Role of LINC00240 on T-helper 9 differentiation in Allergic Rhinitis
through influencing DNMT1-dependent methylation of PU.1
Abstract
Background Allergic rhinitis (AR) is a common allergic disease with
increasing prevalence globally. However, the molecular mechanism
underlying AR pathogenesis remains largely undefined. Methods Samples of
peripheral blood and nasal mucosa from patients with AR, as well as the
ovalbumin-induced AR mice model was obtained. qRT-PCR and western blot
were used to detect the expression of LINC00240, miR-155-5p, PU.1 and
other key molecules. ELISA assay and flow cytometry were employed to
evaluate the secretion of IL-9 and T-helper 9 (Th9) cell ratio,
respectively. Bioinformatics analysis, RNA immunoprecipitation (RIP),
chromatin immunoprecipitation (ChIP) and luciferase reporter assays were
employed to further elucidate the regulatory network of
LINC00240/miR-155-5p/DNMT1. The methylation of PU.1 promoter was
assessed by methylation-specific PCR (MSP). This signaling axis was
finally confirmed in the AR mice model. Results LINC00240 was
downregulated, while miR-155-5p and PU.1 were upregulated in the
peripheral blood and nasal mucosa of AR patients, as well as in the AR
mice. This was accompanied with the increased ratio of Th9 cells and
elevated IL-9 secretion. Mechanistically, LINC00240 served as a
miR-155-5p sponge, and DNMT1 was a target of miR-155-5p. In addition,
DNMT1 mediated the methylation of PU.1 promoter. In vivo studies
verified that LINC00240 mitigated AR progression, possibly via
miR-155-5p/DNMT1/PU.1-dependent Th9 differentiation. Conclusion In
summary, the involvement of LINC00240 in AR pathogenesis is closely
associated with Th9 differentiation through modulating DNMT1-dependent
methylation of PU.1 by sponging miR-155-5p.