Phosphatidylinositol 3-kinase activity is required for epidermal growth factor to suppress proteolysis
Phosphatidylinositol 3-kinase activity is required for epidermal growth factor to suppress proteolysis
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DOI：
10.1681/asn.v134903
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发表时间：
2002-04-01
影响因子：
13.6
通讯作者：
Du, J
中科院分区：
文献类型：
--
作者：
Franch, HA;Wang, XN;Du, J
蛋白质分解的抑制通常发生在细胞生长中，但对负责控制蛋白质水解的途径知之甚少。测量用表皮生长因子（EGF）和细胞内信号传导抑制剂或腺病毒载体中含有的显性负信号传导分子处理的NRK-52 E肾上皮细胞中的蛋白质分解。酪氨酸激酶抑制剂，除莠霉素A，消除抑制蛋白水解诱导的EGF。相比之下，Src抑制剂PP 1没有影响。显性负性H-RasY 57的表达阻断了EGF刺激Ras下游靶点的能力，也降低了EGF抑制蛋白水解的能力。抑制MEK并不影响EGF抑制蛋白水解的能力，但磷脂酰肌醇3-激酶（PI 3-激酶）抑制剂LY 249002，刺激基础蛋白水解，并完全消除了EGF的蛋白水解反应。使用腺病毒表达的显性负性p85亚基1类PI 3-激酶完全阻断EGF抑制蛋白水解的能力，而使用腺病毒表达的K227 E组成型活性p110亚基再现蛋白质分解的减少。得出的结论是，EGF抑制蛋白水解的机制，涉及Ras和1类PI 3-激酶。
Suppression of protein breakdown occurs commonly in cell growth, but the pathways responsible for controlling proteolysis are poorly understood. Protein breakdown in NRK-52E renal epithelial cells treated with epidermal growth factor (EGF) and intracellular signaling inhibitors or dominant negative signaling molecules contained in an adenoviral vector were measured. The tyrosine kinase inhibitor, herbimycin A, eliminated the suppression of proteolysis induced by EGF. In contrast, the Src inhibitor, PP1, had no effect. Expression of dominant negative H-RasY57 blocked the ability of EGF to stimulate downstream targets of Ras and also reduced the ability of EGF to suppress proteolysis. Inhibiting MEK did not influence the ability of EGF to suppress proteolysis, but the phosphatidylinositol 3-kinase (PI 3-kinase) inhibitor, LY249002, stimulated basal proteolysis and completely eliminated the proteolytic response to EGF. Use of an adenovirus that expresses a dominant negative p85 subunit of class 1 PI 3-kinase completely blocked the ability of EGF to suppress proteolysis, whereas use of an adenovirus expressing a K227E constitutively active p110 subunit reproduced the reduction in protein breakdown. It was concluded that EGF suppresses proteolysis by a mechanism that involves Ras and class 1 PI 3-kinase.