Developmental genes, miRNAs and adipose tissue

项目摘要/摘要 这是NIH资助DK 082659的竞争性更新，题为“发育基因，miRNA和 脂肪组织”。肥胖正在以流行病的比例增加，并且是发病机制的主要驱动力 2型糖尿病和代谢综合征的风险在过去的十年里，人们已经清楚地看到，无论是白色还是白色， 棕色脂肪是异质的。因此，内脏WAT的积累与胰岛素抵抗相关， 增加代谢疾病的风险，而皮下WAT的积累甚至可能具有保护作用。 这至少部分是由于固有的，即，脂肪细胞之间的细胞自主性、功能差异 这些仓库。事实上，我们和其他人最近的研究表明， 单个贮库内白色脂肪细胞的异质性。使用生物信息学方法和单细胞 克隆，我们现在已经确定了至少三类白色脂肪细胞的谱系示踪标记， 除了上面的那些。我们还发现，不同的脂肪储存库在其表达的miRNAs不同， 并且在肥胖和衰老中脂肪组织中存在miRNA和miRNA加工的改变。 此外，脂肪特异性敲除miRNA加工酶Dicer改变了WAT和BAT的发育， 全身葡萄糖和脂质代谢以及对应激的反应。在最近令人兴奋的数据中，我们已经表明， 脂肪组织是循环外泌体miRNAs的主要来源，这些miRNAs可以调节基因表达， 在其他组织中，形成与其他组织的脂肪交流的新模式。这些数据导致 两个相互关联的假设。首先，我们假设-除了将脂肪组织分为 白色、棕色和米色脂肪-白色脂肪细胞本身在性质上是异质的， 异质性导致mRNA表达和脂肪细胞功能的差异。其次，这些不同的 白色和棕色脂肪细胞的miRNA表达不同，这些miRNA的一个子集是 在外泌体中释放到循环中，在那里它们作为脂肪在其他组织中的作用的新调节剂。 组织中下一个资助期的具体目标是：1）完成白色脂肪细胞的表征 使用新鉴定的谱系标志物来确定异质性，并使用单细胞RNAseq来扩展该异质性， 前脂肪细胞/脂肪细胞的不同亚型，其在代谢调节中的功能和作用不同。（二） 继续探索脂肪组织来源的循环外泌体miRNA在代谢中的作用， 在体外鉴定控制脂肪细胞miRNA外泌体分泌的分子特征，并开发一种 用于鉴定脂肪和其它组织来源循环外泌体miRNA的体内方法。我们还将 评估患有脂肪代谢障碍和肥胖症的人的血清中的外来体miRNA， 外泌体miRNA调节其他组织中的基因表达。这些数据将加深我们的 了解脂肪器官的复杂性质，并阐明循环脂肪源性 外泌体miRNAs作为新的脂肪因子调节代谢。

Project Abstract/Summary This is a competitive renewal of NIH grant DK082659 entitled “Developmental Genes, miRNAs and Adipose Tissue”. Obesity is increasing at epidemic proportions and is a major driving force in the pathogenesis of type 2 diabetes and metabolic syndrome. Over the past decade it has become clear that both white and brown fat are heterogeneous. Thus, accumulation of visceral WAT is associated with insulin resistance and increased risk of metabolic disease, whereas accumulation of subcutaneous WAT may even be protective. This is due, at least in part, to intrinsic, i.e., cell-autonomous, functional differences between adipocytes in these depots. Indeed, recent studies by us and others have shown that there is genetic and functional heterogeneity of white adipocytes within a single depot. Using bioinformatics approaches and single cell cloning, we have now identified lineage tracing markers for at least three classes of white adipocytes in addition to those above. We have also found that different adipose depots differ in their expression of miRNAs and that there are alterations in miRNAs and miRNA processing in adipose tissue in obesity and aging. Furthermore, fat-specific knockout of the miRNA processing enzyme Dicer alters WAT and BAT development, systemic glucose and lipid metabolism, and response to stress. In exciting recent data, we have shown that adipose tissue is a major source of circulating exosomal miRNAs and that these can regulate gene expression in other tissues, forming a novel mode of adipose communication with other tissues. These data have led to two inter-related hypotheses. First, we hypothesize that - in addition to classification of adipose tissue into white, brown and beige fat - white adipocytes themselves are heterogeneous in nature and that this heterogeneity programs differences in mRNA expression and adipocyte function. Secondly, these different classes of white and brown adipocytes differ in their miRNA expression and that a subset of these miRNAs is released in exosomes into the circulation where they act as novel regulators of the effects of fat in other tissues. The specific aims for the next grant period are to: 1) Complete the characterization of white adipocyte heterogeneity using the newly identified lineage markers and expand this using single cell RNAseq to define different subtypes of preadipocyte/adipocytes which differ in function and role in metabolic regulation. 2) Continue to explore the role of adipose tissue derived circulating exosomal miRNAs in metabolism by identifying the molecular signature governing adipocyte miRNA exosomal secretion in vitro and developing an in vivo method for identification of fat- and other tissue-derived circulating exosomal miRNAs. We will also assess exosomal miRNAs in serum of humans with lipodystrophy and obesity and assess the ability of exosomal miRNAs to regulate gene expression in other tissues. Together these data will deepen our understanding of the complex nature of the adipose organ and elucidate the role of circulating adipose-derived exosomal miRNAs as novel adipokines in regulation of metabolism.