Background/Purpose: Our recent study uncovered a role for dysregulation of the Hippo signaling pathway in systemic lupus erythematosus (SLE) keratinocytes (KCs) driven by overexpression of WW domain containing protein 1 (WWC1). This overexpression results in chronic overactivation of Hippo signaling. SLE is also characterized by increased production of type I interferon (IFN) driven in part by activation of the cGAS-STING-TBK1-IRF3 pathway. This investigation sought to evaluate the interplay between WWC1-mediated HIPPO activation and type I IFN production via cGAS-STING signaling.

Methods: Human N/TERT keratinocytes that stably overexpress WWC1or GFP control were treated with the STING agonist 2’3’ cyclic GMP-AMP (cGAMP, 10 µg/mL)) or transfected with Z-DNA (625ng/well of 12 well plate) to activate cGAS-STING pathway. At 6 hours, phosphorylation of STING and TBK1 was assessed via Western blot, and total downstream gene expression was analyzed by RNA-seq and type I IFN and IFN-stimulated-genes (ISG) were evaluated by RT-qPCR. Similar experiments also were performed with or without IFNα priming.

Results: GFP-WWC1 in WWC1OE cell lines was localized to the perinuclear and cytoplasmic regions. As expected, WWC1OE upregulated the activity of LATS1/2 and increased phosphorylation of Yes-associated protein (YAP) at Ser397. Surprisingly, WWC1OE decreased the phosphorylation of TBK1 and STING in response to cGAMP induction and Z-DNA transfection, which led to a significant reduction of IFNB1, ISG15 and IRF7 expression. Furthermore, RNA-seq analysis confirmed a striking downregulation of type 1 interferon mediated signaling pathways when WWC1 was overexpressed. Upon further investigation, WWC1OE may also downregulate STING and YAP total protein content, suggesting that WWC1 may regulate the stability of cGAS-STING signaling components.

Conclusion: Our study reveals a novel role of WWC1 in regulation of type I interferon production through modulation of cGAS-STING signaling in keratinocytes. Further investigations will determine how the regulation of STING signaling by WWC1 can be utilized to understand and treat disease with high type I IFN expression.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/wwc1-regulates-type-i-interferon-production-through-modulation-of-cgas-sting-signaling-in-keratinocytes/