Role of Periostin in Polycystic Kidney Disease

描述（由申请人提供）：常染色体显性多囊肾病（ADPKD）是一种增生性疾病，其中小管上皮细胞异常生长导致大量充满液体的囊肿形成，肾脏大量增大和肾功能进行性丧失。虽然囊肿是良性肿瘤，但它们最终会通过广泛的肾单位损失和相邻实质纤维化取代而导致肾功能不全。囊肿破坏肾脏的机制尚不清楚；然而，细胞外基质（ECM）沉积的变化可能是重要的。在培养的人ADPKD囊肿上皮细胞的微阵列分析中，与正常人肾（NHK）细胞相比，骨膜蛋白mRNA过表达15倍。骨膜蛋白最初在成骨细胞中被鉴定为一种可溶性ECM分子，在正常成人肾脏中不表达，但在肾脏发育过程中，在肾源区（肾元形成和血管形成的部位）短暂表达。在ADPKD中，骨膜蛋白在原位囊肿内膜细胞、囊肿附近的细胞外基质和囊肿液中表达。与NHK细胞相比，ADPKD细胞中av -整合素（一种骨膜蛋白受体）的表达量高出9倍，阻断av -整合素的抗体抑制了骨膜蛋白诱导的细胞增殖。相比之下，骨膜素不影响正常肾细胞的增殖。我们发现，periostin激活整合素连接激酶（integrin-linked kinase， ILK）， ILK是一种通过激活Akt、GSK-32/2-catenin和mTOR信号通路来调节细胞增殖和存活的激酶。在初步数据中，我们发现pcy/pcy和Pkd2WS25/-小鼠（人类PKD模型）肾脏中的骨膜蛋白表达升高；基因敲除骨膜蛋白（PN-/-）可降低pcy/pcy小鼠的肾脏重量（占体重的百分比）。我们还发现，与正常志愿者（n = 8）相比，非azotic ADPKD患者（n = 14）血清中的骨膜蛋白水平升高，这表明骨膜蛋白可能是PKD进展的早期指标。我们的一般假设是，在ADPKD中，骨膜蛋白是一种新的自分泌丝裂原，具有加速囊肿生长和促进间质重塑的潜力。公共卫生相关性：ADPKD是最常见的遗传性肾脏疾病，基因频率为500至1,000例新生儿中有1例，约占所有终末期肾脏疾病的5-9%。仅在美国，肾脏移植、透析和PKD相关治疗的费用就接近20亿美元/年，据估计，到本十年末，全球治疗费用将达到900亿美元/年。这些研究的完成将提供有关骨膜蛋白作用的新信息，骨膜蛋白是一种由壁上皮细胞分泌的新型自分泌丝裂原，具有加速囊肿生长和促进ADPKD间质重塑的潜力。

DESCRIPTION (provided by applicant): Autosomal dominant polycystic kidney disease (ADPKD) is a hyperplastic disorder in which aberrant growth of tubule epithelial cells causes the formation of numerous fluid-filled cysts, massively enlarged kidneys and progressive loss of renal function. Although cysts are benign neoplasms, they ultimately cause renal insufficiency through extensive nephron loss and replacement of adjacent parenchyma with fibrosis. The mechanisms by which cysts destroy the kidneys are poorly understood; however changes in the deposition of the extracellular matrix (ECM) are likely to be important. In a microarray analysis of cultured human ADPKD cyst epithelial cells, periostin mRNA was over expressed 15-fold compared to normal human kidney (NHK) cells. Periostin, initially identified in osteoblasts as a soluble ECM molecule, is not expressed in normal adult kidneys but is expressed transiently during renal development within the nephrogenic zone, a site of nephron formation and vascularization. In ADPKD, periostin was expressed in cyst-lining cells in situ, in extracellular matrix adjacent to the cysts and within cyst fluid. Expression of aV-integrin, a receptor for periostin, was 9-fold higher in ADPKD cells compared to NHK cells, and antibodies that block aV-integrin inhibited periostin-induced cell proliferation. By contrast, periostin did not affect the proliferation of normal kidney cells. We found that periostin activates integrin-linked kinase (ILK), a kinase that regulates cell proliferation and survival through activation of Akt, GSK-32/2-catenin and mTOR signaling pathways. In preliminary data, we found that periostin expression was elevated in the kidneys of pcy/pcy and Pkd2WS25/- mice, models of human PKD; and that genetic knockout of periostin (PN-/-) reduced kidney weight (as a % of body weight) in the pcy/pcy mouse. We also found that periostin levels were elevated sera of non-azotemic ADPKD patients (n = 14) compared to normal volunteers (n = 8), suggesting that periostin may be an early indicator of PKD progression. Our general hypothesis is that periostin is a novel autocrine mitogen with the potential to accelerate cyst growth and promote interstitial remodeling in ADPKD. PUBLIC HEALTH RELEVANCE: ADPKD is the most frequently inherited kidney disorder with a gene frequency of 1 in 500 to 1,000 births and accounts for approximately 5-9% of all end-stage renal diseases. Costs for renal transplantation, dialysis and related treatments for PKD approach $2 billion/yr in the US alone and it is estimated that by the end of this decade treatments will cost $90 billion/yr worldwide. Completion of the proposed studies will provide new information on the role of periostin, a novel autocrine mitogen secreted by mural epithelial cells with the potential to accelerate cyst growth and promote interstitial remodeling in ADPKD.