人M-07e白血病细胞凋亡过程中激活Caspase-3引起的Bcl-2蛋白酶解与Lyn^(p53/56)激酶失活相关(英文)  

Cleavage of Bcl-2 Protein by Activated Caspase-3 Is Associated with Inactivation of Lyn~ (p53/56) Kinase Activity in Human M-07e Leukemic Cells during Apoptosis

作　　者：张学敏[1] 胡美茹[2] 兰雨[2] 于鸣[2] Ben D-M Chen 

机构地区：[1]国家生物医学分析中心 [2]军事医学科学院基础医学研究所,北京100850 [3]Department of Internal Medicine,and Barbara Ann Karmanos Cancer Institutes,Wayne State University School of Medicine

出　　处：《中国实验血液学杂志》2000年第3期166-175,共10页Journal of Experimental Hematology

摘　　要：人巨核白血病细胞系M 0 7e的生长严格依赖于GM CSF。在M 0 7e细胞 ,GM CSF受体 (GM CSFR)由两个亚基所组成 :低亲合力的配体特异的α亚基和一个磷酸化的 β亚基 ,后者与lynp53 56 酪氨酸蛋白激酶固定相连。本研究检测了lyn激酶在调节TGF β 1诱导的M 0 7e细胞凋亡过程中的作用。从培养液中去除rhGM CSF首先导致了lyn激酶活性受抑 ,接着发生细胞生长受阻和凋亡。M 0 7e细胞凋亡过程中伴随有大量Bcl 2和Bax蛋白分别被酶解为 2 2kD和 18kD的较小片段。应用特异性的抑制剂 ,发现上述Bcl 2蛋白的变化是循激活的caspase 3(CPP32 )途径发生的 ,后者在M 0 7e细胞中大量表达。Bax蛋白变化的机制尚不清楚。TGF β 1对rhGM CSF刺激的细胞生长具有抑制作用 ,促进M 0 7e细胞凋亡的机制与去除rhGM CSF所致相同 ,包括大量Bcl 2和Bax蛋白被特异酶解和lyn激酶失活。TGF β 1并不影响lyn蛋白和 β链的表达水平 ,也不阻止这两个信号传导元件的相互作用。研究结果表明 ,TGF β 1通过抑制GM CSFR相关的lyn激酶活性而抑制M 0 7e细胞生长并促进凋亡发生。本实验还表明激活的CPP32对Bcl 2蛋白的酶解是与细胞凋亡发生相关的一个自然过程 。The growth of M-07e human megakaryocytic leukemia cells is strictly dependent on GM-CSF. In M-07e cells, the GM-CSF receptor (GM-CSF R) is composed of two subunits: a low affinity α subunit and a phosphorylated β subunit, which is constitutively linked to lyn 53/56 protein tyrosine kinase. In this study, The role of lyn kinase in regulating TGF-β 1-induced apoptosis in M-07e cells was examined. The removal of rhGM-CSF from the culture medium resulted in down-regulation of lyn kinase activity, followed by growth inhibition and programmed cell death. Apoptosis of M-07e cells was accompanied with a massive cleavage of Bcl-2 and Bax proteins into shortened fragments with molecular mass of 22 kD and 18 kD, respectively. Using specific inhibitors, the cleavage of Bcl-2, but not Bax, was found to be processed through activated caspase-3 (CPP32), which is abundantly expressed in M-07e cells. TGF-β 1 inhibited rhGM-CSF-stimulated cell growth and promoted apoptosis in M-07e cells with a pattern identical to that induced by rhGM-CSF depletion, which included massive cleavage of both Bcl-2 and Bax proteins and inactivation of lyn kinase activity. TGF-β 1 did not affect the levels of lyn protein or the β-subunit, neither did it block the interaction between these two components. Also, TGF-β 1 treatment did not diminish the expression of the α subunit in M-07e cells. Our results showed that TGF-β 1 inhibits cell proliferation and promotes apoptosis in M-07e cells by inactivating the GM-CSF R-associated lyn kinase activity. Further, This study showed that Bcl-2 cleavage by activated CPP32 is a naturally occurring event associated with apoptosis, which is under the regulation of lyn kinase activation.

关 键 词：BC1-2 lyn蛋白激酶 细胞凋亡 白血病 

分 类 号：R733.703[医药卫生—肿瘤]