Autoimmunity-associated DIORA1 binds the MRCK family of serine/threonine kinases and controls cell motility

Genetic association links disordered autoimmunity 1 (DIORA1) to numerous autoimmune rheumatic diseases, including systemic lupus erythematosus, Sjögren's disease, rheumatoid arthritis, polymyositis, and systemic sclerosis. However, its cellular function has remained unknown. Here, we identify the Myotonic Dystrophy Kinase-Related Cdc42-Binding Kinases (MRCK kinases) family of serine/threonine kinases-key regulators of actomyosin contractility and cell motility-as direct interactors of DIORA1. Through interaction mapping, we show that DIORA1 binds three distinct modules of MRCK kinases, including the conserved kinase inhibitory motif, C1-PH, and citron homology domains. DIORA1 knockdown in human cells altered cellular phosphorylation patterns and reduced phosphorylation of known MRCK targets. RNA-sequencing and proteomic analyses revealed upregulation of epithelial-mesenchymal transition genes and proteins, and functional analyses confirmed increased cell invasion, following knockdown of DIORA1. Together, these findings identify the autoimmunity-associated DIORA1 protein as an interactor of MRCK kinases and a regulator of cell motility.