The Study On The Role And Mechanisms Of RNA Binding Protein HuB In Regulation Of Expression Of Pro-inflammatory Genes

In eukaryotes, gene expression regulation is a multistage regulation system, it mainly occurs in five relatively independent to each other horizontally. They are regulated on the pre-transcriptional level; on the transcriptional level; on the post-transcriptional level; on the translational level; on the post-translational level. So far, the transcriptional level of regulation as well as the translational level of regulation and its mechanism have thorough researched. In recent years, more and more people began to focus on the regulation and mechanism of post-transcriptional level. The post-transcriptional gene regulation levels, including mRNA processing, degradation, maturation and translation initiation and so on. mRNA stability of the post-transcriptional level of regulation is a crucial aspect of the regulation, and is one of the hot topics in the study of gene expression regulation.mRNA stability commonly regulate by their own domains (cis-acting elements) and the corresponding mRNA-binding protein (trans-acting factor). Some of mRNA (eg:Early response factors, cytokines, etc.) contained AU or U-rich element (ARE) in the 3’-UTR. ARE is an unstable factor, and have closely relationship with mRNA half-life. The present study show that many RNA binding proteins are capable of specifically binding to ARE element and affect the stability of the mRNA. Such as HuR, TTP, etc. And HuR is the only ARE binding protein that can improve its stability.HuR belongs to Hu family, also known as embryonic lethal abnormal visual family (ELAV). The family contains four family members, respectively is HuR, HuB, HuC, HuD. Like two other Hu family members (HuC and HuD), HuB was believed to be expressed specifically in neurons, while the remaining member, HuR was ubiquitous. However, a recent survey revealed that HuD also ubiquitously expressed in different tissues.In laboratory previous research of the protein of poly ADP ribose (PAR-based) to regulatory of HuR function mechanisms, accidentally discovered that HuB gene can induce expression in inflammatory stimulation in mice peritoneal macrophages. Therefore, this paper select Raw264.7 mouse macrophage cell line, mouse peritoneal macrophages in lung tissue of mice as the experimental materials to study the expression of HuB, intracellular localization, the impact of proinflammatory gene expression and so on. The study found that HuB has a capable of ubiquitously expressed in various tissues of mice, and the lower level of expression in the lung. But in response to inflammatory stimuli, the expression was significantly increased. Induced expression of HuB protein was mainly distributed in the cytoplasm, there is no nucleocytoplasmic shuttling phenomenon. Because of HuB interference, inflammatory stimulation induced Cxcl-2 mRNA expression increased by blocking. In addition,the upregulation of the expression of HuB protein caused by LPS were also influenced by the catalytic enzyme PARP-1 activity of the PAR. PARP-1 how to affects the expression of HuB protein, thereby affecting the expression level of mRNA cytokines, the detailed mechanism remains to be further revealed.This study proposed pathways in activation of a PARP1-HuB-proinflammatory gene expression signal, as preliminary data for further study of this pathway can affect proinflammatory gene mRNA stability laid the foundation. Also induced the expression of HuB for proinflammatory gene mRNA expression in the role of tips HuB expression inhibition as anti-inflammatory treatment of potential target.