Control of type III interferon expression and Herpes simplex virus type 1 replication by miR-200

Interferons are proteins that are released by cells to combat viruses. There are 3 different types of interferons which differ by the cells that produce them but also the pathogens against which they are active. In our previous work using a new type of genomic screen we showed that the virus that causes cold sores and some other diseases, Herpes simplex virus type 1 (HSV-1), is mainly controlled by a so-called type III interferon (IFN-lambda). Micro RNAs (miRNAs) are small pieces of genetic material within cells that control which proteins are produced. In our recent work we applied another type of genomic screen and identified which miRNAs combat HSV-1. In this project we will combine the outcome of these two genomic screens to investigate how antiviral miRNAs work. From other work which we recently did we know that one of them, miR-200, leads to an increase of IFN-lambda. miR-200 is known to be regulated by an inhibitory protein called ZEB1, but also inhibits ZEB1 itself. This regulatory feedback loop between miR-200 and ZEB1 is known to control a range of different biological processes, both in normal development and cancer. In this project we will investigate if miR-200 inhibits HSV-1 through ZEB1 and IFN-lambda. If this is the case, miRNA creates a functional link between the immune response, normal development and cancer. Our unique approach will help to understand the mechanisms of antiviral miRNAs and could be instrumental for the development of novel drugs against viruses and cancer.

In our previous work we revealed by a genome-scale RNA interference (RNAi) screen that type III interferons (IFN-lambda) play a crucial role in the innate immune control of HSV-1 [1]. There is increasing evidence that IFN-lambda, which is the least well investigated IFN, is crucial in the innate immune response against a range of different RNA and DNA viruses, as well as against tumours. It is mainly important for skin and mucosal infections, infections of organs containing epithelial cells, and for viral hepatitis. In preliminary work we tested a set of about 400 cellular miRNAs by a mimic and inhibitor screen for their effect on HSV-1 replication, and identified antiviral miRNAs including several miR families with common seed target sequence such as miR-200 that strongly inhibited HSV-1. In the project proposed, we will investigate how these antiviral miRNAs inhibit HSV replication and which cellular genes are involved, with the help of the genome-scale RNAi screening results. In particular, we will investigate miR-200, which plays a role in epithelial-to-mesenchymal transition (EMT) and oncogenesis, and which is regulated by a feedback loop with the transcriptional repressors ZEB1/2. Since in preliminary results miR-200 led to an induction of IFN-lambda, we hypothesize that it inhibits HSV-1 by downregulating ZEB1/2 and thereby inducing IFN-lambda. If this is the case, miR-200 creates a link between EMT, oncogenesis and innate immunity and is one of the key regulator in these processes. Our unique approach will help to understand the mechanisms of antiviral miRNAs and could be instrumental for the development of novel anti-viral and anti-tumour therapeutics.

The proposed research project is multidisciplinary and it's scientific outcome will have impact in several different areas of research: virology, immunology, biochemistry (miRNA research), and oncology. If the working hypothesis of the proposal is confirmed, miR-200 creates a link between EMT, oncogenesis and innate immunity and is one of the key regulator in these processes, thus connected all four areas mentioned above. Although the project is basic research it has translational character, as our unique approach will help to understand the mechanisms of antiviral miRNAs and could be instrumental for the development of novel anti-viral and anti-tumour therapeutics. If results of possible clinical or commercial relevance will be created, we will seek to obtain intellectual property rights and commercialization. This study will advance the academic discipline through contributing to the training of researchers skilled in a wide range of techniques. The postdoc and the technician will acquire additional expertise in molecular biological, immunological and virological research that would be widely applicable in the UK biotech industry. They will also contribute to training and teaching of postgraduate and undergraduate students in the laboratory. These students will also acquire both specialised as well as transferable skills such as giving presentations, using networking opportunities at conferences and writing papers and reports during the course of the grant. Our findings will be disseminated to both a scientific as well as a lay auditorium as detailed in the communications plan. Additionally, we will present the key facts from our research on our website, with link to publications and the notification of MRC support.