Identification of potential anticancer protein targets in cytotoxicity mediated by tropical medicinal fern extracts

Background: Medicinal fern species represent a potentially important source for both food and medicinal applications. Previously, two underutilized tropical fern species (Blechnum orientale and Phymatopteris triloba) were reported with cytotoxic activities against selected cancer cell lines. However, the exact mechanism remains elusive. Objective: In this paper, we reported the identification of six differentially expressed proteins isolated from cancer cells, following exposure to the cytotoxic fern extracts. Materials and Methods: The identities of these cancer proteins were determined by matrix-assisted laser desorption ionization time-of-flight protein sequencing. Results: The cancer proteins were identified as follows: elongation factor 1-γ, glyceraldehydes-3-phosphate dehydrogenase, heat shock protein 90-β, heterogeneous nuclear ribonucleoprotein-A2/B1, truncated nucleolar phosphoprotein B23, and tubulin-β chain. To the best of our knowledge, this paper represents thefirst time these cancer proteins are being reported, following exposure to the aforementioned cytotoxic fern extracts. Conclusion: It is hoped that further efforts in this direction could lead to the identification and development of target-specific chemotherapeutic agents

JNK pathway restricts DENV2, ZIKV and CHIKV infection by activating complement and apoptosis in mosquito salivary glands

International audienceArbovirus infection of Aedes aegypti salivary glands (SGs) determines transmission. However , there is a dearth of knowledge on SG immunity. Here, we characterized SG immune response to dengue, Zika and chikungunya viruses using high-throughput transcriptomics. We also describe a transcriptomic response associated to apoptosis, blood-feeding and lipid metabolism. The three viruses differentially regulate components of Toll, Immune deficiency (IMD) and c-Jun N-terminal Kinase (JNK) pathways. However, silencing of the Toll and IMD pathway components showed variable effects on SG infection by each virus. In contrast, regulation of the JNK pathway produced consistent responses in both SGs and midgut. Infection by the three viruses increased with depletion of the activator Kayak and decreased with depletion of the negative regulator Puckered. Virus-induced JNK pathway regulates the complement factor, Thioester containing protein-20 (TEP20), and the apopto-sis activator, Dronc, in SGs. Individual and co-silencing of these genes demonstrate their antiviral effects and that both may function together. Co-silencing either TEP20 or Dronc with Puckered annihilates JNK pathway antiviral effect. Upon infection in SGs, TEP20 induces antimicrobial peptides (AMPs), while Dronc is required for apoptosis independently of TEP20. In conclusion, we revealed the broad antiviral function of JNK pathway in SGs and showed that it is mediated by a TEP20 complement and Dronc-induced apoptosis response. These results expand our understanding of the immune arsenal that blocks arbo-virus transmission

Non-nucleoside inhibitors of Zika virus RNA-dependent RNA polymerase

Zika virus (ZIKV) remains a potentially significant public health concern because it can cause teratogenic effects, such as microcephaly in newborns and neurological disease, like Guillain-Barré syndrome. Together with efforts to develop a vaccine, the discovery of antiviral molecules is important to control ZIKV infections and to prevent its most severe symptoms. Here, we report the development of small nonnucleoside inhibitors (NNIs) of ZIKV RNA-dependent RNA polymerase (RdRp) activity. These NNIs target an allosteric pocket (N pocket) located next to a putative hinge region between the thumb and the palm subdomains that was originally described for dengue virus (DENV) RdRp. We first tested the activity of DENV RdRp N-pocket inhibitors against ZIKV RdRp, introduced chemical modifications into these molecules, and assessed their potency using both enzymatic and cell-based assays. The most potent compound had a 50% inhibitory concentration value of 7.3 μM and inhibited ZIKV replication in a cell-based assay with a 50% effective concentration value of 24.3 μM. Importantly, we report four high-resolution crystal structures detailing how these NNIs insert into the N pocket of ZIKV RdRp. Our observations point to subtle differences in the size, shape, chemical environment, and hydration of the N pocket from ZIKV RdRp from those of the N pocket from DENV RdRp that are crucial for the design of improved antiviral inhibitors with activity against ZIKV.Ministry of Health (MOH)National Medical Research Council (NMRC)National Research Foundation (NRF)Published versionWe thank Chen MingWei and the Protein Production Platform at the NTU School of Biological Sciences for their help in ZIKV RdRp protein purification. We acknowledge the Soleil synchrotron for the provision of beamtime (proposal 20170003) and thank William Shepard and Martin Savko for expert assistance in using beamline Proxima 2A. We thank the NTU Institute of Structural Biology for access to the in-house Rigaku FR-X diffractometer and NanoTemper MicroScale Thermophoresis and Liew Chong Wai for expert help. We declare that we have no competing financial interests. This work was supported by grant NRF2016-CRP001-063 to the laboratories of J.L.and S.G.V. and in part by NMRC grant MOH-000086 (grant MOH-OFIRG18may-0006)