Institute for Genomics and Bioinformatics, Graz University of Technology, Graz, Austria.
RNA Biol. 2011 Sep-Oct;8(5):850-60. doi: 10.4161/rna.8.5.16153. Epub 2011 Aug 31.
Obesity is characterized by excessive adipose tissue mass and associated with type 2 diabetes and cardiovascular diseases. To fight obesity and its sequels, elucidating molecular events that govern adipocyte differentiation and function is of key importance. MicroRNAs (miRNAs) are a novel class of non-coding, regulatory RNAs that have been shown to regulate crucial cellular processes, including differentiation. Several studies have already assigned miRNAs to distinct functions in murine adipocyte differentiation but only a few studies did so for humans. Here, we investigated the function of miR-30c in human adipogenesis. miR-30c expression was increased during adipogenesis of human multipotent adipose-derived stem (hMADS) cells, and miR-30c overexpression enforced adipocyte marker gene induction and triglyceride accumulation. miRNA target prediction revealed two putative direct targets of miR-30c, PAI-1 (SERPINE1) and ALK2 (ACVR1, ACTRI), both inversely regulated to miR-30c during adipogenesis and responsive to miR-30c overexpression. Luciferase reporter assays confirmed PAI-1 and ALK2 as direct miR-30c targets. Moreover, reciprocal expression between miR-30c and PAI-1 could also be demonstrated in white adipose tissue of obesity mouse models, suggesting a potential physiological role of miR-30c for PAI-1 regulation in the obese state. Validating PAI-1 and ALK-2 as miR-30c mediators in adipogenesis revealed that not single silencing of PAI-1 or ALK2, but only co-silencing of both phenocopied the pro-adipogenic miR-30c effect. Thus, miR-30c can target two, so far not interconnected genes in distinct pathways, supporting the idea that miRNAs might coordinate larger regulatory networks than previously anticipated.
肥胖症的特征是脂肪组织过多，与 2 型糖尿病和心血管疾病有关。为了对抗肥胖及其后果，阐明调控脂肪细胞分化和功能的分子事件至关重要。MicroRNAs（miRNAs）是一类新型的非编码调节 RNA，已被证明可调控包括分化在内的关键细胞过程。已有几项研究将 miRNAs 分配到了小鼠脂肪细胞分化的不同功能中，但仅有少数研究针对人类进行了相关研究。在这里，我们研究了 miR-30c 在人类脂肪生成中的功能。miR-30c 在人类多能脂肪源性干细胞（hMADS）细胞的脂肪生成过程中表达增加，miR-30c 的过表达强制诱导脂肪细胞标记基因的诱导和甘油三酯的积累。miRNA 靶标预测显示，miR-30c 的两个潜在直接靶标是 PAI-1（SERPINE1）和 ALK2（ACVR1、ACTRI），它们在脂肪生成过程中与 miR-30c 呈负相关，且对 miR-30c 的过表达有反应。荧光素酶报告基因检测证实了 PAI-1 和 ALK2 是 miR-30c 的直接靶标。此外，肥胖小鼠模型的白色脂肪组织中也可以证明 miR-30c 和 PAI-1 之间的表达呈反向关系，这表明 miR-30c 在肥胖状态下对 PAI-1 调节具有潜在的生理作用。验证 PAI-1 和 ALK-2 作为 miR-30c 在脂肪生成中的调节剂表明，只有同时沉默 PAI-1 和 ALK2 才能模拟促脂肪生成的 miR-30c 效应。因此，miR-30c 可以靶向两个不同途径中迄今未相互关联的基因，这支持了 miRNA 可能协调比预期更大的调控网络的观点。
