Down-Regulation of LOC645166 in T Cells of Ankylosing Spondylitis Patients Promotes the NF-κB Signaling via Decreasingly Blocking Recruitment of the IKK Complex to K63-Linked Polyubiquitin Chains

Abstract

Ankylosing spondylitis (AS) is a chronic inflammatory disease that mainly affects the spine. AS is highly associated with the expression of HLA-B27. Up to 95% AS patients are HLA-B27-positive. However, only 1%–2% of the HLA-B27-positive carriers suffer from AS, implying that other factors may also govern the development of AS. Long non-coding RNAs (lncRNAs) can regulate the immune response via their binding proteins. In the present study, we have identified that the levels of lncRNA, LOC645166, in T cells of AS patients were reduced. Overexpression of LOC645166 in Jurkat cells down-regulated the IL-23p19 expression and suppressed the JAK2/STAT3 signaling in response to stimulation by phorbol 12-myristate 13-acetate. Suppression of STAT3 activation by LOC645166 was also observed when Jurkat cells or T cells of AS patient were treated with anti-CD3/CD28 antibodies. In order to explore the role of LOC645166 in the pathogenesis of AS, RNA pull-down assay plus proteomic approach and western blotting were performed and identified that LOC645166 prefers binding the K63-linked polyubiquitin chains. LOC645166 can suppress recruitment of the IKK complex to K63-linked polyubiquitin chains and diminish IKK2 activation, leading to down-regulation of NF-κB activation. Down-regulation of LOC645166 expression in T cells of AS patients up-regulates NF-kB activation via decreasingly impeding recruitment of the IKK complex to K63-linked polyubiquitin chains, allowing AS patients to exhibit more sensitivity to stimulation by the proinflammatory cytokines or by TLR ligands.

Emerging Roles of Long Non-Coding RNAs in Ankylosing Spondylitis

“…Yu et al demonstrated that LOC645166 was one of the most downregulated lncRNAs in T cells from AS patients as compared to those from healthy controls ( 68 ). Enforced expression of LOC645166 suppressed the expression of IL-23p19 (a subunit of IL-23) and inhibited JAK2/STAT3 signaling induced by phorbol 12-myristate 13-acetate or anti-CD28/CD3 antibodies in Jurkat cells (an immortalized line of human T lymphocytes).…”

HLA-B*27 Heavy Chain Homo-Oligomers Promote the Cytotoxicity of NK Cells via Activation of PI3K/AKT Signaling

“…The total RNAs of NK-92MI cells were isolated by using the QIAamp RNA Blood Mini kit (QIAGEN, GmbH, Hilden, Germany). IFN-γ, TNF-α, or IL-6 mRNA amplified with real-time PCR using a One Step SYBR Ex Taq qRT-PCR kit (TaKaRa, Shiga, Japan) followed the methods [ 28 ]. Relative expression levels of mRNA were calculated with the following equation: (40−threshold cycle [Ct], adjusted by the expression of 18S rRNA).…”

Novel regulatory role of non-coding RNAs in ankylosing spondylitis

“…Overexpression of miR-451 suppressed macrophage migration inhibitory factor (MIF) and levels of inflammatory cytokines (24). Yu et al (32) found that LOC645166 expression was downregulated in T cells from AS patients, which upregulated NF-kB activation by reducing the recruitment of polyubiquitin chains that block the IKK complex to K63 linkage, making AS patients more sensitive to stimulation by pro-inflammatory cytokines or TLR ligands. Li et al (33) showed that lncRNA maternally expressed gene 3 (MEG3) plays a partial anti-inflammatory role in AS by targeting miR-146a to regulate the expression of IL-1b, IL-6, and TNF-a.…”