TDP-43 proteinopathies and neurodegeneration: insights from Caenorhabditis elegans models

TDP-linked proteinopathies, including amyotrophic lateral sclerosis (ALS), frontotemporal dementia (FTD) and limbic-predominant age-related TDP-43 encephalopathy (LATE), are characterised by pathogenic deposits containing transactive response DNA-binding protein 43 (TDP-43) in the brain and spinal cord of patients. These hallmark pathological features are associated with widespread neuronal dysfunction and progressive neurodegeneration. TDP-43's role as an essential RNA/DNA-binding protein in RNA metabolism and gene expression regulation is clear, but deciphering the intricate pathophysiological mechanisms underpinning TDP-43-mediated neurodegeneration is paramount for developing effective therapies and novel diagnostic tools for early detection before frank neuronal loss occurs. The nematode Caenorhabditis elegans, with highly conserved TDP-43 orthologue TDP-1, serves as a powerful genetic model to investigate the molecular underpinnings of TDP-43 proteinopathies. Here, we provide a brief overview of the structural and functional characteristics of TDP-43 and TDP-1, highlighting their conserved roles in RNA metabolism, stress responses, and neurodegeneration. We then delve into the pathobiology of TDP-43, drawing insights from C. elegans models expressing either monogenic TDP-43 variants or bigenic combinations with ALS-associated risk genes, and discuss how these models have advanced our understanding of the pathomechanisms of TDP-43 proteinopathies. By employing its simplicity and genetic manipulability, we discuss how these models have helped identify chemical and genetic suppressors of TDP-43-induced phenotypes, including small molecules like Pimozide and the probiotic Lacticaseibacillus rhamnosus HA-114, now in clinical trials. This review underscores the translational value of C. elegans in unraveling the biochemical pathways and interactions in TDP-43 proteinopathies that perturb cellular physiology, potentially facilitating mechanism-based therapy development.