The Laminin Receptors in Kidney Fibrosis

我们的总体目标是确定细胞-细胞外基质相互作用如何调节健康和 疾病。这些相互作用是使用转基因小鼠模型、细胞来研究从动物到分子的。 生物和生化分析。我们之前定义了层粘连蛋白(LM)受体整合素的作用， 整合素α3、β1和α6含有整合素，对输尿管芽(UB)发育有促进作用。最近，我们做了一个意想不到的 LM受体调节肾小管上皮细胞炎症和肾小管间质的新观察 衰老和损伤小鼠的纤维化。这些新的发现构成了这次更新的基础。 整合素是由α和β亚基组成的跨膜受体，介导细胞之间的相互作用 和ECM。有18个α和8个β亚基，它们形成具有不同配体结合性质的二聚体。整合素 整合素分为三种受体，主要为α-3、β-1和RGd受体。 α6β1和α6β4。配体的特异性由胞外结构域定义，而跨膜结构域(TM) 而胞质尾巴则负责调节特定功能的细胞内信号。在上一个资助周期中，我们展示了 在UB中缺失整合素α3亚基会导致轻微的形态发育异常， 而删除ITGα6亚基并没有改变发育。UB中缺乏Itgα3的小鼠极易患上 单侧输尿管梗阻后肾纤维化，而整合素ITGα6缺失小鼠发展为严重 肾小管扩张，细胞凋亡，但无纤维化。UB中缺乏所有LM结合整合素的小鼠(Itgα3/α6- Null)具有与ITGα3缺失小鼠相同的发育表型，但随着年龄的增长，它们会发展成严重的 肾小管间质纤维化和炎症。这些小鼠也容易患严重的炎症、纤维化和 UUO后肾小管细胞凋亡与慢性近端小管损伤利用从这些小鼠身上收集的导管细胞， 我们发现，除了经典的黏附功能外，LM结合的整合素还调节上皮细胞 细胞凋亡、炎症和胶原蛋白的产生。当ITGα3被删除时，过量的胶原合成发生， 当α6缺失时发生细胞凋亡，除了这些过程外，在α3/α6缺失的小鼠中还会发生炎症。在……里面 在这项提议中，我们将研究LM结合受体调节肾小管的机制 上皮细胞对衰老和损伤的反应。我们将检验这样一个假设，即肾小管上皮细胞的缺失 来自LMS的细胞信号，通过α3β1和含有α6的整合素，导致加速炎症和 导致慢性肾脏疾病的过度纤维化和细胞凋亡的目的如下：1)定义 LM结合整合素信号缺失使肾小管易患慢性肾小管病变的机制 肾损伤。2)确定LM结合整合素信号的丢失促进 肾小管上皮细胞凋亡、炎症和胶原生成。

Our overall goal is to define how cell-extracellular matrix interactions regulate kidney homeostasis in health and disease. These interactions are studied from animals to molecules using transgenic mouse models, cell biological and biochemical assays. We previously defined the contribution of laminin (LM) receptor integrins, integrin α3β1 and α6 containing integrins, to ureteric bud (UB) development. Recently, we made an unexpected novel observation that LM receptors regulate tubular epithelial cell inflammation and kidney tubulointerstitial fibrosis in aged and injured mice. These new findings form the basis of this renewal. Integrins are transmembrane receptors composed of α and β subunits that mediate interactions between cells and ECM. There are 18 α and 8 β subunits, which form dimers with different ligand binding properties. Integrins are classified into collagen, LM and RGD binding receptors and the principal LM binding integrins are α3β1, α6β1 and α6β4. Ligand specificity is defined by the extracellular domain while the transmembrane domain (TM) and the cytoplasmic tail mediate specialized functional intracellular signaling. In the last grant cycle, we showed that deleting the integrin (Itg) α3 subunit in the UB causes minor morphological developmental abnormalities, while deleting the Itgα6 subunit did not alter development. Mice lacking Itgα3 in the UB are highly susceptible to kidney fibrosis after unilateral ureteric obstruction (UUO), while the integrin Itgα6-null mice develop severe tubular dilatation and cellular apoptosis, but no fibrosis. Mice lacking all LM binding integrins in the UB (Itgα3/α6- null) have the same developmental phenotype as the Itgα3-null mice, but with age they develop severe tubulointerstitial fibrosis and inflammation. These mice are also susceptible to severe inflammation, fibrosis and tubular apoptosis after UUO and chronic proximal tubule injury. Utilizing collecting duct cells from these mice, we show that in addition to their classical adhesion functions, the LM binding integrins regulate epithelial cell apoptosis, inflammation and collagen production. Excess collagen synthesis occurs when Itgα3 is deleted, apoptosis when α6 is deleted and, in addition to these processes, inflammation occurs in Itgα3/α6-null mice. In this proposal, we will investigate the mechanisms whereby the LM-binding receptors regulate renal tubular epithelial cell responses to aging and injury. We will test the hypothesis that loss of kidney tubule epithelial cell signaling from LMs, via α3β1 an α6-containing integrins, causes accelerated inflammation and excessive fibrosis and apoptosis resulting in chronic kidney disease in the following aims: 1) Define the mechanisms whereby loss of LM binding integrin signaling predisposes kidney tubules to chronic kidney injury. 2) Determine the mechanisms whereby the loss of LM binding integrin signaling promotes renal tubular epithelial cell apoptosis, inflammation and collagen production.