Jiang Fang, Jia Yuzhi, Cohen Isaac
Department of Cell and Molecular Biology, Northwestern University, Chicago, IL 60611, USA.
Blood. 2002 May 15;99(10):3579-84. doi: 10.1182/blood.v99.10.3579.
The megakaryoblastic CHRF-288 cell line was used to investigate signal transduction pathways responsible for proplateletlike formation (PPF). The role of fibronectin (FN) and protein kinase C (PKC) activation in PPF were examined. In the presence of serum and phorbol 12-myristate 13-acetate (PMA), a PKC activator, cells exhibited full megakaryocytic differentiation, manifested by adhesion, shape change, increased cell size, polyploidy, PPF, and expression of CD41(+), CD61(+), and CD62P(+). The same morphologic and phenotypic features were observed in serum-free cultures in the presence of FN/PMA. Only partial differentiation occurred when other integrin ligands were substituted for FN. FN alone induced minimal cell adhesion and spreading, while PMA alone induced only polyploidy without adhesion. Signal transduction changes involved the activation of the extracellular signal-regulated protein kinase 1 (ERK1)/ERK2 as well as c-Jun amino-terminal kinase 1 (JNK1)/stress-activated protein kinase (SAPK). Phosphoinositide-3 kinase and p38 were not stimulated under these conditions. Inhibitors were used to identify the causal relationship between signaling pathways and PPF. PD98059 and GF109203X, inhibitors of ERK1/ERK2 pathway and PKC, respectively, blocked PPF, while adhesion, spreading, and polyploidy were normal. These studies show that activation of ERK1/ERK2 mitogen-activated protein kinase pathway plays a critical role in PPF. The elucidation of the signal transduction pathway on megakaryocyte development and PPF is of crucial importance for understanding this unique biological process.
巨核母细胞性CHRF-288细胞系用于研究负责前血小板样形成（PPF）的信号转导途径。研究了纤连蛋白（FN）和蛋白激酶C（PKC）激活在PPF中的作用。在血清和佛波酯12-肉豆蔻酸酯13-乙酸酯（PMA，一种PKC激活剂）存在的情况下，细胞表现出完全的巨核细胞分化，表现为黏附、形态改变、细胞大小增加、多倍体形成、PPF以及CD41(+)、CD61(+)和CD62P(+)的表达。在存在FN/PMA的无血清培养物中观察到相同的形态和表型特征。当用其他整合素配体替代FN时，仅发生部分分化。单独的FN诱导最小程度的细胞黏附和铺展，而单独的PMA仅诱导多倍体形成而无黏附。信号转导变化涉及细胞外信号调节蛋白激酶1（ERK1）/ERK2以及c-Jun氨基末端激酶1（JNK1）/应激激活蛋白激酶（SAPK）的激活。在这些条件下，磷酸肌醇-3激酶和p38未被激活。使用抑制剂来确定信号通路与PPF之间的因果关系。分别为ERK1/ERK2通路和PKC的抑制剂PD98059和GF109203X阻断了PPF，而黏附、铺展和多倍体形成正常。这些研究表明，ERK1/ERK2丝裂原活化蛋白激酶通路的激活在PPF中起关键作用。阐明巨核细胞发育和PPF的信号转导途径对于理解这一独特的生物学过程至关重要。
