2015 Joint Usage and Research Report
Title of Research Project

ApplicantVisiting

The ADP-Ribosyltransferase, TIPARP, is a critical
mediator of AHR-mediated suppression of theinnate immune response after viral infection

Institution

University of OsloJob title

Professor

and name

Jason Matthews

NameJason Matthews

researcher
Purpose of the Research Project

The purpose of the research project is to investigate the role of(approx. 250 words)

TIPARP

inAHR-dependent

immunosuppression

following

activation of the innate immune response. The AHR is aligand-activated transcription factor that mediates the action ofmanyenvironmental

xenobiotics,including

2,3,7,8-tetrachlorodibenzo-p-dioxin (dioxin). It also has animportant role in the immune system and in T celldifferentiation, but its role in the innate immune response after
viral infection is incompletely understood. Dr. Takaoka’s group is
an expert in innate immune signaling. They have been studyingthat mono-ADP-ribosyltransferase play important roles in theinnate immune response following viral infection. During thecourse of their studies they observed that TIPARP was animportant mediator of AHR-dependent immunosuppression in
response to viral infection. My lab recently found that TIPARP,an AHR target gene, is a critical regulator of many aspects ofAHR activity and its loss increases the sensitivity of mice todioxin toxicities. In our ongoing collaboration with Dr. Takaoka
and colleagues, we have generated evidence that bothendogenous and exogenous AHR ligands suppress the IFN
response after infection with various types of virus, and we haveidentified TIPARP as the key regulator of AHR-dependent
innate immune suppression. A manuscript summarizing ourcollaborative work with focus on the endogenous AHR activationand the innate immune response was recently accepted inNature Immunology.
Development of the Research
Project and Results(approx.. 850 words)

As mentioned above, our collaborative joint research
project has resulted in a publication in NatureImmunology. In that study we found that constitutive
AHR-signaling in the steady state modulates type-I-IFN
response during infection with various types of virus.
Virus-induced IFN-beta production was enhanced in
AHR-deficient cells or mice, with a highly restrictedviral replication. The increased response was alsoobserved upon pharmacological inhibition with an AHR
antagonist or a TDO/IDO inhibitor, which prevents thegeneration of potential endogenous ligands for AHR.
Most interesting and relevant for our collaboration was
the finding that the AHR target gene, TIPARP caused
the AHR-induced downregulation of IFN response.
Mechanistically, TIPARP interacted with TBK1,
mono-ADP-ribosylated TBK1 resulting in a repression ofits activity. Thus, our study revealed the physiologicalsignificance of endogenous activation of AHR-signaling
in shaping the IFN-mediated innate response, andsuggested the AHR-TIPARP axis as a potential
therapeutic target for enhancing antiviral response. We
are continuing this collaboration by investigating theaction of exogenous AHR activation in the context of theAHR/TIPARP axis and the IFN-mediated innate
immune response. These studies will include analysis ofunique genetically modified mouse models of TIPARP
that have been generated in my lab, which Dr. Takaodaand I will use to unravel the role of TIPARP in innate
immunity. These mouse models include Tiparp wholebody knockouts and a CRISPR generated catalytic
mutant of Tiparp to determine the role of its enzymatic
activity in mediating IFN-dependent activity. We will
also investigate the cellular signals beyond the AHR
axis that regulate TIPARP expression. This will involveclassic
promoteranalysis,
chromatin
immunoprecipitation and reporter assays. Moreover, wewill work together to identify the mono-ADP-ribosylated
residues on TBK1 with the intention of using thisinformation to develop inhibitors of TBK1. We have

established a mass spectrometric method that
effectively detects mono-ADP-ribosylation on target
proteins. We have used the approach to identify 6
different mono-ADP-ribosylated peptides in TIPARP and
2 in AHR. Since no consensus ADP-ribosylation sites are
known, the only way to determine which residues are
mono-ADP-ribosylated is by using mass spectrometry. I
look forward to continuing this fruitful and successful
collaboration.
Publication【Conference, symposium, workshop etc.】*Enter the names of conferenceor journal and its vol. No. wherethe above work was presented.
【Journals】

Constitutive aryl hydrocarbon receptor signaling
constrains type I IFN-mediated antiviral innate defense
Taisho Yamada1,9, Hiromasa Horimoto1,2,9, Takeshi
Kameyama1,3, Sumio Hayakawa1,3, Hiroaki Yamato1,2,
Masayoshi Dazai1,2, Ayato Takada4, Hiroshi Kida5, Debbie Bott6,
Angela C. Zhou7, David Hutin6, Tania H. Watts7, Masahiro
Asaka2, Jason Matthews6,8, and Akinori Takaoka1,3Nature Immunology In press.