Chromatin compaction and cell death by high molecular weiht FGF-2 depend on its nuclear localization, intracrine ERK activation, and engagement of mitochondria
Chromatin compaction and cell death by high molecular weiht FGF-2 depend on its nuclear localization, intracrine ERK activation, and engagement of mitochondria
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DOI：
10.1002/jcp.21139
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发表时间：
2007-12-01
影响因子：
5.6
通讯作者：
Kardami, Elissavet
中科院分区：
文献类型：
--
作者：
Ma, Xin;Dang, Xitong;Kardami, Elissavet
成纤维细胞生长因子2（FGF-2）以CUG启动的22-34 kDa或AUG启动的18 kDa亚型（分别为hi-和lo-FGF-2）形式产生，具有潜在的不同功能。我们报告，在HEK 293细胞中表达hi-FGF-2引起染色质致密化，细胞死亡前具有凋亡特征。需要完整蛋白质的核定位，因为非核hi-FGF-2突变体的表达未能引起染色质压缩。尽管核定位，同样无效的是18 kDa核心序列（lo-FGF-2）的过表达。hi-FGF-2的染色质致密化伴随着细胞溶质细胞色素C的增加，并且通过Bcl-2的过度表达或促凋亡蛋白Bax的肽抑制剂而减弱。此外，hi-FGF-2通过内分泌途径引起总细胞外信号调节激酶和细胞核细胞外信号调节激酶（ERK 1/2）的持续激活，因为中和抗FGF-2抗体不能阻止这种激活。显性负性上游激活激酶或PD 98059对ERK 1/2激活途径的抑制阻止了hi-FGF-2对染色质的压实。ERK 1/2激活不受ERK抑制肽的影响，这表明它发生在线粒体参与的上游。我们的结论是hi-FGF-2诱导的染色质致密化和细胞死亡需要其核定位，胞内ERK 1/2激活和线粒体参与。
Fibroblast growth factor 2 (FGF-2) is produced as CUG-initiated, 22-34 kDa or AUG-initiated 18 kDa isoforms (hi- and lo-FGF-2, respectively), with potentially distinct functions. We report that expression of hi-FGF-2 in HEK293 cells elicited chromatin compaction preceding cell death with apoptotic features. Nuclear localization of the intact protein was required as expression of a non-nuclear hi-FGF-2 mutant failed to elicit chromatin compaction. Equally ineffective, despite nuclear localization, was the over-expression of the 18 kDa core sequence (lo-FGF-2). Chromatin compaction by hi-FGF-2 was accompanied by increased cytosolic cytochrome C, and was attenuated either by over-expression of Bcl-2 or by a peptide inhibitor of the pro-apoptotic protein Bax. In addition hi-FGF-2 elicited sustained activation of total and nuclear extracellular signal regulated kinase (ERK 1/2) by an intracrine route, as it was not prevented by neutralizing anti-FGF-2 antibodies. Inhibition of the ERK 1/2 activating pathway by dominant negative upstream activating kinase, or by PD 98059, prevented chromatin compaction by hi-FGF-2. ERK 1/2 activation was not affected by the Bax-inhibiting peptide suggesting that it occurred upstream of mitochondrial involvement. We conclude that the hi-FGF-2-induced chromatin compaction and cell death requires its nuclear localization, intracrine ERK 1/2 activation and mitochondrial engagement.