Transforming growth factor beta stabilizes p15(INK4B) protein, increases p15(INK4B)-cdk4 complexes, and inhibits cyclin D1 cdk4 association in human mammary epithelial cells
Transforming growth factor beta stabilizes p15(INK4B) protein, increases p15(INK4B)-cdk4 complexes, and inhibits cyclin D1 cdk4 association in human mammary epithelial cells
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DOI：
10.1128/mcb.17.5.2458
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发表时间：
1997-05-01
影响因子：
5.3
通讯作者：
Stampfer, MR
中科院分区：
文献类型：
--
作者：
Sandhu, C;Garbe, J;Stampfer, MR
在密切相关的人乳腺上皮细胞（HMEC）中研究了转化生长因子β（TGF-β）的作用，包括有限寿命的184细胞和永生衍生物184 A1（S）和184 A1 L5（R），它们对TGF-β的细胞周期反应不同，但表达I型和II型TGF-β受体并保留TGF-β对细胞外基质的诱导作用。这种抑制抗性表型不是由于细胞周期蛋白依赖性激酶（cdk）抑制剂的丢失。TGF-β至少在两个水平上调节p15（INK 4 B）的表达：mRNA积累和蛋白质稳定性。在TGF-β阻滞的HMEC中，不仅p15 mRNA增加，而且p15（INK 4 B）蛋白稳定性也显著增加。由于cdk 4和cdk 6相关的p15（INK 4 B）在TGF-β阻滞敏感细胞期间增加，这些激酶复合物中的细胞周期蛋白D1、p21（Cip 1）和p27（Kip 1）丢失，细胞周期蛋白E-cdk 2相关的p27（Kip 1）增加。在HMEC中，p15（INK 4 B）复合物不含可检测的细胞周期蛋白。来自敏感和抗性细胞的p15（INK 4 B）可以在体外置换来自敏感细胞分离的cdk 4的细胞周期蛋白D1、p21（Cip 1）和p27（Kip 1）。在抗性184 A1 L5（R）细胞裂解物中，细胞周期蛋白D1不能从cdk 4置换。因此，在TGF-β阻滞中，p15（INK 4 B）可能会从cdk中取代已经结合的细胞周期蛋白D1，并阻止新的细胞周期蛋白D1-cdk复合物的形成。此外，在TGF-β介导的停滞期间，p27（Kip 1）结合从cdk 4转移到细胞周期蛋白E-cdk 2。TGF-β对p15（INK 4 B）的翻译后调节的重要性通过以下观察得到强调：在TGF-β抗性的184 A1 L5（R）中，尽管p15转录物增加，但p15（INK 4 B）蛋白不稳定且不积累，并且细胞周期蛋白D1-cdk结合和激酶活化不受抑制。
The effects of transforming growth factor beta (TGF-beta) were studied in closely related human mammary epithelial cells (HMEC), both finite-life-span 184 cells and immortal derivatives, 184A1(S), and 184A1L5(R), which differ in their cell cycle responses to TGF-beta but express type I and type II TGF-beta receptors and retain TGF-beta induction of extracellular matrix. The arrest-resistant phenotype was not due to loss of cyclin-dependent kinase (cdk) inhibitors. TGF-beta was shown to regulate p15(INK4B) expression at at least two levels: mRNA accumulation and protein stability. In TGF-beta-arrested HMEC, there was not only an increase in p15 mRNA but also a major increase in p15(INK4B) protein stability. As cdk4- and cdk6-associated p15(INK4B) increased during TGF-beta arrest of sensitive cells, there was a loss of cyclin D1, p21(Cip1), and p27(Kip1) from these kinase complexes, and cyclin E-cdk2-associated p27(Kip1) increased. In HMEC, p15(INK4B) complexes did not contain detectable cyclin. p15(INK4B) from both sensitive and resistant cells could displace in vitro cyclin D1, p21(Cip1), and p27(Kip1) from cdk4 isolated from sensitive cells. Cyclin D1 could not be displaced from cdk4 in the resistant 184A1L5(R) cell lysates. Thus, in TGF-beta arrest, p15(INK4B) may displace already associated cyclin D1 from cdks and prevent new cyclin D1-cdk complexes from forming. Furthermore, p27(Kip1) binding shifts from cdk4 to cyclin E-cdk2 during TGF-beta-mediated arrest. The importance of posttranslational regulation of p15(INK4B) by TGF-beta is underlined by the observation that in TGF-beta-resistant 184A1L5(R), although the p15 transcript increased, p15(INK4B) protein was not stabilized and did not accumulate, and cyclin D1-cdk association and kinase activation were not inhibited.