Identification of the regulatory role of lncRNA HCG18 in myasthenia gravis by integrated bioinformatics and experimental analyses

Shuang Li,Xiaoyu Lu,Jianjian Wang,Lifang Li,Li Liu,Xiaotong Kong,Tianfeng Wang,Xu Wang,Shangwei Ning,Lihua Wang,Huixue Zhang,Si Xu,Chunrui Bo

doi:10.1186/s12967-021-03138-0

Abstract

BackgroundLong non-coding RNAs (lncRNAs), functioning as competing endogenous RNAs (ceRNAs), have been reported to play important roles in the pathogenesis of autoimmune diseases. However, little is known about the regulatory roles of lncRNAs underlying the mechanism of myasthenia gravis (MG). The aim of the present study was to explore the roles of lncRNAs as ceRNAs associated with the progression of MG.MethodsMG risk genes and miRNAs were obtained from public databases. Protein–protein interaction (PPI) network analysis and module analysis were performed. A lncRNA-mediated module-associated ceRNA (LMMAC) network, which integrated risk genes in modules, risk miRNAs and predicted lncRNAs, was constructed to systematically explore the regulatory roles of lncRNAs in MG. Through performing random walk with restart on the network, HCG18/miR-145-5p/CD28 ceRNA axis was found to play important roles in MG, potentially. The expression of HCG18 in MG patients was detected using RT-PCR. The effects of HCG18 knockdown on cell proliferation and apoptosis were determined by CCK-8 assay and flow cytometry. The interactions among HCG18, miR-145-5p and CD28 were explored by luciferase assay, RT-PCR and western blot assay.ResultsBased on PPI network, we identified 9 modules. Functional enrichment analyses revealed these modules were enriched in immune-related signaling pathways. We then constructed LMMAC network, containing 25 genes, 50 miRNAs, and 64 lncRNAs. Through bioinformatics algorithm, we found lncRNA HCG18 as a ceRNA, might play important roles in MG. Further experiments indicated that HCG18 was overexpressed in MG patients and was a target of miR-145-5p. Functional assays illustrated that HCG18 suppressed Jurkat cell apoptosis and promoted cell proliferation. Mechanistically, knockdown of HCG18 inhibited the CD28 mRNA and protein expression levels in Jurkat cells, while miR-145-5p inhibitor blocked the reduction of CD28 expression induced by HCG18 suppression.ConclusionWe have reported a novel HCG18/miR-145-5p/CD28 ceRNA axis in MG. Our findings will contribute to a deeper understanding of the molecular mechanism of and provide a novel potential therapeutic target for MG.

Highlights

Myasthenia gravis (MG) is a chronic acquired autoimmune disease characterized by fluctuating muscular weakness and abnormal fatigability, which is mainly caused by antibodies against acetylcholine receptor (AChR) [1]
Random walk with restart to prioritize Long non-coding RNAs (lncRNAs) for myasthenia gravis (MG) We used random walk with restart (RWR) [25, 26] to prioritize potential lncRNAs in the lncRNA-mediated module-associated Competing endogenous RNA (ceRNA) (LMMAC) network for MG by simulating a random walker and randomly moving from a set of source nodes to its network neighbors
In order to explore the roles of modules in MG, we carried out gene ontology (GO) function and KEGG pathway enrichment analysis for each module

Summary

Introduction

Myasthenia gravis (MG) is a chronic acquired autoimmune disease characterized by fluctuating muscular weakness and abnormal fatigability, which is mainly caused by antibodies against acetylcholine receptor (AChR) [1]. The rise of nanomedicine has developed a novel era for the treatment of various diseases [4, 5], which provides a potential treatment strategy for MG patients. Some important genes have been identified to participate in the occurrence and development of MG. The genes in the same module are more likely to play similar roles or share some common properties. It is crucially important to identify functional modules in order to better understand the pathogenesis of MG. Long non-coding RNAs (lncRNAs), functioning as competing endogenous RNAs (ceRNAs), have been reported to play important roles in the pathogenesis of autoimmune diseases. Little is known about the regulatory roles of lncRNAs underlying the mechanism of myasthenia gravis (MG).

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