Retinoic acid causes MEK-dependent RAF phosphorylation through RARα plus RXR activation in HL-60 cells
Retinoic acid causes MEK-dependent RAF phosphorylation through RARα plus RXR activation in HL-60 cells
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DOI：
10.1046/j.1432-0436.2001.068001055.x
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发表时间：
2001-08-01
期刊：
影响因子：
2.9
通讯作者：
Yen, A
中科院分区：
文献类型：
--
作者：
Hong, HY;Varvayanis, S;Yen, A
已知视黄酸（RA）在需要MEK依赖性ERK 2活化的过程中引起HL-60人成髓细胞白血病细胞的髓样分化。这种RA诱导的ERK 2活化在约4小时后出现，并持续至细胞分化和G 0阻滞（Yen et al，1998）。这激发了RA是否也激活RAF作为一个典型的RAF/MEK/MAPK级联反应的一部分的问题。维甲酸也能增加RAF的磷酸化，但以一种不寻常的方式。令人惊讶的是，增加RAF磷酸化是第一次检测12至24小时后，通过磷酸化诱导的聚丙烯酰胺凝胶电泳迁移率的延迟。治疗72小时后，RA诱导的RAF磷酸化增加仍然明显，此时大多数细胞已分化并停滞在G 0期。10（-8）、10（-7）和10（-6）M RA存在进行性剂量反应关系。RA诱导的RAF磷酸化对应于体外激酶活性的增加。用抑制ERK 2磷酸化和随后的细胞分化的PD 98059剂量抑制MEK也抑制RAF磷酸化。RA诱导的MEK依赖性RAF磷酸化不是由于细胞MEK量的变化。诱导的RAF磷酸化以及先前的ERK 2激活依赖于配体诱导的RAR α和ERK 2的激活。受体和RXR受体。这和激活的缓慢动力学表明需要预先RA诱导的基因表达。总之，RA诱导MEK依赖性的RAF激活延长，其缓慢发作发生在ERK 2激活后，但仍然早于细胞周期停滞和细胞分化。因此，RA诱导的RAF磷酸化增加不同于典型的促有丝分裂生长因子信号传导，其特征可能有助于细胞周期停滞和分化，而不是作为细胞结果的分裂。
Retinoic acid (RA) is known to cause the myeloid differentiation of HL-60 human myeloblastic leukemia cells in a process requiring MEK-dependent ERK2 activation. This RA-induced ERK2 activation appears after approximately 4 h and persists until the cells are differentiated and G0 arrested (Yen et al, 1998). This motivates the question of whether RA also activated RAF as part of a typical RAF/MEK/MAPK cascade. Retinoic acid is shown here to also increase the phosphorylation of RAF, but in an unusual way. Surprisingly, increased RAF phosphorylation is first detectable after 12 to 24 hours by phosphorylation-induced retardation of polyacrylamide gel electrophoretic mobility. The RA-induced increased RAF phosphorylation is still apparent after 72 hours of treatment when most cells are differentiated and G0 arrested. There is a progressive dose-response relationship with 10(-8), 10(-7), and 10(-6) M RA. The RA-induced RAF phosphorylation corresponds to increased in vitro kinase activity. Inhibition of MEK with a PD98059 dose which inhibits ERK2 phosphorylation and subsequent cell differentiation also inhibits RAF phosphorylation. RA-induced MEK-dependent RAF phosphorylation is not due to changes in the amount of cellular MEK. The induced RAF phosphorylation, as well as anteceding ERK2 activation, depends on ligand-induced activation of both an RAR alpha. receptor and an RXR receptor. This and the slow kinetics of activation suggest a need for prior RA-induced gene expression. In summary, RA induces a MEK-dependent prolonged RAF activation, whose slow onset occurs after ERK2 activation but still well before cell cycle arrest and cell differentiation. The RA-induced increased RAF phosphorylation thus differs from typical mitogenic growth factor signaling, features that may contribute to cell cycle arrest and differentiation instead of division as the cellular outcome.