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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 ,处于lyn激酶活性的调控之下3
The growth of the human megakaryocyte leukemia cell line M07e is strictly dependent on GM CSF. In M07e cells, the GM CSF receptor (GM CSFR) consists of two subunits: the low-affinity ligand-specific α-subunit and a phosphorylated β-subunit, the latter with lynp53 56 tyrosine. Protein kinases are fixedly linked. This study examined the role of lyn kinase in regulating TGFβ1-induced apoptosis of M 0 7e cells. Removal of rhGM CSF from the culture medium first resulted in inhibited lyn kinase activity followed by impaired cell growth and apoptosis. The apoptosis of M07e cells was accompanied by a large number of Bcl2 and Bax proteins that were enzymatically digested into smaller fragments of 22kD and 18kD, respectively. Using specific inhibitors, it was found that the above changes in Bcl 2 protein occur through the activated caspase 3 (CPP32) pathway, which is abundantly expressed in M 0 7e cells. The mechanism of Bax protein changes is not yet clear. TGF β 1 inhibited the growth of rhGM CSF-stimulated cells, and the mechanism of promoting apoptosis of M 0 7e cells was the same as that caused by removing rhGM CSF, including a large number of Bcl 2 and Bax proteins being specifically enzymatically digested and lyn kinase inactivated. TGFβ1 does not affect the expression level of lyn protein and β chain nor does it prevent the interaction of these two signaling elements. The results of the study indicate that TGFβ1 inhibits the growth of M07e cells and promotes apoptosis by inhibiting GM CSFR-associated lyn kinase activity. This experiment also showed that the enzymatic hydrolysis of Bcl 2 protein by activated CPP32 is a natural process associated with apoptosis, under the regulation of lyn kinase activity 3