Constitutive exclusion of Csk from Hck-positive membrane microdomains permits Src kinase-dependent proliferation of Theileria-transformed B lymphocytes
Constitutive exclusion of Csk from Hck-positive membrane microdomains permits Src kinase-dependent proliferation of Theileria-transformed B lymphocytes
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DOI：
10.1182/blood-2002-02-0456
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发表时间：
2003-03-01
期刊：
影响因子：
20.3
通讯作者：
Langsley, G
中科院分区：
文献类型：
--
作者：
Baumgartner, M;Angelisová, P;Langsley, G
用细胞内原生动物寄生虫微小泰勒虫感染牛T细胞和B细胞诱导具有与白血病细胞相当的特征的转化表型。转化的表型在药物诱导的寄生虫死亡时恢复，并且治愈的淋巴细胞获得静息表型，并且如果不进一步刺激，则最终通过凋亡而死亡。在这里，我们表明，淋巴细胞增殖和激活的转录因子AP-1介导的Src家族蛋白酪氨酸激酶（PTKs）在寄生虫依赖的方式。已知Src家族PTK存在于糖脂富集微结构域（GEM）（也称为脂筏）中，并且受与酪氨酸磷酸化跨膜衔接蛋白PAG（与GEM相关的磷蛋白）（也称为Cbp（Csk结合蛋白））复合的PTK Csk负调控。因此，我们从增殖的受感染B细胞和已被药物治愈的寄生虫生长停滞细胞中纯化了GEM。增殖停滞导致PAG/Cbp表达显著增加;相应地，与PAG/Cbp相关的Csk在GEM中的量显著增加，而PTK Hck在GEM组分中的积累在生长停滞时没有改变。我们提出泰勒虫诱导的淋巴细胞增殖和Hck的永久激活源于PAG/Cbp的下调和伴随的负调节剂Csk从转化的B细胞的GEM的组成性损失。
Infection of bovine T cells and B cells with the intracellular protozoan parasite Theileria parva induces a transformed phenotype with characteristics comparable to leukemic cells. The transformed phenotype reverts on drug-induced parasite death, and the cured lymphocytes acquire a resting phenotype and eventually die by apoptosis if not further stimulated. Here, we show that both lymphocyte proliferation and activation of the transcription factor AP-1 are mediated by Src-family protein tyrosine kinases (PTKs) in a parasite-dependent fashion. Src-family PTKs are known to be present in glycolipid-enriched microdomains (GEMs), also called lipid rafts, and to be negatively regulated by PTK Csk complexed to tyrosine-phosphorylated transmembrane adapter protein PAG (phosphoprotein associated with GEMs) also called Cbp (Csk-binding protein). We, therefore, purified GEMs from proliferating infected B cells and from growth-arrested cells that had been drug-cured of parasites. Proliferation arrest led to a striking increase of PAG/Cbp expression; correspondingly, the amount of Csk associated with PAG/Cbp in GEMs increased markedly, whereas PTK Hck accumulation in GEM fractions did not alter on growth arrest. We propose that Theileria-induced lymphocyte proliferation and permanent activation of Hck stems from down-regulation of PAG/Cbp and the concomitant constitutive loss of the negative regulator Csk from the GEMs of transformed B cells.