Dictyostelium discoideum: An Alternative Nonanimal Model for Developmental Toxicity Testing.

Robert P Baines,Christopher R L Thompson,Kathryn Wolton

doi:10.1093/toxsci/kfab097

Abstract

A critical aspect of toxicity evaluation is developmental and reproductive toxicity (DART) testing. Traditionally, DART testing has been conducted in vivo in mammalian model systems. New legislation aimed at reducing animal use and the prohibitive costs associated with DART testing, together with a need to understand the genetic pathways underlying developmental toxicity means there is a growing demand for alternative model systems for toxicity evaluation. Here we explore the potential of the eukaryotic social amoeba Dictyostelium discoideum, which is already widely used as a simple model system for cell and developmental biology, as a potential nonanimal model for DART testing. We developed assays for high-throughput screening of toxicity during D. discoideum growth and development. This allowed the toxicity of a broad range of test compounds to be characterized, which revealed that D. discoideum can broadly predict mammalian toxicity. In addition, we show that this system can be used to perform functional genomic screens to compare the molecular modes of action of different compounds. For example, genome-wide screens for mutations that affect lithium and valproic acid toxicity allowed common and unique biological targets and molecular processes mediating their toxicity to be identified. These studies illustrate that D. discoideum could represent a predictive nonanimal model for DART testing due to its amenability to high-throughput approaches and molecular genetic tractability.

Highlights

Toxicological safety testing represents a major obstacle for novel pharmaceutical, cosmetic, and agrochemical compounds to reach the market (Brannen et al, 2016)
New legislation aimed at reducing animal use and the prohibitive costs associated with developmental and reproductive toxicity (DART) testing, together with a need to understand the genetic pathways underlying developmental toxicity means there is a growing demand for alternative model systems for toxicity evaluation
We explore the potential of the eukaryotic social amoeba Dictyostelium discoideum, which is already widely used as a simple model system for cell and developmental biology, as a potential nonanimal model for DART testing

Summary

Introduction

Toxicological safety testing represents a major obstacle for novel pharmaceutical, cosmetic, and agrochemical compounds to reach the market (Brannen et al, 2016). High-Throughput D. discoideum Growth and Developmental Toxicity Assays To evaluate the potential of D. discoideum as a predictive model for DART studies 37 test compounds (27 known teratogens, 10 nonteratogens were chosen) (see Materials and Methods and Supplementary Figure 1 and Supplementary Table 1). To quantitatively measure effects on development we developed a new highthroughput assay based on stage-specific fluorescent reporter strains, which does not require D. discoideum expertise and is independent of observer bias (see Materials and Methods and Supplementary Figure 3).

Results

Conclusion