# Cellular Signaling in Drug Induced Toxicity

> **NIH NIH R01** · JOHNS HOPKINS UNIVERSITY · 2022 · $360,250

## Abstract

Drug-induced hepatotoxicity is a leading cause of both the withdrawal of approved drugs from
the market and the attrition of new chemical entities during the drug development process;
however, the mechanisms underlying drug-induced hepatotoxicity are not fully understood. We
have used efavirenz, an antiretroviral drug that is hepatotoxic in certain patients, as a model
compound to investigate cellular signaling mechanisms that may play a causal role in drug-
induced hepatocyte death. Previously, using primary human hepatocytes, we demonstrated that
efavirenz and the major oxidative metabolite of efavirenz, denoted as 8-hydroxyefavirenz (8-
OHefavirenz), stimulate cell death in a manner that is dependent upon activation of the stress
kinase c-Jun N-terminal kinase and upregulation of the proapoptotic protein BimEL (Bcl-2
interacting mediator of cell death extra long). Subsequently, we have reported that efavirenz can
also activate inositol requiring enzyme 1α (IRE1α), a key regulator of cell stress that lies upstream
of JNK and BimEL. The goal of this proposal is to determine the mechanism by which efavirenz
and 8-OHefavirenz activate BimEL and IRE1α, while also gaining a mechanistic understanding of
how genetic variation in IRE1α might impact efavirenz and 8-OHefavirenz-induced cell death.
Importantly, we will leverage the insights we have gained through using efavirenz as a model
compound and employ prototypic hepatotoxic drugs beyond efavirenz, namely carbamazepine,
diclofenac and isoniazid, in order to establish BimEL and IRE1α as central regulators of drug-
induced hepatotoxicity across a range of drug classes. The aims are as follows: (1) to test the
hypothesis that BimEL acts as an executioner of cell death in response to efavirenz and other
prototypic hepatotoxic drugs: BimEL null mice will be used to determine whether the absence of
BimEL prevents hepatotoxicity stimulated by the hepatotoxic drugs being investigated here;
CRISPR/Cas9 systems will be used to determine the role of effector proteins, Bax and Bak, that
are downstream of BimEL in modulating hepatocyte death; CRISPR/Cas9 and reporter gene
assays will be used to define the mechanism by which efavirenz, 8-OHefavirenz and other
hepatotoxic drugs regulate the transcription of BimEL; efavirenz analogs will be employed in order
to elucidate the structure-activity relationship of BimEL activation by efavirenz; (2) to test the
hypothesis that IRE1α is a central upstream regulator of drug-induced hepatotoxicity that is
stimulated by several classes of drugs: we will determine whether efavirenz, 8-OHefavirenz, and
other hepatotoxic drugs stimulate formation of the IRE1α/TRAF2/ASK1/JNK complex that results
in IRE1α-dependent activation of JNK; we will test the impact of naturally occurring genetic
variants of IRE1α on activity and cell death. It is expected that these studies will define BimEL
and IRE1α activation as important molecular mechanisms by which a range of drugs induce-
hepatot...

## Key facts

- **NIH application ID:** 10454370
- **Project number:** 5R01GM103853-10
- **Recipient organization:** JOHNS HOPKINS UNIVERSITY
- **Principal Investigator:** Benjamin Carl Orsburn
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $360,250
- **Award type:** 5
- **Project period:** 2013-04-01 → 2024-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10454370

## Citation

> US National Institutes of Health, RePORTER application 10454370, Cellular Signaling in Drug Induced Toxicity (5R01GM103853-10). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/10454370. Licensed CC0.

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