An alternative cytoplasmic SFPQ isoform with reduced phase separation potential is upregulated in ALS

Splicing factor proline- and glutamine-rich (SFPQ) is an RNA-binding protein that broadly regulates RNA metabolism. Although its nuclear roles are well-studied, evidence of SFPQ’s cytoplasmic functionality is emerging. Altered expression and nuclear-to-cytoplasmic redistribution of SFPQ have been recognised in amyotrophic lateral sclerosis (ALS) pathology, yet the mechanistic basis of this remains undetermined. We identified altered SFPQ splicing in ALS, increasing the expression of an alternative mRNA isoform lacking a nuclear localisation sequence, which we termed ‘altSFPQ’. We find that altSFPQ mRNA contributes to SFPQ autoregulation and is highly unstable yet exhibits context-specific translation with cytoplasm-predominant localisation. Notably, reduced canonical SFPQ coincides with increased altSFPQ transcript expression in familial and sporadic ALS models, providing a mechanistic basis for SFPQ nuclear-to-cytoplasmic redistribution in ALS patients. Finally, we observe that the alt..., , , # An alternative cytoplasmic SFPQ isoform with reduced phase separation potential is upregulated in ALS

Dataset DOI: [10.5061/dryad.gb5mkkx1z](10.5061/dryad.gb5mkkx1z)

## Description of the data and file structure

The attached documents contain raw data relating to the experiments undertaken within the associated manuscript (Neeves et al., 2025).

### File: Doc_1_Neeves_et_al_2025_raw_data_final.xlsx

**Description:** tabulated Excel spreadsheet. Experimental types - qPCR, image analyses

* qPCR - raw Ct values
* High throughput immunofluorescence imaging (Opera phenix) - object data (number, area, immunofluorescence intensities)
* Image analysis of LLPS droplet assays - object data (number, area, immunofluorescence intensities)

The attached documents contain raw data relating to the experiments undertaken within the associated manuscript (Neeves et al., 2025).

Document 1: tabulated Excel spreadsheet. Experimental types - qPCR, image analyses  

* qPCR - raw Ct values
* High throug..., Informed consent was obtained from healthy control donors and patients in this study. Experimental protocols were enacted according to regulations and guidelines outlined by UCLH’s National Hospital for Neurology and Neurosurgery and UCL’s Institute of Neurology joint research ethics committee (09/0272).