2013-08-012024-05-13https://scholars.lib.ntu.edu.tw/handle/123456789/645070末期腎病為腎臟學的重要課題之ㄧ。慢性腎病是導致末期腎病的主要原因，諸多證據 顯示：慢性腎病惡化的機轉最終都是引起腎臟的纖維化，相關機轉包括：腎絲球傷害誘 發腎膈細胞增生、發炎細胞浸潤及細胞外間質累積，導致腎絲球閉塞及有效腎元數目減 少；為了維持有效廓清率，殘餘腎元肥大及超過率的調適作用，使的腎絲球過濾障壁破 壞，進一步造成腎小管凋亡及細胞間質傷害，最終引發腎臟的纖維化。 內質網在細胞內負責許多功能的執行，同時也負責維持蛋白的平衡。許多類型的細胞 壓力，包括：缺血、缺氧、熱休克、基因突變、氧化壓力以及變異蛋白合成的增加都會造 成內質網功能的損傷，並進一步引發內質網壓力（endoplasmic reticulum stress，簡稱ER stress)。當誘發初始內質網壓力時，內質網中的適應性未折疊蛋白反應(adaptive unfolded protein responses, UPRs)被啟動，目的是為了適應環境改變，以重建正常的內質網功能。 然而當適應失敗時，內質網壓力則會執行名為細胞凋亡的最終反應，藉由清除受損細胞來 保護生物體。Splicing X-Box binding protein-1 (sXBP-1)在適應性未折疊蛋白反應中佔有重 要角色，它是經由非傳統催化系統切割信息RNA而產生。sXBP-1調控一系列的應性未折 疊蛋白反應相關基因，進而影響許多細胞功能，如：(a) Metabolic and redox, (b) Apoptosis, (c) Autophagy, (d) ER-associated degradation (ERAD), (e) chaperones and foldases and (f) vesicle traffickling。由於越來越多證據顯示：慢性內質網壓力與神經退化性疾病、癌症、 糖尿病及前驅發炎反應狀態有關，許多研究日漸對適應性未折疊蛋白反應的調控機制感到 興趣，並希望發展潜在治療策略。在吾人過去動物模式研究中亦發現：單側輸尿管阻塞腎 臟纖維化研究中，適應性未折疊蛋白之調控蛋白sXBP-1的表現被明顯抑制；相對的，腎 臟組織會引發C/EBP 同源蛋白(CHOP)表現明顯上升，並引發細胞凋亡及接續的纖維化， 吾人相信XBP1訊息傳導路徑對減緩腎臟傷害佔有重要地位。 由於XBP-1剔除鼠的肝臟發育不良，嚴重貧血而死於胚胎時期；研究XBP-1剔除對器 官的影響，必需使用條件式XBP-1剔除鼠，本研究希望建立腎臟專一性的XBP-1剔除鼠以 研究XBP-1相關適應性未折疊蛋白反應，對腎臟損傷的角色。 本研究將分成三年執行：第一年，吾人將建立腎小管專一XBP-1剔除鼠，並分析 XBP-1剔除鼠對腎小管功能之影響。第二年，吾人將建立腎臟足細胞專一XBP-1剔除鼠， 並分析XBP-1剔除鼠對腎絲球功能之影響。第三年，吾人將利用足細胞專一及腎小管專一 的XBP-1剔除鼠進行慢行腎臟纖維化及糖尿病腎絲球硬化症相關實驗。吾人亦將著手研究 腎臟專一XBP-1剔除對腎臟纖維化的分子機轉，如：細胞凋亡、氧化壓力及前驅發纖維化 相關訊息傳遞路徑的調控，並分析內質網壓力傳導路徑的代償活化與腎臟保護的關係。希 望藉由上述策略所找出的標的，對國家生技創藥計劃（National Research Program for Biopharmaceuticals，簡稱NRPB)能付出心力。Different physiological and pathological perturbations interfere with protein folding processes in the endoplasmic reticulum (ER) lumen, leading to accumulation of unfolded or misfolded proteins, a cellular condition termed “ER stress.” Protein folding stress triggers the activation of an adaptive reaction to cope with ER stress termed the unfolded protein response (UPR). Splicing X-Box binding protein-1 (sXBP-1) catalyzes the unconventional processing of the mRNA, plays the central roles to activate the UPRs. It controls the upregulation of a general pool of UPR-related genes involved in different processes including (a) Metabolic and redox, (b) Apoptosis, (c) Autophagy, (d) ER-associated degradation (ERAD), (e) chaperones and foldases and (f) vesicle traffickling. There is growing biomedical interest in investigating the regulatory mechanisms underlying UPR signaling and the development of strategies to target this pathway, since there is substantial evidence for the involvement of chronic ER stress in many diseases, including neurodegeneration, diverse forms of cancer, diabetes, and proinflammatory conditions. Regardless of etiology, all patients with chronic renal disease show a progressive decline in renal function with time. Chronic inflammation and diabetes are associated with renal fibrosis, so-called scarring, is a key factor of this pathophysiologic changes. Fibrosis involves an excess accumulation of extracellular matrix and usually results in loss of function when normal tissue is replaced with scar tissue. Before the development of chronic fibrosis, renal parenchyma attempts to maintain the integrity of tubules, there is an activation of proliferative pathways within the epithelial cells. If the proliferative forces or homeostatic factors within the kidney dissipate, the apoptotic pathway(s) overwhelms the ability of tubular epithelial cells to survive and tubular atrophy ensues. Our recent publication demonstrated the downregulation of adaptive UPRs and upregulation of overwhelming ER stess in the unilateral ureteral obstruction fibrosis model. Adequate UPRs might contribute to the restoration of renal insult, thus we believe that IRE1-XBP1 pathway plays a significant role in overcoming the kidney insult. However, XBP-1 deficiency leads to embryonic lethality due to impairment of liver function. To bypass this lethality, we need to design experiments by using a conditional KO allele of XBP-1 mice. It is deserved to explore the mechanisms of XBP-1-related signals in renal fibrosis and inflammation. We hope to achieve these goals within 3 years. In the first year, we will generate Kidney Tubular-Specific XBP-1 KO Mice, and then arrange functional analysis. In the second year, we will generation of Kidney Podocyte-Specific XBP-1 KO mice, and them arrange functional analysis. In the third year, we will explore the roles of Kidney-Specific XBP-1 in chronic tubulointerstitial fibrosis and diabetic glomerulosclerosis models. Using these available tools will help us to identify the physiological and pathological roles of adaptive UPR (splicing XBP-1) in the renal tubular and glomerular disease. We will get chances and comprehensive experiences in handling the transgenic and knockout mice. We hope such novel approaches can actively contribute to the National Research Program for Biopharmaceuticals (NRPB) in Taiwan.