de Jong R, Haataja L, Voncken J W, Heisterkamp N, Groffen J
Department of Pathology, Childrens Hospital of Los Angeles, California 90027, USA.
Oncogene. 1995 Oct 19;11(8):1469-74.
The SH2/SH3 adaptor protein Crkl is abnormally phosphorylated on tyrosine by the Bcr/Abl protein in leukemic cells from patients with Philadelphia-chromosome (Ph)positive leukemia. However, the state of tyrosine-phosphorylation of crkl in normal tissues is unknown. In the current study, we identified mouse crkl by cDNA cloning and examined expression levels and tyrosine-phosphorylation of the mouse crkl protein during embryogenesis and in adult tissues. Tyrosine-phosphorylation of crkl was prominent during early development, but decreased at later embryonic stages and in newborn mice. Expression of both crkl and the related crk was ubiquitous in the adult. However, crkl differed considerably from crk in relative tissue distribution, and was more abundant in hematopoietic tissues. With exception of the lung, crkl was mostly present in a non-tyrosine phosphorylated form. Consistent with our previous findings in human patients, murine crkl was phosphorylated on tyrosine in leukemic tissues of BCR/ABL transgenic animals, but was non-tyrosine phosphorylated in normal mouse bone marrow. We conclude that this crkl tyrosine-phosphorylation by Bcr/Abl in hematopoietic cells is clearly aberrant and is consistently linked to the development of leukemia. Identification of proteins interacting with tyrosine-phosphorylated crkl in the leukemic cells of BCR/ABL transgenic mice should reveal members of signal transduction pathways activated in Ph-positive leukemia.
在费城染色体（Ph）阳性白血病患者的白血病细胞中，SH2/SH3衔接蛋白Crkl被Bcr/Abl蛋白异常磷酸化。然而，正常组织中Crkl的酪氨酸磷酸化状态尚不清楚。在本研究中，我们通过cDNA克隆鉴定了小鼠Crkl，并检测了小鼠Crkl蛋白在胚胎发育过程中和成年组织中的表达水平及酪氨酸磷酸化情况。Crkl的酪氨酸磷酸化在早期发育过程中较为显著，但在胚胎后期和新生小鼠中减少。成年小鼠中Crkl和相关的Crk表达均普遍存在。然而，Crkl在相对组织分布上与Crk有很大差异，在造血组织中更为丰富。除肺外，Crkl大多以非酪氨酸磷酸化形式存在。与我们之前在人类患者中的发现一致，在BCR/ABL转基因动物的白血病组织中，小鼠Crkl发生了酪氨酸磷酸化，但在正常小鼠骨髓中未发生酪氨酸磷酸化。我们得出结论，造血细胞中Bcr/Abl介导的这种Crkl酪氨酸磷酸化明显异常，且与白血病的发生始终相关。鉴定在BCR/ABL转基因小鼠白血病细胞中与酪氨酸磷酸化Crkl相互作用的蛋白质，应能揭示在Ph阳性白血病中被激活的信号转导途径成员。
