Department of Gastroenterology and Hematology, Miyazaki University, 5200 Kihara, Kiyotake, Miyazaki 889-1692, Japan.
Ann Hematol. 2012 Oct;91(10):1633-43. doi: 10.1007/s00277-012-1498-y. Epub 2012 May 29.
Fibronectin (FN) plays important roles in the proliferation, differentiation, and maintenance of megakaryocytic-lineage cells through FN receptors. However, substantial role of FN receptors and their functional assignment in proplatelet-like formation (PPF) of megakaryocytes are not yet fully understood. Herein, we investigated the effects of FN receptors on PPF using the CHRF-288 human megakaryoblastic cell line, which expresses VLA-4 and VLA-5 as FN receptors. FN and phorbol 12-myristate 13-acetate (PMA) were essential for inducing PPF in CHRF-288 cells. Blocking experiments using anti-β1-integrin monoclonal antibodies indicated that the adhesive interaction with FN via VLA-4 and VLA-5 were required for PPF. PPF induced by FN plus PMA was accelerated when CHRF-288 cells were enforced adhering to FN by TNIIIA2, a peptide derived from tenascin-C, which we recently found to induce β1-integrin activation. Adhesion to FN enhanced PMA-stimulated activation of extracellular signal-regulated protein kinase 1 (ERK1)/2 and enforced adhesion to FN via VLA-4 and VLA-5 by TNIIIA2-accelerated activation of ERK1/2 with FN plus PMA. However, c-Jun amino-terminal kinase 1 (JNK1), p38, and phosphoinositide-3 kinase (PI3K)/Akt were not stimulated by FN plus PMA, even with TNIIIA2. Thus, the enhanced activation of ERK1/2 by FN, PMA plus TNIIIA2 was responsible for acceleration of PPF with FN plus PMA.
纤连蛋白 (FN) 通过 FN 受体在巨核细胞系细胞的增殖、分化和维持中发挥重要作用。然而，FN 受体的大量作用及其在巨核细胞血小板样形成 (PPF)中的功能分配尚未完全理解。在此，我们使用表达 FN 受体 VLA-4 和 VLA-5 的 CHRF-288 人巨核细胞母细胞系研究了 FN 受体对 PPF 的影响。FN 和佛波醇 12-肉豆蔻酸 13-醋酸酯 (PMA) 是诱导 CHRF-288 细胞 PPF 的必需条件。使用抗-β1-整联蛋白单克隆抗体的阻断实验表明，通过 VLA-4 和 VLA-5 与 FN 的黏附相互作用是 PPF 所必需的。当 CHRF-288 细胞通过我们最近发现能诱导β1-整联蛋白激活的 tenascin-C 衍生肽 TNIIIA2 强制黏附于 FN 时，FN 加 PMA 诱导的 PPF 会加速。FN 增强了 PMA 刺激的细胞外信号调节蛋白激酶 1 (ERK1)/2 的激活，并且通过 TNIIIA2 强制黏附于 FN 增强了 VLA-4 和 VLA-5 对 ERK1/2 的激活，从而加速了 FN 加 PMA 激活 ERK1/2。然而，FN 加 PMA 甚至在 TNIIIA2 存在时也不能刺激 c-Jun 氨基末端激酶 1 (JNK1)、p38 和磷酸肌醇-3-激酶 (PI3K)/Akt。因此，FN、PMA 加 TNIIIA2 增强的 ERK1/2 激活是加速 FN 加 PMA 诱导的 PPF 的原因。
