Expression of constitutively active Raf-1 in the mitochondria restores antiapoptotic and leukemogenic potential of a transformation-deficient BCR/ABL mutant.
Expression of constitutively active Raf-1 in the mitochondria restores antiapoptotic and leukemogenic potential of a transformation-deficient BCR/ABL mutant.
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DOI：
10.1084/jem.187.12.1995
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发表时间：
1998-06-15
期刊：
影响因子：
--
通讯作者：
Calabretta B
中科院分区：
文献类型：
--
作者：
Salomoni P;Wasik MA;Riedel RF;Reiss K;Choi JK;Skorski T;Calabretta B
致癌的bcr/abl蛋白保护造血细胞免受生长因子剥夺诱导的细胞凋亡，但其机制尚不完全清楚。缺失bcr结构域176-426氨基酸的bcr/abl突变体(p185Δbcr)虽然具有酪氨酸激酶活性并能够激活Ras-Raf-MAP激酶通路，但不能保护白细胞介素3剥夺的32Dcl3髓系前体细胞免于凋亡。与p185野生型转染体相比，p185Δbcr转染组细胞Bcl2表达水平显著降低，并表达低磷酸化、促凋亡形式的BAD。P185Δbcr细胞线粒体部分的bcl2表达也明显降低，未检测到线粒体RAF。在p185Δbcr细胞中，以线粒体为靶点的Raf(M-Raf)BAD以过度磷酸化的形式表达，并从线粒体释放到胞浆中。P185Δbcr/M-Raf基因转染的细胞在体外完全抵抗生长因子剥夺诱导的细胞凋亡。此外，显性负性M-Raf(K375W)的结构性表达增加了表达野生型bcr/abl的32Dcl3细胞对凋亡的敏感性。在严重联合免疫缺陷小鼠中，p185Δbcr/M-Raf双转染体具有白血病作用，而仅表达p185Δbcr的细胞不具有白血病作用。综上所述，这些数据支持BCR/ABL依赖通路的存在，该通路导致线粒体中活性RAF的表达，并促进BCR/ABL的抗凋亡和诱导白血病作用。
The oncogenic BCR/ABL protein protects hematopoietic cells from apoptosis induced by growth factor deprivation, but the mechanisms are only partially understood. A BCR/ABL mutant lacking amino acids 176–426 in the BCR domain (p185ΔBCR) failed to protect interleukin 3–deprived 32Dcl3 myeloid precursor cells from apoptosis, although it possessed tyrosine kinase activity and was capable of activating the Ras-Raf-MAP kinase pathway. Compared to p185 wild-type transfectants, p185ΔBCR-transfected cells showed markedly reduced levels of Bcl-2 and expressed the hypophosphorylated, proapoptotic form of BAD. Bcl-2 expression in the mitochondrial fraction of p185ΔBCR cells was also markedly diminished and mitochondrial RAF was undetectable. In p185ΔBCR cells transfected with a mitochondria-targeted, constitutively active RAF (M-Raf) BAD was expressed in the hyperphosphorylated form and released from the mitochondria into the cytosol. p185ΔBCR/M-Raf–transfected cells were completely resistant to apoptosis induced by growth factor deprivation in vitro. Moreover, constitutive expression of dominant-negative M-Raf (K375W) enhanced the susceptibility of 32Dcl3 cells expressing wild-type BCR/ABL to apoptosis. In severe combined immunodeficiency (SCID) mice, p185ΔBCR/M-Raf double transfectants were leukemogenic, whereas cells expressing only p185ΔBCR showed no leukemogenic potential. Together, these data support the existence of a BCR/ABL-dependent pathway that leads to expression of an active RAF in the mitochondria and promotes antiapoptotic and leukemia-inducing effects of BCR/ABL.
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影响因子：
11.4
作者：
MARAIS, R;LIGHT, Y;MARSHALL, CJ
通讯作者：
MARSHALL, CJ
影响因子：
56.9
作者：
CLARK, SS;MCLAUGHLIN, J;WITTE, ON
通讯作者：
WITTE, ON
影响因子：
5.3
作者：
Kelekar, A;Chang, BS;Thompson, CB
通讯作者：
Thompson, CB
影响因子：
5.3
作者：
FABIAN, JR;DAAR, IO;MORRISON, DK
通讯作者：
MORRISON, DK
影响因子：
4.8
作者：
Ito, T;Deng, XM;May, WS
通讯作者：
May, WS