Abstract

Amyotrophic Lateral Sclerosis (ALS) and fronto-temporal lobar dementia (FTD) are associated with the pathological aggregation of proteins involved in RNA processing, most commonly TDP -43 and rarely FUS . Many other mutant genes can contribute to TDP -43 aggregation and some of these are also directly involved in RNA processing (ATXN2, hnRNPA1, hnRNPA2B1 and MATR3 ).

I will present unpublished evidence that novel variants in ARPP21 are associated with ALS and FTD . ARPP21 encodes a neuronally expressed, cytoplasmic RNA -binding protein involved in mRNA transport. Mutations increase the propensity of ARPP21 and TDP -43 to aggregate and become insoluble in an RNA -binding dependent manner. Mutations disrupt RNA granule transport in primary neurons and enhance neurotoxicity in the Drosophila eye. This discovery reveals new insights into the role of RNA granule dysfunction in ALS and FTD and challenges several assumptions about the pathophysiology of these neurodegenerative disorders.