On the potential roles of TDP-43 in the formation of membraneless organelles and their transformation into toxic aggregates.

Trans-activation response (TAR) DNA-binding protein 43 (TDP-43) is an RNA-binding protein involved in the processing, transport, and regulation of mRNA translation. It is distributed in many tissues, including the brain, where it is found mainly in hippocampal neurons. Abnormal localization, hyperphosphorylation, and aggregation of TDP-43 are pathological signs of a group of neurodegenerative diseases known as TDP-43 proteinopathies. Despite the growing understanding of the physiological role of TDP-43 in ensuring neuronal plasticity and the formation of long-term memory, to date, there is no comprehensive data on the molecular and cellular mechanisms of the transformation of functional membraneless organelles (MLOs) containing TDP-43 into toxic aggregates and the pathogenesis of associated diseases, such as amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). This review is devoted to highlighting the role of MLOs in the formation of irreversible aggregates, the role of TDP-43 in the formation of MLOs and their relationship with pathological forms of TDP-43, most often found in people suffering from neurodegenerative diseases.