FUS is a multifunctional nuclear protein that is part of the heterogeneous nuclear ribonucleoprotein (hnRNP) complex, involved in processes such as mRNA pre-mRNA splicing and the export of fully processed mRNA to the cytoplasm. FUS belongs to the FET family of RNA-binding proteins and is implicated in various cellular processes, including gene expression regulation, maintenance of genomic integrity, and mRNA/microRNA processing. FUS plays a role in transcription regulation, RNA splicing, RNA transport, DNA repair, and damage response. It binds to nascent pre-mRNAs and acts as a molecular mediator between RNA polymerase II and U1 small nuclear ribonucleoprotein, thereby coupling transcription and splicing. FUS also participates in DNA repair mechanisms by promoting D-loop formation and homologous recombination during DNA double-strand break repair. The abnormal aggregation of FUS is closely related to the occurrence and development of neurodegenerative diseases, such as Amyotrophic Lateral Sclerosis (ALS) and Frontotemporal Dementia (FTD). Under normal conditions, FUS is located in the cell nucleus, but mutations in the gene can cause FUS to be mislocalized to the cytoplasm, where it forms inclusions, which are characteristic of certain neurodegenerative diseases.