Activin receptor-like kinase-7 induces apoptosis through activation of MAPKs in a Smad3-dependent mechanism in hepatoma cells
Activin receptor-like kinase-7 induces apoptosis through activation of MAPKs in a Smad3-dependent mechanism in hepatoma cells
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DOI：
10.1074/jbc.m313277200
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发表时间：
2004-07-02
影响因子：
4.8
通讯作者：
Kim, SJ
中科院分区：
文献类型：
--
作者：
Kim, BC;van Gelder, H;Kim, SJ
激活素受体样激酶（ALK）7是转化生长因子（TGF）-β蛋白家族的一种I型丝氨酸/苏氨酸激酶受体，在激活时与其他I型受体具有相似的特性。为了观察ALK 7是否能像其他ALK蛋白那样诱导细胞凋亡，我们用表达ALK 7组成型活性形式的腺病毒感染FaO大鼠肝癌细胞系。与用对照蛋白感染的细胞相反，用活性ALK 7腺病毒感染的细胞显示出抗肿瘤阳性表型。DNA片段分析和荧光激活细胞分选仪分析也表明，ALK 7感染诱导FaO细胞凋亡。我们还通过瞬时转染ALK 7的组成型活性形式ALK 7（T194 D）在Hep 3B人肝癌细胞中证实了这一发现。对ALK 7诱导的细胞凋亡中涉及的下游靶点和机制的研究表明，TGF-β信号传导中间体Smad 2和Smad 3以及MAPK JNK和p38被激活。此外，半胱天冬酶-3和-9也被激活，并观察到细胞色素c从线粒体释放。短干扰RNA介导的Smad 3抑制显著抑制ALK 7诱导的caspase-3活化。用蛋白质合成抑制剂或显性负性形式的应激激活蛋白/细胞外信号调节激酶1的表达治疗不仅废除了JNK激活，而且还废除了凋亡。综上所述，这些结果表明ALK 7通过激活传统TGF-β途径组分诱导细胞凋亡，从而导致新基因转录和JNK和p38激活，启动与细胞应激死亡途径的串扰并最终导致细胞凋亡。
Activin receptor-like kinase (ALK)7 is a type I serine/threonine kinase receptor of the transforming growth factor (TGF)-beta family of proteins that has similar properties to other type I receptors when activated. To see whether ALK7 can induce apoptosis as can some of the other ALK proteins, we infected the FaO rat hepatoma cell line with adenovirus expressing a constitutively active form of the ALK7. Cells infected with active ALK7 adenovirus showed an apoptotic-positive phenotype, as opposed to those that were infected with a control protein. DNA fragmentation assays and fluorescence-activated cell sorter analysis also indicated that ALK7 infection induced apoptosis in FaO cells. We also confirmed this finding in Hep3B human hepatoma cells by transiently transfecting the constitutively active form of ALK7, ALK7(T194D). Investigation into the downstream targets and mechanisms involved in ALK7-induced apoptosis revealed that the TGF-beta signaling intermediates, Smad2 and -3, were activated, as well as the MAPKs JNK and p38. In addition, caspase-3 and -9 were also activated, and cytochrome c release from the mitochondria was observed. Short interfering RNA-mediated inhibition of Smad3 markedly suppressed ALK7-induced caspase-3 activation. Treatment with protein synthesis inhibitors or the expression of the dominant-negative form of the stress-activated protein/extracellular signal-regulated kinase 1 abolished not only JNK activation but apoptosis as well. Taken together, these results suggest that ALK7 induces apoptosis through activation of the traditional TGF-beta pathway components, thus resulting in new gene transcription and JNK and p38 activation that initiates cross-talk with the cellular stress death pathway and ultimately leads to apoptosis.