Mechanistic Toxicology in Light of Genetic Compensation

Authors

Mary Jane Elizalde
Daniel A Gorelick

Publication Date

11-6-2023

Journal

Toxicological Sciences

DOI

10.1093/toxsci/kfad113

PMID

37941503

PMCID

PMC10823772

PubMedCentral® Posted Date

11-6-2023

PubMedCentral® Full Text Version

Post-print

Published Open-Access

yes

Keywords

genetic compensation, CRISPR, mutagenesis, exposures, model organisms

Abstract

Mechanistic toxicology seeks to identify the molecular and cellular mechanisms by which toxicants exert their deleterious effects. One powerful approach is to generate mutations in genes that respond to a particular toxicant, and then test how such mutations change the effects of the toxicant. CRISPR is a rapid and versatile approach to generate mutations in cultured cells and in animal models. Many studies use CRISPR to generate short insertions or deletions in a target gene and then assume that the resulting mutation, such as a premature termination codon, causes a loss of functional protein. However, recent studies demonstrate that this assumption is flawed. Cells can compensate for short insertion and deletion mutations, leading toxicologists to draw erroneous conclusions from mutant studies. In this review, we will discuss mechanisms by which a mutation in one gene may be rescued by compensatory activity. We will discuss how CRISPR insertion and deletion mutations are susceptible to compensation by transcriptional adaptation, alternative splicing, and rescue by maternally derived gene products. We will review evidence that measuring levels of messenger RNA transcribed from a mutated gene is an unreliable indicator of the severity of the mutation. Finally, we provide guidelines for using CRISPR to generate mutations that avoid compensation.