摘要:近幾年非傳染性疾病盛行率漸增,尤其是肥胖、第2型糖尿病、高血壓、高血脂及其衍伸的心血管疾病與癌症。而這些都可能與肥胖所造成的胰島素阻抗(insulin resistance)有關。目前也知脂肪組織及其所分泌的脂肪因子(adipokines)會與肝臟和肌肉間進行相互作用,因而影響胰島素阻抗和形成代謝疾病,而脂締素(adiponectin)即是其中重要的脂訪因子之一。目前已知脂締素具有增加胰島素敏感度、抗動脈粥狀硬化、抗發炎和抗癌作用。過去幾年我們致力於研究脂締素的特性與調控,也發表數篇文章有關作用於PPAR的TZD類藥物可增加脂締素表現,及手術減重後可增加脂締素表現並增加胰島素的敏感性。此外,有關基因型的研究也發現RyR3的SNP表現與脂締素表現量有關。而在3T3-L1脂肪細胞研究中也發現抑制RyR3的表現可使脂肪細胞中脂締素的啟動子活性、mRNA、蛋白質分泌量增加。基於這些結果我們認為RyR3可能可作為治療處理目標,經由增加脂締素表現量來改善代謝異常疾病症狀。所以本計畫除了以3T3-L1細胞株進行基礎研究證明RyR3確實與脂締素表現量有關,也將試圖找出其可能的作用機制。此外,也會利用動物實驗來驗證RyR3和脂締素的關係,並評估以RyR3抑制劑及其siRNA作為藥劑治療代謝異常症的可行性。本計畫共計執行三年並預計完成下列工作1. 研究RyR3在脂肪細胞分化時所扮演角色及其表現量變化為何,並比較正常老鼠與糖尿病老鼠中其不同脂肪細胞中RyR3的表現量。2. 利用細胞實驗證明RyR3可影響脂締素的表現,並研究可能的作用機制(粒線體與atf3的參與)。3. 於糖尿病老鼠活體(db/db和ob/ob)中證明抑制RyR3可增加脂締素表現。4. 於高脂飼料老鼠實驗中證明抑制RyR3可增加脂締素表現。5. 於動物實驗中測試以RyR3為處理標的以達到治療的可行性,包含脂締素表現量、胰島素敏感性、抗發炎能力的測定。6. 於人體檢體中檢視RyR3與脂締素表現的相關性和其與各種代謝指數的相關性。
Abstract: Non-communicable diseases have been increasing globally in past years, in particular the increases in the epidemics of obesity, type 2 diabetes, hypertension, dyslipidemia, and their consequences including cardiovascular diseases, cerebral vascular diseases, and cancers. The underlying mechanism is caused largely by the obesity-associated insulin resistance. Through cross talk between adipose tissue with muscle and liver, the adipose-secreted adipokines are implicated in the causation of systemic insulin resistance and its related metabolic disorders. One of the major adipokines, the adiponectin, has been shown to possess insulin sensitizing, anti-atherosclerosis, anti-inflammation, and anti-cancer effects. In the past years, we had been very focused on characterizing effect/regulation of the adiponectin. Importantly, we have published a series of publications related to adiponectin biology in metabolic diseases, including two high citation papers which related to thiazolidinedione (TZD) drug that increases adiponectin via targeting at peroxisome proliferator activator receptor gamma (PPAR); and showed weight-reducing surgery increases adiponectin concentrations which correlated with improvement of insulin sensitivity. Moreover, we also mapped the genetic loci, the QTLs, for circulating adiponectin level with genomewide linkage analyses. Within the prominent region, we found, for the first time, that the adiponectin level was highly associated with the SNP of RyR3 gene. In addition, in the cultured 3T3-L1 cells, the increased expression of adiponectin mRNA and higher level of secreted adiponectin protein were found in RyR3 silenced cells. The adiponectin promoter activity was also increased in RyR3 silenced cells. Based on our findings thus far, we hypothesized that targeting of RyR3 may be a promising approach for treating metabolic syndrome by increasing of adiponectin gene expression. Therefore, in this proposal, we selectively aim to establish proof of principle, with a new therapeutic modality of siRNA technology or the previously known compounds that targeted at RyR3, to show how RyR3 inhibition increases adiponectin expression and confirm the role of adiponectin-raising effect on improvement of insulin sensitivity and glucose homeostasis in animal models of both genetic obesity/diabetes (ob/ob and db/db) mice and the high fat diet (HFD)-induced insulin resistant obese mouse model.In this proposal, we attempt to finish following specific goals in three years:1. Explore the role of RyR3 during adipogenesis and determine RyR3 expression profiles in different adipose tissues among wild-type and db/db diabetic mice.2. To prove the silencing of RyR3 gene can up-regulate adiponectin gene expression and examination the underlying mechanism involved in this response.3. To demonstrate that the siRYR3 is able to up-regulate adiponectin expression in diabeticdb/db and ob/ob animal model.4. To demonstrate that the siRYR3 is able to up-regulate adiponectin expression in high fat diet animal model.5. To test the potential effects of targeting at RyR3 and related pathway in diabetic db/db, ob/ob mice and high fat diet animal model on adiponectin-raising, insulin sensitization, and anti-inflammation effects.6. Test expression of RyR3 and adiponectin expressions in human tissues, and correlate with clinical phenotypes in human subjects.