Modeling stress-induced proteinopathies in Caenorhabditis elegans

Proteinopathies are a type of disorders characterized by the intracellular or extracellular accumulation of misfolded proteins that disrupt cellular proteostasis and exert toxic effects. These proteotoxic effects are a common hallmark of various age-related neurodegenerative diseases, including Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), and polyglutamine disorders such as Huntington's disease (HD). Misfolded protein accumulation can impair numerous cellular processes, including mitochondrial function, protein degradation pathways, the endoplasmic reticulum stress response, and redox homeostasis, ultimately compromising cell viability. The nematode Caenorhabditis elegans (C. elegans) has emerged as a powerful model for studying proteotoxic stress due to its genetic tractability and the high degree of conservation of key cellular pathways when compared to mammals. These include mitochondrial dynamics and function, regulation of reactive oxygen species (ROS), and the cellular capacity to manage protein aggregates in terms of number, size, and clearance efficiency. The integration of these conserved stress response pathways together with C. elegans experimental versatility positioned this nematode as an ideal system to investigate the molecular mechanisms underlying proteinopathy-induced toxicity. In this chapter, we describe a set of complementary methodologies to evaluate proteotoxic stress in C. elegans models of protein misfolding. These include assays to measure mitochondrial reactive oxygen species (ROS) and membrane potential (Δψm), analyses of mitochondrial morphology and oxygen consumption, protein extraction protocols, and in vivo staining and semi-automated quantification of protein aggregates.