microRNA-126在溃疡性结肠炎中表达上调机制的研究

The pathogenesis of chronic ulcerative colitis (UC) is not fuuly understood. Moreover, there is lack of effective treatments for UC. Recent studies identify that microRNAs are diffentially expressed in many human diseases including active UC. However, very few studies investigate the molecular mechanisms for regulation of miRNA expression. We and others found that miR-126 was over-expressed in colonic tissues of UC patients and further demonstrated that miR-126 targets on an inhibitor of NF-κB pathway (IkBa) and overexpression of miR-126 leads to functional activation of NF-κB pathway in UC. However, mechanisms for up-regulation of miR-126 in UC remain unknown. In this proposal, we aim to understand the molecular mechanisms for regulation of miR-126 expression in UC. We will first investigate whether miR-126 and its host gene EGFL7 share the same promoter by examining the correlation of miR-126 and EGFL7 expressions in UC tissue and by a series of functional analysis using promoter-reporter constructs. We will also determine the core promoter genomic regions critical for the expression of miR-126 using a series of deletion constructs. Further, we will proceed to identify the abnormally expressed cytokines, chemokines or TLR agonists which lead to overexpression of miR-126 in UC tissue. Finally, we will determine the important transcription factors (TF) which regulate the expression of miR-126 by EMSA, ChIP-PCR, TF overexpression constructs and TF siRNA. Elucidation of the mechanisms for miR-126 overexpression in UC will provide a fundamental basis for development of novel diagnostic and therapeutic approches for UC and thus have a significant impact on clinical management of UC patients.

研究发现miRNAs在人类疾病包括溃疡性结肠炎(UC)组织中表达异常，但对miRNAs表达调控机制研究很少。我们发现miR-126在UC中表达上调，抑制IκBα而增强NF-κB活性，导致炎症反应，说明miR-126表达上调在UC中起重要作用，但miR-126上调的调控机制仍不清。本课题在我们前期研究基础上探讨miR-126在UC中的分子调控机制。首先了解miR-126及其母基因EGFL7在UC组织的表达和相互关系，再应用含EGFL7/pre-miR-126上游启动子的荧光素酶报告载体了解miR-126与EGFL7是否受同一启动子调节，并明确该启动子基因片段中的核心序列。同时应用多种分子生物学手段寻找调节miR-126表达的重要转录因子及其刺激因子,阐明转录因子与启动子相互作用及对miR-126表达影响。深入研究miR-126在UC中作用及升高原因与机制,为开发新诊疗手段提供理论和实验依据。