2018Joint Usage and Research Report
Title of Research Project

The ADP-Ribosyltransferase, TIPARP, is a critical mediator ofAHR-mediated suppression of the innate immune response
after viral infection

ApplicantInstitution

Institute for Genetic Medicine

Job title

Professor Akinori Takaoka

and name
Visiting

NameProf Jason Matthews University of Osloresearcher
Purpose of the Research Project

The AHR is a transcription factor that is activated by(approx. 250 words)

xenobiotics, dietary products and endogenous metabolites. The
AHR has emerged as an important regulator of numerous
physiological processes, including the immune system where it
plays a role in T cell differentiation, immune tolerance andinnate immunity. Through this collaboration with Dr. Takaoka’slaboratory, we reported that TIPARP/PARP7 is the key regulatorof AHR-dependent innate immune suppression and found that it
specifically ADP-ribosylates TBK1 reducing its ability toactivate type I interferon responses. (Yamada et al. Nature
Immunology2016).

Thissuggests

thatpharmacologicalinhibition of TIPARP could be a beneficial anti-viral therapy.
However, we still know very little about TIPARP’s role in theseprocesses, how it contributes to adaptive immunity, how theTIPARP-AHR axis is regulated during the innate/adaptive
immune responses, and the role of TIPARP in AHR-dependent B
or T cell differentiation and function. Moreover, the inhibition ofTIPARP may serve as potential therapeutic strategy to boost
cancerimmunotherapy

byreversing

immunosuppression

through increases in type I interferon. Our proposed project will
include comprehensive studies of Tiparp knockout mice, primaryand immortalize cell line models, as well as genomic andproteomic methods to characterize the importance of TIPARP in
the immune system and cancer immunotherapy.
Development of the Research

During the past year my lab has gained expertise in

Project and Resultscharacterizing type I interferon response after treatment with(approx.. 850 words)

synthetic pathogen-associated molecular patterns (PAMPs)
like 3pRNA and cGAMP). This was done with the help andexpertise of Prof. Takaoka. For these studies we have focused onmouse embyronic fibroblasts (MEFs) from our Tiparp-/- mice. Wefound that exposure to PAMPs but also LPS dramaticallyincreases the expression of several proinflammatory cytokines inaddition to type I interferons. To confirm that Tiparp catalytic
activity is required for this effect, we are performing studies inMEFs isolated from our Tiparp catalytic mutant mice
TiparpH532A. Our preliminary data suggest that TIPARP
targets more than one component of the NFkB signaling
pathway and with our improve mass spectrometric detection ofmono-ADP-ribosylation, we will map the modified residues on
NFkB as well as other important targets of TIPARP such as
TBK1. To further understand the role of the AHR-TIPARP axis
in innate immunity, Dr. Takaoka’s lab has received and they are
exposing the Tiparp knockout mice to various viruses andevaluating a number of relevant endpoints. These studies arestillongoing.

We

willcomplement

thosestudies,

withexperiments using our catalytic mutant Tiparp mouse. This
unique mouse model will be important in demonstrating theimportance of Tiparp catalytic activity in mediating its role ininnate immunity, as to identify cellular targets of TIPARP
ribosylation. Another research focus of this work will be toinvestigate the role of TIPARP in T and B cell differentiation offunction. We are also working closely with Dr. Takaoka for thesestudies. Once isolated, the cells will be differentiation and thepresence of absence of AHR ligands to determine the impact ofTIPARP and AHR and T and B cell differentiation and function.
Together with a collaborator in the USA, we have evaluated aselective TIPARP inhibitor. We are now poised to begin in vivo
studies to determine if pharmacological inhibition of TIPARP
could be a beneficial anti-viral therapy. This is incredibly
important and a potential breakthrough in this collaboration,
sinceRibon

Therapeutics(https://ribontx.com/parp7/)

has

established a drug development program targeting TIPARP forcancer immunotherapy via its increase in type I interferon
signaling. Finally, we are also creating a panel of CRISPR/Cas9
generated TIPARP knockout cell lines to determine the potential
role the TIPARP in cancer. Our mouse models will be used toevaluate the role of TIPARP in cancer immunotherapy incombination with immune check point inhibitors to boost
therapeutic responses. We feel that this novel, research strategy
to characterize the role of TIPARP in type I interferon responseoffers incredible potential for both anti-viral but also anti-cancer
therapy. Our complementary expertise and access to uniqueanimal and cell line models for studying TIPARP activity, give us
an advantage over other labs pursuing this line of research.
Continued support from the joint research program will ensure
the success of this research.
Publication【Conference, symposium, workshop etc.】*Enter the names of conferenceor journal and its vol. No. where
the above work was presented.
【Journals】
Yamada et al Nature Immunol 2016 Jun;17(6):687-94. doi:
10.1038/ni.3422. Epub 2016 Apr 18.