PT  - JOURNAL ARTICLE
AU  - Jocelyn Widagdo
AU  - Saumya Udagedara
AU  - Nishita Bhembre
AU  - Jing Zhi Anson Tan
AU  - Lara Neureiter
AU  - Jie Huang
AU  - Victor Anggono
AU  - Mihwa Lee
TI  - Familial ALS-associated <em>SFPQ</em> variants promote the formation of SFPQ cytoplasmic aggregates that reduce surface AMPA receptor expression in primary neurons
AID  - 10.1101/2022.03.10.483757
DP  - 2022 Jan 01
TA  - bioRxiv
PG  - 2022.03.10.483757
4099  - http://biorxiv.org/content/early/2022/03/12/2022.03.10.483757.short
4100  - http://biorxiv.org/content/early/2022/03/12/2022.03.10.483757.full
AB  - SFPQ is a nuclear RNA-binding protein that is involved in a wide range of physiological processes including neuronal development and homeostasis. However, the mislocalization and cytoplasmic aggregation of SFPQ are associated with the pathophysiology of amyotrophic lateral sclerosis (ALS). We have previously reported that zinc mediates SFPQ polymerization and promotes the formation of cytoplasmic aggregates in neurons. Here we characterize two familial ALS (fALS)-associated SFPQ variants, which cause amino acid substitutions in the proximity of the SFPQ zinc-coordinating center (N533H and L534I). Both mutants display increased zinc-binding affinities, which can be explained by the presence of a secondary zinc-binding site revealed by the 1.83Å crystal structure of the human SFPQ L534I mutant. Overexpression of these fALS-associated mutants significantly increases the number of SFPQ cytoplasmic aggregates in primary neurons. Although they do not affect the density of dendritic spines, the presence of SFPQ cytoplasmic aggregates causes a marked reduction in the levels of the GluA1, but not the GluA2 subunit of AMPA-type glutamate receptors on the neuronal surface. Taken together, our data demonstrate that fALS-associated mutations enhance the propensity of SFPQ to bind zinc and form aggregates, leading to the dysregulation of AMPA receptor subunit composition, which may contribute to neuronal dysfunction in ALS.Competing Interest StatementThe authors have declared no competing interest.ALSamyotrophic lateral sclerosisAMPAα-amino-3-hydroxy-5-methyl-4- isoxazoleproprionic acidAMPARAMPA receptorDBHSDrosophila behavior human splicingfALSfamilial ALSFUSfused in sarcomaRBPRNA-binding proteinr.m.s.d.root mean square deviationRRMRNA-recognition motifRXRαretinoic X receptor αSFPQsplicing factor proline- and glutamine-richTDP-43trans-activation response element DNA-binding protein 43WTwild-type.