Ebolan immuunievaasion kiertostrategiasta hyödyntämällä cGAS-STING-signaalitietä

MBio. 2017 Apr 4;8(2). pii: e00368-17. doi: 10.1128/mBio.00368-17.

Topoisomerase II Inhibitors Induce DNA Damage-Dependent Interferon Responses Circumventing Ebola Virus Immune Evasion.

Luthra P¹, Aguirre S², Yen BC², Pietzsch CA³, Sanchez-Aparicio MT^2,4, Tigabu B³, Morlock LK⁵, García-Sastre A^2,4,6, Leung DW⁷, Williams NS⁵, Fernandez-Sesma A², Bukreyev A^3,8,9, Basler CF¹⁰.

Abstract

Ebola virus (EBOV) protein VP35 inhibits production of interferon alpha/beta (IFN) by blocking RIG-I-like receptor signaling pathways, thereby promoting virus replication and pathogenesis. A high-throughput screening assay, developed to identify compounds that either inhibit or bypass VP35 IFN-antagonist function, identified five DNA intercalators as reproducible hits from a library of bioactive compounds. Four, including doxorubicin and daunorubicin, are anthracycline antibiotics that inhibit topoisomerase II  and are used clinically as chemotherapeutic drugs.
 These compounds were demonstrated to induce IFN responses in an ATM kinase-dependent manner and to also trigger the DNA-sensing cGAS-STING pathway of IFN induction. These compounds also suppress EBOV replication in vitro and induce IFN in the presence of IFN-antagonist proteins from multiple negative-sense RNA viruses.
These findings provide new insights into signaling pathways activated by important chemotherapy drugs and identify a novel therapeutic approach for IFN induction that may be exploited to inhibit RNA virus replication.
IMPORTANCE Ebola virus and other emerging RNA viruses are significant but unpredictable public health threats. Therapeutic approaches with broad-spectrum activity could provide an attractive response to such infections. We describe a novel assay that can identify small molecules that overcome Ebola virus-encoded innate immune evasion mechanisms. This assay identified as hits cancer chemotherapeutic drugs, including doxorubicin. Follow-up studies provide new insight into how doxorubicin induces interferon (IFN) responses, revealing activation of both the DNA damage response kinase ATM and the DNA sensor cGAS and its partner signaling protein STING. The studies further demonstrate that the ATM and cGAS-STING pathways of IFN induction are a point of vulnerability not only for Ebola virus but for other RNA viruses as well, because viral innate immune antagonists consistently fail to block these signals. These studies thereby define a novel avenue for therapeutic intervention against emerging RNA viruses.

KEYWORDS: ATM signaling; DNA damage; Ebola virus; cGAS-STING pathway; innate immune responses

Free PMC Article

• Miten  EBOV  suhtautuu  isäntäkehon topoisomeraasiin?
• https://www.pubfacts.com/detail/23658456/DNA-topoisomerase-1-facilitates-the-transcription-and-replication-of-the-Ebola-virus-genome
•  Ebola virus (EBOV) protein L (EBOL) acts as a viral RNA-dependent RNA polymerase. To better understand the mechanisms underlying the transcription and replication of the EBOV genome, we sought to identify cellular factors involved in these processes via their coimmunoprecipitation with EBOL and by mass spectrometry. Of 65 candidate proteins identified, we focused on DNA topoisomerase 1 (TOP1), which localizes to the nucleus and unwinds helical DNA. We found that in the presence of EBOL, TOP1 colocalizes and interacts with EBOL in the cytoplasm, where transcription and replication of the EBOV genome occur. Knockdown of TOP1 markedly reduced virus replication and viral polymerase activity. We also found that the phosphodiester bridge-cleaving and recombination activities of TOP1 are required for the polymerase activity of EBOL. These results demonstrate that TOP1 is an important cellular factor for the transcription and replication of the EBOV genome and, as such, plays a key role in the EBOV life cycle. 

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 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5909458/