivo Ricardo De Seabra Rodrigues; Qu, Yuan Qing; Chan, Tsz Wai; et al. (2019-05-23)
      Celastrol exhibits anti-arthritic effect in rheumatoid arthritis (RA), but the role of celastrol-mediated Ca mobilization in treatment of RA remains unelucidated. Here, we illustrate the regulatory role of celastrol-induced Ca signalling in synovial fibroblasts of RA patients and adjuvant-induced arthritis (AIA) in rats. Molecular target of celastrol was determined by computational docking, Ca dynamic and functional assays on SERCA. Ca -mediated autophagy in RASFs/RAFLS and the underlying mechanism were verified by quantification of endogenous LC3-II puncta, immunoblotting, and flow cytometry with the Ca chelator (BAPTA/AM) or suitable inhibitors. The anti-arthritic effect of celastrol, autophagy induction and growth rate of synovial fibroblasts in AIA rats were monitored by microCT and immunofluorescence staining. mRNA from joint tissues of AIA rats was isolated for transcriptional analysis of inflammatory genes. The role of Ca in regulating the identified genes was investigated by knockdown of calmodulin, calpains, and calcineurin. Celastrol inhibited SERCA to induce autophagy-dependent cytotoxicity in RASFs/RAFLS via CaMKKβ-AMPK-mTOR pathway and repressed arthritis symptoms in AIA rats. BAPTA/AM hampered the in vitro and in vivo effectiveness of celastrol. Inflammatory- and autoimmunity-associated genes downregulated by celastrol in joint tissues of AIA rat were restored by BAPTA/AM. Knockdown of calmodulin, calpains, and calcineurin in RAFLS confirmed the role of Ca in celastrol-regulated gene expression. Celastrol triggered Ca signalling to induce autophagic cell death in RASFs/RAFLS and ameliorated arthritis in AIA rats mediated by calcium-dependent/-binding proteins facilitating the exploitation of anti-arthritic drugs based on manipulation of Ca signalling. [Abstract copyright: This article is protected by copyright. All rights reserved.]
    • Neferine induces autophagy-dependent cell death in apoptosis-resistant cancers via ryanodine receptor and Ca

      Law, Betty Yuen Kwan; Michelangeli, Francesco; Qu, Yuan Qing; orcid: 0000-0003-3733-3661; Xu, Su-Wei; Han, Yu; Mok, Simon Wing Fai; Dias, Ivo Ricardo De Seabra Rodrigues; Javed, Masood-Ul-Hassan; Chan, Wai-Kit; Xue, Wei-Wei; et al. (2019-12-27)
      Resistance of cancer cells to chemotherapy is a significant clinical concern and mechanisms regulating cell death in cancer therapy, including apoptosis, autophagy or necrosis, have been extensively investigated over the last decade. Accordingly, the identification of medicinal compounds against chemoresistant cancer cells via new mechanism of action is highly desired. Autophagy is important in inducing cell death or survival in cancer therapy. Recently, novel autophagy activators isolated from natural products were shown to induce autophagic cell death in apoptosis-resistant cancer cells in a calcium-dependent manner. Therefore, enhancement of autophagy may serve as additional therapeutic strategy against these resistant cancers. By computational docking analysis, biochemical assays, and advanced live-cell imaging, we identified that neferine, a natural alkaloid from Nelumbo nucifera, induces autophagy by activating the ryanodine receptor and calcium release. With well-known apoptotic agents, such as staurosporine, taxol, doxorubicin, cisplatin and etoposide, utilized as controls, neferine was shown to induce autophagic cell death in a panel of cancer cells, including apoptosis-defective and -resistant cancer cells or isogenic cancer cells, via calcium mobilization through the activation of ryanodine receptor and Ulk-1-PERK and AMPK-mTOR signaling cascades. Taken together, this study provides insights into the cytotoxic mechanism of neferine-induced autophagy through ryanodine receptor activation in resistant cancers.
    • Occurrence of chemical pollutants in major e-waste sites in West Africa and usefulness of cytotoxicity and induction of ethoxyresorufin-O-deethylase (EROD) in determining the effects of some detected brominated flame retardants and e-waste soil-derived extracts.

      Eze, Chukwuebuka ThankGod; orcid: 0000-0001-8076-2926; email: thankgod.eze@fuoye.edu.ng; Michelangeli, Francesco; Otitoloju, Adebayo Akeem; Eze, Obianuju Oluchukwu; Ibraheem, Omodele; Ogbuene, Emeka Bright; Ogunwole, Germaine Akinola (2020-10-25)
      We investigated the occurrence of chemical pollutants in major e-waste sites in West Africa and usefulness of cytotoxicity and induction of ethoxyresorufin-O-deethylase (EROD) in determining the effects of some detected brominated flame retardants (BFRs) and e-waste soil-derived extracts. Analysis of the e-waste site samples using AAS and GC-MS techniques revealed the presence of a range of toxic metals as well as persistent and toxic organic pollutants, respectively, in the vicinity of the e-waste sites. As expected, the occurrence (%) of all the detected chemical pollutants in experimental soils significantly (P < 0.05) differs from occurrence (%) in control soil. The calculated LC values on RBL-2H3 cells of the detected tetrabromobisphenol A (TBBPA) and hexabromocyclododecane (HBCD) were 3.75 μM and 4.2 μM, respectively. Tribromophenol (TBP), dibromobiphenyl (DBB), and decabromodiphenyl ether (DBDE) were remarkably less toxic on RBL-2H3 cells compared with TBBPA and HBCD as they did not reduce RBL-2H3 cell viability below 50% in the tested concentration range (0-20 μM). The study revealed that TBBPA and HBCD could induce significant RBL-2H3 cell death through caspase-dependent apoptosis. The study further shows that the cytotoxicity of some of these BFRs could increase synergistically when in mixtures and potentially activate inflammation through the stimulation of mast cell degranulation. The e-waste soil-derived extracts induced a concentration-dependent increase in EROD activity in the exposed RTG-W1 cells. Ultimately, nonpolar extracts had higher EROD-inducing potency compared with polar extracts and hence suggesting the presence in higher amounts of AhR agonists in nonpolar e-waste soil-derived extracts than polar extracts. Overall, there is urgent need for actions in order to improve the environmental quality of the e-waste sites.
    • Will Plan S put learned societies in jeopardy?

      Purton, Mary; Michelangeli, Francesco; Fésüs, László (Wiley, 2019-02-25)