EGF-receptor-mediated mammary epithelial cell migration is driven by sustained ERK signaling from autocrine stimulation
EGF-receptor-mediated mammary epithelial cell migration is driven by sustained ERK signaling from autocrine stimulation
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DOI：
10.1242/jcs.010488
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发表时间：
2007-10-15
影响因子：
4
通讯作者：
Lauffenburger, Douglas A.
中科院分区：
文献类型：
--
作者：
Joslin, Elizabeth J.;Opresko, Lee K.;Lauffenburger, Douglas A.
EGF家族配体作为膜锚定前体合成，其蛋白水解释放产生成熟的可扩散因子，其可以自分泌或旁分泌模式激活细胞表面受体。这些配体的表达在病理状态和生理过程中改变，如发育和组织再生。尽管自分泌EGF信号传导的生物学重要性被广泛记录，但蛋白酶介导的配体释放和随后的细胞行为之间的定量关系尚未被严格研究。因此，我们探讨了自分泌EGF释放率和细胞行为反应之间的关系，沿着ERK的激活，一个关键的下游信号，通过表达嵌合配体前体和调节其蛋白水解脱落使用金属蛋白酶抑制剂在人乳腺上皮细胞。我们发现，ERK激活增加单调增加配体释放速率，尽管伴随着下调EGF受体水平。细胞迁移速度与配体释放速率直接相关，并与稳态磷酸化ERK水平成正比.此外，迁移速度显着更大的自分泌刺激相比，外源性刺激，即使在相当的磷酸化ERK水平。相比之下，细胞增殖速率在所有配体释放速率下大致相等，并且无论配体是内源性还是外源性呈递都是相似的。因此，在我们的乳腺上皮细胞系统中，迁移和增殖对EGF配体呈递的模式具有差异敏感性。
EGF family ligands are synthesized as membrane-anchored precursors whose proteolytic release yields mature diffusible factors that can activate cell surface receptors in autocrine or paracrine mode. Expression of these ligands is altered in pathological states and in physiological processes, such as development and tissue regeneration. Despite the widely documented biological importance of autocrine EGF signaling, quantitative relationships between protease- mediated ligand release and consequent cell behavior have not been rigorously investigated. We thus explored the relationship between autocrine EGF release rates and cell behavioral responses along with activation of ERK, a key downstream signal, by expressing chimeric ligand precursors and modulating their proteolytic shedding using a metalloprotease inhibitor in human mammary epithelial cells. We found that ERK activation increased monotonically with increasing ligand release rate despite concomitant downregulation of EGF receptor levels. Cell migration speed was directly related to ligand release rate and proportional to steady- state phospho- ERK levels. Moreover, migration speed was significantly greater for autocrine stimulation compared with exogenous stimulation, even at comparable phospho-ERK levels. By contrast, cell proliferation rates were approximately equivalent at all ligand release rates and were similar regardless of whether the ligand was presented endogenously or exogenously. Thus, in our mammary epithelial cell system, migration and proliferation are differentially sensitive to the mode of EGF ligand presentation.