Mechanisms of Differential Signaling by IFNLR1 Variants

ABSTRACT: Introduction: Lambda interferons signal through the interferon lambda receptor-1 (IFNLR1) and IL10RB heterodimer to induce interferon stimulated genes (ISGs). We previously showed that proteins derived from distinct IFNLR1 splice isoforms uniquely influence gene expression and HBV replication in stem cell-derived hepatocytes (iHeps). Here, we evaluated the mechanisms of signal transduction by full-length IFNLR1 (variant 1) and a truncated variant missing part of the cytoplasmic JAK1-interacting domain (variant 2). Methods: We evaluated HEK293T cells, wild-type (WT), and IFNLR1 knock-out (KO) iHeps with doxycycline-inducible expression FLAG-tagged IFNLR1 variants using the Duolink proximity ligation assay, ImageStream flow cytometry, western blotting of JAK-STAT proteins, susceptibility to JAK1 and TYK2 inhibitors, and gene expression profiling. Results: Each variant demonstrated IFNL-induced colocalization with IL10RB, but variant 1 was more rapidly and extensively internalized. In WT iHeps with intact endogenous IFNLR1, overexpression of either variant 1 or variant 2 enabled higher IFNL-induced JAK1, TYK2, STAT1 and STAT2 phosphorylation, yet variant 2 supported less robust ISG induction than variant 1. In iHeps with abrogated endogenous IFNLR1 expression, variant 2 supported less JAK1 and TYK2 phosphorylation and ISG induction than variant 1 yet was not deficient in supporting STAT1 and STAT2 phosphorylation. Select ISGs had differential constitutive expression in IFNL-untreated variant-expressing iHeps. In iHeps expressing variant 1, WT-iHeps were more resistant than KO-iHeps to TYK2-inhibition of antiviral ISG induction yet conversely were more susceptible to TYK2-inhibition of proinflammatory ISG induction, suggesting endogenously produced noncanonical variants influence the TYK2-dependence of IFNL signaling. Conclusions: IFNLR1 variants promote differential utilization of signaling mediators to influence IFNL-induced gene expression patterns, indicating a putative role in pathway regulation.

ORGANISM(S): Homo sapiens

PROVIDER: GSE329545 | GEO | 2026/04/30

REPOSITORIES: GEO