Enhanced cathepsin L expression is mediated by different Ras effector pathways in fibroblasts and epithelial cells
Enhanced cathepsin L expression is mediated by different Ras effector pathways in fibroblasts and epithelial cells
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DOI：
10.1002/ijc.20398
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发表时间：
2004-11-01
影响因子：
6.4
通讯作者：
Erickson, AH
中科院分区：
文献类型：
--
作者：
Collette, J;Ulku, AS;Erickson, AH
RAS表达可诱导多种细胞中溶酶体蛋白水解酶的表达增加和靶向性改变，但介导这些变化的特定下游胞浆信号通路尚未确定。在这项研究中，我们比较了3种主要的RAS效应因子，Raf，磷脂酰肌醇3-激酶(PI3K)和Ral鸟嘌呤核苷酸交换因子(Ralgef)在RAS介导的大鼠208F成纤维细胞和大鼠卵巢表面上皮(ROSE)细胞溶酶体蛋白表达和靶向性改变中的作用。利用RAS的效应域突变体、Raf、PI3K和Ralgef的成分激活突变体以及MEK和PI3K的药物抑制剂来确定这些下游通路在纤维母细胞转化和溶酶体蛋白水解酶调节中的作用。我们发现，单独激活ERK丝裂原活化蛋白激酶通路的Raf足以引起成纤维细胞的形态和生长转化，并且是改变组织蛋白酶L表达和靶向性的必要条件和充分条件。相反，组织蛋白酶L在上皮细胞中的转化和表达上调需要所有3个RAS效应器的活性。RAS的异位表达不像成纤维细胞那样，上皮细胞的蛋白酶分泌增加，这与两种细胞利用不同的信号通路是一致的。在这两种细胞中，RAS的表达都没有增加另外两种主要溶酶体蛋白的表达、加工或分泌，即组织蛋白酶B和组织蛋白酶D。因此，RAS在成纤维细胞和上皮细胞中利用不同的效应分子来介导转化和去调节组织蛋白酶L的表达和分泌。(C)2004年Wiley-Liss公司
Ras expression induces increased expression and altered targeting of lysosomal proteases in multiple cell types, but the specific downstream cytoplasmic signaling pathways mediating these changes have not been identified. In this study, we compared the involvement of 3 major Ras effectors, Raf, phosphaticlylinositol 3-kinase (PI3K) and Ral guanine nucleotide exchange factor (RalGEF) in the Ras-mediated alteration of lysosomal protease protein expression and targeting in rat 208F fibroblasts and rat ovarian surface epithelial (ROSE) cells. Effector domain mutants of Ras, constitutively activated variants of Raf, PI3K and RalGEF and pharmacologic inhibitors of MEK and PI3K were utilized to determine the role of these downstream pathways in mediating fibroblast transformation and lysosomal protease regulation in the fibroblasts and epithelial cells. We found that Raf activation of the ERK mitogen-activated protein kinase pathway alone was sufficient to cause morphologic and growth transformation of the fibroblasts and was necessary and sufficient to alter cathepsin L expression and targeting. In contrast, transformation and upregulation of cathepsin L expression in the epithelial cells required the activity of all 3 Ras effectors. Increased protease secretion from the epithelial cells was not observed on ectopic expression of Ras, as it was from the fibroblasts, consistent with the utilization of different signaling pathways in the 2 cell types. In neither cell type did Ras expression increase the expression, processing or secretion of 2 other major lysosomal proteases, cathepsin B and cathepsin D. Thus, Ras utilizes different effectors to mediate transformation and to deregulate cathepsin L expression and secretion in fibroblast and epithelial cells. (C) 2004 Wiley-Liss, Inc.