Examining the potential involvement of NONO in TDP-43 proteinopathy in Drosophila

Abstract

The misfolding and aggregation of TAR DNA binding protein-43 (TDP-43), leading to the formation of cytoplasmic inclusions, emerge as a key pathological feature in a spectrum of neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS) and frontotemporal lobar dementia (FTLD). TDP-43 shuttles between the nucleus and cytoplasm but forms nuclear bodies (NBs) in response to stress. These NBs partially colocalise with nuclear speckles and paraspeckles that sequester RNAs and proteins, thereby regulating many cellular functions. The laboratory of Steven Brown has recently found that the non-POU domain-containing octamer-binding protein (NONO), a component of paraspeckles, forms novel nuclear speckle-like structures in mouse cortical neurons in response to stress and sleep deprivation. These findings suggest the possibility of a functional link between NONO and TDP-43, potentially contributing to TDP-43 proteinopathy. Here, we demonstrate that pathological phenotypes caused by TDP-43 gain of function—locomotor defects and life span shortening—are exacerbated by silencing the Drosophila homolog of NONO, no on or off transient A (NonA). Additionally, NonA silencing results in an increase in nuclear TDP-43 NBs. These results provide supporting evidence for the functional link between NONO and TDP-43 and lay the foundation for dissecting underlying mechanisms.